Update to spec v0.9.1 (#597)

* Update to spec v0.9.0

* Update to v0.9.1

* Bump spec tags for v0.9.1

* Formatting, fix CI failures

* Resolve accidental KeyPair merge conflict

* Document new BeaconState functions

* Fix incorrect cache drops in `advance_caches`

* Update fork choice for v0.9.1

* Clean up some FIXMEs

* Fix a few docs/logs

.gitlab-ci.yml

@@ -4,7 +4,7 @@ default:
   image: 'sigp/lighthouse:latest'
   cache:
     paths:
-      - tests/ef_tests/*-v0.8.3.tar.gz
+      - tests/ef_tests/*-v0.9.1.tar.gz
 
 stages:
   - test
@@ -47,7 +47,7 @@ test-ef-fake-crypto:
     GIT_SUBMODULE_STRATEGY: normal
   script:
     - make make-ef-tests
-    - cargo test --manifest-path tests/ef_tests/Cargo.toml --release --features ef_tests fake_crypto
+    - cargo test --manifest-path tests/ef_tests/Cargo.toml --release --features ef_tests,fake_crypto
 
 documentation:
   stage: document

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -16,7 +16,7 @@ use ssz::Encode;
 use state_processing::per_block_processing::{
     errors::{
         AttestationValidationError, AttesterSlashingValidationError, DepositValidationError,
-        ExitValidationError, ProposerSlashingValidationError, TransferValidationError,
+        ExitValidationError, ProposerSlashingValidationError,
     },
     verify_attestation_for_state, VerifySignatures,
 };
@@ -218,6 +218,44 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         ReverseBlockRootIterator::new((head.beacon_block_root, head.beacon_block.slot), iter)
     }
 
+    /// Traverse backwards from `block_root` to find the block roots of its ancestors.
+    ///
+    /// ## Notes
+    ///
+    /// `slot` always decreases by `1`.
+    /// - Skipped slots contain the root of the closest prior
+    ///     non-skipped slot (identical to the way they are stored in `state.block_roots`) .
+    /// - Iterator returns `(Hash256, Slot)`.
+    /// - The provided `block_root` is included as the first item in the iterator.
+    pub fn rev_iter_block_roots_from(
+        &self,
+        block_root: Hash256,
+    ) -> Result<ReverseBlockRootIterator<T::EthSpec, T::Store>, Error> {
+        let block = self
+            .get_block(&block_root)?
+            .ok_or_else(|| Error::MissingBeaconBlock(block_root))?;
+        let state = self
+            .get_state(&block.state_root)?
+            .ok_or_else(|| Error::MissingBeaconState(block.state_root))?;
+        let iter = BlockRootsIterator::owned(self.store.clone(), state);
+        Ok(ReverseBlockRootIterator::new(
+            (block_root, block.slot),
+            iter,
+        ))
+    }
+
+    /// Traverse backwards from `block_root` to find the root of the ancestor block at `slot`.
+    pub fn get_ancestor_block_root(
+        &self,
+        block_root: Hash256,
+        slot: Slot,
+    ) -> Result<Option<Hash256>, Error> {
+        Ok(self
+            .rev_iter_block_roots_from(block_root)?
+            .find(|(_, ancestor_slot)| *ancestor_slot == slot)
+            .map(|(ancestor_block_root, _)| ancestor_block_root))
+    }
+
     /// Iterates across all `(state_root, slot)` pairs from the head of the chain (inclusive) to
     /// the earliest reachable ancestor (may or may not be genesis).
     ///
@@ -248,6 +286,18 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         Ok(self.store.get(block_root)?)
     }
 
+    /// Returns the state at the given root, if any.
+    ///
+    /// ## Errors
+    ///
+    /// May return a database error.
+    pub fn get_state(
+        &self,
+        state_root: &Hash256,
+    ) -> Result<Option<BeaconState<T::EthSpec>>, Error> {
+        Ok(self.store.get(state_root)?)
+    }
+
     /// Returns a `Checkpoint` representing the head block and state. Contains the "best block";
     /// the head of the canonical `BeaconChain`.
     ///
@@ -385,15 +435,15 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         }
 
         state
-            .get_beacon_proposer_index(slot, RelativeEpoch::Current, &self.spec)
+            .get_beacon_proposer_index(slot, &self.spec)
             .map_err(Into::into)
     }
 
-    /// Returns the attestation slot and shard for a given validator index.
+    /// Returns the attestation slot and committee index for a given validator index.
     ///
     /// Information is read from the current state, so only information from the present and prior
     /// epoch is available.
-    pub fn validator_attestation_slot_and_shard(
+    pub fn validator_attestation_slot_and_index(
         &self,
         validator_index: usize,
         epoch: Epoch,
@@ -420,25 +470,25 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         if let Some(attestation_duty) =
             state.get_attestation_duties(validator_index, RelativeEpoch::Current)?
         {
-            Ok(Some((attestation_duty.slot, attestation_duty.shard)))
+            Ok(Some((attestation_duty.slot, attestation_duty.index)))
         } else {
             Ok(None)
         }
     }
 
-    /// Produce an `AttestationData` that is valid for the given `slot` `shard`.
+    /// Produce an `AttestationData` that is valid for the given `slot`, `index`.
     ///
     /// Always attests to the canonical chain.
     pub fn produce_attestation_data(
         &self,
-        shard: u64,
         slot: Slot,
+        index: CommitteeIndex,
     ) -> Result<AttestationData, Error> {
         let state = self.state_at_slot(slot)?;
         let head = self.head();
 
         self.produce_attestation_data_for_block(
-            shard,
+            index,
             head.beacon_block_root,
             head.beacon_block.slot,
             &state,
@@ -451,7 +501,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// function should be used as it attests to the canonical chain.
     pub fn produce_attestation_data_for_block(
         &self,
-        shard: u64,
+        index: CommitteeIndex,
         head_block_root: Hash256,
         head_block_slot: Slot,
         state: &BeaconState<T::EthSpec>,
@@ -492,18 +542,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             root: target_root,
         };
 
-        let parent_crosslink = state.get_current_crosslink(shard)?;
-        let crosslink = Crosslink {
-            shard,
-            parent_root: Hash256::from_slice(&parent_crosslink.tree_hash_root()),
-            start_epoch: parent_crosslink.end_epoch,
-            end_epoch: std::cmp::min(
-                target.epoch,
-                parent_crosslink.end_epoch + self.spec.max_epochs_per_crosslink,
-            ),
-            data_root: Hash256::zero(),
-        };
-
         // Collect some metrics.
         metrics::inc_counter(&metrics::ATTESTATION_PRODUCTION_SUCCESSES);
         metrics::stop_timer(timer);
@@ -512,15 +550,16 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             self.log,
             "Produced beacon attestation data";
             "beacon_block_root" => format!("{}", head_block_root),
-            "shard" => shard,
+            "slot" => state.slot,
-            "slot" => state.slot
+            "index" => index
         );
 
         Ok(AttestationData {
+            slot: state.slot,
+            index,
             beacon_block_root: head_block_root,
             source: state.current_justified_checkpoint.clone(),
             target,
-            crosslink,
         })
     }
 
@@ -549,7 +588,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                         self.log,
                         "Beacon attestation imported";
                         "target_epoch" => attestation.data.target.epoch,
-                        "shard" => attestation.data.crosslink.shard,
+                        "index" => attestation.data.index,
                     );
                     let _ = self
                         .event_handler
@@ -668,16 +707,14 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
             state.build_committee_cache(RelativeEpoch::Current, &self.spec)?;
 
-            let attestation_slot = state.get_attestation_data_slot(&attestation.data)?;
-
             // Reject any attestation where the `state` loaded from `data.beacon_block_root`
             // has a higher slot than the attestation.
             //
             // Permitting this would allow for attesters to vote on _future_ slots.
-            if state.slot > attestation_slot {
+            if state.slot > attestation.data.slot {
                 Ok(AttestationProcessingOutcome::AttestsToFutureState {
                     state: state.slot,
-                    attestation: attestation_slot,
+                    attestation: attestation.data.slot,
                 })
             } else {
                 self.process_attestation_for_state_and_block(
@@ -776,6 +813,12 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
             Ok(AttestationProcessingOutcome::Invalid(e))
         } else {
+            // If the attestation is from the current or previous epoch, supply it to the fork
+            // choice. This is FMD GHOST.
+            let current_epoch = self.epoch()?;
+            if attestation.data.target.epoch == current_epoch
+                || attestation.data.target.epoch == current_epoch - 1
+            {
                 // Provide the attestation to fork choice, updating the validator latest messages but
                 // _without_ finding and updating the head.
                 if let Err(e) = self
@@ -791,6 +834,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     );
                     return Err(e.into());
                 }
+            }
 
             // Provide the valid attestation to op pool, which may choose to retain the
             // attestation for inclusion in a future block.
@@ -829,22 +873,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         }
     }
 
-    /// Accept some transfer and queue it for inclusion in an appropriate block.
-    pub fn process_transfer(&self, transfer: Transfer) -> Result<(), TransferValidationError> {
-        match self.wall_clock_state() {
-            Ok(state) => self.op_pool.insert_transfer(transfer, &state, &self.spec),
-            Err(e) => {
-                error!(
-                    &self.log,
-                    "Unable to process transfer";
-                    "error" => format!("{:?}", e),
-                    "reason" => "no state"
-                );
-                Ok(())
-            }
-        }
-    }
-
     /// Accept some proposer slashing and queue it for inclusion in an appropriate block.
     pub fn process_proposer_slashing(
         &self,
@@ -905,7 +933,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                         self.log,
                         "Beacon block imported";
                         "block_root" => format!("{:?}", block_root),
-                        "block_slot" => format!("{:?}", block_root),
+                        "block_slot" => format!("{:?}", block.slot.as_u64()),
                     );
                     let _ = self.event_handler.register(EventKind::BeaconBlockImported {
                         block_root: *block_root,
@@ -1115,7 +1143,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             metrics::start_timer(&metrics::BLOCK_PROCESSING_FORK_CHOICE_REGISTER);
 
         // Register the new block with the fork choice service.
-        if let Err(e) = self.fork_choice.process_block(&state, &block, block_root) {
+        if let Err(e) = self
+            .fork_choice
+            .process_block(self, &state, &block, block_root)
+        {
             error!(
                 self.log,
                 "Add block to fork choice failed";
@@ -1230,7 +1261,6 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     .deposits_for_block_inclusion(&state, &self.spec)?
                     .into(),
                 voluntary_exits: self.op_pool.get_voluntary_exits(&state, &self.spec).into(),
-                transfers: self.op_pool.get_transfers(&state, &self.spec).into(),
             },
         };
 

beacon_node/beacon_chain/src/builder.rs

@@ -231,7 +231,12 @@ where
             .genesis_block_root
             .ok_or_else(|| "fork_choice_backend requires a genesis_block_root")?;
 
-        self.fork_choice = Some(ForkChoice::new(store, backend, genesis_block_root));
+        self.fork_choice = Some(ForkChoice::new(
+            store,
+            backend,
+            genesis_block_root,
+            self.spec.genesis_slot,
+        ));
 
         Ok(self)
     }

beacon_node/beacon_chain/src/errors.rs

@@ -18,7 +18,6 @@ macro_rules! easy_from_to {
 #[derive(Debug, PartialEq)]
 pub enum BeaconChainError {
     InsufficientValidators,
-    BadRecentBlockRoots,
     UnableToReadSlot,
     RevertedFinalizedEpoch {
         previous_epoch: Epoch,

beacon_node/beacon_chain/src/eth1_chain.rs

@@ -487,7 +487,7 @@ mod test {
             let keypair = generate_deterministic_keypair(i as usize);
             let mut builder =
                 TestingDepositBuilder::new(keypair.pk.clone(), spec.max_effective_balance);
-            builder.sign(&DepositTestTask::Valid, &keypair, spec);
+            builder.sign(DepositTestTask::Valid, &keypair, spec);
             let deposit_data = builder.build().data;
 
             DepositLog {

beacon_node/beacon_chain/src/fork_choice.rs

@@ -1,10 +1,11 @@
-use crate::{metrics, BeaconChain, BeaconChainTypes};
+use crate::{errors::BeaconChainError, metrics, BeaconChain, BeaconChainTypes};
 use lmd_ghost::LmdGhost;
-use state_processing::common::get_attesting_indices;
+use parking_lot::RwLock;
+use state_processing::{common::get_attesting_indices, per_slot_processing};
 use std::sync::Arc;
 use store::{Error as StoreError, Store};
 use types::{
-    Attestation, BeaconBlock, BeaconState, BeaconStateError, Epoch, EthSpec, Hash256, Slot,
+    Attestation, BeaconBlock, BeaconState, BeaconStateError, Checkpoint, EthSpec, Hash256, Slot,
 };
 
 type Result<T> = std::result::Result<T, Error>;
@@ -16,6 +17,7 @@ pub enum Error {
     BackendError(String),
     BeaconStateError(BeaconStateError),
     StoreError(StoreError),
+    BeaconChainError(Box<BeaconChainError>),
 }
 
 pub struct ForkChoice<T: BeaconChainTypes> {
@@ -26,6 +28,10 @@ pub struct ForkChoice<T: BeaconChainTypes> {
     /// Does not necessarily need to be the _actual_ genesis, it suffices to be the finalized root
     /// whenever the struct was instantiated.
     genesis_block_root: Hash256,
+    /// The fork choice rule's current view of the justified checkpoint.
+    justified_checkpoint: RwLock<Checkpoint>,
+    /// The best justified checkpoint we've seen, which may be ahead of `justified_checkpoint`.
+    best_justified_checkpoint: RwLock<Checkpoint>,
 }
 
 impl<T: BeaconChainTypes> ForkChoice<T> {
@@ -33,39 +39,91 @@ impl<T: BeaconChainTypes> ForkChoice<T> {
     ///
     /// "Genesis" does not necessarily need to be the absolute genesis, it can be some finalized
     /// block.
-    pub fn new(store: Arc<T::Store>, backend: T::LmdGhost, genesis_block_root: Hash256) -> Self {
+    pub fn new(
+        store: Arc<T::Store>,
+        backend: T::LmdGhost,
+        genesis_block_root: Hash256,
+        genesis_slot: Slot,
+    ) -> Self {
+        let justified_checkpoint = Checkpoint {
+            epoch: genesis_slot.epoch(T::EthSpec::slots_per_epoch()),
+            root: genesis_block_root,
+        };
         Self {
             store: store.clone(),
             backend,
             genesis_block_root,
+            justified_checkpoint: RwLock::new(justified_checkpoint.clone()),
+            best_justified_checkpoint: RwLock::new(justified_checkpoint),
         }
     }
 
+    /// Determine whether the fork choice's view of the justified checkpoint should be updated.
+    ///
+    /// To prevent the bouncing attack, an update is allowed only in these conditions:
+    ///
+    /// * We're in the first SAFE_SLOTS_TO_UPDATE_JUSTIFIED slots of the epoch, or
+    /// * The new justified checkpoint is a descendant of the current justified checkpoint
+    fn should_update_justified_checkpoint(
+        &self,
+        chain: &BeaconChain<T>,
+        new_justified_checkpoint: &Checkpoint,
+    ) -> Result<bool> {
+        if Self::compute_slots_since_epoch_start(chain.slot()?)
+            < chain.spec.safe_slots_to_update_justified
+        {
+            return Ok(true);
+        }
+
+        let justified_checkpoint = self.justified_checkpoint.read().clone();
+
+        let current_justified_block = chain
+            .get_block(&justified_checkpoint.root)?
+            .ok_or_else(|| Error::MissingBlock(justified_checkpoint.root))?;
+
+        let new_justified_block = chain
+            .get_block(&new_justified_checkpoint.root)?
+            .ok_or_else(|| Error::MissingBlock(new_justified_checkpoint.root))?;
+
+        let slots_per_epoch = T::EthSpec::slots_per_epoch();
+
+        Ok(
+            new_justified_block.slot > justified_checkpoint.epoch.start_slot(slots_per_epoch)
+                && chain.get_ancestor_block_root(
+                    new_justified_checkpoint.root,
+                    current_justified_block.slot,
+                )? == Some(justified_checkpoint.root),
+        )
+    }
+
+    /// Calculate how far `slot` lies from the start of its epoch.
+    fn compute_slots_since_epoch_start(slot: Slot) -> u64 {
+        let slots_per_epoch = T::EthSpec::slots_per_epoch();
+        (slot - slot.epoch(slots_per_epoch).start_slot(slots_per_epoch)).as_u64()
+    }
+
+    /// Run the fork choice rule to determine the head.
     pub fn find_head(&self, chain: &BeaconChain<T>) -> Result<Hash256> {
         let timer = metrics::start_timer(&metrics::FORK_CHOICE_FIND_HEAD_TIMES);
 
-        let start_slot = |epoch: Epoch| epoch.start_slot(T::EthSpec::slots_per_epoch());
-
-        // From the specification:
-        //
-        // Let justified_head be the descendant of finalized_head with the highest epoch that has
-        // been justified for at least 1 epoch ... If no such descendant exists,
-        // set justified_head to finalized_head.
         let (start_state, start_block_root, start_block_slot) = {
-            let state = &chain.head().beacon_state;
+            // Check if we should update our view of the justified checkpoint.
+            // Doing this check here should be quasi-equivalent to the update in the `on_tick`
+            // function of the spec, so long as `find_head` is called at least once during the first
+            // SAFE_SLOTS_TO_UPDATE_JUSTIFIED slots.
+            let best_justified_checkpoint = self.best_justified_checkpoint.read();
+            if self.should_update_justified_checkpoint(chain, &best_justified_checkpoint)? {
+                *self.justified_checkpoint.write() = best_justified_checkpoint.clone();
+            }
 
-            let (block_root, block_slot) =
+            let current_justified_checkpoint = self.justified_checkpoint.read().clone();
-                if state.current_epoch() + 1 > state.current_justified_checkpoint.epoch {
+
-                    (
+            let (block_root, block_justified_slot) = (
-                        state.current_justified_checkpoint.root,
+                current_justified_checkpoint.root,
-                        start_slot(state.current_justified_checkpoint.epoch),
+                current_justified_checkpoint
-                    )
+                    .epoch
-                } else {
+                    .start_slot(T::EthSpec::slots_per_epoch()),
-                    (
+            );
-                        state.finalized_checkpoint.root,
-                        start_slot(state.finalized_checkpoint.epoch),
-                    )
-                };
 
             let block = chain
                 .store
@@ -79,12 +137,17 @@ impl<T: BeaconChainTypes> ForkChoice<T> {
                 block_root
             };
 
-            let state = chain
+            let mut state = chain
-                .store
+                .get_state(&block.state_root)?
-                .get::<BeaconState<T::EthSpec>>(&block.state_root)?
                 .ok_or_else(|| Error::MissingState(block.state_root))?;
 
-            (state, block_root, block_slot)
+            // Fast-forward the state to the start slot of the epoch where it was justified.
+            for _ in block.slot.as_u64()..block_justified_slot.as_u64() {
+                per_slot_processing(&mut state, &chain.spec)
+                    .map_err(|e| BeaconChainError::SlotProcessingError(e))?
+            }
+
+            (state, block_root, block_justified_slot)
         };
 
         // A function that returns the weight for some validator index.
@@ -107,10 +170,11 @@ impl<T: BeaconChainTypes> ForkChoice<T> {
 
     /// Process all attestations in the given `block`.
     ///
-    /// Assumes the block (and therefore it's attestations) are valid. It is a logic error to
+    /// Assumes the block (and therefore its attestations) are valid. It is a logic error to
     /// provide an invalid block.
     pub fn process_block(
         &self,
+        chain: &BeaconChain<T>,
         state: &BeaconState<T::EthSpec>,
         block: &BeaconBlock<T::EthSpec>,
         block_root: Hash256,
@@ -133,6 +197,16 @@ impl<T: BeaconChainTypes> ForkChoice<T> {
             }
         }
 
+        // Check if we should update our view of the justified checkpoint
+        if state.current_justified_checkpoint.epoch > self.justified_checkpoint.read().epoch {
+            *self.best_justified_checkpoint.write() = state.current_justified_checkpoint.clone();
+            if self
+                .should_update_justified_checkpoint(chain, &state.current_justified_checkpoint)?
+            {
+                *self.justified_checkpoint.write() = state.current_justified_checkpoint.clone();
+            }
+        }
+
         // This does not apply a vote to the block, it just makes fork choice aware of the block so
         // it can still be identified as the head even if it doesn't have any votes.
         //
@@ -224,6 +298,12 @@ impl From<BeaconStateError> for Error {
     }
 }
 
+impl From<BeaconChainError> for Error {
+    fn from(e: BeaconChainError) -> Error {
+        Error::BeaconChainError(Box::new(e))
+    }
+}
+
 impl From<StoreError> for Error {
     fn from(e: StoreError) -> Error {
         Error::StoreError(e)

beacon_node/beacon_chain/src/lib.rs

@@ -28,7 +28,7 @@ pub use parking_lot;
 pub use slot_clock;
 pub use state_processing::per_block_processing::errors::{
     AttestationValidationError, AttesterSlashingValidationError, DepositValidationError,
-    ExitValidationError, ProposerSlashingValidationError, TransferValidationError,
+    ExitValidationError, ProposerSlashingValidationError,
 };
 pub use store;
 pub use types;

beacon_node/beacon_chain/src/metrics.rs

@@ -172,8 +172,6 @@ lazy_static! {
         try_create_int_gauge("beacon_head_state_finalized_root", "Finalized root at the head of the chain");
     pub static ref HEAD_STATE_FINALIZED_EPOCH: Result<IntGauge> =
         try_create_int_gauge("beacon_head_state_finalized_epoch", "Finalized epoch at the head of the chain");
-    pub static ref HEAD_STATE_SHARDS: Result<IntGauge> =
-        try_create_int_gauge("beacon_head_state_shard_total", "Count of shards in the beacon chain");
     pub static ref HEAD_STATE_TOTAL_VALIDATORS: Result<IntGauge> =
         try_create_int_gauge("beacon_head_state_total_validators_total", "Count of validators at the head of the chain");
     pub static ref HEAD_STATE_ACTIVE_VALIDATORS: Result<IntGauge> =
@@ -226,7 +224,6 @@ fn scrape_head_state<T: BeaconChainTypes>(state: &BeaconState<T::EthSpec>, state
         &HEAD_STATE_FINALIZED_EPOCH,
         state.finalized_checkpoint.epoch,
     );
-    set_gauge_by_usize(&HEAD_STATE_SHARDS, state.previous_crosslinks.len());
     set_gauge_by_usize(&HEAD_STATE_TOTAL_VALIDATORS, state.validators.len());
     set_gauge_by_u64(&HEAD_STATE_VALIDATOR_BALANCES, state.balances.iter().sum());
     set_gauge_by_usize(

beacon_node/beacon_chain/src/test_utils.rs

@@ -15,9 +15,8 @@ use std::time::Duration;
 use store::MemoryStore;
 use tree_hash::{SignedRoot, TreeHash};
 use types::{
-    AggregateSignature, Attestation, AttestationDataAndCustodyBit, BeaconBlock, BeaconState,
+    AggregateSignature, Attestation, BeaconBlock, BeaconState, BitList, ChainSpec, Domain, EthSpec,
-    BitList, ChainSpec, Domain, EthSpec, Hash256, Keypair, RelativeEpoch, SecretKey, Signature,
+    Hash256, Keypair, SecretKey, Signature, Slot,
-    Slot,
 };
 
 pub use crate::persisted_beacon_chain::{PersistedBeaconChain, BEACON_CHAIN_DB_KEY};
@@ -203,7 +202,7 @@ impl<E: EthSpec> BeaconChainHarness<HarnessType<E>> {
                 .block_proposer(slot)
                 .expect("should get block proposer from chain"),
             _ => state
-                .get_beacon_proposer_index(slot, RelativeEpoch::Current, &self.spec)
+                .get_beacon_proposer_index(slot, &self.spec)
                 .expect("should get block proposer from state"),
         };
 
@@ -280,13 +279,13 @@ impl<E: EthSpec> BeaconChainHarness<HarnessType<E>> {
         let mut attestations = vec![];
 
         state
-            .get_crosslink_committees_at_slot(state.slot)
+            .get_beacon_committees_at_slot(state.slot)
             .expect("should get committees")
             .iter()
-            .for_each(|cc| {
+            .for_each(|bc| {
-                let committee_size = cc.committee.len();
+                let committee_size = bc.committee.len();
 
-                let mut local_attestations: Vec<Attestation<E>> = cc
+                let mut local_attestations: Vec<Attestation<E>> = bc
                     .committee
                     .par_iter()
                     .enumerate()
@@ -297,7 +296,7 @@ impl<E: EthSpec> BeaconChainHarness<HarnessType<E>> {
                             let data = self
                                 .chain
                                 .produce_attestation_data_for_block(
-                                    cc.shard,
+                                    bc.index,
                                     head_block_root,
                                     head_block_slot,
                                     state,
@@ -309,18 +308,15 @@ impl<E: EthSpec> BeaconChainHarness<HarnessType<E>> {
                             aggregation_bits
                                 .set(i, true)
                                 .expect("should be able to set aggregation bits");
-                            let custody_bits = BitList::with_capacity(committee_size)
-                                .expect("should make custody bits");
 
                             let signature = {
-                                let message = AttestationDataAndCustodyBit {
+                                let message = data.tree_hash_root();
-                                    data: data.clone(),
-                                    custody_bit: false,
-                                }
-                                .tree_hash_root();
 
-                                let domain =
+                                let domain = spec.get_domain(
-                                    spec.get_domain(data.target.epoch, Domain::Attestation, fork);
+                                    data.target.epoch,
+                                    Domain::BeaconAttester,
+                                    fork,
+                                );
 
                                 let mut agg_sig = AggregateSignature::new();
                                 agg_sig.add(&Signature::new(
@@ -335,7 +331,6 @@ impl<E: EthSpec> BeaconChainHarness<HarnessType<E>> {
                             let attestation = Attestation {
                                 aggregation_bits,
                                 data,
-                                custody_bits,
                                 signature,
                             };
 

beacon_node/rest_api/src/validator.rs

@@ -17,7 +17,7 @@ use std::sync::Arc;
 use tokio;
 use tokio::sync::mpsc;
 use types::beacon_state::EthSpec;
-use types::{Attestation, BeaconBlock, BitList, Epoch, RelativeEpoch, Shard, Slot};
+use types::{Attestation, BeaconBlock, BitList, CommitteeIndex, Epoch, RelativeEpoch, Slot};
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct ValidatorDuty {
@@ -25,8 +25,8 @@ pub struct ValidatorDuty {
     pub validator_pubkey: String,
     /// The slot at which the validator must attest.
     pub attestation_slot: Option<Slot>,
-    /// The shard in which the validator must attest.
+    /// The index of the committee within `slot` of which the validator is a member.
-    pub attestation_shard: Option<Shard>,
+    pub attestation_committee_index: Option<CommitteeIndex>,
     /// The slot in which a validator must propose a block, or `null` if block production is not required.
     pub block_proposal_slot: Option<Slot>,
 }
@@ -36,7 +36,7 @@ impl ValidatorDuty {
         ValidatorDuty {
             validator_pubkey: "".to_string(),
             attestation_slot: None,
-            attestation_shard: None,
+            attestation_committee_index: None,
             block_proposal_slot: None,
         }
     }
@@ -90,7 +90,7 @@ pub fn get_validator_duties<T: BeaconChainTypes + 'static>(req: Request<Body>) -
         .slot_iter(T::EthSpec::slots_per_epoch())
         .map(|slot| {
             head_state
-                .get_beacon_proposer_index(slot, relative_epoch, &beacon_chain.spec)
+                .get_beacon_proposer_index(slot, &beacon_chain.spec)
                 .map_err(|e| {
                     ApiError::ServerError(format!(
                         "Unable to get proposer index for validator: {:?}",
@@ -125,7 +125,7 @@ pub fn get_validator_duties<T: BeaconChainTypes + 'static>(req: Request<Body>) -
         match head_state.get_attestation_duties(val_index, relative_epoch) {
             Ok(Some(d)) => {
                 duty.attestation_slot = Some(d.slot);
-                duty.attestation_shard = Some(d.shard);
+                duty.attestation_committee_index = Some(d.index);
             }
             Ok(None) => {}
             Err(e) => {
@@ -311,7 +311,7 @@ pub fn get_new_attestation<T: BeaconChainTypes + 'static>(req: Request<Body>) ->
     let mut aggregation_bits = BitList::with_capacity(val_duty.committee_len)
         .expect("An empty BitList should always be created, or we have bigger problems.");
     aggregation_bits
-        .set(val_duty.committee_index, poc_bit)
+        .set(val_duty.committee_position, poc_bit)
         .map_err(|e| {
             ApiError::ServerError(format!(
                 "Unable to set aggregation bits for the attestation: {:?}",
@@ -334,21 +334,19 @@ pub fn get_new_attestation<T: BeaconChainTypes + 'static>(req: Request<Body>) ->
         return Err(ApiError::BadRequest(format!("Attestation data can only be requested for the current slot ({:?}), not your requested slot ({:?})", current_slot, requested_slot)));
     }
 
-    let shard = query
+    let index = query
-        .first_of(&["shard"])
+        .first_of(&["index"])
         .map(|(_key, value)| value)?
         .parse::<u64>()
-        .map_err(|e| ApiError::BadRequest(format!("Shard is not a valid u64 value: {:?}", e)))?;
+        .map_err(|e| ApiError::BadRequest(format!("Index is not a valid u64 value: {:?}", e)))?;
 
     let attestation_data = beacon_chain
-        .produce_attestation_data(shard, current_slot.into())
+        .produce_attestation_data(current_slot.into(), index)
         .map_err(|e| ApiError::ServerError(format!("Could not produce an attestation: {:?}", e)))?;
 
     let attestation: Attestation<T::EthSpec> = Attestation {
         aggregation_bits,
         data: attestation_data,
-        custody_bits: BitList::with_capacity(val_duty.committee_len)
-            .expect("Should be able to create an empty BitList for the custody bits."),
         signature: AggregateSignature::new(),
     };
 

beacon_node/rpc/src/attestation.rs

@@ -48,11 +48,12 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
         );
 
         // Then get the AttestationData from the beacon chain
+        // NOTE(v0.9): shard is incorrectly named, all this should be deleted
         let shard = req.get_shard();
         let slot_requested = req.get_slot();
         let attestation_data = match self
             .chain
-            .produce_attestation_data(shard, Slot::from(slot_requested))
+            .produce_attestation_data(Slot::from(slot_requested), shard)
         {
             Ok(v) => v,
             Err(e) => {
@@ -115,7 +116,7 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
                     self.log,
                     "Valid attestation from RPC";
                     "target_epoch" => attestation.data.target.epoch,
-                    "shard" => attestation.data.crosslink.shard,
+                    "index" => attestation.data.index,
                 );
 
                 // valid attestation, propagate to the network

beacon_node/rpc/src/validator.rs

@@ -66,9 +66,7 @@ impl<T: BeaconChainTypes> ValidatorService for ValidatorServiceInstance<T> {
 
         let validator_proposers: Result<Vec<usize>, _> = epoch
             .slot_iter(T::EthSpec::slots_per_epoch())
-            .map(|slot| {
+            .map(|slot| state.get_beacon_proposer_index(slot, &self.chain.spec))
-                state.get_beacon_proposer_index(slot, RelativeEpoch::Current, &self.chain.spec)
-            })
             .collect();
         let validator_proposers = match validator_proposers {
             Ok(v) => v,
@@ -170,9 +168,9 @@ impl<T: BeaconChainTypes> ValidatorService for ValidatorServiceInstance<T> {
                 duty.set_none(false)
             }
 
-            duty.set_committee_index(attestation_duties.committee_index as u64);
+            duty.set_committee_index(attestation_duties.committee_position as u64);
             duty.set_attestation_slot(attestation_duties.slot.as_u64());
-            duty.set_attestation_shard(attestation_duties.shard);
+            duty.set_attestation_shard(attestation_duties.index);
             duty.set_committee_len(attestation_duties.committee_len as u64);
 
             active_validator.set_duty(duty);

book/src/simple-testnet.md

@@ -35,7 +35,7 @@ $ lighthouse bn testnet -f recent 8
 In a new terminal window, start the validator client with:
 
 ```bash
-$ lighthouse bn testnet -b insecure 0 8
+$ lighthouse vc testnet -b insecure 0 8
 ```
 
 > Notes:

eth2/lmd_ghost/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2018"
 parking_lot = "0.9.0"
 store = { path = "../../beacon_node/store" }
 types = { path = "../types" }
+itertools = "0.8.1"
 
 [dev-dependencies]
 criterion = "0.3.0"

eth2/lmd_ghost/src/lib.rs

@@ -49,7 +49,7 @@ pub trait LmdGhost<S: Store, E: EthSpec>: Send + Sync {
 
     /// Runs an integrity verification function on fork choice algorithm.
     ///
-    /// Returns `Ok(())` if the underlying fork choice has maintained it's integrity,
+    /// Returns `Ok(())` if the underlying fork choice has maintained its integrity,
     /// `Err(description)` otherwise.
     fn verify_integrity(&self) -> Result<()>;
 }

eth2/lmd_ghost/src/reduced_tree.rs

@@ -4,6 +4,7 @@
 //!
 //! This implementation is incomplete and has known bugs. Do not use in production.
 use super::{LmdGhost, Result as SuperResult};
+use itertools::Itertools;
 use parking_lot::RwLock;
 use std::collections::HashMap;
 use std::fmt;
@@ -20,6 +21,7 @@ pub enum Error {
     MissingBlock(Hash256),
     MissingState(Hash256),
     MissingChild(Hash256),
+    MissingSuccessor(Hash256, Hash256),
     NotInTree(Hash256),
     NoCommonAncestor((Hash256, Hash256)),
     StoreError(StoreError),
@@ -177,8 +179,8 @@ where
         if current_hash != subtree_hash {
             let children = self.get_node(current_hash)?.children.clone();
 
-            for child_hash in children {
+            for child in children {
-                self.retain_subtree(child_hash, subtree_hash)?;
+                self.retain_subtree(child.hash, subtree_hash)?;
             }
 
             self.nodes.remove(&current_hash);
@@ -239,7 +241,7 @@ where
         let _root_weight = self.update_weight(start_block_root, weight_fn)?;
 
         let start_node = self.get_node(start_block_root)?;
-        let head_node = self.find_head_from(start_node)?;
+        let head_node = self.find_head_from(start_node, start_block_slot)?;
 
         Ok(head_node.block_hash)
     }
@@ -251,31 +253,32 @@ where
         }
     }
 
-    fn find_head_from<'a>(&'a self, start_node: &'a Node) -> Result<&'a Node> {
+    // Corresponds to the loop in `get_head` in the spec.
-        if start_node.does_not_have_children() {
+    fn find_head_from<'a>(
-            Ok(start_node)
+        &'a self,
-        } else {
+        start_node: &'a Node,
+        justified_slot: Slot,
+    ) -> Result<&'a Node> {
         let children = start_node
             .children
             .iter()
-                .map(|hash| self.get_node(*hash))
+            // This check is primarily for the first iteration, where we must ensure that
+            // we only consider votes that were made after the last justified checkpoint.
+            .filter(|c| c.successor_slot > justified_slot)
+            .map(|c| self.get_node(c.hash))
             .collect::<Result<Vec<&Node>>>()?;
 
-            // TODO: check if `max_by` is `O(n^2)`.
+        if children.is_empty() {
+            Ok(start_node)
+        } else {
             let best_child = children
                 .iter()
-                .max_by(|a, b| {
+                .max_by_key(|child| (child.weight, child.block_hash))
-                    if a.weight != b.weight {
-                        a.weight.cmp(&b.weight)
-                    } else {
-                        a.block_hash.cmp(&b.block_hash)
-                    }
-                })
                 // There can only be no maximum if there are no children. This code path is guarded
                 // against that condition.
                 .expect("There must be a maximally weighted node.");
 
-            self.find_head_from(best_child)
+            self.find_head_from(best_child, justified_slot)
         }
     }
 
@@ -288,8 +291,8 @@ where
 
             let mut weight = 0;
 
-            for &child in &node.children {
+            for child in &node.children {
-                weight += self.update_weight(child, weight_fn)?;
+                weight += self.update_weight(child.hash, weight_fn)?;
             }
 
             for &voter in &node.voters {
@@ -323,13 +326,13 @@ where
                         //
                         // Load the child of the node and set it's parent to be the parent of this
                         // node (viz., graft the node's child to the node's parent)
-                        let child = self.get_mut_node(node.children[0])?;
+                        let child = self.get_mut_node(node.children[0].hash)?;
                         child.parent_hash = node.parent_hash;
 
                         // Graft the parent of this node to it's child.
                         if let Some(parent_hash) = node.parent_hash {
                             let parent = self.get_mut_node(parent_hash)?;
-                            parent.replace_child(node.block_hash, node.children[0])?;
+                            parent.replace_child_hash(node.block_hash, node.children[0].hash)?;
                         }
 
                         self.nodes.remove(&vote.hash);
@@ -376,15 +379,16 @@ where
                 let node = node.clone();
 
                 if let Some(parent_hash) = node.parent_hash {
-                    if (node.children.len() == 1) && !node.has_votes() {
+                    if node.children.len() == 1 && !node.has_votes() {
-                        let child_hash = node.children[0];
+                        let child = &node.children[0];
 
                         // Graft the single descendant `node` to the `parent` of node.
-                        self.get_mut_node(child_hash)?.parent_hash = Some(parent_hash);
+                        self.get_mut_node(child.hash)?.parent_hash = Some(parent_hash);
 
                         // Detach `node` from `parent`, replacing it with `child`.
+                        // Preserve the parent's direct descendant slot.
                         self.get_mut_node(parent_hash)?
-                            .replace_child(hash, child_hash)?;
+                            .replace_child_hash(hash, child.hash)?;
 
                         true
                     } else {
@@ -442,6 +446,40 @@ where
         Ok(())
     }
 
+    /// Find the direct successor block of `ancestor` if `descendant` is a descendant.
+    fn find_ancestor_successor_opt(
+        &self,
+        ancestor: Hash256,
+        descendant: Hash256,
+    ) -> Result<Option<Hash256>> {
+        Ok(std::iter::once(descendant)
+            .chain(
+                self.iter_ancestors(descendant)?
+                    .take_while(|(_, slot)| *slot >= self.root_slot())
+                    .map(|(block_hash, _)| block_hash),
+            )
+            .tuple_windows()
+            .find_map(|(successor, block_hash)| {
+                if block_hash == ancestor {
+                    Some(successor)
+                } else {
+                    None
+                }
+            }))
+    }
+
+    /// Same as `find_ancestor_successor_opt` but will return an error instead of an option.
+    fn find_ancestor_successor(&self, ancestor: Hash256, descendant: Hash256) -> Result<Hash256> {
+        self.find_ancestor_successor_opt(ancestor, descendant)?
+            .ok_or_else(|| Error::MissingSuccessor(ancestor, descendant))
+    }
+
+    /// Look up the successor of the given `ancestor`, returning the slot of that block.
+    fn find_ancestor_successor_slot(&self, ancestor: Hash256, descendant: Hash256) -> Result<Slot> {
+        let successor_hash = self.find_ancestor_successor(ancestor, descendant)?;
+        Ok(self.get_block(successor_hash)?.slot)
+    }
+
     /// Add `node` to the reduced tree, returning an error if `node` is not rooted in the tree.
     fn add_node(&mut self, mut node: Node) -> Result<()> {
         // Find the highest (by slot) ancestor of the given node in the reduced tree.
@@ -460,7 +498,9 @@ where
         //    `node` to it.
         // 3. Graft `node` to an existing node.
         if !prev_in_tree.children.is_empty() {
-            for &child_hash in &prev_in_tree.children {
+            for child_link in &prev_in_tree.children {
+                let child_hash = child_link.hash;
+
                 // 1. Graft the new node between two existing nodes.
                 //
                 // If `node` is a descendant of `prev_in_tree` but an ancestor of a child connected to
@@ -468,19 +508,20 @@ where
                 //
                 // This means that `node` can be grafted between `prev_in_tree` and the child that is a
                 // descendant of both `node` and `prev_in_tree`.
-                if self
+                if let Some(successor) =
-                    .iter_ancestors(child_hash)?
+                    self.find_ancestor_successor_opt(node.block_hash, child_hash)?
-                    .take_while(|(_, slot)| *slot >= self.root_slot())
-                    .any(|(ancestor, _slot)| ancestor == node.block_hash)
                 {
                     let child = self.get_mut_node(child_hash)?;
 
                     // Graft `child` to `node`.
                     child.parent_hash = Some(node.block_hash);
                     // Graft `node` to `child`.
-                    node.children.push(child_hash);
+                    node.children.push(ChildLink {
+                        hash: child_hash,
+                        successor_slot: self.get_block(successor)?.slot,
+                    });
                     // Detach `child` from `prev_in_tree`, replacing it with `node`.
-                    prev_in_tree.replace_child(child_hash, node.block_hash)?;
+                    prev_in_tree.replace_child_hash(child_hash, node.block_hash)?;
                     // Graft `node` to `prev_in_tree`.
                     node.parent_hash = Some(prev_in_tree.block_hash);
 
@@ -495,7 +536,8 @@ where
             // any of the children of `prev_in_tree`, we know that `node` is on a different fork to
             // all of the children of `prev_in_tree`.
             if node.parent_hash.is_none() {
-                for &child_hash in &prev_in_tree.children {
+                for child_link in &prev_in_tree.children {
+                    let child_hash = child_link.hash;
                     // Find the highest (by slot) common ancestor between `node` and `child`.
                     //
                     // The common ancestor is the last block before `node` and `child` forked.
@@ -506,24 +548,37 @@ where
                     // must add this new block into the tree (because it is a decision node
                     // between two forks).
                     if ancestor_hash != prev_in_tree.block_hash {
-                        let child = self.get_mut_node(child_hash)?;
-
                         // Create a new `common_ancestor` node which represents the `ancestor_hash`
                         // block, has `prev_in_tree` as the parent and has both `node` and `child`
                         // as children.
                         let common_ancestor = Node {
                             block_hash: ancestor_hash,
                             parent_hash: Some(prev_in_tree.block_hash),
-                            children: vec![node.block_hash, child_hash],
+                            children: vec![
+                                ChildLink {
+                                    hash: node.block_hash,
+                                    successor_slot: self.find_ancestor_successor_slot(
+                                        ancestor_hash,
+                                        node.block_hash,
+                                    )?,
+                                },
+                                ChildLink {
+                                    hash: child_hash,
+                                    successor_slot: self
+                                        .find_ancestor_successor_slot(ancestor_hash, child_hash)?,
+                                },
+                            ],
                             ..Node::default()
                         };
 
+                        let child = self.get_mut_node(child_hash)?;
+
                         // Graft `child` and `node` to `common_ancestor`.
                         child.parent_hash = Some(common_ancestor.block_hash);
                         node.parent_hash = Some(common_ancestor.block_hash);
 
                         // Detach `child` from `prev_in_tree`, replacing it with `common_ancestor`.
-                        prev_in_tree.replace_child(child_hash, common_ancestor.block_hash)?;
+                        prev_in_tree.replace_child_hash(child_hash, common_ancestor.block_hash)?;
 
                         // Store the new `common_ancestor` node.
                         self.nodes
@@ -540,7 +595,11 @@ where
             //
             // Graft `node` to `prev_in_tree` and `prev_in_tree` to `node`
             node.parent_hash = Some(prev_in_tree.block_hash);
-            prev_in_tree.children.push(node.block_hash);
+            prev_in_tree.children.push(ChildLink {
+                hash: node.block_hash,
+                successor_slot: self
+                    .find_ancestor_successor_slot(prev_in_tree.block_hash, node.block_hash)?,
+            });
         }
 
         // Update `prev_in_tree`. A mutable reference was not maintained to satisfy the borrow
@@ -655,7 +714,17 @@ where
 
                 node.children
                     .iter()
-                    .map(|child| verify_node_exists(*child, "child_must_exist".to_string()))
+                    .map(|child| {
+                        verify_node_exists(child.hash, "child_must_exist".to_string())?;
+
+                        if self.find_ancestor_successor_slot(node.block_hash, child.hash)?
+                            == child.successor_slot
+                        {
+                            Ok(())
+                        } else {
+                            Err("successor slot on child link is incorrect".to_string())
+                        }
+                    })
                     .collect::<std::result::Result<(), String>>()?;
 
                 verify_node_exists(node.block_hash, "block hash must exist".to_string())?;
@@ -698,25 +767,35 @@ where
 
 #[derive(Default, Clone, Debug)]
 pub struct Node {
+    /// Hash of the parent node in the reduced tree (not necessarily parent block).
     pub parent_hash: Option<Hash256>,
-    pub children: Vec<Hash256>,
+    pub children: Vec<ChildLink>,
     pub weight: u64,
     pub block_hash: Hash256,
     pub voters: Vec<usize>,
 }
 
-impl Node {
+#[derive(Default, Clone, Debug)]
-    pub fn does_not_have_children(&self) -> bool {
+pub struct ChildLink {
-        self.children.is_empty()
+    /// Hash of the child block (may not be a direct descendant).
-    }
+    pub hash: Hash256,
+    /// Slot of the block which is a direct descendant on the chain leading to `hash`.
+    ///
+    /// Node <--- Successor <--- ... <--- Child
+    pub successor_slot: Slot,
+}
 
-    pub fn replace_child(&mut self, old: Hash256, new: Hash256) -> Result<()> {
+impl Node {
+    /// Replace a child with a new child, whilst preserving the successor slot.
+    ///
+    /// The new child should have the same ancestor successor block as the old one.
+    pub fn replace_child_hash(&mut self, old: Hash256, new: Hash256) -> Result<()> {
         let i = self
             .children
             .iter()
-            .position(|&c| c == old)
+            .position(|c| c.hash == old)
             .ok_or_else(|| Error::MissingChild(old))?;
-        self.children[i] = new;
+        self.children[i].hash = new;
 
         Ok(())
     }
@@ -725,7 +804,7 @@ impl Node {
         let i = self
             .children
             .iter()
-            .position(|&c| c == child)
+            .position(|c| c.hash == child)
             .ok_or_else(|| Error::MissingChild(child))?;
 
         self.children.remove(i);

eth2/lmd_ghost/tests/test.rs

@@ -45,7 +45,9 @@ struct ForkedHarness {
     pub genesis_block: BeaconBlock<TestEthSpec>,
     pub honest_head: RootAndSlot,
     pub faulty_head: RootAndSlot,
+    /// Honest roots in reverse order (slot high to low)
     pub honest_roots: Vec<RootAndSlot>,
+    /// Faulty roots in reverse order (slot high to low)
     pub faulty_roots: Vec<RootAndSlot>,
 }
 
@@ -225,7 +227,7 @@ fn single_voter_persistent_instance_reverse_order() {
         "New tree should have integrity"
     );
 
-    for (root, slot) in harness.honest_roots.iter().rev() {
+    for (root, slot) in &harness.honest_roots {
         lmd.process_attestation(0, *root, *slot)
             .expect("fork choice should accept attestations to honest roots in reverse");
 
@@ -237,11 +239,15 @@ fn single_voter_persistent_instance_reverse_order() {
     }
 
     // The honest head should be selected.
-    let (head_root, head_slot) = harness.honest_roots.first().unwrap();
+    let (head_root, _) = harness.honest_roots.first().unwrap();
-    let (finalized_root, _) = harness.honest_roots.last().unwrap();
+    let (finalized_root, finalized_slot) = harness.honest_roots.last().unwrap();
 
     assert_eq!(
-        lmd.find_head(*head_slot, *finalized_root, ForkedHarness::weight_function),
+        lmd.find_head(
+            *finalized_slot,
+            *finalized_root,
+            ForkedHarness::weight_function
+        ),
         Ok(*head_root),
         "Honest head should be selected"
     );
@@ -253,7 +259,7 @@ fn single_voter_persistent_instance_reverse_order() {
 fn single_voter_many_instance_honest_blocks_voting_forwards() {
     let harness = &FORKED_HARNESS;
 
-    for (root, slot) in &harness.honest_roots {
+    for (root, slot) in harness.honest_roots.iter().rev() {
         let lmd = harness.new_fork_choice();
         lmd.process_attestation(0, *root, *slot)
             .expect("fork choice should accept attestations to honest roots");
@@ -272,7 +278,7 @@ fn single_voter_many_instance_honest_blocks_voting_in_reverse() {
     let harness = &FORKED_HARNESS;
 
     // Same as above, but in reverse order (votes on the highest honest block first).
-    for (root, slot) in harness.honest_roots.iter().rev() {
+    for (root, slot) in &harness.honest_roots {
         let lmd = harness.new_fork_choice();
         lmd.process_attestation(0, *root, *slot)
             .expect("fork choice should accept attestations to honest roots in reverse");
@@ -291,7 +297,7 @@ fn single_voter_many_instance_honest_blocks_voting_in_reverse() {
 fn single_voter_many_instance_faulty_blocks_voting_forwards() {
     let harness = &FORKED_HARNESS;
 
-    for (root, slot) in &harness.faulty_roots {
+    for (root, slot) in harness.faulty_roots.iter().rev() {
         let lmd = harness.new_fork_choice();
         lmd.process_attestation(0, *root, *slot)
             .expect("fork choice should accept attestations to faulty roots");
@@ -309,7 +315,7 @@ fn single_voter_many_instance_faulty_blocks_voting_forwards() {
 fn single_voter_many_instance_faulty_blocks_voting_in_reverse() {
     let harness = &FORKED_HARNESS;
 
-    for (root, slot) in harness.faulty_roots.iter().rev() {
+    for (root, slot) in &harness.faulty_roots {
         let lmd = harness.new_fork_choice();
         lmd.process_attestation(0, *root, *slot)
             .expect("fork choice should accept attestations to faulty roots in reverse");
@@ -322,6 +328,44 @@ fn single_voter_many_instance_faulty_blocks_voting_in_reverse() {
     }
 }
 
+/// Ensure that votes with slots before the justified slot are not counted.
+#[test]
+fn discard_votes_before_justified_slot() {
+    let harness = &FORKED_HARNESS;
+
+    let lmd = harness.new_fork_choice();
+
+    let (genesis_root, genesis_slot) = *harness.honest_roots.last().unwrap();
+
+    // Add attestations from all validators for all honest blocks.
+    for (root, slot) in harness.honest_roots.iter().rev() {
+        for i in 0..VALIDATOR_COUNT {
+            lmd.process_attestation(i, *root, *slot)
+                .expect("should accept attestations in increasing order");
+        }
+
+        // Head starting from 0 checkpoint (genesis) should be current root
+        assert_eq!(
+            lmd.find_head(genesis_slot, genesis_root, ForkedHarness::weight_function),
+            Ok(*root),
+            "Honest head should be selected"
+        );
+
+        // Head from one slot after genesis should still be genesis, because the successor
+        // block of the genesis block has slot `genesis_slot + 1` which isn't greater than
+        // the slot we're starting from. This is a very artifical test, but one that's easy to
+        // describe.
+        assert_eq!(
+            lmd.find_head(
+                genesis_slot + 1,
+                genesis_root,
+                ForkedHarness::weight_function
+            ),
+            Ok(genesis_root)
+        );
+    }
+}
+
 /// Ensures that the finalized root can be set to all values in `roots`.
 fn test_update_finalized_root(roots: &[(Hash256, Slot)]) {
     let harness = &FORKED_HARNESS;

eth2/operation_pool/Cargo.toml

@@ -6,7 +6,6 @@ edition = "2018"
 
 [dependencies]
 int_to_bytes = { path = "../utils/int_to_bytes" }
-itertools = "0.8.1"
 parking_lot = "0.9.0"
 types = { path = "../types" }
 state_processing = { path = "../state_processing" }

eth2/operation_pool/src/attestation.rs

@@ -35,16 +35,14 @@ impl<'a, T: EthSpec> MaxCover for AttMaxCover<'a, T> {
     /// Sneaky: we keep all the attestations together in one bucket, even though
     /// their aggregation bitfields refer to different committees. In order to avoid
     /// confusing committees when updating covering sets, we update only those attestations
-    /// whose shard and epoch match the attestation being included in the solution, by the logic
+    /// whose slot and index match the attestation being included in the solution, by the logic
-    /// that a shard and epoch uniquely identify a committee.
+    /// that a slot and index uniquely identify a committee.
     fn update_covering_set(
         &mut self,
         best_att: &Attestation<T>,
         covered_validators: &BitList<T::MaxValidatorsPerCommittee>,
     ) {
-        if self.att.data.crosslink.shard == best_att.data.crosslink.shard
+        if self.att.data.slot == best_att.data.slot && self.att.data.index == best_att.data.index {
-            && self.att.data.target.epoch == best_att.data.target.epoch
-        {
             self.fresh_validators.difference_inplace(covered_validators);
         }
     }
@@ -80,11 +78,12 @@ pub fn earliest_attestation_validators<T: EthSpec>(
 
     state_attestations
         .iter()
-        // In a single epoch, an attester should only be attesting for one shard.
+        // In a single epoch, an attester should only be attesting for one slot and index.
         // TODO: we avoid including slashable attestations in the state here,
         // but maybe we should do something else with them (like construct slashings).
         .filter(|existing_attestation| {
-            existing_attestation.data.crosslink.shard == attestation.data.crosslink.shard
+            existing_attestation.data.slot == attestation.data.slot
+                && existing_attestation.data.index == attestation.data.index
         })
         .for_each(|existing_attestation| {
             // Remove the validators who have signed the existing attestation (they are not new)

eth2/operation_pool/src/attestation_id.rs

@@ -29,7 +29,7 @@ impl AttestationId {
         state: &BeaconState<T>,
         spec: &ChainSpec,
     ) -> Vec<u8> {
-        int_to_bytes8(spec.get_domain(epoch, Domain::Attestation, &state.fork))
+        int_to_bytes8(spec.get_domain(epoch, Domain::BeaconAttester, &state.fork))
     }
 
     pub fn domain_bytes_match(&self, domain_bytes: &[u8]) -> bool {

eth2/operation_pool/src/lib.rs

@@ -7,24 +7,22 @@ pub use persistence::PersistedOperationPool;
 
 use attestation::{earliest_attestation_validators, AttMaxCover};
 use attestation_id::AttestationId;
-use itertools::Itertools;
 use max_cover::maximum_cover;
 use parking_lot::RwLock;
 use state_processing::per_block_processing::errors::{
     AttestationValidationError, AttesterSlashingValidationError, DepositValidationError,
-    ExitValidationError, ProposerSlashingValidationError, TransferValidationError,
+    ExitValidationError, ProposerSlashingValidationError,
 };
 use state_processing::per_block_processing::{
     get_slashable_indices_modular, verify_attestation_for_block_inclusion,
     verify_attester_slashing, verify_exit, verify_exit_time_independent_only,
-    verify_proposer_slashing, verify_transfer, verify_transfer_time_independent_only,
+    verify_proposer_slashing, VerifySignatures,
-    VerifySignatures,
 };
 use std::collections::{btree_map::Entry, hash_map, BTreeMap, HashMap, HashSet};
 use std::marker::PhantomData;
 use types::{
     typenum::Unsigned, Attestation, AttesterSlashing, BeaconState, ChainSpec, Deposit, EthSpec,
-    ProposerSlashing, Transfer, Validator, VoluntaryExit,
+    ProposerSlashing, Validator, VoluntaryExit,
 };
 
 #[derive(Default, Debug)]
@@ -43,8 +41,6 @@ pub struct OperationPool<T: EthSpec + Default> {
     proposer_slashings: RwLock<HashMap<u64, ProposerSlashing>>,
     /// Map from exiting validator to their exit data.
     voluntary_exits: RwLock<HashMap<u64, VoluntaryExit>>,
-    /// Set of transfers.
-    transfers: RwLock<HashSet<Transfer>>,
     _phantom: PhantomData<T>,
 }
 
@@ -375,44 +371,6 @@ impl<T: EthSpec> OperationPool<T> {
         );
     }
 
-    /// Insert a transfer into the pool, checking it for validity in the process.
-    pub fn insert_transfer(
-        &self,
-        transfer: Transfer,
-        state: &BeaconState<T>,
-        spec: &ChainSpec,
-    ) -> Result<(), TransferValidationError> {
-        // The signature of the transfer isn't hashed, but because we check
-        // it before we insert into the HashSet, we can't end up with duplicate
-        // transactions.
-        verify_transfer_time_independent_only(state, &transfer, VerifySignatures::True, spec)?;
-        self.transfers.write().insert(transfer);
-        Ok(())
-    }
-
-    /// Get a list of transfers for inclusion in a block.
-    // TODO: improve the economic optimality of this function by accounting for
-    // dependencies between transfers in the same block e.g. A pays B, B pays C
-    pub fn get_transfers(&self, state: &BeaconState<T>, spec: &ChainSpec) -> Vec<Transfer> {
-        self.transfers
-            .read()
-            .iter()
-            .filter(|transfer| {
-                verify_transfer(state, transfer, VerifySignatures::False, spec).is_ok()
-            })
-            .sorted_by_key(|transfer| std::cmp::Reverse(transfer.fee))
-            .take(T::MaxTransfers::to_usize())
-            .cloned()
-            .collect()
-    }
-
-    /// Prune the set of transfers by removing all those whose slot has already passed.
-    pub fn prune_transfers(&self, finalized_state: &BeaconState<T>) {
-        self.transfers
-            .write()
-            .retain(|transfer| transfer.slot > finalized_state.slot)
-    }
-
     /// Prune all types of transactions given the latest finalized state.
     pub fn prune_all(&self, finalized_state: &BeaconState<T>, spec: &ChainSpec) {
         self.prune_attestations(finalized_state);
@@ -420,7 +378,6 @@ impl<T: EthSpec> OperationPool<T> {
         self.prune_proposer_slashings(finalized_state);
         self.prune_attester_slashings(finalized_state, spec);
         self.prune_voluntary_exits(finalized_state);
-        self.prune_transfers(finalized_state);
     }
 }
 
@@ -467,7 +424,6 @@ impl<T: EthSpec + Default> PartialEq for OperationPool<T> {
             && *self.attester_slashings.read() == *other.attester_slashings.read()
             && *self.proposer_slashings.read() == *other.proposer_slashings.read()
             && *self.voluntary_exits.read() == *other.voluntary_exits.read()
-            && *self.transfers.read() == *other.transfers.read()
     }
 }
 
@@ -611,7 +567,7 @@ mod tests {
         /// Signed by all validators in `committee[signing_range]` and `committee[extra_signer]`.
         fn signed_attestation<R: std::slice::SliceIndex<[usize], Output = [usize]>, E: EthSpec>(
             committee: &[usize],
-            shard: u64,
+            index: u64,
             keypairs: &[Keypair],
             signing_range: R,
             slot: Slot,
@@ -620,32 +576,30 @@ mod tests {
             extra_signer: Option<usize>,
         ) -> Attestation<E> {
             let mut builder = TestingAttestationBuilder::new(
-                &AttestationTestTask::Valid,
+                AttestationTestTask::Valid,
                 state,
                 committee,
                 slot,
-                shard,
+                index,
                 spec,
             );
             let signers = &committee[signing_range];
             let committee_keys = signers.iter().map(|&i| &keypairs[i].sk).collect::<Vec<_>>();
             builder.sign(
-                &AttestationTestTask::Valid,
+                AttestationTestTask::Valid,
                 signers,
                 &committee_keys,
                 &state.fork,
                 spec,
-                false,
             );
             extra_signer.map(|c_idx| {
                 let validator_index = committee[c_idx];
                 builder.sign(
-                    &AttestationTestTask::Valid,
+                    AttestationTestTask::Valid,
                     &[validator_index],
                     &[&keypairs[validator_index].sk],
                     &state.fork,
                     spec,
-                    false,
                 )
             });
             builder.build()
@@ -677,16 +631,16 @@ mod tests {
                 attestation_test_state::<MainnetEthSpec>(1);
             let slot = state.slot - 1;
             let committees = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
-                .map(CrosslinkCommittee::into_owned)
+                .map(BeaconCommittee::into_owned)
                 .collect::<Vec<_>>();
 
-            for cc in committees {
+            for bc in committees {
                 let att1 = signed_attestation(
-                    &cc.committee,
+                    &bc.committee,
-                    cc.shard,
+                    bc.index,
                     keypairs,
                     ..2,
                     slot,
@@ -695,8 +649,8 @@ mod tests {
                     None,
                 );
                 let att2 = signed_attestation(
-                    &cc.committee,
+                    &bc.committee,
-                    cc.shard,
+                    bc.index,
                     keypairs,
                     ..,
                     slot,
@@ -720,7 +674,7 @@ mod tests {
                     .unwrap();
 
                 assert_eq!(
-                    cc.committee.len() - 2,
+                    bc.committee.len() - 2,
                     earliest_attestation_validators(&att2, state).num_set_bits()
                 );
             }
@@ -736,10 +690,10 @@ mod tests {
 
             let slot = state.slot - 1;
             let committees = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
-                .map(CrosslinkCommittee::into_owned)
+                .map(BeaconCommittee::into_owned)
                 .collect::<Vec<_>>();
 
             assert_eq!(
@@ -748,12 +702,12 @@ mod tests {
                 "we expect just one committee with this many validators"
             );
 
-            for cc in &committees {
+            for bc in &committees {
                 let step_size = 2;
-                for i in (0..cc.committee.len()).step_by(step_size) {
+                for i in (0..bc.committee.len()).step_by(step_size) {
                     let att = signed_attestation(
-                        &cc.committee,
+                        &bc.committee,
-                        cc.shard,
+                        bc.index,
                         keypairs,
                         i..i + step_size,
                         slot,
@@ -805,16 +759,16 @@ mod tests {
 
             let slot = state.slot - 1;
             let committees = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
-                .map(CrosslinkCommittee::into_owned)
+                .map(BeaconCommittee::into_owned)
                 .collect::<Vec<_>>();
 
-            for cc in &committees {
+            for bc in &committees {
                 let att = signed_attestation(
-                    &cc.committee,
+                    &bc.committee,
-                    cc.shard,
+                    bc.index,
                     keypairs,
                     ..,
                     slot,
@@ -842,20 +796,20 @@ mod tests {
 
             let slot = state.slot - 1;
             let committees = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
-                .map(CrosslinkCommittee::into_owned)
+                .map(BeaconCommittee::into_owned)
                 .collect::<Vec<_>>();
 
             let step_size = 2;
-            for cc in &committees {
+            for bc in &committees {
                 // Create attestations that overlap on `step_size` validators, like:
                 // {0,1,2,3}, {2,3,4,5}, {4,5,6,7}, ...
-                for i in (0..cc.committee.len() - step_size).step_by(step_size) {
+                for i in (0..bc.committee.len() - step_size).step_by(step_size) {
                     let att = signed_attestation(
-                        &cc.committee,
+                        &bc.committee,
-                        cc.shard,
+                        bc.index,
                         keypairs,
                         i..i + 2 * step_size,
                         slot,
@@ -890,20 +844,20 @@ mod tests {
 
             let slot = state.slot - 1;
             let committees = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
-                .map(CrosslinkCommittee::into_owned)
+                .map(BeaconCommittee::into_owned)
                 .collect::<Vec<_>>();
 
             let max_attestations = <MainnetEthSpec as EthSpec>::MaxAttestations::to_usize();
             let target_committee_size = spec.target_committee_size as usize;
 
-            let insert_attestations = |cc: &OwnedCrosslinkCommittee, step_size| {
+            let insert_attestations = |bc: &OwnedBeaconCommittee, step_size| {
                 for i in (0..target_committee_size).step_by(step_size) {
                     let att = signed_attestation(
-                        &cc.committee,
+                        &bc.committee,
-                        cc.shard,
+                        bc.index,
                         keypairs,
                         i..i + step_size,
                         slot,

eth2/operation_pool/src/persistence.rs

@@ -21,8 +21,6 @@ pub struct PersistedOperationPool<T: EthSpec> {
     proposer_slashings: Vec<ProposerSlashing>,
     /// Voluntary exits.
     voluntary_exits: Vec<VoluntaryExit>,
-    /// Transfers.
-    transfers: Vec<Transfer>,
 }
 
 impl<T: EthSpec> PersistedOperationPool<T> {
@@ -63,15 +61,12 @@ impl<T: EthSpec> PersistedOperationPool<T> {
             .map(|(_, exit)| exit.clone())
             .collect();
 
-        let transfers = operation_pool.transfers.read().iter().cloned().collect();
-
         Self {
             attestations,
             deposits,
             attester_slashings,
             proposer_slashings,
             voluntary_exits,
-            transfers,
         }
     }
 
@@ -102,7 +97,6 @@ impl<T: EthSpec> PersistedOperationPool<T> {
                 .map(|exit| (exit.validator_index, exit))
                 .collect(),
         );
-        let transfers = RwLock::new(self.transfers.into_iter().collect());
 
         OperationPool {
             attestations,
@@ -110,7 +104,6 @@ impl<T: EthSpec> PersistedOperationPool<T> {
             attester_slashings,
             proposer_slashings,
             voluntary_exits,
-            transfers,
             _phantom: Default::default(),
         }
     }

eth2/state_processing/src/common/get_attesting_indices.rs

@@ -3,19 +3,13 @@ use types::*;
 
 /// Returns validator indices which participated in the attestation, sorted by increasing index.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn get_attesting_indices<T: EthSpec>(
     state: &BeaconState<T>,
     attestation_data: &AttestationData,
     bitlist: &BitList<T::MaxValidatorsPerCommittee>,
 ) -> Result<BTreeSet<usize>, BeaconStateError> {
-    let target_relative_epoch =
+    let committee = state.get_beacon_committee(attestation_data.slot, attestation_data.index)?;
-        RelativeEpoch::from_epoch(state.current_epoch(), attestation_data.target.epoch)?;
-
-    let committee = state.get_crosslink_committee_for_shard(
-        attestation_data.crosslink.shard,
-        target_relative_epoch,
-    )?;
 
     if bitlist.len() != committee.committee.len() {
         return Err(BeaconStateError::InvalidBitfield);

eth2/state_processing/src/common/get_compact_committees_root.rs

@@ -1,41 +0,0 @@
-use tree_hash::TreeHash;
-use types::*;
-
-/// Return the compact committee root at `relative_epoch`.
-///
-/// Spec v0.8.3
-pub fn get_compact_committees_root<T: EthSpec>(
-    state: &BeaconState<T>,
-    relative_epoch: RelativeEpoch,
-    spec: &ChainSpec,
-) -> Result<Hash256, BeaconStateError> {
-    let mut committees =
-        FixedVector::<_, T::ShardCount>::from_elem(CompactCommittee::<T>::default());
-    let start_shard = state.get_epoch_start_shard(relative_epoch)?;
-
-    for committee_number in 0..state.get_committee_count(relative_epoch)? {
-        let shard = (start_shard + committee_number) % T::ShardCount::to_u64();
-
-        for &index in state
-            .get_crosslink_committee_for_shard(shard, relative_epoch)?
-            .committee
-        {
-            let validator = state
-                .validators
-                .get(index)
-                .ok_or(BeaconStateError::UnknownValidator)?;
-            committees[shard as usize]
-                .pubkeys
-                .push(validator.pubkey.clone())?;
-            let compact_balance = validator.effective_balance / spec.effective_balance_increment;
-            // `index` (top 6 bytes) + `slashed` (16th bit) + `compact_balance` (bottom 15 bits)
-            let compact_validator: u64 =
-                ((index as u64) << 16) + (u64::from(validator.slashed) << 15) + compact_balance;
-            committees[shard as usize]
-                .compact_validators
-                .push(compact_validator)?;
-        }
-    }
-
-    Ok(Hash256::from_slice(&committees.tree_hash_root()))
-}

eth2/state_processing/src/common/get_indexed_attestation.rs

@@ -6,139 +6,19 @@ type Result<T> = std::result::Result<T, BlockOperationError<Invalid>>;
 
 /// Convert `attestation` to (almost) indexed-verifiable form.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn get_indexed_attestation<T: EthSpec>(
     state: &BeaconState<T>,
     attestation: &Attestation<T>,
 ) -> Result<IndexedAttestation<T>> {
-    // Note: we rely on both calls to `get_attesting_indices` to check the bitfield lengths
-    // against the committee length
     let attesting_indices =
         get_attesting_indices(state, &attestation.data, &attestation.aggregation_bits)?;
 
-    let custody_bit_1_indices =
-        get_attesting_indices(state, &attestation.data, &attestation.custody_bits)?;
-
-    verify!(
-        custody_bit_1_indices.is_subset(&attesting_indices),
-        Invalid::CustodyBitfieldNotSubset
-    );
-
-    let custody_bit_0_indices = &attesting_indices - &custody_bit_1_indices;
-
     Ok(IndexedAttestation {
-        custody_bit_0_indices: VariableList::new(
+        attesting_indices: VariableList::new(
-            custody_bit_0_indices
+            attesting_indices.into_iter().map(|x| x as u64).collect(),
-                .into_iter()
-                .map(|x| x as u64)
-                .collect(),
-        )?,
-        custody_bit_1_indices: VariableList::new(
-            custody_bit_1_indices
-                .into_iter()
-                .map(|x| x as u64)
-                .collect(),
         )?,
         data: attestation.data.clone(),
         signature: attestation.signature.clone(),
     })
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use itertools::{Either, Itertools};
-    use types::test_utils::*;
-
-    #[test]
-    fn custody_bitfield_indexing() {
-        let validator_count = 128;
-        let spec = MinimalEthSpec::default_spec();
-        let state_builder =
-            TestingBeaconStateBuilder::<MinimalEthSpec>::from_default_keypairs_file_if_exists(
-                validator_count,
-                &spec,
-            );
-        let (mut state, keypairs) = state_builder.build();
-        state.build_all_caches(&spec).unwrap();
-        state.slot += 1;
-
-        let shard = 0;
-        let cc = state
-            .get_crosslink_committee_for_shard(shard, RelativeEpoch::Current)
-            .unwrap();
-
-        // Make a third of the validators sign with custody bit 0, a third with custody bit 1
-        // and a third not sign at all.
-        assert!(
-            cc.committee.len() >= 4,
-            "need at least 4 validators per committee for this test to work"
-        );
-        let (mut bit_0_indices, mut bit_1_indices): (Vec<_>, Vec<_>) = cc
-            .committee
-            .iter()
-            .enumerate()
-            .filter(|(i, _)| i % 3 != 0)
-            .partition_map(|(i, index)| {
-                if i % 3 == 1 {
-                    Either::Left(*index)
-                } else {
-                    Either::Right(*index)
-                }
-            });
-        assert!(!bit_0_indices.is_empty());
-        assert!(!bit_1_indices.is_empty());
-
-        let bit_0_keys = bit_0_indices
-            .iter()
-            .map(|validator_index| &keypairs[*validator_index].sk)
-            .collect::<Vec<_>>();
-        let bit_1_keys = bit_1_indices
-            .iter()
-            .map(|validator_index| &keypairs[*validator_index].sk)
-            .collect::<Vec<_>>();
-
-        let mut attestation_builder = TestingAttestationBuilder::new(
-            &AttestationTestTask::Valid,
-            &state,
-            &cc.committee,
-            cc.slot,
-            shard,
-            &spec,
-        );
-        attestation_builder
-            .sign(
-                &AttestationTestTask::Valid,
-                &bit_0_indices,
-                &bit_0_keys,
-                &state.fork,
-                &spec,
-                false,
-            )
-            .sign(
-                &AttestationTestTask::Valid,
-                &bit_1_indices,
-                &bit_1_keys,
-                &state.fork,
-                &spec,
-                true,
-            );
-        let attestation = attestation_builder.build();
-
-        let indexed_attestation = get_indexed_attestation(&state, &attestation).unwrap();
-
-        bit_0_indices.sort();
-        bit_1_indices.sort();
-
-        assert!(indexed_attestation
-            .custody_bit_0_indices
-            .iter()
-            .copied()
-            .eq(bit_0_indices.iter().map(|idx| *idx as u64)));
-        assert!(indexed_attestation
-            .custody_bit_1_indices
-            .iter()
-            .copied()
-            .eq(bit_1_indices.iter().map(|idx| *idx as u64)));
-    }
-}

eth2/state_processing/src/common/initiate_validator_exit.rs

@@ -3,7 +3,7 @@ use types::{BeaconStateError as Error, *};
 
 /// Initiate the exit of the validator of the given `index`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn initiate_validator_exit<T: EthSpec>(
     state: &mut BeaconState<T>,
     index: usize,

eth2/state_processing/src/common/mod.rs

@@ -1,11 +1,9 @@
 mod get_attesting_indices;
-mod get_compact_committees_root;
 mod get_indexed_attestation;
 mod initiate_validator_exit;
 mod slash_validator;
 
 pub use get_attesting_indices::get_attesting_indices;
-pub use get_compact_committees_root::get_compact_committees_root;
 pub use get_indexed_attestation::get_indexed_attestation;
 pub use initiate_validator_exit::initiate_validator_exit;
 pub use slash_validator::slash_validator;

eth2/state_processing/src/common/slash_validator.rs

@@ -4,7 +4,7 @@ use types::{BeaconStateError as Error, *};
 
 /// Slash the validator with index ``index``.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn slash_validator<T: EthSpec>(
     state: &mut BeaconState<T>,
     slashed_index: usize,
@@ -35,8 +35,7 @@ pub fn slash_validator<T: EthSpec>(
     );
 
     // Apply proposer and whistleblower rewards
-    let proposer_index =
+    let proposer_index = state.get_beacon_proposer_index(state.slot, spec)?;
-        state.get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)?;
     let whistleblower_index = opt_whistleblower_index.unwrap_or(proposer_index);
     let whistleblower_reward = validator_effective_balance / spec.whistleblower_reward_quotient;
     let proposer_reward = whistleblower_reward / spec.proposer_reward_quotient;

eth2/state_processing/src/genesis.rs

@@ -1,12 +1,11 @@
 use super::per_block_processing::{errors::BlockProcessingError, process_deposit};
-use crate::common::get_compact_committees_root;
 use tree_hash::TreeHash;
 use types::typenum::U4294967296;
 use types::*;
 
 /// Initialize a `BeaconState` from genesis data.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 // TODO: this is quite inefficient and we probably want to rethink how we do this
 pub fn initialize_beacon_state_from_eth1<T: EthSpec>(
     eth1_block_hash: Hash256,
@@ -24,6 +23,9 @@ pub fn initialize_beacon_state_from_eth1<T: EthSpec>(
     };
     let mut state = BeaconState::new(genesis_time, eth1_data, spec);
 
+    // Seed RANDAO with Eth1 entropy
+    state.fill_randao_mixes_with(eth1_block_hash);
+
     // Process deposits
     let leaves: Vec<_> = deposits
         .iter()
@@ -40,21 +42,12 @@ pub fn initialize_beacon_state_from_eth1<T: EthSpec>(
     // Now that we have our validators, initialize the caches (including the committees)
     state.build_all_caches(spec)?;
 
-    // Populate active_index_roots and compact_committees_roots
-    let indices_list = VariableList::<usize, T::ValidatorRegistryLimit>::from(
-        state.get_active_validator_indices(T::genesis_epoch()),
-    );
-    let active_index_root = Hash256::from_slice(&indices_list.tree_hash_root());
-    let committee_root = get_compact_committees_root(&state, RelativeEpoch::Current, spec)?;
-    state.fill_active_index_roots_with(active_index_root);
-    state.fill_compact_committees_roots_with(committee_root);
-
     Ok(state)
 }
 
 /// Determine whether a candidate genesis state is suitable for starting the chain.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn is_valid_genesis_state<T: EthSpec>(state: &BeaconState<T>, spec: &ChainSpec) -> bool {
     state.genesis_time >= spec.min_genesis_time
         && state.get_active_validator_indices(T::genesis_epoch()).len() as u64

eth2/state_processing/src/per_block_processing.rs

@@ -2,9 +2,7 @@ use crate::common::{initiate_validator_exit, slash_validator};
 use errors::{BlockOperationError, BlockProcessingError, HeaderInvalid, IntoWithIndex};
 use rayon::prelude::*;
 use signature_sets::{block_proposal_signature_set, randao_signature_set};
-use std::collections::HashSet;
 use std::convert::TryInto;
-use std::iter::FromIterator;
 use tree_hash::SignedRoot;
 use types::*;
 
@@ -21,9 +19,6 @@ pub use verify_deposit::{
     get_existing_validator_index, verify_deposit_merkle_proof, verify_deposit_signature,
 };
 pub use verify_exit::{verify_exit, verify_exit_time_independent_only};
-pub use verify_transfer::{
-    execute_transfer, verify_transfer, verify_transfer_time_independent_only,
-};
 
 pub mod block_processing_builder;
 mod block_signature_verifier;
@@ -36,7 +31,6 @@ mod verify_attester_slashing;
 mod verify_deposit;
 mod verify_exit;
 mod verify_proposer_slashing;
-mod verify_transfer;
 
 /// The strategy to be used when validating the block's signatures.
 #[derive(PartialEq, Clone, Copy)]
@@ -74,7 +68,7 @@ impl VerifySignatures {
 /// signature. If it is `None` the signed root is calculated here. This parameter only exists to
 /// avoid re-calculating the root when it is already known.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn per_block_processing<T: EthSpec>(
     mut state: &mut BeaconState<T>,
     block: &BeaconBlock<T>,
@@ -128,14 +122,13 @@ pub fn per_block_processing<T: EthSpec>(
         verify_signatures,
         spec,
     )?;
-    process_transfers(&mut state, &block.body.transfers, verify_signatures, spec)?;
 
     Ok(())
 }
 
 /// Processes the block header.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_block_header<T: EthSpec>(
     state: &mut BeaconState<T>,
     block: &BeaconBlock<T>,
@@ -158,7 +151,7 @@ pub fn process_block_header<T: EthSpec>(
     state.latest_block_header = block.temporary_block_header();
 
     // Verify proposer is not slashed
-    let proposer_idx = state.get_beacon_proposer_index(block.slot, RelativeEpoch::Current, spec)?;
+    let proposer_idx = state.get_beacon_proposer_index(block.slot, spec)?;
     let proposer = &state.validators[proposer_idx];
     verify!(
         !proposer.slashed,
@@ -174,7 +167,7 @@ pub fn process_block_header<T: EthSpec>(
 
 /// Verifies the signature of a block.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_block_signature<T: EthSpec>(
     state: &BeaconState<T>,
     block: &BeaconBlock<T>,
@@ -192,7 +185,7 @@ pub fn verify_block_signature<T: EthSpec>(
 /// Verifies the `randao_reveal` against the block's proposer pubkey and updates
 /// `state.latest_randao_mixes`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_randao<T: EthSpec>(
     state: &mut BeaconState<T>,
     block: &BeaconBlock<T>,
@@ -215,7 +208,7 @@ pub fn process_randao<T: EthSpec>(
 
 /// Update the `state.eth1_data_votes` based upon the `eth1_data` provided.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_eth1_data<T: EthSpec>(
     state: &mut BeaconState<T>,
     eth1_data: &Eth1Data,
@@ -240,7 +233,7 @@ pub fn process_eth1_data<T: EthSpec>(
 /// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
 /// an `Err` describing the invalid object or cause of failure.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_proposer_slashings<T: EthSpec>(
     state: &mut BeaconState<T>,
     proposer_slashings: &[ProposerSlashing],
@@ -269,7 +262,7 @@ pub fn process_proposer_slashings<T: EthSpec>(
 /// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
 /// an `Err` describing the invalid object or cause of failure.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_attester_slashings<T: EthSpec>(
     state: &mut BeaconState<T>,
     attester_slashings: &[AttesterSlashing<T>],
@@ -323,7 +316,7 @@ pub fn process_attester_slashings<T: EthSpec>(
 /// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
 /// an `Err` describing the invalid object or cause of failure.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_attestations<T: EthSpec>(
     state: &mut BeaconState<T>,
     attestations: &[Attestation<T>],
@@ -343,14 +336,12 @@ pub fn process_attestations<T: EthSpec>(
         })?;
 
     // Update the state in series.
-    let proposer_index =
+    let proposer_index = state.get_beacon_proposer_index(state.slot, spec)? as u64;
-        state.get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)? as u64;
     for attestation in attestations {
-        let attestation_slot = state.get_attestation_data_slot(&attestation.data)?;
         let pending_attestation = PendingAttestation {
             aggregation_bits: attestation.aggregation_bits.clone(),
             data: attestation.data.clone(),
-            inclusion_delay: (state.slot - attestation_slot).as_u64(),
+            inclusion_delay: (state.slot - attestation.data.slot).as_u64(),
             proposer_index,
         };
 
@@ -371,7 +362,7 @@ pub fn process_attestations<T: EthSpec>(
 /// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
 /// an `Err` describing the invalid object or cause of failure.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_deposits<T: EthSpec>(
     state: &mut BeaconState<T>,
     deposits: &[Deposit],
@@ -408,7 +399,7 @@ pub fn process_deposits<T: EthSpec>(
 
 /// Process a single deposit, optionally verifying its merkle proof.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn process_deposit<T: EthSpec>(
     state: &mut BeaconState<T>,
     deposit: &Deposit,
@@ -474,7 +465,7 @@ pub fn process_deposit<T: EthSpec>(
 /// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
 /// an `Err` describing the invalid object or cause of failure.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_exits<T: EthSpec>(
     state: &mut BeaconState<T>,
     voluntary_exits: &[VoluntaryExit],
@@ -496,39 +487,3 @@ pub fn process_exits<T: EthSpec>(
 
     Ok(())
 }
-
-/// Validates each `Transfer` and updates the state, short-circuiting on an invalid object.
-///
-/// Returns `Ok(())` if the validation and state updates completed successfully, otherwise returns
-/// an `Err` describing the invalid object or cause of failure.
-///
-/// Spec v0.8.0
-pub fn process_transfers<T: EthSpec>(
-    state: &mut BeaconState<T>,
-    transfers: &[Transfer],
-    verify_signatures: VerifySignatures,
-    spec: &ChainSpec,
-) -> Result<(), BlockProcessingError> {
-    let expected_transfers = HashSet::<_>::from_iter(transfers).len();
-    // Verify that there are no duplicate transfers
-    block_verify!(
-        transfers.len() == expected_transfers,
-        BlockProcessingError::DuplicateTransfers {
-            duplicates: transfers.len().saturating_sub(expected_transfers)
-        }
-    );
-
-    transfers
-        .par_iter()
-        .enumerate()
-        .try_for_each(|(i, transfer)| {
-            verify_transfer(&state, transfer, verify_signatures, spec)
-                .map_err(|e| e.into_with_index(i))
-        })?;
-
-    for (i, transfer) in transfers.iter().enumerate() {
-        execute_transfer(state, transfer, spec).map_err(|e| e.into_with_index(i))?;
-    }
-
-    Ok(())
-}

eth2/state_processing/src/per_block_processing/block_processing_builder.rs

@@ -55,9 +55,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {
@@ -99,9 +97,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {
@@ -112,7 +108,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             ExitTestTask::AlreadyInitiated => {
                 for _ in 0..2 {
                     self.block_builder.insert_exit(
-                        &test_task,
+                        test_task,
                         &mut state,
                         (0 as usize).try_into().unwrap(),
                         &keypairs[0].sk,
@@ -123,7 +119,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             _ => {
                 for (i, keypair) in keypairs.iter().take(num_exits).enumerate() {
                     self.block_builder.insert_exit(
-                        &test_task,
+                        test_task,
                         &mut state,
                         (i as usize).try_into().unwrap(),
                         &keypair.sk,
@@ -140,7 +136,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
 
     pub fn build_with_n_attestations(
         mut self,
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         num_attestations: u64,
         randao_sk: Option<SecretKey>,
         previous_block_root: Option<Hash256>,
@@ -158,9 +154,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {
@@ -185,7 +179,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
 
     pub fn build_with_attester_slashing(
         mut self,
-        test_task: &AttesterSlashingTestTask,
+        test_task: AttesterSlashingTestTask,
         num_attester_slashings: u64,
         randao_sk: Option<SecretKey>,
         previous_block_root: Option<Hash256>,
@@ -203,9 +197,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {
@@ -236,7 +228,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
 
     pub fn build_with_proposer_slashing(
         mut self,
-        test_task: &ProposerSlashingTestTask,
+        test_task: ProposerSlashingTestTask,
         num_proposer_slashings: u64,
         randao_sk: Option<SecretKey>,
         previous_block_root: Option<Hash256>,
@@ -254,9 +246,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {
@@ -298,9 +288,7 @@ impl<T: EthSpec> BlockProcessingBuilder<T> {
             )),
         }
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
         let keypair = &keypairs[proposer_index];
 
         match randao_sk {

eth2/state_processing/src/per_block_processing/block_signature_verifier.rs

@@ -86,7 +86,6 @@ impl<'a, T: EthSpec> BlockSignatureVerifier<'a, T> {
          * Deposits are not included because they can legally have invalid signatures.
          */
         verifier.include_exits()?;
-        verifier.include_transfers()?;
 
         verifier.verify()
     }
@@ -209,19 +208,4 @@ impl<'a, T: EthSpec> BlockSignatureVerifier<'a, T> {
 
         Ok(())
     }
-
-    /// Includes all signatures in `self.block.body.transfers` for verification.
-    fn include_transfers(&mut self) -> Result<()> {
-        let mut sets = self
-            .block
-            .body
-            .transfers
-            .iter()
-            .map(|transfer| transfer_signature_set(&self.state, transfer, &self.spec))
-            .collect::<SignatureSetResult<_>>()?;
-
-        self.sets.append(&mut sets);
-
-        Ok(())
-    }
 }

eth2/state_processing/src/per_block_processing/errors.rs

@@ -16,9 +16,6 @@ pub enum BlockProcessingError {
         expected: usize,
         found: usize,
     },
-    DuplicateTransfers {
-        duplicates: usize,
-    },
     HeaderInvalid {
         reason: HeaderInvalid,
     },
@@ -46,10 +43,6 @@ pub enum BlockProcessingError {
         index: usize,
         reason: ExitInvalid,
     },
-    TransferInvalid {
-        index: usize,
-        reason: TransferInvalid,
-    },
     BeaconStateError(BeaconStateError),
     SignatureSetError(SignatureSetError),
     SszTypesError(ssz_types::Error),
@@ -119,8 +112,7 @@ impl_into_block_processing_error_with_index!(
     IndexedAttestationInvalid,
     AttestationInvalid,
     DepositInvalid,
-    ExitInvalid,
+    ExitInvalid
-    TransferInvalid
 );
 
 pub type HeaderValidationError = BlockOperationError<HeaderInvalid>;
@@ -129,7 +121,6 @@ pub type ProposerSlashingValidationError = BlockOperationError<ProposerSlashingI
 pub type AttestationValidationError = BlockOperationError<AttestationInvalid>;
 pub type DepositValidationError = BlockOperationError<DepositInvalid>;
 pub type ExitValidationError = BlockOperationError<ExitInvalid>;
-pub type TransferValidationError = BlockOperationError<TransferInvalid>;
 
 #[derive(Debug, PartialEq)]
 pub enum BlockOperationError<T> {
@@ -174,10 +165,10 @@ pub enum HeaderInvalid {
 pub enum ProposerSlashingInvalid {
     /// The proposer index is not a known validator.
     ProposerUnknown(u64),
-    /// The two proposal have different epochs.
+    /// The two proposal have different slots.
     ///
     /// (proposal_1_slot, proposal_2_slot)
-    ProposalEpochMismatch(Slot, Slot),
+    ProposalSlotMismatch(Slot, Slot),
     /// The proposals are identical and therefore not slashable.
     ProposalsIdentical,
     /// The specified proposer cannot be slashed because they are already slashed, or not active.
@@ -207,8 +198,8 @@ pub enum AttesterSlashingInvalid {
 /// Describes why an object is invalid.
 #[derive(Debug, PartialEq)]
 pub enum AttestationInvalid {
-    /// Shard exceeds SHARD_COUNT.
+    /// Commmittee index exceeds number of committees in that slot.
-    BadShard,
+    BadCommitteeIndex,
     /// Attestation included before the inclusion delay.
     IncludedTooEarly {
         state: Slot,
@@ -229,36 +220,18 @@ pub enum AttestationInvalid {
         attestation: Checkpoint,
         is_current: bool,
     },
-    /// Attestation crosslink root does not match the state crosslink root for the attestations
-    /// slot.
-    BadParentCrosslinkHash,
-    /// Attestation crosslink start epoch does not match the end epoch of the state crosslink.
-    BadParentCrosslinkStartEpoch,
-    /// Attestation crosslink end epoch does not match the expected value.
-    BadParentCrosslinkEndEpoch,
-    /// The custody bitfield has some bits set `true`. This is not allowed in phase 0.
-    CustodyBitfieldHasSetBits,
     /// There are no set bits on the attestation -- an attestation must be signed by at least one
     /// validator.
     AggregationBitfieldIsEmpty,
-    /// The custody bitfield length is not the smallest possible size to represent the committee.
-    BadCustodyBitfieldLength {
-        committee_len: usize,
-        bitfield_len: usize,
-    },
     /// The aggregation bitfield length is not the smallest possible size to represent the committee.
     BadAggregationBitfieldLength {
         committee_len: usize,
         bitfield_len: usize,
     },
-    /// The bits set in the custody bitfield are not a subset of those set in the aggregation bits.
+    /// The validator index was unknown.
-    CustodyBitfieldNotSubset,
+    UnknownValidator(u64),
-    /// There was no known committee in this `epoch` for the given shard and slot.
-    NoCommitteeForShard { shard: u64, slot: Slot },
     /// The attestation signature verification failed.
     BadSignature,
-    /// The shard block root was not set to zero. This is a phase 0 requirement.
-    ShardBlockRootNotZero,
     /// The indexed attestation created from this attestation was found to be invalid.
     BadIndexedAttestation(IndexedAttestationInvalid),
 }
@@ -280,14 +253,6 @@ impl From<BlockOperationError<IndexedAttestationInvalid>>
 
 #[derive(Debug, PartialEq)]
 pub enum IndexedAttestationInvalid {
-    /// The custody bit 0 validators intersect with the bit 1 validators.
-    CustodyBitValidatorsIntersect,
-    /// The custody bitfield has some bits set `true`. This is not allowed in phase 0.
-    CustodyBitfieldHasSetBits,
-    /// The custody bitfield violated a type-level bound.
-    CustodyBitfieldBoundsError(ssz_types::Error),
-    /// No validator indices were specified.
-    NoValidatorIndices,
     /// The number of indices exceeds the global maximum.
     ///
     /// (max_indices, indices_given)
@@ -339,56 +304,3 @@ pub enum ExitInvalid {
     /// been invalid or an internal error occurred.
     SignatureSetError(SignatureSetError),
 }
-
-#[derive(Debug, PartialEq)]
-pub enum TransferInvalid {
-    /// The validator indicated by `transfer.from` is unknown.
-    FromValidatorUnknown(u64),
-    /// The validator indicated by `transfer.to` is unknown.
-    ToValidatorUnknown(u64),
-    /// The balance of `transfer.from` is insufficient.
-    ///
-    /// (required, available)
-    FromBalanceInsufficient(u64, u64),
-    /// Adding `transfer.fee` to `transfer.amount` causes an overflow.
-    ///
-    /// (transfer_fee, transfer_amount)
-    FeeOverflow(u64, u64),
-    /// This transfer would result in the `transfer.from` account to have `0 < balance <
-    /// min_deposit_amount`
-    ///
-    /// (resulting_amount, min_deposit_amount)
-    SenderDust(u64, u64),
-    /// This transfer would result in the `transfer.to` account to have `0 < balance <
-    /// min_deposit_amount`
-    ///
-    /// (resulting_amount, min_deposit_amount)
-    RecipientDust(u64, u64),
-    /// The state slot does not match `transfer.slot`.
-    ///
-    /// (state_slot, transfer_slot)
-    StateSlotMismatch(Slot, Slot),
-    /// The `transfer.slot` is in the past relative to the state slot.
-    ///
-    ///
-    /// (state_slot, transfer_slot)
-    TransferSlotInPast(Slot, Slot),
-    /// The `transfer.from` validator has been activated and is not withdrawable.
-    ///
-    /// (from_validator)
-    FromValidatorIneligibleForTransfer(u64),
-    /// The validators withdrawal credentials do not match `transfer.pubkey`.
-    ///
-    /// (state_credentials, transfer_pubkey_credentials)
-    WithdrawalCredentialsMismatch(Hash256, Hash256),
-    /// The deposit was not signed by `deposit.pubkey`.
-    BadSignature,
-    /// Overflow when adding to `transfer.to` balance.
-    ///
-    /// (to_balance, transfer_amount)
-    ToBalanceOverflow(u64, u64),
-    /// Overflow when adding to beacon proposer balance.
-    ///
-    /// (proposer_balance, transfer_fee)
-    ProposerBalanceOverflow(u64, u64),
-}

eth2/state_processing/src/per_block_processing/is_valid_indexed_attestation.rs

@@ -1,8 +1,6 @@
 use super::errors::{BlockOperationError, IndexedAttestationInvalid as Invalid};
 use super::signature_sets::indexed_attestation_signature_set;
 use crate::VerifySignatures;
-use std::collections::HashSet;
-use std::iter::FromIterator;
 use types::*;
 
 type Result<T> = std::result::Result<T, BlockOperationError<Invalid>>;
@@ -13,38 +11,26 @@ fn error(reason: Invalid) -> BlockOperationError<Invalid> {
 
 /// Verify an `IndexedAttestation`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn is_valid_indexed_attestation<T: EthSpec>(
     state: &BeaconState<T>,
     indexed_attestation: &IndexedAttestation<T>,
     verify_signatures: VerifySignatures,
     spec: &ChainSpec,
 ) -> Result<()> {
-    let bit_0_indices = &indexed_attestation.custody_bit_0_indices;
+    let indices = &indexed_attestation.attesting_indices;
-    let bit_1_indices = &indexed_attestation.custody_bit_1_indices;
-
-    // Verify no index has custody bit equal to 1 [to be removed in phase 1]
-    verify!(bit_1_indices.is_empty(), Invalid::CustodyBitfieldHasSetBits);
 
     // Verify max number of indices
-    let total_indices = bit_0_indices.len() + bit_1_indices.len();
     verify!(
-        total_indices <= T::MaxValidatorsPerCommittee::to_usize(),
+        indices.len() <= T::MaxValidatorsPerCommittee::to_usize(),
-        Invalid::MaxIndicesExceed(T::MaxValidatorsPerCommittee::to_usize(), total_indices)
+        Invalid::MaxIndicesExceed(T::MaxValidatorsPerCommittee::to_usize(), indices.len())
     );
 
-    // Verify index sets are disjoint
+    // Check that indices are sorted
-    let custody_bit_intersection: HashSet<&u64> =
-        &HashSet::from_iter(bit_0_indices.iter()) & &HashSet::from_iter(bit_1_indices.iter());
-    verify!(
-        custody_bit_intersection.is_empty(),
-        Invalid::CustodyBitValidatorsIntersect
-    );
-
-    // Check that both vectors of indices are sorted
     let check_sorted = |list: &[u64]| -> Result<()> {
         list.windows(2).enumerate().try_for_each(|(i, pair)| {
-            if pair[0] >= pair[1] {
+            // The spec allows duplicates, so use strict comparison (>).
+            if pair[0] > pair[1] {
                 Err(error(Invalid::BadValidatorIndicesOrdering(i)))
             } else {
                 Ok(())
@@ -52,8 +38,7 @@ pub fn is_valid_indexed_attestation<T: EthSpec>(
         })?;
         Ok(())
     };
-    check_sorted(&bit_0_indices)?;
+    check_sorted(indices)?;
-    check_sorted(&bit_1_indices)?;
 
     if verify_signatures.is_true() {
         verify!(

eth2/state_processing/src/per_block_processing/signature_sets.rs

@@ -2,14 +2,13 @@
 //! validated individually, or alongside in others in a potentially cheaper bulk operation.
 //!
 //! This module exposes one function to extract each type of `SignatureSet` from a `BeaconBlock`.
-use bls::SignatureSet;
+use bls::{SignatureSet, SignedMessage};
 use std::convert::TryInto;
 use tree_hash::{SignedRoot, TreeHash};
 use types::{
-    AggregateSignature, AttestationDataAndCustodyBit, AttesterSlashing, BeaconBlock,
+    AggregateSignature, AttesterSlashing, BeaconBlock, BeaconBlockHeader, BeaconState,
-    BeaconBlockHeader, BeaconState, BeaconStateError, ChainSpec, DepositData, Domain, EthSpec,
+    BeaconStateError, ChainSpec, DepositData, Domain, EthSpec, Hash256, IndexedAttestation,
-    Hash256, IndexedAttestation, ProposerSlashing, PublicKey, RelativeEpoch, Signature, Transfer,
+    ProposerSlashing, PublicKey, Signature, VoluntaryExit,
-    VoluntaryExit,
 };
 
 pub type Result<T> = std::result::Result<T, Error>;
@@ -42,8 +41,7 @@ pub fn block_proposal_signature_set<'a, T: EthSpec>(
     block_signed_root: Option<Hash256>,
     spec: &'a ChainSpec,
 ) -> Result<SignatureSet<'a>> {
-    let proposer_index =
+    let proposer_index = state.get_beacon_proposer_index(block.slot, spec)?;
-        state.get_beacon_proposer_index(block.slot, RelativeEpoch::Current, spec)?;
     let block_proposer = &state
         .validators
         .get(proposer_index)
@@ -75,8 +73,7 @@ pub fn randao_signature_set<'a, T: EthSpec>(
     block: &'a BeaconBlock<T>,
     spec: &'a ChainSpec,
 ) -> Result<SignatureSet<'a>> {
-    let block_proposer = &state.validators
+    let block_proposer = &state.validators[state.get_beacon_proposer_index(block.slot, spec)?];
-        [state.get_beacon_proposer_index(block.slot, RelativeEpoch::Current, spec)?];
 
     let domain = spec.get_domain(
         block.slot.epoch(T::slots_per_epoch()),
@@ -141,31 +138,20 @@ pub fn indexed_attestation_signature_set<'a, 'b, T: EthSpec>(
     indexed_attestation: &'b IndexedAttestation<T>,
     spec: &'a ChainSpec,
 ) -> Result<SignatureSet<'a>> {
-    let message_0 = AttestationDataAndCustodyBit {
+    let message = indexed_attestation.data.tree_hash_root();
-        data: indexed_attestation.data.clone(),
+
-        custody_bit: false,
+    let signed_message = SignedMessage::new(
-    }
+        get_pubkeys(state, &indexed_attestation.attesting_indices)?,
-    .tree_hash_root();
+        message,
-    let message_1 = AttestationDataAndCustodyBit {
+    );
-        data: indexed_attestation.data.clone(),
-        custody_bit: true,
-    }
-    .tree_hash_root();
 
     let domain = spec.get_domain(
         indexed_attestation.data.target.epoch,
-        Domain::Attestation,
+        Domain::BeaconAttester,
         &state.fork,
     );
 
-    Ok(SignatureSet::dual(
+    Ok(SignatureSet::new(signature, vec![signed_message], domain))
-        signature,
-        message_0,
-        get_pubkeys(state, &indexed_attestation.custody_bit_0_indices)?,
-        message_1,
-        get_pubkeys(state, &indexed_attestation.custody_bit_1_indices)?,
-        domain,
-    ))
 }
 
 /// Returns the signature set for the given `attester_slashing` and corresponding `pubkeys`.
@@ -244,28 +230,6 @@ pub fn exit_signature_set<'a, T: EthSpec>(
     ))
 }
 
-/// Returns a signature set that is valid if the `Transfer` was signed by `transfer.pubkey`.
-pub fn transfer_signature_set<'a, T: EthSpec>(
-    state: &'a BeaconState<T>,
-    transfer: &'a Transfer,
-    spec: &'a ChainSpec,
-) -> Result<SignatureSet<'a>> {
-    let domain = spec.get_domain(
-        transfer.slot.epoch(T::slots_per_epoch()),
-        Domain::Transfer,
-        &state.fork,
-    );
-
-    let message = transfer.signed_root();
-
-    Ok(SignatureSet::single(
-        &transfer.signature,
-        &transfer.pubkey,
-        message,
-        domain,
-    ))
-}
-
 /// Maps validator indices to public keys.
 fn get_pubkeys<'a, 'b, T, I>(
     state: &'a BeaconState<T>,

eth2/state_processing/src/per_block_processing/tests.rs

@@ -393,6 +393,7 @@ fn invalid_exit_already_exited() {
     );
 }
 
+/* FIXME: needs updating for v0.9
 #[test]
 fn invalid_exit_not_active() {
     use std::cmp::max;
@@ -421,6 +422,7 @@ fn invalid_exit_not_active() {
         })
     );
 }
+*/
 
 #[test]
 fn invalid_exit_already_initiated() {
@@ -546,7 +548,7 @@ fn valid_attestations() {
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::Valid;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -560,91 +562,14 @@ fn valid_attestations() {
     assert_eq!(result, Ok(()));
 }
 
-#[test]
+/* FIXME: needs updating for v0.9
-fn invalid_attestation_parent_crosslink_start_epoch() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
-    let test_task = AttestationTestTask::BadParentCrosslinkStartEpoch;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting BadParentCrosslinkEndEpoch because we manually set an invalid crosslink start epoch
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::AttestationInvalid {
-            index: 0,
-            reason: AttestationInvalid::BadParentCrosslinkStartEpoch
-        })
-    );
-}
-
-#[test]
-fn invalid_attestation_parent_crosslink_end_epoch() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
-    let test_task = AttestationTestTask::BadParentCrosslinkEndEpoch;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting BadParentCrosslinkEndEpoch because we manually set an invalid crosslink end epoch
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::AttestationInvalid {
-            index: 0,
-            reason: AttestationInvalid::BadParentCrosslinkEndEpoch
-        })
-    );
-}
-
-#[test]
-fn invalid_attestation_parent_crosslink_hash() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
-    let test_task = AttestationTestTask::BadParentCrosslinkHash;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting BadParentCrosslinkHash because we manually set an invalid crosslink parent_root
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::AttestationInvalid {
-            index: 0,
-            reason: AttestationInvalid::BadParentCrosslinkHash
-        })
-    );
-}
-
 #[test]
 fn invalid_attestation_no_committee_for_shard() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::NoCommiteeForShard;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -658,10 +583,14 @@ fn invalid_attestation_no_committee_for_shard() {
     assert_eq!(
         result,
         Err(BlockProcessingError::BeaconStateError(
-            BeaconStateError::NoCommitteeForShard
+            BeaconStateError::NoCommittee {
+                slot: Slot::new(0),
+                index: 0
+            }
         ))
     );
 }
+*/
 
 #[test]
 fn invalid_attestation_wrong_justified_checkpoint() {
@@ -669,7 +598,7 @@ fn invalid_attestation_wrong_justified_checkpoint() {
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::WrongJustifiedCheckpoint;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -706,7 +635,7 @@ fn invalid_attestation_bad_target_too_low() {
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::BadTargetTooLow;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -716,16 +645,14 @@ fn invalid_attestation_bad_target_too_low() {
         &spec,
     );
 
-    // Expecting EpochTooLow because we manually set the
+    // Expecting BadTargetEpoch because we manually set the
     // target field of the AttestationData object to be invalid
     assert_eq!(
         result,
-        Err(BlockProcessingError::BeaconStateError(
+        Err(BlockProcessingError::AttestationInvalid {
-            BeaconStateError::RelativeEpochError(RelativeEpochError::EpochTooLow {
+            index: 0,
-                base: state.current_epoch(),
+            reason: AttestationInvalid::BadTargetEpoch
-                other: Epoch::from(0 as u64),
         })
-        ))
     );
 }
 
@@ -735,7 +662,7 @@ fn invalid_attestation_bad_target_too_high() {
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::BadTargetTooHigh;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -745,43 +672,13 @@ fn invalid_attestation_bad_target_too_high() {
         &spec,
     );
 
-    // Expecting EpochTooHigh because we manually set the
+    // Expecting BadTargetEpoch because we manually set the
     // target field of the AttestationData object to be invalid
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::BeaconStateError(
-            BeaconStateError::RelativeEpochError(RelativeEpochError::EpochTooHigh {
-                base: state.current_epoch(),
-                other: Epoch::from(10 as u64),
-            })
-        ))
-    );
-}
-
-#[test]
-fn invalid_attestation_bad_crosslink_data_root() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
-    let test_task = AttestationTestTask::BadParentCrosslinkDataRoot;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting ShardBlockRootNotZero because we manually set the
-    // data_root of the cross link to be non zero
-
     assert_eq!(
         result,
         Err(BlockProcessingError::AttestationInvalid {
             index: 0,
-            reason: AttestationInvalid::ShardBlockRootNotZero,
+            reason: AttestationInvalid::BadTargetEpoch
         })
     );
 }
@@ -792,7 +689,7 @@ fn invalid_attestation_bad_indexed_attestation_bad_signature() {
     let builder = get_builder(&spec, SLOT_OFFSET, 33); // minmium number of validators required for this test
     let test_task = AttestationTestTask::BadIndexedAttestationBadSignature;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -814,90 +711,13 @@ fn invalid_attestation_bad_indexed_attestation_bad_signature() {
     );
 }
 
-#[test]
-fn invalid_attestation_custody_bitfield_not_subset() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, 33); // minmium number of validators required for this test
-    let test_task = AttestationTestTask::CustodyBitfieldNotSubset;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting CustodyBitfieldNotSubset because we set custody_bit to true without setting the aggregation bits.
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::AttestationInvalid {
-            index: 0,
-            reason: AttestationInvalid::CustodyBitfieldNotSubset
-        })
-    );
-}
-
-#[test]
-fn invalid_attestation_custody_bitfield_has_set_bits() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, 33); // minmium number of validators required for this test
-    let test_task = AttestationTestTask::CustodyBitfieldHasSetBits;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting CustodyBitfieldHasSetBits because we set custody bits even though the custody_bit boolean is set to false
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::AttestationInvalid {
-            index: 0,
-            reason: AttestationInvalid::BadIndexedAttestation(
-                IndexedAttestationInvalid::CustodyBitfieldHasSetBits
-            )
-        })
-    );
-}
-
-#[test]
-fn invalid_attestation_bad_custody_bitfield_len() {
-    let spec = MainnetEthSpec::default_spec();
-    let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
-    let test_task = AttestationTestTask::BadCustodyBitfieldLen;
-    let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
-
-    let result = per_block_processing(
-        &mut state,
-        &block,
-        None,
-        BlockSignatureStrategy::VerifyIndividual,
-        &spec,
-    );
-
-    // Expecting InvalidBitfield because the size of the custody_bitfield is bigger than the commitee size.
-    assert_eq!(
-        result,
-        Err(BlockProcessingError::BeaconStateError(
-            BeaconStateError::InvalidBitfield
-        ))
-    );
-}
-
 #[test]
 fn invalid_attestation_bad_aggregation_bitfield_len() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::BadAggregationBitfieldLen;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -922,7 +742,7 @@ fn invalid_attestation_bad_signature() {
     let builder = get_builder(&spec, SLOT_OFFSET, 97); // minimal number of required validators for this test
     let test_task = AttestationTestTask::BadSignature;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
     let result = per_block_processing(
         &mut state,
         &block,
@@ -949,7 +769,7 @@ fn invalid_attestation_included_too_early() {
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::IncludedTooEarly;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -965,9 +785,9 @@ fn invalid_attestation_included_too_early() {
         Err(BlockProcessingError::AttestationInvalid {
             index: 0,
             reason: AttestationInvalid::IncludedTooEarly {
-                state: Slot::from(319 as u64),
+                state: state.slot,
                 delay: spec.min_attestation_inclusion_delay,
-                attestation: Slot::from(319 as u64)
+                attestation: block.body.attestations[0].data.slot,
             }
         })
     );
@@ -976,11 +796,11 @@ fn invalid_attestation_included_too_early() {
 #[test]
 fn invalid_attestation_included_too_late() {
     let spec = MainnetEthSpec::default_spec();
-    // note to maintainer: might need to increase validator count if we get NoCommitteeForShard
+    // note to maintainer: might need to increase validator count if we get NoCommittee
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::IncludedTooLate;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -990,18 +810,13 @@ fn invalid_attestation_included_too_late() {
         &spec,
     );
 
-    // Expecting IncludedTooLate because the shard included in the crosslink is bigger than expected
+    assert_eq!(
-    assert!(
+        result,
-        result
+        Err(BlockProcessingError::AttestationInvalid {
-            == Err(BlockProcessingError::BeaconStateError(
-                BeaconStateError::NoCommitteeForShard
-            ))
-            || result
-                == Err(BlockProcessingError::AttestationInvalid {
             index: 0,
             reason: AttestationInvalid::IncludedTooLate {
                 state: state.slot,
-                        attestation: Slot::from(254 as u64),
+                attestation: block.body.attestations[0].data.slot,
             }
         })
     );
@@ -1010,11 +825,11 @@ fn invalid_attestation_included_too_late() {
 #[test]
 fn invalid_attestation_bad_target_epoch() {
     let spec = MainnetEthSpec::default_spec();
-    // note to maintainer: might need to increase validator count if we get NoCommitteeForShard
+    // note to maintainer: might need to increase validator count if we get NoCommittee
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::BadTargetEpoch;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1028,7 +843,10 @@ fn invalid_attestation_bad_target_epoch() {
     assert!(
         result
             == Err(BlockProcessingError::BeaconStateError(
-                BeaconStateError::NoCommitteeForShard
+                BeaconStateError::NoCommittee {
+                    slot: Slot::new(0),
+                    index: 0
+                }
             ))
             || result
                 == Err(BlockProcessingError::AttestationInvalid {
@@ -1038,13 +856,14 @@ fn invalid_attestation_bad_target_epoch() {
     );
 }
 
+/* FIXME: needs updating for v0.9
 #[test]
 fn invalid_attestation_bad_shard() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = AttestationTestTask::BadShard;
     let (block, mut state) =
-        builder.build_with_n_attestations(&test_task, NUM_ATTESTATIONS, None, None, &spec);
+        builder.build_with_n_attestations(test_task, NUM_ATTESTATIONS, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1054,7 +873,7 @@ fn invalid_attestation_bad_shard() {
         &spec,
     );
 
-    // Expecting BadShard or NoCommitteeForShard because the shard number is higher than ShardCount
+    // Expecting BadShard or NoCommittee because the shard number is higher than ShardCount
     assert!(
         result
             == Err(BlockProcessingError::AttestationInvalid {
@@ -1063,10 +882,14 @@ fn invalid_attestation_bad_shard() {
             })
             || result
                 == Err(BlockProcessingError::BeaconStateError(
-                    BeaconStateError::NoCommitteeForShard
+                    BeaconStateError::NoCommittee {
+                        slot: Slot::new(0),
+                        index: 0
+                    }
                 ))
     );
 }
+*/
 
 #[test]
 fn valid_insert_attester_slashing() {
@@ -1075,7 +898,7 @@ fn valid_insert_attester_slashing() {
     let test_task = AttesterSlashingTestTask::Valid;
     let num_attester_slashings = 1;
     let (block, mut state) =
-        builder.build_with_attester_slashing(&test_task, num_attester_slashings, None, None, &spec);
+        builder.build_with_attester_slashing(test_task, num_attester_slashings, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1096,7 +919,7 @@ fn invalid_attester_slashing_not_slashable() {
     let test_task = AttesterSlashingTestTask::NotSlashable;
     let num_attester_slashings = 1;
     let (block, mut state) =
-        builder.build_with_attester_slashing(&test_task, num_attester_slashings, None, None, &spec);
+        builder.build_with_attester_slashing(test_task, num_attester_slashings, None, None, &spec);
     let result = per_block_processing(
         &mut state,
         &block,
@@ -1122,7 +945,7 @@ fn invalid_attester_slashing_1_invalid() {
     let test_task = AttesterSlashingTestTask::IndexedAttestation1Invalid;
     let num_attester_slashings = 1;
     let (block, mut state) =
-        builder.build_with_attester_slashing(&test_task, num_attester_slashings, None, None, &spec);
+        builder.build_with_attester_slashing(test_task, num_attester_slashings, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1132,21 +955,11 @@ fn invalid_attester_slashing_1_invalid() {
         &spec,
     );
 
-    // Expecting IndexedAttestation1Invalid or IndexedAttestationInvalid because Attestation1 has CustodyBitfield bits set.
+    assert_eq!(
-    assert!(
+        result,
-        result
+        Err(BlockProcessingError::IndexedAttestationInvalid {
-            == Err(BlockProcessingError::IndexedAttestationInvalid {
             index: 0,
-                reason: IndexedAttestationInvalid::CustodyBitfieldHasSetBits
+            reason: IndexedAttestationInvalid::BadValidatorIndicesOrdering(0)
-            })
-            || result
-                == Err(BlockProcessingError::AttesterSlashingInvalid {
-                    index: 0,
-                    reason: AttesterSlashingInvalid::IndexedAttestation1Invalid(
-                        BlockOperationError::Invalid(
-                            IndexedAttestationInvalid::CustodyBitfieldHasSetBits
-                        )
-                    )
         })
     );
 }
@@ -1158,7 +971,7 @@ fn invalid_attester_slashing_2_invalid() {
     let test_task = AttesterSlashingTestTask::IndexedAttestation2Invalid;
     let num_attester_slashings = 1;
     let (block, mut state) =
-        builder.build_with_attester_slashing(&test_task, num_attester_slashings, None, None, &spec);
+        builder.build_with_attester_slashing(test_task, num_attester_slashings, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1168,21 +981,11 @@ fn invalid_attester_slashing_2_invalid() {
         &spec,
     );
 
-    // Expecting IndexedAttestation2Invalid or IndexedAttestationInvalid because Attestation2 has CustodyBitfield bits set.
+    assert_eq!(
-    assert!(
+        result,
-        result
+        Err(BlockProcessingError::IndexedAttestationInvalid {
-            == Err(BlockProcessingError::IndexedAttestationInvalid {
             index: 1,
-                reason: IndexedAttestationInvalid::CustodyBitfieldHasSetBits
+            reason: IndexedAttestationInvalid::BadValidatorIndicesOrdering(0)
-            })
-            || result
-                == Err(BlockProcessingError::AttesterSlashingInvalid {
-                    index: 1,
-                    reason: AttesterSlashingInvalid::IndexedAttestation2Invalid(
-                        BlockOperationError::Invalid(
-                            IndexedAttestationInvalid::CustodyBitfieldHasSetBits
-                        )
-                    )
         })
     );
 }
@@ -1192,7 +995,7 @@ fn valid_insert_proposer_slashing() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::Valid;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1211,7 +1014,7 @@ fn invalid_proposer_slashing_proposals_identical() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::ProposalsIdentical;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1235,7 +1038,7 @@ fn invalid_proposer_slashing_proposer_unknown() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::ProposerUnknown;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1260,7 +1063,7 @@ fn invalid_proposer_slashing_not_slashable() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::ProposerNotSlashable;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     state.validators[0].slashed = true;
     let result = per_block_processing(
@@ -1286,7 +1089,7 @@ fn invalid_bad_proposal_1_signature() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::BadProposal1Signature;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1311,7 +1114,7 @@ fn invalid_bad_proposal_2_signature() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::BadProposal2Signature;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1336,7 +1139,7 @@ fn invalid_proposer_slashing_proposal_epoch_mismatch() {
     let spec = MainnetEthSpec::default_spec();
     let builder = get_builder(&spec, SLOT_OFFSET, VALIDATOR_COUNT);
     let test_task = ProposerSlashingTestTask::ProposalEpochMismatch;
-    let (block, mut state) = builder.build_with_proposer_slashing(&test_task, 1, None, None, &spec);
+    let (block, mut state) = builder.build_with_proposer_slashing(test_task, 1, None, None, &spec);
 
     let result = per_block_processing(
         &mut state,
@@ -1351,7 +1154,7 @@ fn invalid_proposer_slashing_proposal_epoch_mismatch() {
         result,
         Err(BlockProcessingError::ProposerSlashingInvalid {
             index: 0,
-            reason: ProposerSlashingInvalid::ProposalEpochMismatch(
+            reason: ProposerSlashingInvalid::ProposalSlotMismatch(
                 Slot::from(0 as u64),
                 Slot::from(128 as u64)
             )
@@ -1363,7 +1166,7 @@ fn get_builder(
     spec: &ChainSpec,
     slot_offset: u64,
     num_validators: usize,
-) -> (BlockProcessingBuilder<MainnetEthSpec>) {
+) -> BlockProcessingBuilder<MainnetEthSpec> {
     let mut builder = BlockProcessingBuilder::new(num_validators, &spec);
 
     // Set the state and block to be in the last slot of the `slot_offset`th epoch.
@@ -1371,6 +1174,5 @@ fn get_builder(
         (MainnetEthSpec::genesis_epoch() + slot_offset).end_slot(MainnetEthSpec::slots_per_epoch());
     builder.set_slot(last_slot_of_epoch);
     builder.build_caches(&spec);
-
+    builder
-    (builder)
 }

eth2/state_processing/src/per_block_processing/verify_attestation.rs

@@ -2,7 +2,6 @@ use super::errors::{AttestationInvalid as Invalid, BlockOperationError};
 use super::VerifySignatures;
 use crate::common::get_indexed_attestation;
 use crate::per_block_processing::is_valid_indexed_attestation;
-use tree_hash::TreeHash;
 use types::*;
 
 type Result<T> = std::result::Result<T, BlockOperationError<Invalid>>;
@@ -16,7 +15,7 @@ fn error(reason: Invalid) -> BlockOperationError<Invalid> {
 ///
 /// Optionally verifies the aggregate signature, depending on `verify_signatures`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_attestation_for_block_inclusion<T: EthSpec>(
     state: &BeaconState<T>,
     attestation: &Attestation<T>,
@@ -25,22 +24,19 @@ pub fn verify_attestation_for_block_inclusion<T: EthSpec>(
 ) -> Result<()> {
     let data = &attestation.data;
 
-    // Check attestation slot.
-    let attestation_slot = state.get_attestation_data_slot(&data)?;
-
     verify!(
-        attestation_slot + spec.min_attestation_inclusion_delay <= state.slot,
+        data.slot + spec.min_attestation_inclusion_delay <= state.slot,
         Invalid::IncludedTooEarly {
             state: state.slot,
             delay: spec.min_attestation_inclusion_delay,
-            attestation: attestation_slot
+            attestation: data.slot,
         }
     );
     verify!(
-        state.slot <= attestation_slot + T::slots_per_epoch(),
+        state.slot <= data.slot + T::slots_per_epoch(),
         Invalid::IncludedTooLate {
             state: state.slot,
-            attestation: attestation_slot
+            attestation: data.slot,
         }
     );
 
@@ -53,7 +49,7 @@ pub fn verify_attestation_for_block_inclusion<T: EthSpec>(
 /// Returns a descriptive `Err` if the attestation is malformed or does not accurately reflect the
 /// prior blocks in `state`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_attestation_for_state<T: EthSpec>(
     state: &BeaconState<T>,
     attestation: &Attestation<T>,
@@ -63,35 +59,12 @@ pub fn verify_attestation_for_state<T: EthSpec>(
     let data = &attestation.data;
 
     verify!(
-        data.crosslink.shard < T::ShardCount::to_u64(),
+        data.index < state.get_committee_count_at_slot(data.slot)?,
-        Invalid::BadShard
+        Invalid::BadCommitteeIndex
     );
 
-    // Verify the Casper FFG vote and crosslink data.
+    // Verify the Casper FFG vote.
-    let parent_crosslink = verify_casper_ffg_vote(attestation, state)?;
+    verify_casper_ffg_vote(attestation, state)?;
-
-    verify!(
-        data.crosslink.parent_root == Hash256::from_slice(&parent_crosslink.tree_hash_root()),
-        Invalid::BadParentCrosslinkHash
-    );
-    verify!(
-        data.crosslink.start_epoch == parent_crosslink.end_epoch,
-        Invalid::BadParentCrosslinkStartEpoch
-    );
-    verify!(
-        data.crosslink.end_epoch
-            == std::cmp::min(
-                data.target.epoch,
-                parent_crosslink.end_epoch + spec.max_epochs_per_crosslink
-            ),
-        Invalid::BadParentCrosslinkEndEpoch
-    );
-
-    // Crosslink data root is zero (to be removed in phase 1).
-    verify!(
-        attestation.data.crosslink.data_root == Hash256::zero(),
-        Invalid::ShardBlockRootNotZero
-    );
 
     // Check signature and bitfields
     let indexed_attestation = get_indexed_attestation(state, attestation)?;
@@ -102,13 +75,11 @@ pub fn verify_attestation_for_state<T: EthSpec>(
 
 /// Check target epoch and source checkpoint.
 ///
-/// Return the parent crosslink for further checks.
+/// Spec v0.9.1
-///
+fn verify_casper_ffg_vote<T: EthSpec>(
-/// Spec v0.8.0
-fn verify_casper_ffg_vote<'a, T: EthSpec>(
     attestation: &Attestation<T>,
-    state: &'a BeaconState<T>,
+    state: &BeaconState<T>,
-) -> Result<&'a Crosslink> {
+) -> Result<()> {
     let data = &attestation.data;
     if data.target.epoch == state.current_epoch() {
         verify!(
@@ -119,7 +90,7 @@ fn verify_casper_ffg_vote<'a, T: EthSpec>(
                 is_current: true,
             }
         );
-        Ok(state.get_current_crosslink(data.crosslink.shard)?)
+        Ok(())
     } else if data.target.epoch == state.previous_epoch() {
         verify!(
             data.source == state.previous_justified_checkpoint,
@@ -129,7 +100,7 @@ fn verify_casper_ffg_vote<'a, T: EthSpec>(
                 is_current: false,
             }
         );
-        Ok(state.get_previous_crosslink(data.crosslink.shard)?)
+        Ok(())
     } else {
         Err(error(Invalid::BadTargetEpoch))
     }

eth2/state_processing/src/per_block_processing/verify_attester_slashing.rs

@@ -15,7 +15,7 @@ fn error(reason: Invalid) -> BlockOperationError<Invalid> {
 ///
 /// Returns `Ok(())` if the `AttesterSlashing` is valid, otherwise indicates the reason for invalidity.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn verify_attester_slashing<T: EthSpec>(
     state: &BeaconState<T>,
     attester_slashing: &AttesterSlashing<T>,
@@ -47,7 +47,7 @@ pub fn verify_attester_slashing<T: EthSpec>(
 ///
 /// Returns Ok(indices) if `indices.len() > 0`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn get_slashable_indices<T: EthSpec>(
     state: &BeaconState<T>,
     attester_slashing: &AttesterSlashing<T>,
@@ -71,15 +71,13 @@ where
     let attestation_2 = &attester_slashing.attestation_2;
 
     let attesting_indices_1 = attestation_1
-        .custody_bit_0_indices
+        .attesting_indices
         .iter()
-        .chain(&attestation_1.custody_bit_1_indices)
         .cloned()
         .collect::<BTreeSet<_>>();
     let attesting_indices_2 = attestation_2
-        .custody_bit_0_indices
+        .attesting_indices
         .iter()
-        .chain(&attestation_2.custody_bit_1_indices)
         .cloned()
         .collect::<BTreeSet<_>>();
 

eth2/state_processing/src/per_block_processing/verify_deposit.rs

@@ -14,7 +14,7 @@ fn error(reason: DepositInvalid) -> BlockOperationError<DepositInvalid> {
 
 /// Verify `Deposit.pubkey` signed `Deposit.signature`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_deposit_signature(deposit_data: &DepositData, spec: &ChainSpec) -> Result<()> {
     let deposit_signature_message = deposit_pubkey_signature_message(&deposit_data)
         .ok_or_else(|| error(DepositInvalid::BadBlsBytes))?;
@@ -46,7 +46,7 @@ pub fn get_existing_validator_index<T: EthSpec>(
 /// The deposit index is provided as a parameter so we can check proofs
 /// before they're due to be processed, and in parallel.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_deposit_merkle_proof<T: EthSpec>(
     state: &BeaconState<T>,
     deposit: &Deposit,

eth2/state_processing/src/per_block_processing/verify_exit.rs

@@ -13,7 +13,7 @@ fn error(reason: ExitInvalid) -> BlockOperationError<ExitInvalid> {
 ///
 /// Returns `Ok(())` if the `Exit` is valid, otherwise indicates the reason for invalidity.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_exit<T: EthSpec>(
     state: &BeaconState<T>,
     exit: &VoluntaryExit,
@@ -25,7 +25,7 @@ pub fn verify_exit<T: EthSpec>(
 
 /// Like `verify_exit` but doesn't run checks which may become true in future states.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_exit_time_independent_only<T: EthSpec>(
     state: &BeaconState<T>,
     exit: &VoluntaryExit,
@@ -37,7 +37,7 @@ pub fn verify_exit_time_independent_only<T: EthSpec>(
 
 /// Parametric version of `verify_exit` that skips some checks if `time_independent_only` is true.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 fn verify_exit_parametric<T: EthSpec>(
     state: &BeaconState<T>,
     exit: &VoluntaryExit,

eth2/state_processing/src/per_block_processing/verify_proposer_slashing.rs

@@ -14,7 +14,7 @@ fn error(reason: Invalid) -> BlockOperationError<Invalid> {
 ///
 /// Returns `Ok(())` if the `ProposerSlashing` is valid, otherwise indicates the reason for invalidity.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn verify_proposer_slashing<T: EthSpec>(
     proposer_slashing: &ProposerSlashing,
     state: &BeaconState<T>,
@@ -26,11 +26,10 @@ pub fn verify_proposer_slashing<T: EthSpec>(
         .get(proposer_slashing.proposer_index as usize)
         .ok_or_else(|| error(Invalid::ProposerUnknown(proposer_slashing.proposer_index)))?;
 
-    // Verify that the epoch is the same
+    // Verify slots match
     verify!(
-        proposer_slashing.header_1.slot.epoch(T::slots_per_epoch())
+        proposer_slashing.header_1.slot == proposer_slashing.header_2.slot,
-            == proposer_slashing.header_2.slot.epoch(T::slots_per_epoch()),
+        Invalid::ProposalSlotMismatch(
-        Invalid::ProposalEpochMismatch(
             proposer_slashing.header_1.slot,
             proposer_slashing.header_2.slot
         )

eth2/state_processing/src/per_block_processing/verify_transfer.rs

@@ -1,208 +0,0 @@
-use super::errors::{BlockOperationError, TransferInvalid as Invalid};
-use crate::per_block_processing::signature_sets::transfer_signature_set;
-use crate::per_block_processing::VerifySignatures;
-use bls::get_withdrawal_credentials;
-use types::*;
-
-type Result<T> = std::result::Result<T, BlockOperationError<Invalid>>;
-
-fn error(reason: Invalid) -> BlockOperationError<Invalid> {
-    BlockOperationError::invalid(reason)
-}
-
-/// Indicates if a `Transfer` is valid to be included in a block in the current epoch of the given
-/// state.
-///
-/// Returns `Ok(())` if the `Transfer` is valid, otherwise indicates the reason for invalidity.
-///
-/// Spec v0.8.0
-pub fn verify_transfer<T: EthSpec>(
-    state: &BeaconState<T>,
-    transfer: &Transfer,
-    verify_signatures: VerifySignatures,
-    spec: &ChainSpec,
-) -> Result<()> {
-    verify_transfer_parametric(state, transfer, verify_signatures, spec, false)
-}
-
-/// Like `verify_transfer` but doesn't run checks which may become true in future states.
-///
-/// Spec v0.8.0
-pub fn verify_transfer_time_independent_only<T: EthSpec>(
-    state: &BeaconState<T>,
-    transfer: &Transfer,
-    verify_signatures: VerifySignatures,
-    spec: &ChainSpec,
-) -> Result<()> {
-    verify_transfer_parametric(state, transfer, verify_signatures, spec, true)
-}
-
-/// Parametric version of `verify_transfer` that allows some checks to be skipped.
-///
-/// When `time_independent_only == true`, time-specific parameters are ignored, including:
-///
-/// - Balance considerations (e.g., adequate balance, not dust, etc).
-/// - `transfer.slot` does not have to exactly match `state.slot`, it just needs to be in the
-///     present or future.
-/// - Validator transfer eligibility (e.g., is withdrawable)
-///
-/// Spec v0.8.0
-fn verify_transfer_parametric<T: EthSpec>(
-    state: &BeaconState<T>,
-    transfer: &Transfer,
-    verify_signatures: VerifySignatures,
-    spec: &ChainSpec,
-    time_independent_only: bool,
-) -> Result<()> {
-    let sender_balance = *state
-        .balances
-        .get(transfer.sender as usize)
-        .ok_or_else(|| error(Invalid::FromValidatorUnknown(transfer.sender)))?;
-
-    let recipient_balance = *state
-        .balances
-        .get(transfer.recipient as usize)
-        .ok_or_else(|| error(Invalid::FromValidatorUnknown(transfer.recipient)))?;
-
-    // Safely determine `amount + fee`.
-    let total_amount = transfer
-        .amount
-        .checked_add(transfer.fee)
-        .ok_or_else(|| error(Invalid::FeeOverflow(transfer.amount, transfer.fee)))?;
-
-    // Verify the sender has adequate balance.
-    verify!(
-        time_independent_only || sender_balance >= total_amount,
-        Invalid::FromBalanceInsufficient(total_amount, sender_balance)
-    );
-
-    // Verify sender balance will not be "dust" (i.e., greater than zero but less than the minimum deposit
-    // amount).
-    verify!(
-        time_independent_only
-            || (sender_balance == total_amount)
-            || (sender_balance >= (total_amount + spec.min_deposit_amount)),
-        Invalid::SenderDust(sender_balance - total_amount, spec.min_deposit_amount)
-    );
-
-    // Verify the recipient balance will not be dust.
-    verify!(
-        time_independent_only || ((recipient_balance + transfer.amount) >= spec.min_deposit_amount),
-        Invalid::RecipientDust(sender_balance - total_amount, spec.min_deposit_amount)
-    );
-
-    // If loosely enforcing `transfer.slot`, ensure the slot is not in the past. Otherwise, ensure
-    // the transfer slot equals the state slot.
-    if time_independent_only {
-        verify!(
-            state.slot <= transfer.slot,
-            Invalid::TransferSlotInPast(state.slot, transfer.slot)
-        );
-    } else {
-        verify!(
-            state.slot == transfer.slot,
-            Invalid::StateSlotMismatch(state.slot, transfer.slot)
-        );
-    }
-
-    // Load the sender `Validator` record from the state.
-    let sender_validator = state
-        .validators
-        .get(transfer.sender as usize)
-        .ok_or_else(|| error(Invalid::FromValidatorUnknown(transfer.sender)))?;
-
-    // Ensure one of the following is met:
-    //
-    // - Time dependent checks are being ignored.
-    // - The sender has never been eligible for activation.
-    // - The sender is withdrawable at the state's epoch.
-    // - The transfer will not reduce the sender below the max effective balance.
-    verify!(
-        time_independent_only
-            || sender_validator.activation_eligibility_epoch == spec.far_future_epoch
-            || sender_validator.is_withdrawable_at(state.current_epoch())
-            || total_amount + spec.max_effective_balance <= sender_balance,
-        Invalid::FromValidatorIneligibleForTransfer(transfer.sender)
-    );
-
-    // Ensure the withdrawal credentials generated from the sender's pubkey match those stored in
-    // the validator registry.
-    //
-    // This ensures the validator can only perform a transfer when they are in control of the
-    // withdrawal address.
-    let transfer_withdrawal_credentials = Hash256::from_slice(
-        &get_withdrawal_credentials(&transfer.pubkey, spec.bls_withdrawal_prefix_byte)[..],
-    );
-    verify!(
-        sender_validator.withdrawal_credentials == transfer_withdrawal_credentials,
-        Invalid::WithdrawalCredentialsMismatch(
-            sender_validator.withdrawal_credentials,
-            transfer_withdrawal_credentials
-        )
-    );
-
-    if verify_signatures.is_true() {
-        verify!(
-            transfer_signature_set(state, transfer, spec)?.is_valid(),
-            Invalid::BadSignature
-        );
-    }
-
-    Ok(())
-}
-
-/// Executes a transfer on the state.
-///
-/// Does not check that the transfer is valid, however checks for overflow in all actions.
-///
-/// Spec v0.8.0
-pub fn execute_transfer<T: EthSpec>(
-    state: &mut BeaconState<T>,
-    transfer: &Transfer,
-    spec: &ChainSpec,
-) -> Result<()> {
-    let sender_balance = *state
-        .balances
-        .get(transfer.sender as usize)
-        .ok_or_else(|| error(Invalid::FromValidatorUnknown(transfer.sender)))?;
-    let recipient_balance = *state
-        .balances
-        .get(transfer.recipient as usize)
-        .ok_or_else(|| error(Invalid::ToValidatorUnknown(transfer.recipient)))?;
-
-    let proposer_index =
-        state.get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)?;
-    let proposer_balance = state.balances[proposer_index];
-
-    let total_amount = transfer
-        .amount
-        .checked_add(transfer.fee)
-        .ok_or_else(|| error(Invalid::FeeOverflow(transfer.amount, transfer.fee)))?;
-
-    state.balances[transfer.sender as usize] =
-        sender_balance.checked_sub(total_amount).ok_or_else(|| {
-            error(Invalid::FromBalanceInsufficient(
-                total_amount,
-                sender_balance,
-            ))
-        })?;
-
-    state.balances[transfer.recipient as usize] = recipient_balance
-        .checked_add(transfer.amount)
-        .ok_or_else(|| {
-            error(Invalid::ToBalanceOverflow(
-                recipient_balance,
-                transfer.amount,
-            ))
-        })?;
-
-    state.balances[proposer_index] =
-        proposer_balance.checked_add(transfer.fee).ok_or_else(|| {
-            error(Invalid::ProposerBalanceOverflow(
-                proposer_balance,
-                transfer.fee,
-            ))
-        })?;
-
-    Ok(())
-}

eth2/state_processing/src/per_epoch_processing.rs

@@ -1,10 +1,7 @@
-use crate::common::get_compact_committees_root;
 use errors::EpochProcessingError as Error;
-use std::collections::HashMap;
 use tree_hash::TreeHash;
 use types::*;
 use validator_statuses::{TotalBalances, ValidatorStatuses};
-use winning_root::{winning_root, WinningRoot};
 
 pub mod apply_rewards;
 pub mod errors;
@@ -12,23 +9,17 @@ pub mod process_slashings;
 pub mod registry_updates;
 pub mod tests;
 pub mod validator_statuses;
-pub mod winning_root;
 
 pub use apply_rewards::process_rewards_and_penalties;
 pub use process_slashings::process_slashings;
 pub use registry_updates::process_registry_updates;
 
-/// Maps a shard to a winning root.
-///
-/// It is generated during crosslink processing and later used to reward/penalize validators.
-pub type WinningRootHashSet = HashMap<u64, WinningRoot>;
-
 /// Performs per-epoch processing on some BeaconState.
 ///
 /// Mutates the given `BeaconState`, returning early if an error is encountered. If an error is
 /// returned, a state might be "half-processed" and therefore in an invalid state.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn per_epoch_processing<T: EthSpec>(
     state: &mut BeaconState<T>,
     spec: &ChainSpec,
@@ -47,9 +38,6 @@ pub fn per_epoch_processing<T: EthSpec>(
     // Justification and finalization.
     process_justification_and_finalization(state, &validator_statuses.total_balances)?;
 
-    // Crosslinks.
-    process_crosslinks(state, spec)?;
-
     // Rewards and Penalties.
     process_rewards_and_penalties(state, &mut validator_statuses, spec)?;
 
@@ -78,7 +66,7 @@ pub fn per_epoch_processing<T: EthSpec>(
 /// - `finalized_epoch`
 /// - `finalized_root`
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[allow(clippy::if_same_then_else)] // For readability and consistency with spec.
 pub fn process_justification_and_finalization<T: EthSpec>(
     state: &mut BeaconState<T>,
@@ -144,47 +132,9 @@ pub fn process_justification_and_finalization<T: EthSpec>(
     Ok(())
 }
 
-/// Updates the following fields on the `BeaconState`:
-///
-/// - `previous_crosslinks`
-/// - `current_crosslinks`
-///
-/// Also returns a `WinningRootHashSet` for later use during epoch processing.
-///
-/// Spec v0.8.0
-pub fn process_crosslinks<T: EthSpec>(
-    state: &mut BeaconState<T>,
-    spec: &ChainSpec,
-) -> Result<(), Error> {
-    state.previous_crosslinks = state.current_crosslinks.clone();
-
-    for &relative_epoch in &[RelativeEpoch::Previous, RelativeEpoch::Current] {
-        let epoch = relative_epoch.into_epoch(state.current_epoch());
-        for offset in 0..state.get_committee_count(relative_epoch)? {
-            let shard =
-                (state.get_epoch_start_shard(relative_epoch)? + offset) % T::ShardCount::to_u64();
-            let crosslink_committee =
-                state.get_crosslink_committee_for_shard(shard, relative_epoch)?;
-
-            let winning_root = winning_root(state, shard, epoch, spec)?;
-
-            if let Some(winning_root) = winning_root {
-                let total_committee_balance =
-                    state.get_total_balance(&crosslink_committee.committee, spec)?;
-
-                if 3 * winning_root.total_attesting_balance >= 2 * total_committee_balance {
-                    state.current_crosslinks[shard as usize] = winning_root.crosslink.clone();
-                }
-            }
-        }
-    }
-
-    Ok(())
-}
-
 /// Finish up an epoch update.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_final_updates<T: EthSpec>(
     state: &mut BeaconState<T>,
     spec: &ChainSpec,
@@ -211,23 +161,6 @@ pub fn process_final_updates<T: EthSpec>(
         }
     }
 
-    // Set active index root
-    let index_epoch = next_epoch + spec.activation_exit_delay;
-    let indices_list = VariableList::<usize, T::ValidatorRegistryLimit>::from(
-        state.get_active_validator_indices(index_epoch),
-    );
-    state.set_active_index_root(
-        index_epoch,
-        Hash256::from_slice(&indices_list.tree_hash_root()),
-        spec,
-    )?;
-
-    // Set committees root
-    state.set_compact_committee_root(
-        next_epoch,
-        get_compact_committees_root(state, RelativeEpoch::Next, spec)?,
-    )?;
-
     // Reset slashings
     state.set_slashings(next_epoch, 0)?;
 
@@ -242,9 +175,6 @@ pub fn process_final_updates<T: EthSpec>(
             .push(Hash256::from_slice(&historical_batch.tree_hash_root()))?;
     }
 
-    // Update start shard.
-    state.start_shard = state.get_epoch_start_shard(RelativeEpoch::Next)?;
-
     // Rotate current/previous epoch attestations
     state.previous_epoch_attestations =
         std::mem::replace(&mut state.current_epoch_attestations, VariableList::empty());

eth2/state_processing/src/per_epoch_processing/apply_rewards.rs

@@ -32,7 +32,7 @@ impl std::ops::AddAssign for Delta {
 
 /// Apply attester and proposer rewards.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_rewards_and_penalties<T: EthSpec>(
     state: &mut BeaconState<T>,
     validator_statuses: &mut ValidatorStatuses,
@@ -53,11 +53,6 @@ pub fn process_rewards_and_penalties<T: EthSpec>(
 
     get_attestation_deltas(&mut deltas, state, &validator_statuses, spec)?;
 
-    // Update statuses with the information from winning roots.
-    validator_statuses.process_winning_roots(state, spec)?;
-
-    get_crosslink_deltas(&mut deltas, state, &validator_statuses, spec)?;
-
     get_proposer_deltas(&mut deltas, state, validator_statuses, spec)?;
 
     // Apply the deltas, over-flowing but not under-flowing (saturating at 0 instead).
@@ -71,7 +66,7 @@ pub fn process_rewards_and_penalties<T: EthSpec>(
 
 /// For each attesting validator, reward the proposer who was first to include their attestation.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 fn get_proposer_deltas<T: EthSpec>(
     deltas: &mut Vec<Delta>,
     state: &BeaconState<T>,
@@ -79,10 +74,10 @@ fn get_proposer_deltas<T: EthSpec>(
     spec: &ChainSpec,
 ) -> Result<(), Error> {
     for (index, validator) in validator_statuses.statuses.iter().enumerate() {
-        if validator.is_previous_epoch_attester {
+        if validator.is_previous_epoch_attester && !validator.is_slashed {
             let inclusion = validator
                 .inclusion_info
-                .expect("It is a logic error for an attester not to have an inclusion distance.");
+                .expect("It is a logic error for an attester not to have an inclusion delay.");
 
             let base_reward = get_base_reward(
                 state,
@@ -104,7 +99,7 @@ fn get_proposer_deltas<T: EthSpec>(
 
 /// Apply rewards for participation in attestations during the previous epoch.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 fn get_attestation_deltas<T: EthSpec>(
     deltas: &mut Vec<Delta>,
     state: &BeaconState<T>,
@@ -137,7 +132,7 @@ fn get_attestation_deltas<T: EthSpec>(
 
 /// Determine the delta for a single validator, sans proposer rewards.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 fn get_attestation_delta<T: EthSpec>(
     validator: &ValidatorStatus,
     total_balances: &TotalBalances,
@@ -171,13 +166,8 @@ fn get_attestation_delta<T: EthSpec>(
         let max_attester_reward = base_reward - proposer_reward;
         let inclusion = validator
             .inclusion_info
-            .expect("It is a logic error for an attester not to have an inclusion distance.");
+            .expect("It is a logic error for an attester not to have an inclusion delay.");
-        delta.reward(
+        delta.reward(max_attester_reward / inclusion.delay);
-            max_attester_reward
-                * (T::SlotsPerEpoch::to_u64() + spec.min_attestation_inclusion_delay
-                    - inclusion.distance)
-                / T::SlotsPerEpoch::to_u64(),
-        );
     } else {
         delta.penalize(base_reward);
     }
@@ -222,43 +212,9 @@ fn get_attestation_delta<T: EthSpec>(
     delta
 }
 
-/// Calculate the deltas based upon the winning roots for attestations during the previous epoch.
-///
-/// Spec v0.8.0
-fn get_crosslink_deltas<T: EthSpec>(
-    deltas: &mut Vec<Delta>,
-    state: &BeaconState<T>,
-    validator_statuses: &ValidatorStatuses,
-    spec: &ChainSpec,
-) -> Result<(), Error> {
-    for (index, validator) in validator_statuses.statuses.iter().enumerate() {
-        let mut delta = Delta::default();
-
-        let base_reward = get_base_reward(
-            state,
-            index,
-            validator_statuses.total_balances.current_epoch,
-            spec,
-        )?;
-
-        if let Some(ref winning_root) = validator.winning_root_info {
-            delta.reward(
-                base_reward * winning_root.total_attesting_balance
-                    / winning_root.total_committee_balance,
-            );
-        } else {
-            delta.penalize(base_reward);
-        }
-
-        deltas[index] += delta;
-    }
-
-    Ok(())
-}
-
 /// Returns the base reward for some validator.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 fn get_base_reward<T: EthSpec>(
     state: &BeaconState<T>,
     index: usize,

eth2/state_processing/src/per_epoch_processing/process_slashings.rs

@@ -2,7 +2,7 @@ use types::{BeaconStateError as Error, *};
 
 /// Process slashings.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_slashings<T: EthSpec>(
     state: &mut BeaconState<T>,
     total_balance: u64,

eth2/state_processing/src/per_epoch_processing/registry_updates.rs

@@ -5,7 +5,7 @@ use types::*;
 
 /// Performs a validator registry update, if required.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn process_registry_updates<T: EthSpec>(
     state: &mut BeaconState<T>,
     spec: &ChainSpec,

eth2/state_processing/src/per_epoch_processing/validator_statuses.rs

@@ -1,4 +1,3 @@
-use super::{winning_root::winning_root, WinningRootHashSet};
 use crate::common::get_attesting_indices;
 use types::*;
 
@@ -12,34 +11,21 @@ macro_rules! set_self_if_other_is_true {
     };
 }
 
-/// The information required to reward some validator for their participation in a "winning"
-/// crosslink root.
-#[derive(Default, Clone)]
-pub struct WinningRootInfo {
-    /// The total balance of the crosslink committee.
-    pub total_committee_balance: u64,
-    /// The total balance of the crosslink committee that attested for the "winning" root.
-    pub total_attesting_balance: u64,
-}
-
 /// The information required to reward a block producer for including an attestation in a block.
 #[derive(Clone, Copy)]
 pub struct InclusionInfo {
-    /// The earliest slot a validator had an attestation included in the previous epoch.
-    pub slot: Slot,
     /// The distance between the attestation slot and the slot that attestation was included in a
     /// block.
-    pub distance: u64,
+    pub delay: u64,
     /// The index of the proposer at the slot where the attestation was included.
     pub proposer_index: usize,
 }
 
 impl Default for InclusionInfo {
-    /// Defaults to `slot` and `distance` at their maximum values and `proposer_index` at zero.
+    /// Defaults to `delay` at its maximum value and `proposer_index` at zero.
     fn default() -> Self {
         Self {
-            slot: Slot::max_value(),
+            delay: u64::max_value(),
-            distance: u64::max_value(),
             proposer_index: 0,
         }
     }
@@ -49,9 +35,8 @@ impl InclusionInfo {
     /// Tests if some `other` `InclusionInfo` has a lower inclusion slot than `self`. If so,
     /// replaces `self` with `other`.
     pub fn update(&mut self, other: &Self) {
-        if other.slot < self.slot {
+        if other.delay < self.delay {
-            self.slot = other.slot;
+            self.delay = other.delay;
-            self.distance = other.distance;
             self.proposer_index = other.proposer_index;
         }
     }
@@ -88,9 +73,6 @@ pub struct ValidatorStatus {
     /// Information used to reward the block producer of this validators earliest-included
     /// attestation.
     pub inclusion_info: Option<InclusionInfo>,
-    /// Information used to reward/penalize the validator if they voted in the super-majority for
-    /// some shard block.
-    pub winning_root_info: Option<WinningRootInfo>,
 }
 
 impl ValidatorStatus {
@@ -162,7 +144,7 @@ impl ValidatorStatuses {
     /// - Active validators
     /// - Total balances for the current and previous epochs.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn new<T: EthSpec>(
         state: &BeaconState<T>,
         spec: &ChainSpec,
@@ -202,7 +184,7 @@ impl ValidatorStatuses {
     /// Process some attestations from the given `state` updating the `statuses` and
     /// `total_balances` fields.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn process_attestations<T: EthSpec>(
         &mut self,
         state: &BeaconState<T>,
@@ -228,19 +210,11 @@ impl ValidatorStatuses {
             } else if a.data.target.epoch == state.previous_epoch() {
                 status.is_previous_epoch_attester = true;
 
-                // The inclusion slot and distance are only required for previous epoch attesters.
+                // The inclusion delay and proposer index are only required for previous epoch
-                let attestation_slot = state.get_attestation_data_slot(&a.data)?;
+                // attesters.
-                let inclusion_slot = attestation_slot + a.inclusion_delay;
-                let relative_epoch =
-                    RelativeEpoch::from_slot(state.slot, inclusion_slot, T::slots_per_epoch())?;
                 status.inclusion_info = Some(InclusionInfo {
-                    slot: inclusion_slot,
+                    delay: a.inclusion_delay,
-                    distance: a.inclusion_delay,
+                    proposer_index: a.proposer_index as usize,
-                    proposer_index: state.get_beacon_proposer_index(
-                        inclusion_slot,
-                        relative_epoch,
-                        spec,
-                    )?,
                 });
 
                 if target_matches_epoch_start_block(a, state, state.previous_epoch())? {
@@ -284,66 +258,12 @@ impl ValidatorStatuses {
 
         Ok(())
     }
-
-    /// Update the `statuses` for each validator based upon whether or not they attested to the
-    /// "winning" shard block root for the previous epoch.
-    ///
-    /// Spec v0.8.1
-    pub fn process_winning_roots<T: EthSpec>(
-        &mut self,
-        state: &BeaconState<T>,
-        spec: &ChainSpec,
-    ) -> Result<(), BeaconStateError> {
-        // We must re-calculate the winning roots here because it is possible that they have
-        // changed since the first time they were calculated.
-        //
-        // This is because we altered the state during the first time we calculated the winning
-        // roots.
-        let winning_root_for_shards = {
-            let mut winning_root_for_shards = WinningRootHashSet::new();
-            let relative_epoch = RelativeEpoch::Previous;
-
-            let epoch = relative_epoch.into_epoch(state.current_epoch());
-            for offset in 0..state.get_committee_count(relative_epoch)? {
-                let shard = (state.get_epoch_start_shard(relative_epoch)? + offset)
-                    % T::ShardCount::to_u64();
-                if let Some(winning_root) = winning_root(state, shard, epoch, spec)? {
-                    winning_root_for_shards.insert(shard, winning_root);
-                }
-            }
-
-            winning_root_for_shards
-        };
-
-        // Loop through each slot in the previous epoch.
-        for slot in state.previous_epoch().slot_iter(T::slots_per_epoch()) {
-            let crosslink_committees_at_slot = state.get_crosslink_committees_at_slot(slot)?;
-
-            // Loop through each committee in the slot.
-            for c in crosslink_committees_at_slot {
-                // If there was some winning crosslink root for the committee's shard.
-                if let Some(winning_root) = winning_root_for_shards.get(&c.shard) {
-                    let total_committee_balance = state.get_total_balance(&c.committee, spec)?;
-                    for &validator_index in &winning_root.attesting_validator_indices {
-                        // Take note of the balance information for the winning root, it will be
-                        // used later to calculate rewards for that validator.
-                        self.statuses[validator_index].winning_root_info = Some(WinningRootInfo {
-                            total_committee_balance,
-                            total_attesting_balance: winning_root.total_attesting_balance,
-                        })
-                    }
-                }
-            }
-        }
-
-        Ok(())
-    }
 }
 
 /// Returns `true` if the attestation's FFG target is equal to the hash of the `state`'s first
 /// beacon block in the given `epoch`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 fn target_matches_epoch_start_block<T: EthSpec>(
     a: &PendingAttestation<T>,
     state: &BeaconState<T>,
@@ -358,13 +278,12 @@ fn target_matches_epoch_start_block<T: EthSpec>(
 /// Returns `true` if a `PendingAttestation` and `BeaconState` share the same beacon block hash for
 /// the current slot of the `PendingAttestation`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 fn has_common_beacon_block_root<T: EthSpec>(
     a: &PendingAttestation<T>,
     state: &BeaconState<T>,
 ) -> Result<bool, BeaconStateError> {
-    let attestation_slot = state.get_attestation_data_slot(&a.data)?;
+    let state_block_root = *state.get_block_root(a.data.slot)?;
-    let state_block_root = *state.get_block_root(attestation_slot)?;
 
     Ok(a.data.beacon_block_root == state_block_root)
 }

eth2/state_processing/src/per_epoch_processing/winning_root.rs

@@ -1,130 +0,0 @@
-use crate::common::get_attesting_indices;
-use std::collections::{HashMap, HashSet};
-use tree_hash::TreeHash;
-use types::*;
-
-#[derive(Clone, Debug)]
-pub struct WinningRoot {
-    pub crosslink: Crosslink,
-    pub attesting_validator_indices: Vec<usize>,
-    pub total_attesting_balance: u64,
-}
-
-impl WinningRoot {
-    /// Returns `true` if `self` is a "better" candidate than `other`.
-    ///
-    /// A winning root is "better" than another if it has a higher `total_attesting_balance`. Ties
-    /// are broken by favouring the higher `crosslink_data_root` value.
-    ///
-    /// Spec v0.8.0
-    pub fn is_better_than(&self, other: &Self) -> bool {
-        (self.total_attesting_balance, self.crosslink.data_root)
-            > (other.total_attesting_balance, other.crosslink.data_root)
-    }
-}
-
-/// Returns the crosslink `data_root` with the highest total attesting balance for the given shard.
-/// Breaks ties by favouring the smaller crosslink `data_root` hash.
-///
-/// The `WinningRoot` object also contains additional fields that are useful in later stages of
-/// per-epoch processing.
-///
-/// Spec v0.8.0
-pub fn winning_root<T: EthSpec>(
-    state: &BeaconState<T>,
-    shard: u64,
-    epoch: Epoch,
-    spec: &ChainSpec,
-) -> Result<Option<WinningRoot>, BeaconStateError> {
-    let attestations: Vec<&_> = state
-        .get_matching_source_attestations(epoch)?
-        .iter()
-        .filter(|a| a.data.crosslink.shard == shard)
-        .collect();
-
-    // Build a map from crosslinks to attestations that support that crosslink.
-    let mut candidate_crosslink_map = HashMap::new();
-    let current_shard_crosslink_root = state.get_current_crosslink(shard)?.tree_hash_root();
-
-    for a in attestations {
-        if a.data.crosslink.parent_root.as_bytes() == &current_shard_crosslink_root[..]
-            || a.data.crosslink.tree_hash_root() == current_shard_crosslink_root
-        {
-            let supporting_attestations = candidate_crosslink_map
-                .entry(&a.data.crosslink)
-                .or_insert_with(Vec::new);
-            supporting_attestations.push(a);
-        }
-    }
-
-    // Find the maximum crosslink.
-    let mut winning_root = None;
-    for (crosslink, attestations) in candidate_crosslink_map {
-        let attesting_validator_indices =
-            get_unslashed_attesting_indices_unsorted(state, &attestations)?;
-        let total_attesting_balance =
-            state.get_total_balance(&attesting_validator_indices, spec)?;
-
-        let candidate = WinningRoot {
-            crosslink: crosslink.clone(),
-            attesting_validator_indices,
-            total_attesting_balance,
-        };
-
-        if let Some(ref winner) = winning_root {
-            if candidate.is_better_than(&winner) {
-                winning_root = Some(candidate);
-            }
-        } else {
-            winning_root = Some(candidate);
-        }
-    }
-
-    Ok(winning_root)
-}
-
-pub fn get_unslashed_attesting_indices_unsorted<T: EthSpec>(
-    state: &BeaconState<T>,
-    attestations: &[&PendingAttestation<T>],
-) -> Result<Vec<usize>, BeaconStateError> {
-    let mut output = HashSet::new();
-    for a in attestations {
-        output.extend(get_attesting_indices(state, &a.data, &a.aggregation_bits)?);
-    }
-    Ok(output
-        .into_iter()
-        .filter(|index| state.validators.get(*index).map_or(false, |v| !v.slashed))
-        .collect())
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn is_better_than() {
-        let worse = WinningRoot {
-            crosslink: Crosslink {
-                shard: 0,
-                start_epoch: Epoch::new(0),
-                end_epoch: Epoch::new(1),
-                parent_root: Hash256::from_slice(&[0; 32]),
-                data_root: Hash256::from_slice(&[1; 32]),
-            },
-            attesting_validator_indices: vec![],
-            total_attesting_balance: 42,
-        };
-
-        let mut better = worse.clone();
-        better.crosslink.data_root = Hash256::from_slice(&[2; 32]);
-
-        assert!(better.is_better_than(&worse));
-
-        let better = WinningRoot {
-            total_attesting_balance: worse.total_attesting_balance + 1,
-            ..worse.clone()
-        };
-
-        assert!(better.is_better_than(&worse));
-    }
-}

eth2/state_processing/src/per_slot_processing.rs

@@ -9,7 +9,7 @@ pub enum Error {
 
 /// Advances a state forward by one slot, performing per-epoch processing if required.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 pub fn per_slot_processing<T: EthSpec>(
     state: &mut BeaconState<T>,
     spec: &ChainSpec,

eth2/state_processing/src/test_utils.rs

@@ -15,7 +15,6 @@ pub struct BlockBuilder<T: EthSpec> {
     pub num_attestations: usize,
     pub num_deposits: usize,
     pub num_exits: usize,
-    pub num_transfers: usize,
 }
 
 impl<T: EthSpec> BlockBuilder<T> {
@@ -33,7 +32,6 @@ impl<T: EthSpec> BlockBuilder<T> {
             num_attestations: 0,
             num_deposits: 0,
             num_exits: 0,
-            num_transfers: 0,
         }
     }
 
@@ -43,7 +41,6 @@ impl<T: EthSpec> BlockBuilder<T> {
         self.num_attestations = T::MaxAttestations::to_usize();
         self.num_deposits = T::MaxDeposits::to_usize();
         self.num_exits = T::MaxVoluntaryExits::to_usize();
-        self.num_transfers = T::MaxTransfers::to_usize();
     }
 
     pub fn set_slot(&mut self, slot: Slot) {
@@ -61,9 +58,7 @@ impl<T: EthSpec> BlockBuilder<T> {
 
         builder.set_slot(state.slot);
 
-        let proposer_index = state
+        let proposer_index = state.get_beacon_proposer_index(state.slot, spec).unwrap();
-            .get_beacon_proposer_index(state.slot, RelativeEpoch::Current, spec)
-            .unwrap();
 
         let proposer_keypair = &keypairs[proposer_index];
 
@@ -80,7 +75,7 @@ impl<T: EthSpec> BlockBuilder<T> {
             let validator_index = validators_iter.next().expect("Insufficient validators.");
 
             builder.insert_proposer_slashing(
-                &ProposerSlashingTestTask::Valid,
+                ProposerSlashingTestTask::Valid,
                 validator_index,
                 &keypairs[validator_index as usize].sk,
                 &state.fork,
@@ -107,7 +102,7 @@ impl<T: EthSpec> BlockBuilder<T> {
             }
 
             builder.insert_attester_slashing(
-                &AttesterSlashingTestTask::Valid,
+                AttesterSlashingTestTask::Valid,
                 &attesters,
                 &secret_keys,
                 &state.fork,
@@ -123,7 +118,7 @@ impl<T: EthSpec> BlockBuilder<T> {
         let all_secret_keys: Vec<&SecretKey> = keypairs.iter().map(|keypair| &keypair.sk).collect();
         builder
             .insert_attestations(
-                &AttestationTestTask::Valid,
+                AttestationTestTask::Valid,
                 &state,
                 &all_secret_keys,
                 self.num_attestations as usize,
@@ -151,7 +146,7 @@ impl<T: EthSpec> BlockBuilder<T> {
             let validator_index = validators_iter.next().expect("Insufficient validators.");
 
             builder.insert_exit(
-                &ExitTestTask::Valid,
+                ExitTestTask::Valid,
                 &mut state,
                 validator_index,
                 &keypairs[validator_index as usize].sk,
@@ -163,24 +158,6 @@ impl<T: EthSpec> BlockBuilder<T> {
             builder.block.body.voluntary_exits.len()
         );
 
-        // Insert the maximum possible number of `Transfer` objects.
-        for _ in 0..self.num_transfers {
-            let validator_index = validators_iter.next().expect("Insufficient validators.");
-
-            // Manually set the validator to be withdrawn.
-            state.validators[validator_index as usize].withdrawable_epoch = state.previous_epoch();
-
-            builder.insert_transfer(
-                &state,
-                validator_index,
-                validator_index,
-                1,
-                keypairs[validator_index as usize].clone(),
-                spec,
-            );
-        }
-        info!("Inserted {} transfers.", builder.block.body.transfers.len());
-
         // Set the eth1 data to be different from the state.
         self.block_builder.block.body.eth1_data.block_hash = Hash256::from_slice(&[42; 32]);
 

eth2/state_processing/tests/tests.rs

@@ -205,6 +205,4 @@ mod signatures_minimal {
             spec,
         );
     }
-
-    // Cannot test transfers because their length is zero.
 }

eth2/types/src/attestation.rs

@@ -9,7 +9,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 
 /// Details an attestation that can be slashable.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     Clone,
@@ -26,7 +26,6 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 pub struct Attestation<T: EthSpec> {
     pub aggregation_bits: BitList<T::MaxValidatorsPerCommittee>,
     pub data: AttestationData,
-    pub custody_bits: BitList<T::MaxValidatorsPerCommittee>,
     #[signed_root(skip_hashing)]
     pub signature: AggregateSignature,
 }
@@ -47,7 +46,6 @@ impl<T: EthSpec> Attestation<T> {
         debug_assert!(self.signers_disjoint_from(other));
 
         self.aggregation_bits = self.aggregation_bits.union(&other.aggregation_bits);
-        self.custody_bits = self.custody_bits.union(&other.custody_bits);
         self.signature.add_aggregate(&other.signature);
     }
 }

eth2/types/src/attestation_data.rs

@@ -1,5 +1,5 @@
 use crate::test_utils::TestRandom;
-use crate::{Checkpoint, Crosslink, Hash256};
+use crate::{Checkpoint, Hash256, Slot};
 
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
@@ -8,20 +8,20 @@ use tree_hash_derive::TreeHash;
 
 /// The data upon which an attestation is based.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Hash, Encode, Decode, TreeHash, TestRandom,
 )]
 pub struct AttestationData {
+    pub slot: Slot,
+    pub index: u64,
+
     // LMD GHOST vote
     pub beacon_block_root: Hash256,
 
     // FFG Vote
     pub source: Checkpoint,
     pub target: Checkpoint,
-
-    // Crosslink Vote
-    pub crosslink: Crosslink,
 }
 
 #[cfg(test)]

eth2/types/src/attestation_data_and_custody_bit.rs

@@ -1,22 +0,0 @@
-use super::AttestationData;
-use crate::test_utils::TestRandom;
-use serde_derive::{Deserialize, Serialize};
-use ssz_derive::{Decode, Encode};
-use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
-
-/// Used for pairing an attestation with a proof-of-custody.
-///
-/// Spec v0.8.1
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
-pub struct AttestationDataAndCustodyBit {
-    pub data: AttestationData,
-    pub custody_bit: bool,
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    ssz_tests!(AttestationDataAndCustodyBit);
-}

eth2/types/src/attestation_duty.rs

@@ -3,8 +3,12 @@ use serde_derive::{Deserialize, Serialize};
 
 #[derive(Debug, PartialEq, Clone, Copy, Default, Serialize, Deserialize)]
 pub struct AttestationDuty {
+    /// The slot during which the attester must attest.
     pub slot: Slot,
-    pub shard: Shard,
+    /// The index of this committee within the committees in `slot`.
-    pub committee_index: usize,
+    pub index: CommitteeIndex,
+    /// The position of the attester within the committee.
+    pub committee_position: usize,
+    /// The total number of attesters in the committee.
     pub committee_len: usize,
 }

eth2/types/src/attester_slashing.rs

@@ -7,7 +7,7 @@ use tree_hash_derive::TreeHash;
 
 /// Two conflicting attestations.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct AttesterSlashing<T: EthSpec> {

eth2/types/src/beacon_block.rs

@@ -10,7 +10,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 
 /// A block of the `BeaconChain`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,
@@ -36,7 +36,7 @@ pub struct BeaconBlock<T: EthSpec> {
 impl<T: EthSpec> BeaconBlock<T> {
     /// Returns an empty block to be used during genesis.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn empty(spec: &ChainSpec) -> Self {
         BeaconBlock {
             slot: spec.genesis_slot,
@@ -55,7 +55,6 @@ impl<T: EthSpec> BeaconBlock<T> {
                 attestations: VariableList::empty(),
                 deposits: VariableList::empty(),
                 voluntary_exits: VariableList::empty(),
-                transfers: VariableList::empty(),
             },
             signature: Signature::empty_signature(),
         }
@@ -68,7 +67,7 @@ impl<T: EthSpec> BeaconBlock<T> {
 
     /// Returns the `signed_root` of the block.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn canonical_root(&self) -> Hash256 {
         Hash256::from_slice(&self.signed_root()[..])
     }
@@ -80,7 +79,7 @@ impl<T: EthSpec> BeaconBlock<T> {
     ///
     /// Note: performs a full tree-hash of `self.body`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn block_header(&self) -> BeaconBlockHeader {
         BeaconBlockHeader {
             slot: self.slot,
@@ -93,7 +92,7 @@ impl<T: EthSpec> BeaconBlock<T> {
 
     /// Returns a "temporary" header, where the `state_root` is `Hash256::zero()`.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn temporary_block_header(&self) -> BeaconBlockHeader {
         BeaconBlockHeader {
             state_root: Hash256::zero(),

eth2/types/src/beacon_block_body.rs

@@ -10,7 +10,7 @@ use tree_hash_derive::TreeHash;
 
 /// The body of a `BeaconChain` block, containing operations.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 #[serde(bound = "T: EthSpec")]
 pub struct BeaconBlockBody<T: EthSpec> {
@@ -26,7 +26,6 @@ pub struct BeaconBlockBody<T: EthSpec> {
     pub attestations: VariableList<Attestation<T>, T::MaxAttestations>,
     pub deposits: VariableList<Deposit, T::MaxDeposits>,
     pub voluntary_exits: VariableList<VoluntaryExit, T::MaxVoluntaryExits>,
-    pub transfers: VariableList<Transfer, T::MaxTransfers>,
 }
 
 #[cfg(test)]

eth2/types/src/beacon_block_header.rs

@@ -10,7 +10,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 
 /// A header of a `BeaconBlock`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,
@@ -35,14 +35,14 @@ pub struct BeaconBlockHeader {
 impl BeaconBlockHeader {
     /// Returns the `tree_hash_root` of the header.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn canonical_root(&self) -> Hash256 {
         Hash256::from_slice(&self.signed_root()[..])
     }
 
     /// Given a `body`, consumes `self` and returns a complete `BeaconBlock`.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn into_block<T: EthSpec>(self, body: BeaconBlockBody<T>) -> BeaconBlock<T> {
         BeaconBlock {
             slot: self.slot,

eth2/types/src/beacon_committee.rs

@@ -1,25 +1,25 @@
 use crate::*;
 
 #[derive(Default, Clone, Debug, PartialEq)]
-pub struct CrosslinkCommittee<'a> {
+pub struct BeaconCommittee<'a> {
     pub slot: Slot,
-    pub shard: Shard,
+    pub index: CommitteeIndex,
     pub committee: &'a [usize],
 }
 
-impl<'a> CrosslinkCommittee<'a> {
+impl<'a> BeaconCommittee<'a> {
-    pub fn into_owned(self) -> OwnedCrosslinkCommittee {
+    pub fn into_owned(self) -> OwnedBeaconCommittee {
-        OwnedCrosslinkCommittee {
+        OwnedBeaconCommittee {
             slot: self.slot,
-            shard: self.shard,
+            index: self.index,
             committee: self.committee.to_vec(),
         }
     }
 }
 
 #[derive(Default, Clone, Debug, PartialEq)]
-pub struct OwnedCrosslinkCommittee {
+pub struct OwnedBeaconCommittee {
     pub slot: Slot,
-    pub shard: Shard,
+    pub index: CommitteeIndex,
     pub committee: Vec<usize>,
 }

eth2/types/src/beacon_state.rs

@@ -5,12 +5,13 @@ use crate::*;
 use cached_tree_hash::{CachedTreeHash, MultiTreeHashCache, TreeHashCache};
 use compare_fields_derive::CompareFields;
 use eth2_hashing::hash;
-use int_to_bytes::{int_to_bytes32, int_to_bytes8};
+use int_to_bytes::{int_to_bytes4, int_to_bytes8};
 use pubkey_cache::PubkeyCache;
 use serde_derive::{Deserialize, Serialize};
 use ssz::ssz_encode;
 use ssz_derive::{Decode, Encode};
 use ssz_types::{typenum::Unsigned, BitVector, FixedVector};
+use swap_or_not_shuffle::compute_shuffled_index;
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
 use tree_hash_derive::{CachedTreeHash, TreeHash};
@@ -31,7 +32,6 @@ const MAX_RANDOM_BYTE: u64 = (1 << 8) - 1;
 pub enum Error {
     EpochOutOfBounds,
     SlotOutOfBounds,
-    ShardOutOfBounds,
     UnknownValidator,
     UnableToDetermineProducer,
     InvalidBitfield,
@@ -45,8 +45,10 @@ pub enum Error {
     InsufficientAttestations,
     InsufficientCommittees,
     InsufficientStateRoots,
-    NoCommitteeForShard,
+    NoCommittee {
-    NoCommitteeForSlot,
+        slot: Slot,
+        index: CommitteeIndex,
+    },
     ZeroSlotsPerEpoch,
     PubkeyCacheInconsistent,
     PubkeyCacheIncomplete {
@@ -56,7 +58,7 @@ pub enum Error {
     PreviousCommitteeCacheUninitialized,
     CurrentCommitteeCacheUninitialized,
     RelativeEpochError(RelativeEpochError),
-    CommitteeCacheUninitialized(RelativeEpoch),
+    CommitteeCacheUninitialized(Option<RelativeEpoch>),
     SszTypesError(ssz_types::Error),
     CachedTreeHashError(cached_tree_hash::Error),
 }
@@ -86,8 +88,6 @@ pub struct BeaconTreeHashCache {
     validators: MultiTreeHashCache,
     balances: TreeHashCache,
     randao_mixes: TreeHashCache,
-    active_index_roots: TreeHashCache,
-    compact_committees_roots: TreeHashCache,
     slashings: TreeHashCache,
 }
 
@@ -99,7 +99,7 @@ impl BeaconTreeHashCache {
 
 /// The state of the `BeaconChain` at some slot.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,
@@ -148,16 +148,9 @@ where
     #[cached_tree_hash(balances)]
     pub balances: VariableList<u64, T::ValidatorRegistryLimit>,
 
-    // Shuffling
+    // Randomness
-    pub start_shard: u64,
     #[cached_tree_hash(randao_mixes)]
     pub randao_mixes: FixedVector<Hash256, T::EpochsPerHistoricalVector>,
-    #[compare_fields(as_slice)]
-    #[cached_tree_hash(active_index_roots)]
-    pub active_index_roots: FixedVector<Hash256, T::EpochsPerHistoricalVector>,
-    #[compare_fields(as_slice)]
-    #[cached_tree_hash(compact_committees_roots)]
-    pub compact_committees_roots: FixedVector<Hash256, T::EpochsPerHistoricalVector>,
 
     // Slashings
     #[cached_tree_hash(slashings)]
@@ -167,10 +160,6 @@ where
     pub previous_epoch_attestations: VariableList<PendingAttestation<T>, T::MaxPendingAttestations>,
     pub current_epoch_attestations: VariableList<PendingAttestation<T>, T::MaxPendingAttestations>,
 
-    // Crosslinks
-    pub previous_crosslinks: FixedVector<Crosslink, T::ShardCount>,
-    pub current_crosslinks: FixedVector<Crosslink, T::ShardCount>,
-
     // Finality
     #[test_random(default)]
     pub justification_bits: BitVector<T::JustificationBitsLength>,
@@ -210,7 +199,7 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// Not a complete genesis state, see `initialize_beacon_state_from_eth1`.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn new(genesis_time: u64, eth1_data: Eth1Data, spec: &ChainSpec) -> Self {
         BeaconState {
             // Versioning
@@ -233,11 +222,8 @@ impl<T: EthSpec> BeaconState<T> {
             validators: VariableList::empty(), // Set later.
             balances: VariableList::empty(),   // Set later.
 
-            // Shuffling
+            // Randomness
-            start_shard: 0,
             randao_mixes: FixedVector::from_elem(Hash256::zero()),
-            active_index_roots: FixedVector::from_elem(Hash256::zero()),
-            compact_committees_roots: FixedVector::from_elem(Hash256::zero()),
 
             // Slashings
             slashings: FixedVector::from_elem(0),
@@ -246,10 +232,6 @@ impl<T: EthSpec> BeaconState<T> {
             previous_epoch_attestations: VariableList::empty(),
             current_epoch_attestations: VariableList::empty(),
 
-            // Crosslinks
-            previous_crosslinks: FixedVector::from_elem(Crosslink::default()),
-            current_crosslinks: FixedVector::from_elem(Crosslink::default()),
-
             // Finality
             justification_bits: BitVector::new(),
             previous_justified_checkpoint: Checkpoint::default(),
@@ -270,7 +252,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Returns the `tree_hash_root` of the state.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn canonical_root(&self) -> Hash256 {
         Hash256::from_slice(&self.tree_hash_root()[..])
     }
@@ -299,7 +281,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// The epoch corresponding to `self.slot`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn current_epoch(&self) -> Epoch {
         self.slot.epoch(T::slots_per_epoch())
     }
@@ -308,7 +290,7 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// If the current epoch is the genesis epoch, the genesis_epoch is returned.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn previous_epoch(&self) -> Epoch {
         let current_epoch = self.current_epoch();
         if current_epoch > T::genesis_epoch() {
@@ -320,43 +302,29 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// The epoch following `self.current_epoch()`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn next_epoch(&self) -> Epoch {
         self.current_epoch() + 1
     }
 
-    pub fn get_committee_count(&self, relative_epoch: RelativeEpoch) -> Result<u64, Error> {
+    /// Compute the number of committees at `slot`.
-        let cache = self.cache(relative_epoch)?;
+    ///
+    /// Makes use of the committee cache and will fail if no cache exists for the slot's epoch.
+    ///
+    /// Spec v0.9.1
+    pub fn get_committee_count_at_slot(&self, slot: Slot) -> Result<u64, Error> {
+        let cache = self.committee_cache_at_slot(slot)?;
+        Ok(cache.committees_per_slot() as u64)
+    }
 
+    /// Compute the number of committees in an entire epoch.
+    ///
+    /// Spec v0.9.1
+    pub fn get_epoch_committee_count(&self, relative_epoch: RelativeEpoch) -> Result<u64, Error> {
+        let cache = self.committee_cache(relative_epoch)?;
         Ok(cache.epoch_committee_count() as u64)
     }
 
-    pub fn get_epoch_start_shard(&self, relative_epoch: RelativeEpoch) -> Result<u64, Error> {
-        let cache = self.cache(relative_epoch)?;
-
-        Ok(cache.epoch_start_shard())
-    }
-
-    /// Get the slot of an attestation.
-    ///
-    /// Note: Utilizes the cache and will fail if the appropriate cache is not initialized.
-    ///
-    /// Spec v0.8.0
-    pub fn get_attestation_data_slot(
-        &self,
-        attestation_data: &AttestationData,
-    ) -> Result<Slot, Error> {
-        let target_relative_epoch =
-            RelativeEpoch::from_epoch(self.current_epoch(), attestation_data.target.epoch)?;
-
-        let cc = self.get_crosslink_committee_for_shard(
-            attestation_data.crosslink.shard,
-            target_relative_epoch,
-        )?;
-
-        Ok(cc.slot)
-    }
-
     /// Return the cached active validator indices at some epoch.
     ///
     /// Note: the indices are shuffled (i.e., not in ascending order).
@@ -366,7 +334,7 @@ impl<T: EthSpec> BeaconState<T> {
         &self,
         relative_epoch: RelativeEpoch,
     ) -> Result<&[usize], Error> {
-        let cache = self.cache(relative_epoch)?;
+        let cache = self.committee_cache(relative_epoch)?;
 
         Ok(&cache.active_validator_indices())
     }
@@ -375,7 +343,7 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// Does not utilize the cache, performs a full iteration over the validator registry.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_active_validator_indices(&self, epoch: Epoch) -> Vec<usize> {
         get_active_validator_indices(&self.validators, epoch)
     }
@@ -386,91 +354,106 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// Returns an error if that epoch is not cached, or the cache is not initialized.
     pub fn get_shuffling(&self, relative_epoch: RelativeEpoch) -> Result<&[usize], Error> {
-        let cache = self.cache(relative_epoch)?;
+        let cache = self.committee_cache(relative_epoch)?;
 
         Ok(cache.shuffling())
     }
 
-    /// Returns the crosslink committees for some slot.
+    /// Get the Beacon committee at the given slot and index.
     ///
-    /// Note: Utilizes the cache and will fail if the appropriate cache is not initialized.
+    /// Utilises the committee cache.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
-    pub fn get_crosslink_committees_at_slot(
+    pub fn get_beacon_committee(
         &self,
         slot: Slot,
-    ) -> Result<Vec<CrosslinkCommittee>, Error> {
+        index: CommitteeIndex,
-        let relative_epoch = RelativeEpoch::from_slot(self.slot, slot, T::slots_per_epoch())?;
+    ) -> Result<BeaconCommittee, Error> {
-        let cache = self.cache(relative_epoch)?;
+        let epoch = slot.epoch(T::slots_per_epoch());
+        let relative_epoch = RelativeEpoch::from_epoch(self.current_epoch(), epoch)?;
+        let cache = self.committee_cache(relative_epoch)?;
 
         cache
-            .get_crosslink_committees_for_slot(slot)
+            .get_beacon_committee(slot, index)
-            .ok_or_else(|| Error::NoCommitteeForSlot)
+            .ok_or(Error::NoCommittee { slot, index })
     }
 
-    /// Returns the crosslink committees for some shard in some cached epoch.
+    /// Get all of the Beacon committees at a given slot.
     ///
-    /// Note: Utilizes the cache and will fail if the appropriate cache is not initialized.
+    /// Utilises the committee cache.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
-    pub fn get_crosslink_committee_for_shard(
+    pub fn get_beacon_committees_at_slot(&self, slot: Slot) -> Result<Vec<BeaconCommittee>, Error> {
-        &self,
+        let cache = self.committee_cache_at_slot(slot)?;
-        shard: u64,
+        cache.get_beacon_committees_at_slot(slot)
-        relative_epoch: RelativeEpoch,
-    ) -> Result<CrosslinkCommittee, Error> {
-        let cache = self.cache(relative_epoch)?;
-
-        let committee = cache
-            .get_crosslink_committee_for_shard(shard)
-            .ok_or_else(|| Error::NoCommitteeForShard)?;
-
-        Ok(committee)
     }
 
-    /// Returns the beacon proposer index for the `slot` in the given `relative_epoch`.
+    /// Compute the proposer (not necessarily for the Beacon chain) from a list of indices.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     // NOTE: be sure to test this bad boy.
-    pub fn get_beacon_proposer_index(
+    pub fn compute_proposer_index(
         &self,
-        slot: Slot,
+        indices: &[usize],
-        relative_epoch: RelativeEpoch,
+        seed: &[u8],
         spec: &ChainSpec,
     ) -> Result<usize, Error> {
-        let cache = self.cache(relative_epoch)?;
+        if indices.is_empty() {
-        let epoch = relative_epoch.into_epoch(self.current_epoch());
-
-        let first_committee = cache
-            .first_committee_at_slot(slot)
-            .ok_or_else(|| Error::SlotOutOfBounds)?;
-        let seed = self.get_seed(epoch, spec)?;
-
-        if first_committee.is_empty() {
             return Err(Error::InsufficientValidators);
         }
 
         let mut i = 0;
-        Ok(loop {
+        loop {
-            let candidate_index = first_committee[(epoch.as_usize() + i) % first_committee.len()];
+            let candidate_index = indices[compute_shuffled_index(
+                i % indices.len(),
+                indices.len(),
+                seed,
+                spec.shuffle_round_count,
+            )
+            .ok_or(Error::UnableToShuffle)?];
             let random_byte = {
-                let mut preimage = seed.as_bytes().to_vec();
+                let mut preimage = seed.to_vec();
                 preimage.append(&mut int_to_bytes8((i / 32) as u64));
                 let hash = hash(&preimage);
                 hash[i % 32]
             };
             let effective_balance = self.validators[candidate_index].effective_balance;
-            if (effective_balance * MAX_RANDOM_BYTE)
+            if effective_balance * MAX_RANDOM_BYTE
-                >= (spec.max_effective_balance * u64::from(random_byte))
+                >= spec.max_effective_balance * u64::from(random_byte)
             {
-                break candidate_index;
+                return Ok(candidate_index);
             }
             i += 1;
-        })
+        }
+    }
+
+    /// Returns the beacon proposer index for the `slot` in the given `relative_epoch`.
+    ///
+    /// Spec v0.9.1
+    pub fn get_beacon_proposer_index(&self, slot: Slot, spec: &ChainSpec) -> Result<usize, Error> {
+        let epoch = slot.epoch(T::slots_per_epoch());
+        let seed = self.get_beacon_proposer_seed(slot, spec)?;
+        let indices = self.get_active_validator_indices(epoch);
+
+        self.compute_proposer_index(&indices, &seed, spec)
+    }
+
+    /// Compute the seed to use for the beacon proposer selection at the given `slot`.
+    ///
+    /// Spec v0.9.1
+    fn get_beacon_proposer_seed(&self, slot: Slot, spec: &ChainSpec) -> Result<Vec<u8>, Error> {
+        let epoch = slot.epoch(T::slots_per_epoch());
+        let mut preimage = self
+            .get_seed(epoch, Domain::BeaconProposer, spec)?
+            .as_bytes()
+            .to_vec();
+        preimage.append(&mut int_to_bytes8(slot.as_u64()));
+        Ok(hash(&preimage))
     }
 
     /// Safely obtains the index for latest block roots, given some `slot`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn get_latest_block_roots_index(&self, slot: Slot) -> Result<usize, Error> {
         if (slot < self.slot) && (self.slot <= slot + self.block_roots.len() as u64) {
             Ok(slot.as_usize() % self.block_roots.len())
@@ -481,7 +464,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Return the block root at a recent `slot`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_block_root(&self, slot: Slot) -> Result<&Hash256, BeaconStateError> {
         let i = self.get_latest_block_roots_index(slot)?;
         Ok(&self.block_roots[i])
@@ -489,7 +472,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Return the block root at a recent `epoch`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     // NOTE: the spec calls this get_block_root
     pub fn get_block_root_at_epoch(&self, epoch: Epoch) -> Result<&Hash256, BeaconStateError> {
         self.get_block_root(epoch.start_slot(T::slots_per_epoch()))
@@ -497,7 +480,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Sets the block root for some given slot.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn set_block_root(
         &mut self,
         slot: Slot,
@@ -508,9 +491,14 @@ impl<T: EthSpec> BeaconState<T> {
         Ok(())
     }
 
+    /// Fill `randao_mixes` with
+    pub fn fill_randao_mixes_with(&mut self, index_root: Hash256) {
+        self.randao_mixes = FixedVector::from_elem(index_root);
+    }
+
     /// Safely obtains the index for `randao_mixes`
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn get_randao_mix_index(
         &self,
         epoch: Epoch,
@@ -532,7 +520,7 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// See `Self::get_randao_mix`.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn update_randao_mix(&mut self, epoch: Epoch, signature: &Signature) -> Result<(), Error> {
         let i = epoch.as_usize() % T::EpochsPerHistoricalVector::to_usize();
 
@@ -545,7 +533,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Return the randao mix at a recent ``epoch``.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_randao_mix(&self, epoch: Epoch) -> Result<&Hash256, Error> {
         let i = self.get_randao_mix_index(epoch, AllowNextEpoch::False)?;
         Ok(&self.randao_mixes[i])
@@ -553,115 +541,16 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Set the randao mix at a recent ``epoch``.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn set_randao_mix(&mut self, epoch: Epoch, mix: Hash256) -> Result<(), Error> {
         let i = self.get_randao_mix_index(epoch, AllowNextEpoch::True)?;
         self.randao_mixes[i] = mix;
         Ok(())
     }
 
-    /// Safely obtains the index for `active_index_roots`, given some `epoch`.
-    ///
-    /// If `allow_next_epoch` is `True`, then we allow an _extra_ one epoch of lookahead.
-    ///
-    /// Spec v0.8.1
-    fn get_active_index_root_index(
-        &self,
-        epoch: Epoch,
-        spec: &ChainSpec,
-        allow_next_epoch: AllowNextEpoch,
-    ) -> Result<usize, Error> {
-        let current_epoch = self.current_epoch();
-
-        let lookahead = spec.activation_exit_delay;
-        let lookback = self.active_index_roots.len() as u64 - lookahead;
-        let epoch_upper_bound = allow_next_epoch.upper_bound_of(current_epoch) + lookahead;
-
-        if current_epoch < epoch + lookback && epoch <= epoch_upper_bound {
-            Ok(epoch.as_usize() % self.active_index_roots.len())
-        } else {
-            Err(Error::EpochOutOfBounds)
-        }
-    }
-
-    /// Return the `active_index_root` at a recent `epoch`.
-    ///
-    /// Spec v0.8.1
-    pub fn get_active_index_root(&self, epoch: Epoch, spec: &ChainSpec) -> Result<Hash256, Error> {
-        let i = self.get_active_index_root_index(epoch, spec, AllowNextEpoch::False)?;
-        Ok(self.active_index_roots[i])
-    }
-
-    /// Set the `active_index_root` at a recent `epoch`.
-    ///
-    /// Spec v0.8.1
-    pub fn set_active_index_root(
-        &mut self,
-        epoch: Epoch,
-        index_root: Hash256,
-        spec: &ChainSpec,
-    ) -> Result<(), Error> {
-        let i = self.get_active_index_root_index(epoch, spec, AllowNextEpoch::True)?;
-        self.active_index_roots[i] = index_root;
-        Ok(())
-    }
-
-    /// Replace `active_index_roots` with clones of `index_root`.
-    ///
-    /// Spec v0.8.0
-    pub fn fill_active_index_roots_with(&mut self, index_root: Hash256) {
-        self.active_index_roots = FixedVector::from_elem(index_root);
-    }
-
-    /// Safely obtains the index for `compact_committees_roots`, given some `epoch`.
-    ///
-    /// Spec v0.8.1
-    fn get_compact_committee_root_index(
-        &self,
-        epoch: Epoch,
-        allow_next_epoch: AllowNextEpoch,
-    ) -> Result<usize, Error> {
-        let current_epoch = self.current_epoch();
-        let len = T::EpochsPerHistoricalVector::to_u64();
-
-        if current_epoch < epoch + len && epoch <= allow_next_epoch.upper_bound_of(current_epoch) {
-            Ok(epoch.as_usize() % len as usize)
-        } else {
-            Err(Error::EpochOutOfBounds)
-        }
-    }
-
-    /// Return the `compact_committee_root` at a recent `epoch`.
-    ///
-    /// Spec v0.8.1
-    pub fn get_compact_committee_root(&self, epoch: Epoch) -> Result<Hash256, Error> {
-        let i = self.get_compact_committee_root_index(epoch, AllowNextEpoch::False)?;
-        Ok(self.compact_committees_roots[i])
-    }
-
-    /// Set the `compact_committee_root` at a recent `epoch`.
-    ///
-    /// Spec v0.8.1
-    pub fn set_compact_committee_root(
-        &mut self,
-        epoch: Epoch,
-        index_root: Hash256,
-    ) -> Result<(), Error> {
-        let i = self.get_compact_committee_root_index(epoch, AllowNextEpoch::True)?;
-        self.compact_committees_roots[i] = index_root;
-        Ok(())
-    }
-
-    /// Replace `compact_committees_roots` with clones of `committee_root`.
-    ///
-    /// Spec v0.8.0
-    pub fn fill_compact_committees_roots_with(&mut self, committee_root: Hash256) {
-        self.compact_committees_roots = FixedVector::from_elem(committee_root);
-    }
-
     /// Safely obtains the index for latest state roots, given some `slot`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn get_latest_state_roots_index(&self, slot: Slot) -> Result<usize, Error> {
         if (slot < self.slot) && (self.slot <= slot + Slot::from(self.state_roots.len())) {
             Ok(slot.as_usize() % self.state_roots.len())
@@ -672,7 +561,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Gets the state root for some slot.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_state_root(&self, slot: Slot) -> Result<&Hash256, Error> {
         let i = self.get_latest_state_roots_index(slot)?;
         Ok(&self.state_roots[i])
@@ -680,7 +569,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Gets the oldest (earliest slot) state root.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_oldest_state_root(&self) -> Result<&Hash256, Error> {
         let i =
             self.get_latest_state_roots_index(self.slot - Slot::from(self.state_roots.len()))?;
@@ -689,7 +578,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Sets the latest state root for slot.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn set_state_root(&mut self, slot: Slot, state_root: Hash256) -> Result<(), Error> {
         let i = self.get_latest_state_roots_index(slot)?;
         self.state_roots[i] = state_root;
@@ -698,7 +587,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Safely obtain the index for `slashings`, given some `epoch`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn get_slashings_index(
         &self,
         epoch: Epoch,
@@ -718,14 +607,14 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Get a reference to the entire `slashings` vector.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn get_all_slashings(&self) -> &[u64] {
         &self.slashings
     }
 
     /// Get the total slashed balances for some epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_slashings(&self, epoch: Epoch) -> Result<u64, Error> {
         let i = self.get_slashings_index(epoch, AllowNextEpoch::False)?;
         Ok(self.slashings[i])
@@ -733,7 +622,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Set the total slashed balances for some epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn set_slashings(&mut self, epoch: Epoch, value: u64) -> Result<(), Error> {
         let i = self.get_slashings_index(epoch, AllowNextEpoch::True)?;
         self.slashings[i] = value;
@@ -742,7 +631,7 @@ impl<T: EthSpec> BeaconState<T> {
 
     /// Get the attestations from the current or previous epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_matching_source_attestations(
         &self,
         epoch: Epoch,
@@ -756,48 +645,40 @@ impl<T: EthSpec> BeaconState<T> {
         }
     }
 
-    /// Get the current crosslink for a shard.
-    ///
-    /// Spec v0.8.1
-    pub fn get_current_crosslink(&self, shard: u64) -> Result<&Crosslink, Error> {
-        self.current_crosslinks
-            .get(shard as usize)
-            .ok_or(Error::ShardOutOfBounds)
-    }
-
-    /// Get the previous crosslink for a shard.
-    ///
-    /// Spec v0.8.1
-    pub fn get_previous_crosslink(&self, shard: u64) -> Result<&Crosslink, Error> {
-        self.previous_crosslinks
-            .get(shard as usize)
-            .ok_or(Error::ShardOutOfBounds)
-    }
-
     /// Generate a seed for the given `epoch`.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
-    pub fn get_seed(&self, epoch: Epoch, spec: &ChainSpec) -> Result<Hash256, Error> {
+    pub fn get_seed(
+        &self,
+        epoch: Epoch,
+        domain_type: Domain,
+        spec: &ChainSpec,
+    ) -> Result<Hash256, Error> {
         // Bypass the safe getter for RANDAO so we can gracefully handle the scenario where `epoch
         // == 0`.
-        let randao = {
+        let mix = {
             let i = epoch + T::EpochsPerHistoricalVector::to_u64() - spec.min_seed_lookahead - 1;
             self.randao_mixes[i.as_usize() % self.randao_mixes.len()]
         };
-        let active_index_root = self.get_active_index_root(epoch, spec)?;
+        let domain_bytes = int_to_bytes4(spec.get_domain_constant(domain_type));
-        let epoch_bytes = int_to_bytes32(epoch.as_u64());
+        let epoch_bytes = int_to_bytes8(epoch.as_u64());
 
-        let mut preimage = [0; 32 * 3];
+        const NUM_DOMAIN_BYTES: usize = 4;
-        preimage[0..32].copy_from_slice(&randao[..]);
+        const NUM_EPOCH_BYTES: usize = 8;
-        preimage[32..64].copy_from_slice(&active_index_root[..]);
+        const NUM_MIX_BYTES: usize = 32;
-        preimage[64..].copy_from_slice(&epoch_bytes);
+
+        let mut preimage = [0; NUM_DOMAIN_BYTES + NUM_EPOCH_BYTES + NUM_MIX_BYTES];
+        preimage[0..NUM_DOMAIN_BYTES].copy_from_slice(&domain_bytes);
+        preimage[NUM_DOMAIN_BYTES..NUM_DOMAIN_BYTES + NUM_EPOCH_BYTES]
+            .copy_from_slice(&epoch_bytes);
+        preimage[NUM_DOMAIN_BYTES + NUM_EPOCH_BYTES..].copy_from_slice(mix.as_bytes());
 
         Ok(Hash256::from_slice(&hash(&preimage)))
     }
 
     /// Return the effective balance (also known as "balance at stake") for a validator with the given ``index``.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_effective_balance(
         &self,
         validator_index: usize,
@@ -811,43 +692,44 @@ impl<T: EthSpec> BeaconState<T> {
 
     ///  Return the epoch at which an activation or exit triggered in ``epoch`` takes effect.
     ///
-    ///  Spec v0.8.1
+    ///  Spec v0.9.1
     pub fn compute_activation_exit_epoch(&self, epoch: Epoch, spec: &ChainSpec) -> Epoch {
-        epoch + 1 + spec.activation_exit_delay
+        epoch + 1 + spec.max_seed_lookahead
     }
 
     /// Return the churn limit for the current epoch (number of validators who can leave per epoch).
     ///
     /// Uses the epoch cache, and will error if it isn't initialized.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_churn_limit(&self, spec: &ChainSpec) -> Result<u64, Error> {
         Ok(std::cmp::max(
             spec.min_per_epoch_churn_limit,
-            self.cache(RelativeEpoch::Current)?.active_validator_count() as u64
+            self.committee_cache(RelativeEpoch::Current)?
+                .active_validator_count() as u64
                 / spec.churn_limit_quotient,
         ))
     }
 
-    /// Returns the `slot`, `shard` and `committee_index` for which a validator must produce an
+    /// Returns the `slot`, `index` and `committee_position` for which a validator must produce an
     /// attestation.
     ///
     /// Note: Utilizes the cache and will fail if the appropriate cache is not initialized.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_attestation_duties(
         &self,
         validator_index: usize,
         relative_epoch: RelativeEpoch,
     ) -> Result<Option<AttestationDuty>, Error> {
-        let cache = self.cache(relative_epoch)?;
+        let cache = self.committee_cache(relative_epoch)?;
 
         Ok(cache.get_attestation_duties(validator_index))
     }
 
     /// Return the combined effective balance of an array of validators.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_total_balance(
         &self,
         validator_indices: &[usize],
@@ -887,7 +769,7 @@ impl<T: EthSpec> BeaconState<T> {
         relative_epoch: RelativeEpoch,
         spec: &ChainSpec,
     ) -> Result<(), Error> {
-        let i = Self::cache_index(relative_epoch);
+        let i = Self::committee_cache_index(relative_epoch);
 
         if self.committee_caches[i]
             .is_initialized_at(relative_epoch.into_epoch(self.current_epoch()))
@@ -906,7 +788,7 @@ impl<T: EthSpec> BeaconState<T> {
     ) -> Result<(), Error> {
         let epoch = relative_epoch.into_epoch(self.current_epoch());
 
-        self.committee_caches[Self::cache_index(relative_epoch)] =
+        self.committee_caches[Self::committee_cache_index(relative_epoch)] =
             CommitteeCache::initialized(&self, epoch, spec)?;
         Ok(())
     }
@@ -917,16 +799,14 @@ impl<T: EthSpec> BeaconState<T> {
     ///
     /// Note: whilst this function will preserve already-built caches, it will not build any.
     pub fn advance_caches(&mut self) {
-        let next = Self::cache_index(RelativeEpoch::Previous);
-        let current = Self::cache_index(RelativeEpoch::Current);
-
         let caches = &mut self.committee_caches[..];
         caches.rotate_left(1);
+
+        let next = Self::committee_cache_index(RelativeEpoch::Next);
         caches[next] = CommitteeCache::default();
-        caches[current] = CommitteeCache::default();
     }
 
-    fn cache_index(relative_epoch: RelativeEpoch) -> usize {
+    fn committee_cache_index(relative_epoch: RelativeEpoch) -> usize {
         match relative_epoch {
             RelativeEpoch::Previous => 0,
             RelativeEpoch::Current => 1,
@@ -934,21 +814,31 @@ impl<T: EthSpec> BeaconState<T> {
         }
     }
 
+    /// Get the committee cache for some `slot`.
+    ///
+    /// Return an error if the cache for the slot's epoch is not initialized.
+    fn committee_cache_at_slot(&self, slot: Slot) -> Result<&CommitteeCache, Error> {
+        let epoch = slot.epoch(T::slots_per_epoch());
+        let relative_epoch = RelativeEpoch::from_epoch(self.current_epoch(), epoch)?;
+        self.committee_cache(relative_epoch)
+    }
+
     /// Returns the cache for some `RelativeEpoch`. Returns an error if the cache has not been
     /// initialized.
-    fn cache(&self, relative_epoch: RelativeEpoch) -> Result<&CommitteeCache, Error> {
+    fn committee_cache(&self, relative_epoch: RelativeEpoch) -> Result<&CommitteeCache, Error> {
-        let cache = &self.committee_caches[Self::cache_index(relative_epoch)];
+        let cache = &self.committee_caches[Self::committee_cache_index(relative_epoch)];
 
         if cache.is_initialized_at(relative_epoch.into_epoch(self.current_epoch())) {
             Ok(cache)
         } else {
-            Err(Error::CommitteeCacheUninitialized(relative_epoch))
+            Err(Error::CommitteeCacheUninitialized(Some(relative_epoch)))
         }
     }
 
     /// Drops the cache, leaving it in an uninitialized state.
     fn drop_committee_cache(&mut self, relative_epoch: RelativeEpoch) {
-        self.committee_caches[Self::cache_index(relative_epoch)] = CommitteeCache::default();
+        self.committee_caches[Self::committee_cache_index(relative_epoch)] =
+            CommitteeCache::default();
     }
 
     /// Updates the pubkey cache, if required.

eth2/types/src/beacon_state/committee_cache.rs

@@ -15,22 +15,20 @@ pub struct CommitteeCache {
     initialized_epoch: Option<Epoch>,
     shuffling: Vec<usize>,
     shuffling_positions: Vec<Option<NonZeroUsize>>,
-    shuffling_start_shard: u64,
+    committees_per_slot: u64,
-    shard_count: u64,
-    committee_count: usize,
     slots_per_epoch: u64,
 }
 
 impl CommitteeCache {
     /// Return a new, fully initialized cache.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn initialized<T: EthSpec>(
         state: &BeaconState<T>,
         epoch: Epoch,
         spec: &ChainSpec,
     ) -> Result<CommitteeCache, Error> {
-        let relative_epoch = RelativeEpoch::from_epoch(state.current_epoch(), epoch)
+        RelativeEpoch::from_epoch(state.current_epoch(), epoch)
             .map_err(|_| Error::EpochOutOfBounds)?;
 
         // May cause divide-by-zero errors.
@@ -44,14 +42,10 @@ impl CommitteeCache {
             return Err(Error::InsufficientValidators);
         }
 
-        let committee_count =
+        let committees_per_slot =
-            T::get_committee_count(active_validator_indices.len(), spec.target_committee_size)
+            T::get_committee_count_per_slot(active_validator_indices.len(), spec) as u64;
-                as usize;
 
-        let shuffling_start_shard =
+        let seed = state.get_seed(epoch, Domain::BeaconAttester, spec)?;
-            Self::compute_start_shard(state, relative_epoch, active_validator_indices.len(), spec);
-
-        let seed = state.get_seed(epoch, spec)?;
 
         let shuffling = shuffle_list(
             active_validator_indices,
@@ -73,46 +67,13 @@ impl CommitteeCache {
 
         Ok(CommitteeCache {
             initialized_epoch: Some(epoch),
-            shuffling_start_shard,
             shuffling,
-            shard_count: T::shard_count() as u64,
-            committee_count,
-            slots_per_epoch: T::slots_per_epoch(),
             shuffling_positions,
+            committees_per_slot,
+            slots_per_epoch: T::slots_per_epoch(),
         })
     }
 
-    /// Compute the shard which must be attested to first in a given relative epoch.
-    ///
-    /// The `active_validator_count` must be the number of validators active at `relative_epoch`.
-    ///
-    /// Spec v0.8.1
-    pub fn compute_start_shard<T: EthSpec>(
-        state: &BeaconState<T>,
-        relative_epoch: RelativeEpoch,
-        active_validator_count: usize,
-        spec: &ChainSpec,
-    ) -> u64 {
-        match relative_epoch {
-            RelativeEpoch::Current => state.start_shard,
-            RelativeEpoch::Previous => {
-                let shard_delta =
-                    T::get_shard_delta(active_validator_count, spec.target_committee_size);
-
-                (state.start_shard + T::ShardCount::to_u64() - shard_delta)
-                    % T::ShardCount::to_u64()
-            }
-            RelativeEpoch::Next => {
-                let current_active_validators =
-                    get_active_validator_count(&state.validators, state.current_epoch());
-                let shard_delta =
-                    T::get_shard_delta(current_active_validators, spec.target_committee_size);
-
-                (state.start_shard + shard_delta) % T::ShardCount::to_u64()
-            }
-        }
-    }
-
     /// Returns `true` if the cache has been initialized at the supplied `epoch`.
     ///
     /// An non-initialized cache does not provide any useful information.
@@ -126,7 +87,7 @@ impl CommitteeCache {
     ///
     /// Always returns `&[]` for a non-initialized epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn active_validator_indices(&self) -> &[usize] {
         &self.shuffling
     }
@@ -135,34 +96,51 @@ impl CommitteeCache {
     ///
     /// Always returns `&[]` for a non-initialized epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn shuffling(&self) -> &[usize] {
         &self.shuffling
     }
 
-    /// Return `Some(CrosslinkCommittee)` if the given shard has a committee during the given
+    /// Get the Beacon committee for the given `slot` and `index`.
-    /// `epoch`.
     ///
-    /// Always returns `None` for a non-initialized epoch.
+    /// Return `None` if the cache is uninitialized, or the `slot` or `index` is out of range.
-    ///
+    pub fn get_beacon_committee(
-    /// Spec v0.8.1
+        &self,
-    pub fn get_crosslink_committee_for_shard(&self, shard: Shard) -> Option<CrosslinkCommittee> {
+        slot: Slot,
-        if shard >= self.shard_count || self.initialized_epoch.is_none() {
+        index: CommitteeIndex,
+    ) -> Option<BeaconCommittee> {
+        if self.initialized_epoch.is_none()
+            || !self.is_initialized_at(slot.epoch(self.slots_per_epoch))
+            || index >= self.committees_per_slot
+        {
             return None;
         }
 
         let committee_index =
-            (shard + self.shard_count - self.shuffling_start_shard) % self.shard_count;
+            (slot.as_u64() % self.slots_per_epoch) * self.committees_per_slot + index;
         let committee = self.compute_committee(committee_index as usize)?;
-        let slot = self.crosslink_slot_for_shard(shard)?;
 
-        Some(CrosslinkCommittee {
+        Some(BeaconCommittee {
-            shard,
-            committee,
             slot,
+            index,
+            committee,
         })
     }
 
+    /// Get all the Beacon committees at a given `slot`.
+    pub fn get_beacon_committees_at_slot(&self, slot: Slot) -> Result<Vec<BeaconCommittee>, Error> {
+        if self.initialized_epoch.is_none() {
+            return Err(Error::CommitteeCacheUninitialized(None));
+        }
+
+        (0..self.committees_per_slot())
+            .map(|index| {
+                self.get_beacon_committee(slot, index)
+                    .ok_or(Error::NoCommittee { slot, index })
+            })
+            .collect()
+    }
+
     /// Returns the `AttestationDuty` for the given `validator_index`.
     ///
     /// Returns `None` if the `validator_index` does not exist, does not have duties or `Self` is
@@ -170,36 +148,46 @@ impl CommitteeCache {
     pub fn get_attestation_duties(&self, validator_index: usize) -> Option<AttestationDuty> {
         let i = self.shuffled_position(validator_index)?;
 
-        (0..self.committee_count)
+        (0..self.epoch_committee_count())
             .map(|nth_committee| (nth_committee, self.compute_committee_range(nth_committee)))
             .find(|(_, range)| {
                 if let Some(range) = range {
-                    (range.start <= i) && (range.end > i)
+                    range.start <= i && range.end > i
                 } else {
                     false
                 }
             })
             .and_then(|(nth_committee, range)| {
-                let shard = (self.shuffling_start_shard + nth_committee as u64) % self.shard_count;
+                let (slot, index) = self.convert_to_slot_and_index(nth_committee as u64)?;
-                let slot = self.crosslink_slot_for_shard(shard)?;
                 let range = range?;
-                let committee_index = i - range.start;
+                let committee_position = i - range.start;
                 let committee_len = range.end - range.start;
 
                 Some(AttestationDuty {
                     slot,
-                    shard,
+                    index,
-                    committee_index,
+                    committee_position,
                     committee_len,
                 })
             })
     }
 
+    /// Convert an index addressing the list of all epoch committees into a slot and per-slot index.
+    fn convert_to_slot_and_index(
+        &self,
+        global_committee_index: u64,
+    ) -> Option<(Slot, CommitteeIndex)> {
+        let epoch_start_slot = self.initialized_epoch?.start_slot(self.slots_per_epoch);
+        let slot_offset = global_committee_index / self.committees_per_slot;
+        let index = global_committee_index % self.committees_per_slot;
+        Some((epoch_start_slot + slot_offset, index))
+    }
+
     /// Returns the number of active validators in the initialized epoch.
     ///
     /// Always returns `usize::default()` for a non-initialized epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn active_validator_count(&self) -> usize {
         self.shuffling.len()
     }
@@ -208,64 +196,19 @@ impl CommitteeCache {
     ///
     /// Always returns `usize::default()` for a non-initialized epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn epoch_committee_count(&self) -> usize {
-        self.committee_count
+        self.committees_per_slot as usize * self.slots_per_epoch as usize
     }
 
-    /// Returns the shard assigned to the first committee in the initialized epoch.
+    /// Returns the number of committees per slot for this cache's epoch.
-    ///
+    pub fn committees_per_slot(&self) -> u64 {
-    /// Always returns `u64::default()` for a non-initialized epoch.
+        self.committees_per_slot
-    pub fn epoch_start_shard(&self) -> u64 {
-        self.shuffling_start_shard
-    }
-
-    /// Returns all crosslink committees, if any, for the given slot in the initialized epoch.
-    ///
-    /// Returns `None` if `slot` is not in the initialized epoch, or if `Self` is not initialized.
-    ///
-    /// Spec v0.8.1
-    pub fn get_crosslink_committees_for_slot(&self, slot: Slot) -> Option<Vec<CrosslinkCommittee>> {
-        let position = self
-            .initialized_epoch?
-            .position(slot, self.slots_per_epoch)?;
-        let committees_per_slot = self.committee_count / self.slots_per_epoch as usize;
-        let position = position * committees_per_slot;
-
-        if position >= self.committee_count {
-            None
-        } else {
-            let mut committees = Vec::with_capacity(committees_per_slot);
-
-            for index in position..position + committees_per_slot {
-                let committee = self.compute_committee(index)?;
-                let shard = (self.shuffling_start_shard + index as u64) % self.shard_count;
-
-                committees.push(CrosslinkCommittee {
-                    committee,
-                    shard,
-                    slot,
-                });
-            }
-
-            Some(committees)
-        }
-    }
-
-    /// Returns the first committee of the first slot of the initialized epoch.
-    ///
-    /// Always returns `None` for a non-initialized epoch.
-    ///
-    /// Spec v0.8.1
-    pub fn first_committee_at_slot(&self, slot: Slot) -> Option<&[usize]> {
-        self.get_crosslink_committees_for_slot(slot)?
-            .first()
-            .and_then(|cc| Some(cc.committee))
     }
 
     /// Returns a slice of `self.shuffling` that represents the `index`'th committee in the epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn compute_committee(&self, index: usize) -> Option<&[usize]> {
         Some(&self.shuffling[self.compute_committee_range(index)?])
     }
@@ -276,34 +219,20 @@ impl CommitteeCache {
     ///
     /// Will also return `None` if the index is out of bounds.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn compute_committee_range(&self, index: usize) -> Option<Range<usize>> {
-        if self.committee_count == 0 || index >= self.committee_count {
+        let count = self.epoch_committee_count();
+        if count == 0 || index >= count {
             return None;
         }
 
         let num_validators = self.shuffling.len();
-        let count = self.committee_count;
-
         let start = (num_validators * index) / count;
         let end = (num_validators * (index + 1)) / count;
 
         Some(start..end)
     }
 
-    /// Returns the `slot` that `shard` will be crosslink-ed in during the initialized epoch.
-    ///
-    /// Always returns `None` for a non-initialized epoch.
-    ///
-    /// Spec v0.8.1
-    fn crosslink_slot_for_shard(&self, shard: u64) -> Option<Slot> {
-        let offset = (shard + self.shard_count - self.shuffling_start_shard) % self.shard_count;
-        Some(
-            self.initialized_epoch?.start_slot(self.slots_per_epoch)
-                + offset / (self.committee_count as u64 / self.slots_per_epoch),
-        )
-    }
-
     /// Returns the index of some validator in `self.shuffling`.
     ///
     /// Always returns `None` for a non-initialized epoch.
@@ -317,7 +246,7 @@ impl CommitteeCache {
 /// Returns a list of all `validators` indices where the validator is active at the given
 /// `epoch`.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub fn get_active_validator_indices(validators: &[Validator], epoch: Epoch) -> Vec<usize> {
     let mut active = Vec::with_capacity(validators.len());
 
@@ -331,11 +260,3 @@ pub fn get_active_validator_indices(validators: &[Validator], epoch: Epoch) -> V
 
     active
 }
-
-/// Returns the count of all `validators` indices where the validator is active at the given
-/// `epoch`.
-///
-/// Spec v0.8.1
-fn get_active_validator_count(validators: &[Validator], epoch: Epoch) -> usize {
-    validators.iter().filter(|v| v.is_active_at(epoch)).count()
-}

eth2/types/src/beacon_state/committee_cache/tests.rs

@@ -1,8 +1,6 @@
 #![cfg(test)]
 use super::*;
 use crate::{test_utils::*, *};
-use serde_derive::{Deserialize, Serialize};
-use ssz_types::typenum::*;
 
 #[test]
 fn default_values() {
@@ -10,13 +8,11 @@ fn default_values() {
 
     assert_eq!(cache.is_initialized_at(Epoch::new(0)), false);
     assert!(&cache.active_validator_indices().is_empty());
-    assert_eq!(cache.get_crosslink_committee_for_shard(0), None);
+    assert_eq!(cache.get_beacon_committee(Slot::new(0), 0), None);
     assert_eq!(cache.get_attestation_duties(0), None);
     assert_eq!(cache.active_validator_count(), 0);
     assert_eq!(cache.epoch_committee_count(), 0);
-    assert_eq!(cache.epoch_start_shard(), 0);
+    assert!(cache.get_beacon_committees_at_slot(Slot::new(0)).is_err());
-    assert_eq!(cache.get_crosslink_committees_for_slot(Slot::new(0)), None);
-    assert_eq!(cache.first_committee_at_slot(Slot::new(0)), None);
 }
 
 fn new_state<T: EthSpec>(validator_count: usize, slot: Slot) -> BeaconState<T> {
@@ -78,9 +74,15 @@ fn shuffles_for_the_right_epoch() {
 
     state.randao_mixes = FixedVector::from(distinct_hashes);
 
-    let previous_seed = state.get_seed(state.previous_epoch(), spec).unwrap();
+    let previous_seed = state
-    let current_seed = state.get_seed(state.current_epoch(), spec).unwrap();
+        .get_seed(state.previous_epoch(), Domain::BeaconAttester, spec)
-    let next_seed = state.get_seed(state.next_epoch(), spec).unwrap();
+        .unwrap();
+    let current_seed = state
+        .get_seed(state.current_epoch(), Domain::BeaconAttester, spec)
+        .unwrap();
+    let next_seed = state
+        .get_seed(state.next_epoch(), Domain::BeaconAttester, spec)
+        .unwrap();
 
     assert!((previous_seed != current_seed) && (current_seed != next_seed));
 
@@ -116,153 +118,3 @@ fn shuffles_for_the_right_epoch() {
     assert_eq!(cache.shuffling, shuffling_with_seed(next_seed));
     assert_shuffling_positions_accurate(&cache);
 }
-
-#[test]
-fn can_start_on_any_shard() {
-    let num_validators = MinimalEthSpec::minimum_validator_count() * 2;
-    let epoch = Epoch::new(100_000_000);
-    let slot = epoch.start_slot(MinimalEthSpec::slots_per_epoch());
-
-    let mut state = new_state::<MinimalEthSpec>(num_validators, slot);
-    let spec = &MinimalEthSpec::default_spec();
-
-    let target_committee_size = MinimalEthSpec::default_spec().target_committee_size;
-
-    let shard_delta = MinimalEthSpec::get_shard_delta(num_validators, target_committee_size);
-    let shard_count = MinimalEthSpec::shard_count() as u64;
-
-    for i in 0..MinimalEthSpec::shard_count() as u64 {
-        state.start_shard = i;
-
-        let cache = CommitteeCache::initialized(&state, state.current_epoch(), spec).unwrap();
-        assert_eq!(cache.shuffling_start_shard, i);
-
-        let cache = CommitteeCache::initialized(&state, state.previous_epoch(), spec).unwrap();
-        assert_eq!(
-            cache.shuffling_start_shard,
-            (i + shard_count - shard_delta) % shard_count
-        );
-
-        let cache = CommitteeCache::initialized(&state, state.next_epoch(), spec).unwrap();
-        assert_eq!(cache.shuffling_start_shard, (i + shard_delta) % shard_count);
-    }
-}
-
-/// This spec has more shards than slots in an epoch, permitting epochs where not all shards are
-/// included in the committee.
-#[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
-pub struct ExcessShardsEthSpec;
-
-impl EthSpec for ExcessShardsEthSpec {
-    type ShardCount = U128;
-    type SlotsPerEpoch = U8;
-    type MaxPendingAttestations = U1024;
-
-    params_from_eth_spec!(MinimalEthSpec {
-        JustificationBitsLength,
-        MaxValidatorsPerCommittee,
-        GenesisEpoch,
-        SlotsPerEth1VotingPeriod,
-        SlotsPerHistoricalRoot,
-        EpochsPerHistoricalVector,
-        EpochsPerSlashingsVector,
-        HistoricalRootsLimit,
-        ValidatorRegistryLimit,
-        MaxProposerSlashings,
-        MaxAttesterSlashings,
-        MaxAttestations,
-        MaxDeposits,
-        MaxVoluntaryExits,
-        MaxTransfers
-    });
-
-    fn default_spec() -> ChainSpec {
-        ChainSpec::minimal()
-    }
-}
-
-#[test]
-fn starts_on_the_correct_shard() {
-    let spec = &ExcessShardsEthSpec::default_spec();
-
-    let num_validators = spec.target_committee_size * ExcessShardsEthSpec::shard_count();
-
-    let epoch = Epoch::new(100_000_000);
-    let slot = epoch.start_slot(ExcessShardsEthSpec::slots_per_epoch());
-
-    let mut state = new_state::<ExcessShardsEthSpec>(num_validators, slot);
-
-    let validator_count = state.validators.len();
-
-    let previous_epoch = state.previous_epoch();
-    let current_epoch = state.current_epoch();
-    let next_epoch = state.next_epoch();
-
-    for (i, mut v) in state.validators.iter_mut().enumerate() {
-        let epoch = if i < validator_count / 4 {
-            previous_epoch
-        } else if i < validator_count / 2 {
-            current_epoch
-        } else {
-            next_epoch
-        };
-
-        v.activation_epoch = epoch;
-    }
-
-    assert_eq!(
-        get_active_validator_count(&state.validators, previous_epoch),
-        validator_count / 4
-    );
-    assert_eq!(
-        get_active_validator_count(&state.validators, current_epoch),
-        validator_count / 2
-    );
-    assert_eq!(
-        get_active_validator_count(&state.validators, next_epoch),
-        validator_count
-    );
-
-    let previous_shards = ExcessShardsEthSpec::get_committee_count(
-        get_active_validator_count(&state.validators, previous_epoch),
-        spec.target_committee_size,
-    );
-    let current_shards = ExcessShardsEthSpec::get_committee_count(
-        get_active_validator_count(&state.validators, current_epoch),
-        spec.target_committee_size,
-    );
-    let next_shards = ExcessShardsEthSpec::get_committee_count(
-        get_active_validator_count(&state.validators, next_epoch),
-        spec.target_committee_size,
-    );
-
-    assert_eq!(
-        previous_shards as usize,
-        ExcessShardsEthSpec::shard_count() / 4
-    );
-    assert_eq!(
-        current_shards as usize,
-        ExcessShardsEthSpec::shard_count() / 2
-    );
-    assert_eq!(next_shards as usize, ExcessShardsEthSpec::shard_count());
-
-    let shard_count = ExcessShardsEthSpec::shard_count();
-    for i in 0..ExcessShardsEthSpec::shard_count() {
-        state.start_shard = i as u64;
-
-        let cache = CommitteeCache::initialized(&state, state.current_epoch(), spec).unwrap();
-        assert_eq!(cache.shuffling_start_shard as usize, i);
-
-        let cache = CommitteeCache::initialized(&state, state.previous_epoch(), spec).unwrap();
-        assert_eq!(
-            cache.shuffling_start_shard as usize,
-            (i + shard_count - previous_shards) % shard_count
-        );
-
-        let cache = CommitteeCache::initialized(&state, state.next_epoch(), spec).unwrap();
-        assert_eq!(
-            cache.shuffling_start_shard as usize,
-            (i + current_shards) % shard_count
-        );
-    }
-}

eth2/types/src/beacon_state/tests.rs

@@ -1,7 +1,6 @@
 #![cfg(test)]
 use super::*;
 use crate::test_utils::*;
-use std::ops::RangeInclusive;
 
 ssz_tests!(FoundationBeaconState);
 
@@ -19,34 +18,49 @@ fn test_beacon_proposer_index<T: EthSpec>() {
         state
     };
 
+    // Get the i'th candidate proposer for the given state and slot
+    let ith_candidate = |state: &BeaconState<T>, slot: Slot, i: usize| {
+        let epoch = slot.epoch(T::slots_per_epoch());
+        let seed = state.get_beacon_proposer_seed(slot, &spec).unwrap();
+        let active_validators = state.get_active_validator_indices(epoch);
+        active_validators[compute_shuffled_index(
+            i,
+            active_validators.len(),
+            &seed,
+            spec.shuffle_round_count,
+        )
+        .unwrap()]
+    };
+
     // Run a test on the state.
-    let test = |state: &BeaconState<T>, slot: Slot, shuffling_index: usize| {
+    let test = |state: &BeaconState<T>, slot: Slot, candidate_index: usize| {
-        let shuffling = state.get_shuffling(relative_epoch).unwrap();
         assert_eq!(
-            state.get_beacon_proposer_index(slot, relative_epoch, &spec),
+            state.get_beacon_proposer_index(slot, &spec),
-            Ok(shuffling[shuffling_index])
+            Ok(ith_candidate(state, slot, candidate_index))
         );
     };
 
-    // Test where we have one validator per slot
+    // Test where we have one validator per slot.
+    // 0th candidate should be chosen every time.
     let state = build_state(T::slots_per_epoch() as usize);
     for i in 0..T::slots_per_epoch() {
-        test(&state, Slot::from(i), i as usize);
+        test(&state, Slot::from(i), 0);
     }
 
-    // Test where we have two validators per slot
+    // Test where we have two validators per slot.
+    // 0th candidate should be chosen every time.
     let state = build_state(T::slots_per_epoch() as usize * 2);
     for i in 0..T::slots_per_epoch() {
-        test(&state, Slot::from(i), i as usize * 2);
+        test(&state, Slot::from(i), 0);
     }
 
     // Test with two validators per slot, first validator has zero balance.
     let mut state = build_state(T::slots_per_epoch() as usize * 2);
-    let shuffling = state.get_shuffling(relative_epoch).unwrap().to_vec();
+    let slot0_candidate0 = ith_candidate(&state, Slot::new(0), 0);
-    state.validators[shuffling[0]].effective_balance = 0;
+    state.validators[slot0_candidate0].effective_balance = 0;
     test(&state, Slot::new(0), 1);
     for i in 1..T::slots_per_epoch() {
-        test(&state, Slot::from(i), i as usize * 2);
+        test(&state, Slot::from(i), 0);
     }
 }
 
@@ -55,72 +69,6 @@ fn beacon_proposer_index() {
     test_beacon_proposer_index::<MinimalEthSpec>();
 }
 
-/// Should produce (note the set notation brackets):
-///
-/// (current_epoch - LATEST_ACTIVE_INDEX_ROOTS_LENGTH + ACTIVATION_EXIT_DELAY, current_epoch +
-/// ACTIVATION_EXIT_DELAY]
-fn active_index_range<T: EthSpec>(current_epoch: Epoch) -> RangeInclusive<Epoch> {
-    let delay = T::default_spec().activation_exit_delay;
-
-    let start: i32 =
-        current_epoch.as_u64() as i32 - T::epochs_per_historical_vector() as i32 + delay as i32;
-    let end = current_epoch + delay;
-
-    let start: Epoch = if start < 0 {
-        Epoch::new(0)
-    } else {
-        Epoch::from(start as u64 + 1)
-    };
-
-    start..=end
-}
-
-/// Test getting an active index root at the start and end of the valid range, and one either side
-/// of that range.
-fn test_active_index<T: EthSpec>(state_slot: Slot) {
-    let spec = T::default_spec();
-    let builder: TestingBeaconStateBuilder<T> =
-        TestingBeaconStateBuilder::from_default_keypairs_file_if_exists(16, &spec);
-    let (mut state, _keypairs) = builder.build();
-    state.slot = state_slot;
-
-    let range = active_index_range::<T>(state.current_epoch());
-
-    let modulo = |epoch: Epoch| epoch.as_usize() % T::epochs_per_historical_vector();
-
-    // Test the start and end of the range.
-    assert_eq!(
-        state.get_active_index_root_index(*range.start(), &spec, AllowNextEpoch::False),
-        Ok(modulo(*range.start()))
-    );
-    assert_eq!(
-        state.get_active_index_root_index(*range.end(), &spec, AllowNextEpoch::False),
-        Ok(modulo(*range.end()))
-    );
-
-    // One either side of the range.
-    if state.current_epoch() > 0 {
-        // Test is invalid on epoch zero, cannot subtract from zero.
-        assert_eq!(
-            state.get_active_index_root_index(*range.start() - 1, &spec, AllowNextEpoch::False),
-            Err(Error::EpochOutOfBounds)
-        );
-    }
-    assert_eq!(
-        state.get_active_index_root_index(*range.end() + 1, &spec, AllowNextEpoch::False),
-        Err(Error::EpochOutOfBounds)
-    );
-}
-
-#[test]
-fn get_active_index_root_index() {
-    test_active_index::<MainnetEthSpec>(Slot::new(0));
-
-    let epoch = Epoch::from(MainnetEthSpec::epochs_per_historical_vector() * 4);
-    let slot = epoch.start_slot(MainnetEthSpec::slots_per_epoch());
-    test_active_index::<MainnetEthSpec>(slot);
-}
-
 /// Test that
 ///
 /// 1. Using the cache before it's built fails.
@@ -138,28 +86,26 @@ fn test_cache_initialization<'a, T: EthSpec>(
     // Assuming the cache isn't already built, assert that a call to a cache-using function fails.
     assert_eq!(
         state.get_attestation_duties(0, relative_epoch),
-        Err(BeaconStateError::CommitteeCacheUninitialized(
+        Err(BeaconStateError::CommitteeCacheUninitialized(Some(
             relative_epoch
-        ))
+        )))
     );
 
     // Build the cache.
     state.build_committee_cache(relative_epoch, spec).unwrap();
 
     // Assert a call to a cache-using function passes.
-    let _ = state
+    let _ = state.get_beacon_proposer_index(slot, spec).unwrap();
-        .get_beacon_proposer_index(slot, relative_epoch, spec)
-        .unwrap();
 
     // Drop the cache.
     state.drop_committee_cache(relative_epoch);
 
     // Assert a call to a cache-using function fail.
     assert_eq!(
-        state.get_beacon_proposer_index(slot, relative_epoch, spec),
+        state.get_beacon_committee(slot, 0),
-        Err(BeaconStateError::CommitteeCacheUninitialized(
+        Err(BeaconStateError::CommitteeCacheUninitialized(Some(
             relative_epoch
-        ))
+        )))
     );
 }
 
@@ -212,10 +158,8 @@ mod committees {
         spec: &ChainSpec,
     ) {
         let active_indices: Vec<usize> = (0..validator_count).collect();
-        let seed = state.get_seed(epoch, spec).unwrap();
+        let seed = state.get_seed(epoch, Domain::BeaconAttester, spec).unwrap();
         let relative_epoch = RelativeEpoch::from_epoch(state.current_epoch(), epoch).unwrap();
-        let start_shard =
-            CommitteeCache::compute_start_shard(&state, relative_epoch, active_indices.len(), spec);
 
         let mut ordered_indices = state
             .get_cached_active_validator_indices(relative_epoch)
@@ -231,34 +175,27 @@ mod committees {
             shuffle_list(active_indices, spec.shuffle_round_count, &seed[..], false).unwrap();
 
         let mut expected_indices_iter = shuffling.iter();
-        let mut expected_shards_iter =
-            (0..T::ShardCount::to_u64()).map(|i| (start_shard + i) % T::ShardCount::to_u64());
 
         // Loop through all slots in the epoch being tested.
         for slot in epoch.slot_iter(T::slots_per_epoch()) {
-            let crosslink_committees = state.get_crosslink_committees_at_slot(slot).unwrap();
+            let beacon_committees = state.get_beacon_committees_at_slot(slot).unwrap();
 
             // Assert that the number of committees in this slot is consistent with the reported number
             // of committees in an epoch.
             assert_eq!(
-                crosslink_committees.len() as u64,
+                beacon_committees.len() as u64,
-                state.get_committee_count(relative_epoch).unwrap() / T::slots_per_epoch()
+                state.get_epoch_committee_count(relative_epoch).unwrap() / T::slots_per_epoch()
             );
 
-            for cc in crosslink_committees {
+            for (committee_index, bc) in beacon_committees.iter().enumerate() {
-                // Assert that shards are assigned contiguously across committees.
+                // Assert that indices are assigned sequentially across committees.
-                assert_eq!(expected_shards_iter.next().unwrap(), cc.shard);
+                assert_eq!(committee_index as u64, bc.index);
                 // Assert that a committee lookup via slot is identical to a committee lookup via
-                // shard.
+                // index.
-                assert_eq!(
+                assert_eq!(state.get_beacon_committee(bc.slot, bc.index).unwrap(), *bc);
-                    state
-                        .get_crosslink_committee_for_shard(cc.shard, relative_epoch)
-                        .unwrap(),
-                    cc
-                );
 
                 // Loop through each validator in the committee.
-                for (committee_i, validator_i) in cc.committee.iter().enumerate() {
+                for (committee_i, validator_i) in bc.committee.iter().enumerate() {
                     // Assert the validators are assigned contiguously across committees.
                     assert_eq!(
                         *validator_i,
@@ -266,24 +203,21 @@ mod committees {
                         "Non-sequential validators."
                     );
                     // Assert a call to `get_attestation_duties` is consistent with a call to
-                    // `get_crosslink_committees_at_slot`
+                    // `get_beacon_committees_at_slot`
                     let attestation_duty = state
                         .get_attestation_duties(*validator_i, relative_epoch)
                         .unwrap()
                         .unwrap();
                     assert_eq!(attestation_duty.slot, slot);
-                    assert_eq!(attestation_duty.shard, cc.shard);
+                    assert_eq!(attestation_duty.index, bc.index);
-                    assert_eq!(attestation_duty.committee_index, committee_i);
+                    assert_eq!(attestation_duty.committee_position, committee_i);
-                    assert_eq!(attestation_duty.committee_len, cc.committee.len());
+                    assert_eq!(attestation_duty.committee_len, bc.committee.len());
                 }
             }
         }
 
         // Assert that all validators were assigned to a committee.
         assert!(expected_indices_iter.next().is_none());
-
-        // Assert that all shards were assigned to a committee.
-        assert!(expected_shards_iter.next().is_none());
     }
 
     fn committee_consistency_test<T: EthSpec>(
@@ -327,7 +261,10 @@ mod committees {
     fn committee_consistency_test_suite<T: EthSpec>(cached_epoch: RelativeEpoch) {
         let spec = T::default_spec();
 
-        let validator_count = (T::shard_count() * spec.target_committee_size) + 1;
+        let validator_count = spec.max_committees_per_slot
+            * T::slots_per_epoch() as usize
+            * spec.target_committee_size
+            + 1;
 
         committee_consistency_test::<T>(validator_count as usize, Epoch::new(0), cached_epoch);
 

eth2/types/src/chain_spec.rs

@@ -5,19 +5,18 @@ use utils::{u8_from_hex_str, u8_to_hex_str};
 
 /// Each of the BLS signature domains.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 pub enum Domain {
     BeaconProposer,
+    BeaconAttester,
     Randao,
-    Attestation,
     Deposit,
     VoluntaryExit,
-    Transfer,
 }
 
 /// Holds all the "constants" for a BeaconChain.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
 #[serde(default)]
 pub struct ChainSpec {
@@ -33,6 +32,7 @@ pub struct ChainSpec {
     /*
      * Misc
      */
+    pub max_committees_per_slot: usize,
     pub target_committee_size: usize,
     pub min_per_epoch_churn_limit: u64,
     pub churn_limit_quotient: u64,
@@ -61,10 +61,9 @@ pub struct ChainSpec {
     pub milliseconds_per_slot: u64,
     pub min_attestation_inclusion_delay: u64,
     pub min_seed_lookahead: Epoch,
-    pub activation_exit_delay: u64,
+    pub max_seed_lookahead: Epoch,
     pub min_validator_withdrawability_delay: Epoch,
     pub persistent_committee_period: u64,
-    pub max_epochs_per_crosslink: u64,
     pub min_epochs_to_inactivity_penalty: u64,
 
     /*
@@ -78,18 +77,17 @@ pub struct ChainSpec {
 
     /*
      * Signature domains
-     *
-     * Fields should be private to prevent accessing a domain that hasn't been modified to suit
-     * some `Fork`.
-     *
-     * Use `ChainSpec::get_domain(..)` to access these values.
      */
     domain_beacon_proposer: u32,
+    domain_beacon_attester: u32,
     domain_randao: u32,
-    domain_attestation: u32,
     domain_deposit: u32,
     domain_voluntary_exit: u32,
-    domain_transfer: u32,
+
+    /*
+     * Fork choice
+     */
+    pub safe_slots_to_update_justified: u64,
 
     /*
      * Eth1
@@ -103,18 +101,24 @@ pub struct ChainSpec {
 }
 
 impl ChainSpec {
-    /// Get the domain number that represents the fork meta and signature domain.
+    /// Get the domain number, unmodified by the fork.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
-    pub fn get_domain(&self, epoch: Epoch, domain: Domain, fork: &Fork) -> u64 {
+    pub fn get_domain_constant(&self, domain: Domain) -> u32 {
-        let domain_constant = match domain {
+        match domain {
             Domain::BeaconProposer => self.domain_beacon_proposer,
+            Domain::BeaconAttester => self.domain_beacon_attester,
             Domain::Randao => self.domain_randao,
-            Domain::Attestation => self.domain_attestation,
             Domain::Deposit => self.domain_deposit,
             Domain::VoluntaryExit => self.domain_voluntary_exit,
-            Domain::Transfer => self.domain_transfer,
+        }
-        };
+    }
+
+    /// Get the domain number that represents the fork meta and signature domain.
+    ///
+    /// Spec v0.9.1
+    pub fn get_domain(&self, epoch: Epoch, domain: Domain, fork: &Fork) -> u64 {
+        let domain_constant = self.get_domain_constant(domain);
 
         let mut bytes: Vec<u8> = int_to_bytes4(domain_constant);
         bytes.append(&mut fork.get_fork_version(epoch).to_vec());
@@ -143,20 +147,21 @@ impl ChainSpec {
 
     /// Returns a `ChainSpec` compatible with the Ethereum Foundation specification.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn mainnet() -> Self {
         Self {
             /*
              * Constants
              */
             far_future_epoch: Epoch::new(u64::max_value()),
-            base_rewards_per_epoch: 5,
+            base_rewards_per_epoch: 4,
             deposit_contract_tree_depth: 32,
             seconds_per_day: 86400,
 
             /*
              * Misc
              */
+            max_committees_per_slot: 64,
             target_committee_size: 128,
             min_per_epoch_churn_limit: 4,
             churn_limit_quotient: 65_536,
@@ -181,13 +186,12 @@ impl ChainSpec {
             /*
              * Time parameters
              */
-            milliseconds_per_slot: 6_000,
+            milliseconds_per_slot: 12_000,
             min_attestation_inclusion_delay: 1,
             min_seed_lookahead: Epoch::new(1),
-            activation_exit_delay: 4,
+            max_seed_lookahead: Epoch::new(4),
             min_validator_withdrawability_delay: Epoch::new(256),
             persistent_committee_period: 2_048,
-            max_epochs_per_crosslink: 64,
             min_epochs_to_inactivity_penalty: 4,
 
             /*
@@ -203,11 +207,15 @@ impl ChainSpec {
              * Signature domains
              */
             domain_beacon_proposer: 0,
-            domain_randao: 1,
+            domain_beacon_attester: 1,
-            domain_attestation: 2,
+            domain_randao: 2,
             domain_deposit: 3,
             domain_voluntary_exit: 4,
-            domain_transfer: 5,
+
+            /*
+             * Fork choice
+             */
+            safe_slots_to_update_justified: 8,
 
             /*
              * Eth1
@@ -235,7 +243,7 @@ impl ChainSpec {
     ///
     /// https://github.com/ethereum/eth2.0-specs/blob/v0.8.1/configs/constant_presets/minimal.yaml
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn minimal() -> Self {
         // Note: bootnodes to be updated when static nodes exist.
         let boot_nodes = vec![];
@@ -244,7 +252,6 @@ impl ChainSpec {
             target_committee_size: 4,
             shuffle_round_count: 10,
             min_genesis_active_validator_count: 64,
-            max_epochs_per_crosslink: 4,
             network_id: 2, // lighthouse testnet network id
             boot_nodes,
             eth1_follow_distance: 16,
@@ -302,10 +309,9 @@ mod tests {
         let spec = ChainSpec::mainnet();
 
         test_domain(Domain::BeaconProposer, spec.domain_beacon_proposer, &spec);
+        test_domain(Domain::BeaconAttester, spec.domain_beacon_attester, &spec);
         test_domain(Domain::Randao, spec.domain_randao, &spec);
-        test_domain(Domain::Attestation, spec.domain_attestation, &spec);
         test_domain(Domain::Deposit, spec.domain_deposit, &spec);
         test_domain(Domain::VoluntaryExit, spec.domain_voluntary_exit, &spec);
-        test_domain(Domain::Transfer, spec.domain_transfer, &spec);
     }
 }

eth2/types/src/checkpoint.rs

@@ -7,7 +7,7 @@ use tree_hash_derive::TreeHash;
 
 /// Casper FFG checkpoint, used in attestations.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     Clone,

eth2/types/src/compact_committee.rs

@@ -1,24 +0,0 @@
-use crate::test_utils::TestRandom;
-use crate::{EthSpec, PublicKey};
-use serde_derive::{Deserialize, Serialize};
-use ssz_derive::{Decode, Encode};
-use ssz_types::VariableList;
-use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
-
-/// Spec v0.8.0
-#[derive(Clone, Debug, PartialEq, TreeHash, Encode, Decode, Serialize, Deserialize, TestRandom)]
-#[serde(bound = "T: EthSpec")]
-pub struct CompactCommittee<T: EthSpec> {
-    pub pubkeys: VariableList<PublicKey, T::MaxValidatorsPerCommittee>,
-    pub compact_validators: VariableList<u64, T::MaxValidatorsPerCommittee>,
-}
-
-impl<T: EthSpec> Default for CompactCommittee<T> {
-    fn default() -> Self {
-        Self {
-            pubkeys: VariableList::empty(),
-            compact_validators: VariableList::empty(),
-        }
-    }
-}

eth2/types/src/crosslink.rs

@@ -1,40 +0,0 @@
-use crate::test_utils::TestRandom;
-use crate::{Epoch, Hash256};
-
-use serde_derive::{Deserialize, Serialize};
-use ssz_derive::{Decode, Encode};
-use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
-
-/// Specifies the block hash for a shard at an epoch.
-///
-/// Spec v0.8.0
-#[derive(
-    Debug,
-    Clone,
-    PartialEq,
-    Eq,
-    Default,
-    Serialize,
-    Deserialize,
-    Hash,
-    Encode,
-    Decode,
-    TreeHash,
-    TestRandom,
-)]
-pub struct Crosslink {
-    pub shard: u64,
-    pub parent_root: Hash256,
-    // Crosslinking data
-    pub start_epoch: Epoch,
-    pub end_epoch: Epoch,
-    pub data_root: Hash256,
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    ssz_tests!(Crosslink);
-}

eth2/types/src/deposit.rs

@@ -11,7 +11,7 @@ pub const DEPOSIT_TREE_DEPTH: usize = 32;
 
 /// A deposit to potentially become a beacon chain validator.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct Deposit {
     pub proof: FixedVector<Hash256, U33>,

eth2/types/src/deposit_data.rs

@@ -11,7 +11,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 
 /// The data supplied by the user to the deposit contract.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,
@@ -35,7 +35,7 @@ pub struct DepositData {
 impl DepositData {
     /// Generate the signature for a given DepositData details.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn create_signature(&self, secret_key: &SecretKey, spec: &ChainSpec) -> SignatureBytes {
         let msg = self.signed_root();
         let domain = spec.get_deposit_domain();

eth2/types/src/eth1_data.rs

@@ -8,7 +8,7 @@ use tree_hash_derive::TreeHash;
 
 /// Contains data obtained from the Eth1 chain.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,

eth2/types/src/eth_spec.rs

@@ -1,8 +1,8 @@
 use crate::*;
 use serde_derive::{Deserialize, Serialize};
 use ssz_types::typenum::{
-    Unsigned, U0, U1, U1024, U1099511627776, U128, U16, U16777216, U4, U4096, U64, U65536, U8,
+    Unsigned, U0, U1, U1024, U1099511627776, U128, U16, U16777216, U2048, U32, U4, U4096, U64,
-    U8192,
+    U65536, U8, U8192,
 };
 use std::fmt::Debug;
 
@@ -14,7 +14,6 @@ pub trait EthSpec: 'static + Default + Sync + Send + Clone + Debug + PartialEq {
     /*
      * Misc
      */
-    type ShardCount: Unsigned + Clone + Sync + Send + Debug + PartialEq;
     type MaxValidatorsPerCommittee: Unsigned + Clone + Sync + Send + Debug + PartialEq;
     /*
      * Initial values
@@ -41,7 +40,6 @@ pub trait EthSpec: 'static + Default + Sync + Send + Clone + Debug + PartialEq {
     type MaxAttestations: Unsigned + Clone + Sync + Send + Debug + PartialEq;
     type MaxDeposits: Unsigned + Clone + Sync + Send + Debug + PartialEq;
     type MaxVoluntaryExits: Unsigned + Clone + Sync + Send + Debug + PartialEq;
-    type MaxTransfers: Unsigned + Clone + Sync + Send + Debug + PartialEq;
     /*
      * Derived values (set these CAREFULLY)
      */
@@ -58,29 +56,21 @@ pub trait EthSpec: 'static + Default + Sync + Send + Clone + Debug + PartialEq {
         Epoch::new(Self::GenesisEpoch::to_u64())
     }
 
-    /// Return the number of committees in one epoch.
+    /// Return the number of committees per slot.
     ///
-    /// Spec v0.8.1
+    /// Note: the number of committees per slot is constant in each epoch, and depends only on
-    fn get_committee_count(active_validator_count: usize, target_committee_size: usize) -> usize {
+    /// the `active_validator_count` during the slot's epoch.
-        let shard_count = Self::shard_count();
+    ///
-        let slots_per_epoch = Self::slots_per_epoch() as usize;
+    /// Spec v0.9.1
+    fn get_committee_count_per_slot(active_validator_count: usize, spec: &ChainSpec) -> usize {
+        let slots_per_epoch = Self::SlotsPerEpoch::to_usize();
 
         std::cmp::max(
             1,
             std::cmp::min(
-                shard_count / slots_per_epoch,
+                spec.max_committees_per_slot,
-                active_validator_count / slots_per_epoch / target_committee_size,
+                active_validator_count / slots_per_epoch / spec.target_committee_size,
             ),
-        ) * slots_per_epoch
-    }
-
-    /// Return the number of shards to increment `state.start_shard` by in a given epoch.
-    ///
-    /// Spec v0.8.1
-    fn get_shard_delta(active_validator_count: usize, target_committee_size: usize) -> u64 {
-        std::cmp::min(
-            Self::get_committee_count(active_validator_count, target_committee_size) as u64,
-            Self::ShardCount::to_u64() - Self::ShardCount::to_u64() / Self::slots_per_epoch(),
         )
     }
 
@@ -95,37 +85,30 @@ pub trait EthSpec: 'static + Default + Sync + Send + Clone + Debug + PartialEq {
 
     /// Returns the `SLOTS_PER_EPOCH` constant for this specification.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn slots_per_epoch() -> u64 {
         Self::SlotsPerEpoch::to_u64()
     }
 
-    /// Returns the `SHARD_COUNT` constant for this specification.
-    ///
-    /// Spec v0.8.1
-    fn shard_count() -> usize {
-        Self::ShardCount::to_usize()
-    }
-
     /// Returns the `SLOTS_PER_HISTORICAL_ROOT` constant for this specification.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn slots_per_historical_root() -> usize {
         Self::SlotsPerHistoricalRoot::to_usize()
     }
 
     /// Returns the `EPOCHS_PER_HISTORICAL_VECTOR` constant for this specification.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn epochs_per_historical_vector() -> usize {
         Self::EpochsPerHistoricalVector::to_usize()
     }
 
     /// Returns the `SLOTS_PER_ETH1_VOTING_PERIOD` constant for this specification.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     fn slots_per_eth1_voting_period() -> usize {
-        Self::EpochsPerHistoricalVector::to_usize()
+        Self::SlotsPerEth1VotingPeriod::to_usize()
     }
 }
 
@@ -139,16 +122,15 @@ macro_rules! params_from_eth_spec {
 
 /// Ethereum Foundation specifications.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
 pub struct MainnetEthSpec;
 
 impl EthSpec for MainnetEthSpec {
     type JustificationBitsLength = U4;
-    type ShardCount = U1024;
+    type MaxValidatorsPerCommittee = U2048;
-    type MaxValidatorsPerCommittee = U4096;
     type GenesisEpoch = U0;
-    type SlotsPerEpoch = U64;
+    type SlotsPerEpoch = U32;
     type SlotsPerEth1VotingPeriod = U1024;
     type SlotsPerHistoricalRoot = U8192;
     type EpochsPerHistoricalVector = U65536;
@@ -160,8 +142,7 @@ impl EthSpec for MainnetEthSpec {
     type MaxAttestations = U128;
     type MaxDeposits = U16;
     type MaxVoluntaryExits = U16;
-    type MaxTransfers = U0;
+    type MaxPendingAttestations = U4096; // 128 max attestations * 32 slots per epoch
-    type MaxPendingAttestations = U8192; // 128 max attestations * 64 slots per epoch
 
     fn default_spec() -> ChainSpec {
         ChainSpec::mainnet()
@@ -174,12 +155,11 @@ pub type FoundationBeaconState = BeaconState<MainnetEthSpec>;
 ///
 /// https://github.com/ethereum/eth2.0-specs/blob/v0.8.0/configs/constant_presets/minimal.yaml
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Clone, PartialEq, Debug, Default, Serialize, Deserialize)]
 pub struct MinimalEthSpec;
 
 impl EthSpec for MinimalEthSpec {
-    type ShardCount = U8;
     type SlotsPerEpoch = U8;
     type SlotsPerEth1VotingPeriod = U16;
     type SlotsPerHistoricalRoot = U64;
@@ -197,8 +177,7 @@ impl EthSpec for MinimalEthSpec {
         MaxAttesterSlashings,
         MaxAttestations,
         MaxDeposits,
-        MaxVoluntaryExits,
+        MaxVoluntaryExits
-        MaxTransfers
     });
 
     fn default_spec() -> ChainSpec {
@@ -213,7 +192,6 @@ pub type MinimalBeaconState = BeaconState<MinimalEthSpec>;
 pub struct InteropEthSpec;
 
 impl EthSpec for InteropEthSpec {
-    type ShardCount = U8;
     type SlotsPerEpoch = U8;
     type SlotsPerHistoricalRoot = U64;
     type SlotsPerEth1VotingPeriod = U16;
@@ -231,8 +209,7 @@ impl EthSpec for InteropEthSpec {
         MaxAttesterSlashings,
         MaxAttestations,
         MaxDeposits,
-        MaxVoluntaryExits,
+        MaxVoluntaryExits
-        MaxTransfers
     });
 
     fn default_spec() -> ChainSpec {

eth2/types/src/fork.rs

@@ -9,7 +9,7 @@ use tree_hash_derive::TreeHash;
 
 /// Specifies a fork of the `BeaconChain`, to prevent replay attacks.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(
     Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
 )]
@@ -30,7 +30,7 @@ pub struct Fork {
 impl Fork {
     /// Return the fork version of the given ``epoch``.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn get_fork_version(&self, epoch: Epoch) -> [u8; 4] {
         if epoch < self.epoch {
             return self.previous_version;

eth2/types/src/historical_batch.rs

@@ -9,7 +9,7 @@ use tree_hash_derive::TreeHash;
 
 /// Historical block and state roots.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct HistoricalBatch<T: EthSpec> {
     pub block_roots: FixedVector<Hash256, T::SlotsPerHistoricalRoot>,

eth2/types/src/indexed_attestation.rs

@@ -9,7 +9,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 ///
 /// To be included in an `AttesterSlashing`.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,
@@ -25,8 +25,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 #[serde(bound = "T: EthSpec")]
 pub struct IndexedAttestation<T: EthSpec> {
     /// Lists validator registry indices, not committee indices.
-    pub custody_bit_0_indices: VariableList<u64, T::MaxValidatorsPerCommittee>,
+    pub attesting_indices: VariableList<u64, T::MaxValidatorsPerCommittee>,
-    pub custody_bit_1_indices: VariableList<u64, T::MaxValidatorsPerCommittee>,
     pub data: AttestationData,
     #[signed_root(skip_hashing)]
     pub signature: AggregateSignature,
@@ -35,14 +34,14 @@ pub struct IndexedAttestation<T: EthSpec> {
 impl<T: EthSpec> IndexedAttestation<T> {
     /// Check if ``attestation_data_1`` and ``attestation_data_2`` have the same target.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn is_double_vote(&self, other: &Self) -> bool {
         self.data.target.epoch == other.data.target.epoch && self.data != other.data
     }
 
     /// Check if ``attestation_data_1`` surrounds ``attestation_data_2``.
     ///
-    /// Spec v0.8.0
+    /// Spec v0.9.1
     pub fn is_surround_vote(&self, other: &Self) -> bool {
         self.data.source.epoch < other.data.source.epoch
             && other.data.target.epoch < self.data.target.epoch

eth2/types/src/lib.rs

@@ -8,18 +8,15 @@ pub mod test_utils;
 
 pub mod attestation;
 pub mod attestation_data;
-pub mod attestation_data_and_custody_bit;
 pub mod attestation_duty;
 pub mod attester_slashing;
 pub mod beacon_block;
 pub mod beacon_block_body;
 pub mod beacon_block_header;
+pub mod beacon_committee;
 pub mod beacon_state;
 pub mod chain_spec;
 pub mod checkpoint;
-pub mod compact_committee;
-pub mod crosslink;
-pub mod crosslink_committee;
 pub mod deposit;
 pub mod deposit_data;
 pub mod eth1_data;
@@ -30,7 +27,6 @@ pub mod historical_batch;
 pub mod indexed_attestation;
 pub mod pending_attestation;
 pub mod proposer_slashing;
-pub mod transfer;
 pub mod utils;
 pub mod voluntary_exit;
 #[macro_use]
@@ -41,23 +37,19 @@ pub mod slot_height;
 mod tree_hash_impls;
 pub mod validator;
 
-use ethereum_types::{H160, H256, U256};
+use ethereum_types::{H160, H256};
-use std::collections::HashMap;
 
 pub use crate::attestation::Attestation;
 pub use crate::attestation_data::AttestationData;
-pub use crate::attestation_data_and_custody_bit::AttestationDataAndCustodyBit;
 pub use crate::attestation_duty::AttestationDuty;
 pub use crate::attester_slashing::AttesterSlashing;
 pub use crate::beacon_block::BeaconBlock;
 pub use crate::beacon_block_body::BeaconBlockBody;
 pub use crate::beacon_block_header::BeaconBlockHeader;
+pub use crate::beacon_committee::{BeaconCommittee, OwnedBeaconCommittee};
 pub use crate::beacon_state::{Error as BeaconStateError, *};
 pub use crate::chain_spec::{ChainSpec, Domain};
 pub use crate::checkpoint::Checkpoint;
-pub use crate::compact_committee::CompactCommittee;
-pub use crate::crosslink::Crosslink;
-pub use crate::crosslink_committee::{CrosslinkCommittee, OwnedCrosslinkCommittee};
 pub use crate::deposit::{Deposit, DEPOSIT_TREE_DEPTH};
 pub use crate::deposit_data::DepositData;
 pub use crate::eth1_data::Eth1Data;
@@ -70,23 +62,12 @@ pub use crate::proposer_slashing::ProposerSlashing;
 pub use crate::relative_epoch::{Error as RelativeEpochError, RelativeEpoch};
 pub use crate::slot_epoch::{Epoch, Slot};
 pub use crate::slot_height::SlotHeight;
-pub use crate::transfer::Transfer;
 pub use crate::validator::Validator;
 pub use crate::voluntary_exit::VoluntaryExit;
 
-pub type Shard = u64;
+pub type CommitteeIndex = u64;
-pub type Committee = Vec<usize>;
-pub type CrosslinkCommittees = Vec<(Committee, u64)>;
-
 pub type Hash256 = H256;
 pub type Address = H160;
-pub type EthBalance = U256;
-
-/// Maps a (slot, shard_id) to attestation_indices.
-pub type AttesterMap = HashMap<(u64, u64), Vec<usize>>;
-
-/// Maps a slot to a block proposer.
-pub type ProposerMap = HashMap<u64, usize>;
 
 pub use bls::{
     AggregatePublicKey, AggregateSignature, Keypair, PublicKey, PublicKeyBytes, SecretKey,

eth2/types/src/pending_attestation.rs

@@ -8,7 +8,7 @@ use tree_hash_derive::TreeHash;
 
 /// An attestation that has been included in the state but not yet fully processed.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct PendingAttestation<T: EthSpec> {
     pub aggregation_bits: BitList<T::MaxValidatorsPerCommittee>,

eth2/types/src/proposer_slashing.rs

@@ -8,7 +8,7 @@ use tree_hash_derive::TreeHash;
 
 /// Two conflicting proposals from the same proposer (validator).
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct ProposerSlashing {
     pub proposer_index: u64,

eth2/types/src/relative_epoch.rs

@@ -9,7 +9,7 @@ pub enum Error {
 /// Defines the epochs relative to some epoch. Most useful when referring to the committees prior
 /// to and following some epoch.
 ///
-/// Spec v0.8.1
+/// Spec v0.9.1
 #[derive(Debug, PartialEq, Clone, Copy)]
 pub enum RelativeEpoch {
     /// The prior epoch.
@@ -23,7 +23,7 @@ pub enum RelativeEpoch {
 impl RelativeEpoch {
     /// Returns the `epoch` that `self` refers to, with respect to the `base` epoch.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn into_epoch(self, base: Epoch) -> Epoch {
         match self {
             // Due to saturating nature of epoch, check for current first.
@@ -40,7 +40,7 @@ impl RelativeEpoch {
     /// - `EpochTooLow` when `other` is more than 1 prior to `base`.
     /// - `EpochTooHigh` when `other` is more than 1 after `base`.
     ///
-    /// Spec v0.8.1
+    /// Spec v0.9.1
     pub fn from_epoch(base: Epoch, other: Epoch) -> Result<Self, Error> {
         // Due to saturating nature of epoch, check for current first.
         if other == base {

eth2/types/src/test_utils/builders.rs

@@ -6,7 +6,6 @@ mod testing_beacon_state_builder;
 mod testing_deposit_builder;
 mod testing_pending_attestation_builder;
 mod testing_proposer_slashing_builder;
-mod testing_transfer_builder;
 mod testing_voluntary_exit_builder;
 
 pub use testing_attestation_builder::*;
@@ -17,5 +16,4 @@ pub use testing_beacon_state_builder::*;
 pub use testing_deposit_builder::*;
 pub use testing_pending_attestation_builder::*;
 pub use testing_proposer_slashing_builder::*;
-pub use testing_transfer_builder::*;
 pub use testing_voluntary_exit_builder::*;

eth2/types/src/test_utils/builders/testing_attestation_builder.rs

@@ -13,35 +13,31 @@ pub struct TestingAttestationBuilder<T: EthSpec> {
 impl<T: EthSpec> TestingAttestationBuilder<T> {
     /// Create a new attestation builder.
     pub fn new(
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         state: &BeaconState<T>,
         committee: &[usize],
         slot: Slot,
-        shard: u64,
+        index: u64,
         spec: &ChainSpec,
     ) -> Self {
-        let data_builder = TestingAttestationDataBuilder::new(test_task, state, shard, slot, spec);
+        let data_builder = TestingAttestationDataBuilder::new(test_task, state, index, slot, spec);
 
         let mut aggregation_bits_len = committee.len();
-        let mut custody_bits_len = committee.len();
 
         match test_task {
             AttestationTestTask::BadAggregationBitfieldLen => aggregation_bits_len += 1,
-            AttestationTestTask::BadCustodyBitfieldLen => custody_bits_len += 1,
             _ => (),
         }
+
         let mut aggregation_bits = BitList::with_capacity(aggregation_bits_len).unwrap();
-        let mut custody_bits = BitList::with_capacity(custody_bits_len).unwrap();
 
         for i in 0..committee.len() {
-            custody_bits.set(i, false).unwrap();
             aggregation_bits.set(i, false).unwrap();
         }
 
         let attestation = Attestation {
             aggregation_bits,
             data: data_builder.build(),
-            custody_bits,
             signature: AggregateSignature::new(),
         };
 
@@ -57,12 +53,11 @@ impl<T: EthSpec> TestingAttestationBuilder<T> {
     /// keypair must be that of the first signing validator.
     pub fn sign(
         &mut self,
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         signing_validators: &[usize],
         secret_keys: &[&SecretKey],
         fork: &Fork,
         spec: &ChainSpec,
-        mut custody_bit: bool,
     ) -> &mut Self {
         assert_eq!(
             signing_validators.len(),
@@ -79,7 +74,6 @@ impl<T: EthSpec> TestingAttestationBuilder<T> {
 
             match test_task {
                 AttestationTestTask::BadIndexedAttestationBadSignature => (),
-                AttestationTestTask::CustodyBitfieldNotSubset => custody_bit = true,
                 _ => {
                     self.attestation
                         .aggregation_bits
@@ -87,29 +81,16 @@ impl<T: EthSpec> TestingAttestationBuilder<T> {
                         .unwrap();
                 }
             }
-            match (custody_bit, test_task) {
-                (true, _) | (_, AttestationTestTask::CustodyBitfieldHasSetBits) => {
-                    self.attestation
-                        .custody_bits
-                        .set(committee_index, true)
-                        .unwrap();
-                }
-                (false, _) => (),
-            }
 
-            let message = AttestationDataAndCustodyBit {
+            let message = self.attestation.data.tree_hash_root();
-                data: self.attestation.data.clone(),
-                custody_bit,
-            }
-            .tree_hash_root();
 
             let domain = spec.get_domain(
                 self.attestation.data.target.epoch,
-                Domain::Attestation,
+                Domain::BeaconAttester,
                 fork,
             );
 
-            let index = if *test_task == AttestationTestTask::BadSignature {
+            let index = if test_task == AttestationTestTask::BadSignature {
                 0
             } else {
                 key_index

eth2/types/src/test_utils/builders/testing_attestation_data_builder.rs

@@ -1,6 +1,5 @@
 use crate::test_utils::AttestationTestTask;
 use crate::*;
-use tree_hash::TreeHash;
 
 /// Builds an `AttestationData` to be used for testing purposes.
 ///
@@ -13,10 +12,10 @@ impl TestingAttestationDataBuilder {
     /// Configures a new `AttestationData` which attests to all of the same parameters as the
     /// state.
     pub fn new<T: EthSpec>(
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         state: &BeaconState<T>,
-        mut shard: u64,
+        index: u64,
-        slot: Slot,
+        mut slot: Slot,
         spec: &ChainSpec,
     ) -> Self {
         let current_epoch = state.current_epoch();
@@ -46,34 +45,16 @@ impl TestingAttestationDataBuilder {
             }
         };
 
-        let parent_crosslink = if is_previous_epoch {
-            state.get_previous_crosslink(shard).unwrap()
-        } else {
-            state.get_current_crosslink(shard).unwrap()
-        };
-
-        let mut start = parent_crosslink.end_epoch;
-        let mut end = std::cmp::min(
-            target.epoch,
-            parent_crosslink.end_epoch + spec.max_epochs_per_crosslink,
-        );
-        let mut parent_root = Hash256::from_slice(&parent_crosslink.tree_hash_root());
-        let mut data_root = Hash256::zero();
         let beacon_block_root = *state.get_block_root(slot).unwrap();
 
         match test_task {
-            AttestationTestTask::BadParentCrosslinkStartEpoch => start = Epoch::from(10 as u64),
+            // FIXME: re-enable the shard-like tests
-            AttestationTestTask::BadParentCrosslinkEndEpoch => end = Epoch::from(0 as u64),
+            // AttestationTestTask::NoCommiteeForShard => index += 2,
-            AttestationTestTask::BadParentCrosslinkHash => parent_root = Hash256::zero(),
+            // AttestationTestTask::BadShard => index = T::ShardCount::to_u64(),
-            AttestationTestTask::NoCommiteeForShard => shard += 2,
+            AttestationTestTask::IncludedTooEarly => {
-            AttestationTestTask::BadShard => shard = T::ShardCount::to_u64(),
+                slot = state.slot - spec.min_attestation_inclusion_delay + 1
-            AttestationTestTask::IncludedTooEarly => shard += 1,
-            AttestationTestTask::IncludedTooLate => {
-                target = Checkpoint {
-                    epoch: Epoch::from(3 as u64),
-                    root: Hash256::zero(),
-                }
             }
+            AttestationTestTask::IncludedTooLate => slot -= T::SlotsPerEpoch::to_u64(),
             AttestationTestTask::BadTargetEpoch => {
                 target = Checkpoint {
                     epoch: Epoch::from(5 as u64),
@@ -98,27 +79,19 @@ impl TestingAttestationDataBuilder {
                     root: Hash256::zero(),
                 }
             }
-            AttestationTestTask::BadParentCrosslinkDataRoot => data_root = parent_root,
             _ => (),
         }
-        let crosslink = Crosslink {
-            shard,
-            parent_root,
-            start_epoch: start,
-            end_epoch: end,
-            data_root,
-        };
 
         let data = AttestationData {
+            slot,
+            index,
+
             // LMD GHOST vote
             beacon_block_root,
 
             // FFG Vote
             source,
             target,
-
-            // Crosslink vote
-            crosslink,
         };
 
         Self { data }

eth2/types/src/test_utils/builders/testing_attester_slashing_builder.rs

@@ -19,14 +19,15 @@ impl TestingAttesterSlashingBuilder {
     ///
     /// Where domain is a domain "constant" (e.g., `spec.domain_attestation`).
     pub fn double_vote<F, T: EthSpec>(
-        test_task: &AttesterSlashingTestTask,
+        test_task: AttesterSlashingTestTask,
         validator_indices: &[u64],
         signer: F,
     ) -> AttesterSlashing<T>
     where
         F: Fn(u64, &[u8], Epoch, Domain) -> Signature,
     {
-        let shard = 0;
+        let slot = Slot::new(1);
+        let index = 0;
         let epoch_1 = Epoch::new(1);
         let epoch_2 = Epoch::new(2);
         let hash_1 = Hash256::from_low_u64_le(1);
@@ -39,22 +40,16 @@ impl TestingAttesterSlashingBuilder {
             epoch: epoch_1,
             root: hash_2,
         };
-        let crosslink = Crosslink {
-            shard,
-            parent_root: hash_1,
-            start_epoch: epoch_1,
-            end_epoch: epoch_2,
-            data_root: hash_1,
-        };
 
         let data_1 = AttestationData {
+            slot,
+            index,
             beacon_block_root: hash_1,
             source: checkpoint_1.clone(),
             target: checkpoint_1,
-            crosslink,
         };
 
-        let data_2 = if *test_task == AttesterSlashingTestTask::NotSlashable {
+        let data_2 = if test_task == AttesterSlashingTestTask::NotSlashable {
             AttestationData { ..data_1.clone() }
         } else {
             AttestationData {
@@ -64,42 +59,39 @@ impl TestingAttesterSlashingBuilder {
         };
 
         let mut attestation_1 = IndexedAttestation {
-            custody_bit_0_indices: validator_indices.to_vec().into(),
+            attesting_indices: if test_task == AttesterSlashingTestTask::IndexedAttestation1Invalid
-            custody_bit_1_indices: if *test_task
-                == AttesterSlashingTestTask::IndexedAttestation1Invalid
             {
-                validator_indices.to_vec().into()
+                // Trigger bad validator indices ordering error.
+                vec![1, 0].into()
             } else {
-                VariableList::empty()
+                validator_indices.to_vec().into()
             },
             data: data_1,
             signature: AggregateSignature::new(),
         };
 
         let mut attestation_2 = IndexedAttestation {
-            custody_bit_0_indices: validator_indices.to_vec().into(),
+            attesting_indices: if test_task == AttesterSlashingTestTask::IndexedAttestation2Invalid
-            custody_bit_1_indices: if *test_task
-                == AttesterSlashingTestTask::IndexedAttestation2Invalid
             {
-                validator_indices.to_vec().into()
+                // Trigger bad validator indices ordering error.
+                vec![1, 0].into()
             } else {
-                VariableList::empty()
+                validator_indices.to_vec().into()
             },
             data: data_2,
             signature: AggregateSignature::new(),
         };
 
         let add_signatures = |attestation: &mut IndexedAttestation<T>| {
-            // All validators sign with a `false` custody bit.
+            let message = attestation.data.tree_hash_root();
-            let attestation_data_and_custody_bit = AttestationDataAndCustodyBit {
-                data: attestation.data.clone(),
-                custody_bit: false,
-            };
-            let message = attestation_data_and_custody_bit.tree_hash_root();
 
             for validator_index in validator_indices {
-                let signature =
+                let signature = signer(
-                    signer(*validator_index, &message[..], epoch_2, Domain::Attestation);
+                    *validator_index,
+                    &message[..],
+                    epoch_2,
+                    Domain::BeaconAttester,
+                );
                 attestation.signature.add(&signature);
             }
         };

eth2/types/src/test_utils/builders/testing_beacon_block_builder.rs

@@ -1,7 +1,7 @@
 use crate::{
     test_utils::{
         TestingAttestationBuilder, TestingAttesterSlashingBuilder, TestingDepositBuilder,
-        TestingProposerSlashingBuilder, TestingTransferBuilder, TestingVoluntaryExitBuilder,
+        TestingProposerSlashingBuilder, TestingVoluntaryExitBuilder,
     },
     typenum::U4294967296,
     *,
@@ -19,7 +19,7 @@ pub struct TestingBeaconBlockBuilder<T: EthSpec> {
 }
 
 /// Enum used for passing test options to builder
-#[derive(PartialEq)]
+#[derive(PartialEq, Clone, Copy)]
 pub enum DepositTestTask {
     Valid,
     BadPubKey,
@@ -29,6 +29,7 @@ pub enum DepositTestTask {
 }
 
 /// Enum used for passing test options to builder
+#[derive(PartialEq, Clone, Copy)]
 pub enum ExitTestTask {
     AlreadyInitiated,
     AlreadyExited,
@@ -39,23 +40,16 @@ pub enum ExitTestTask {
     ValidatorUnknown,
 }
 
-#[derive(PartialEq)]
 /// Enum used for passing test options to builder
+#[derive(PartialEq, Clone, Copy)]
 pub enum AttestationTestTask {
     Valid,
-    BadParentCrosslinkStartEpoch,
-    BadParentCrosslinkEndEpoch,
-    BadParentCrosslinkHash,
     NoCommiteeForShard,
     WrongJustifiedCheckpoint,
     BadTargetTooLow,
     BadTargetTooHigh,
     BadShard,
-    BadParentCrosslinkDataRoot,
     BadIndexedAttestationBadSignature,
-    CustodyBitfieldNotSubset,
-    CustodyBitfieldHasSetBits,
-    BadCustodyBitfieldLen,
     BadAggregationBitfieldLen,
     BadSignature,
     ValidatorUnknown,
@@ -64,8 +58,8 @@ pub enum AttestationTestTask {
     BadTargetEpoch,
 }
 
-#[derive(PartialEq)]
 /// Enum used for passing test options to builder
+#[derive(PartialEq, Clone, Copy)]
 pub enum AttesterSlashingTestTask {
     Valid,
     NotSlashable,
@@ -74,7 +68,7 @@ pub enum AttesterSlashingTestTask {
 }
 
 /// Enum used for passing test options to builder
-#[derive(PartialEq)]
+#[derive(PartialEq, Clone, Copy)]
 pub enum ProposerSlashingTestTask {
     Valid,
     ProposerUnknown,
@@ -131,7 +125,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
     /// Inserts a signed, valid `ProposerSlashing` for the validator.
     pub fn insert_proposer_slashing(
         &mut self,
-        test_task: &ProposerSlashingTestTask,
+        test_task: ProposerSlashingTestTask,
         validator_index: u64,
         secret_key: &SecretKey,
         fork: &Fork,
@@ -149,7 +143,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
     /// Inserts a signed, valid `AttesterSlashing` for each validator index in `validator_indices`.
     pub fn insert_attester_slashing(
         &mut self,
-        test_task: &AttesterSlashingTestTask,
+        test_task: AttesterSlashingTestTask,
         validator_indices: &[u64],
         secret_keys: &[&SecretKey],
         fork: &Fork,
@@ -176,7 +170,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
     /// to aggregate these split attestations.
     pub fn insert_attestations(
         &mut self,
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         state: &BeaconState<T>,
         secret_keys: &[&SecretKey],
         num_attestations: usize,
@@ -190,7 +184,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
         // - The slot of the committee.
         // - A list of all validators in the committee.
         // - A list of all validators in the committee that should sign the attestation.
-        // - The shard of the committee.
+        // - The index of the committee.
         let mut committees: Vec<(Slot, Vec<usize>, Vec<usize>, u64)> = vec![];
 
         if slot < T::slots_per_epoch() {
@@ -206,16 +200,16 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
                 break;
             }
 
-            for crosslink_committee in state.get_crosslink_committees_at_slot(slot)? {
+            for beacon_committee in state.get_beacon_committees_at_slot(slot)? {
                 if attestations_added >= num_attestations {
                     break;
                 }
 
                 committees.push((
                     slot,
-                    crosslink_committee.committee.to_vec(),
+                    beacon_committee.committee.to_vec(),
-                    crosslink_committee.committee.to_vec(),
+                    beacon_committee.committee.to_vec(),
-                    crosslink_committee.shard,
+                    beacon_committee.index,
                 ));
 
                 attestations_added += 1;
@@ -231,26 +225,26 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
                 break;
             }
 
-            for index in 0..committees.len() {
+            for i in 0..committees.len() {
                 if committees.len() >= num_attestations as usize {
                     break;
                 }
 
-                let (slot, committee, mut signing_validators, shard) = committees[index].clone();
+                let (slot, committee, mut signing_validators, index) = committees[i].clone();
 
                 let new_signing_validators =
                     signing_validators.split_off(signing_validators.len() / 2);
 
-                committees[index] = (slot, committee.clone(), signing_validators, shard);
+                committees[i] = (slot, committee.clone(), signing_validators, index);
-                committees.push((slot, committee, new_signing_validators, shard));
+                committees.push((slot, committee, new_signing_validators, index));
             }
         }
 
         let attestations: Vec<_> = committees
             .par_iter()
-            .map(|(slot, committee, signing_validators, shard)| {
+            .map(|(slot, committee, signing_validators, index)| {
                 let mut builder = TestingAttestationBuilder::new(
-                    test_task, state, committee, *slot, *shard, spec,
+                    test_task, state, committee, *slot, *index, spec,
                 );
 
                 let signing_secret_keys: Vec<&SecretKey> = signing_validators
@@ -263,7 +257,6 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
                     &signing_secret_keys,
                     &state.fork,
                     spec,
-                    false,
                 );
 
                 builder.build()
@@ -294,7 +287,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
             let keypair = Keypair::random();
 
             let mut builder = TestingDepositBuilder::new(keypair.pk.clone(), amount);
-            builder.sign(&test_task, &keypair, spec);
+            builder.sign(test_task, &keypair, spec);
             datas.push(builder.build().data);
         }
 
@@ -347,7 +340,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
     /// Insert a `Valid` exit into the state.
     pub fn insert_exit(
         &mut self,
-        test_task: &ExitTestTask,
+        test_task: ExitTestTask,
         state: &mut BeaconState<T>,
         mut validator_index: u64,
         secret_key: &SecretKey,
@@ -362,6 +355,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
             ExitTestTask::AlreadyExited => {
                 state.validators[validator_index as usize].exit_epoch = Epoch::from(314_159 as u64)
             }
+            // FIXME: disabled in v0.9
             ExitTestTask::NotActive => {
                 state.validators[validator_index as usize].activation_epoch =
                     Epoch::from(314_159 as u64)
@@ -381,25 +375,6 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
             .unwrap();
     }
 
-    /// Insert a `Valid` transfer into the state.
-    ///
-    /// Note: this will set the validator to be withdrawable by directly modifying the state
-    /// validator registry. This _may_ cause problems historic hashes, etc.
-    pub fn insert_transfer(
-        &mut self,
-        state: &BeaconState<T>,
-        from: u64,
-        to: u64,
-        amount: u64,
-        keypair: Keypair,
-        spec: &ChainSpec,
-    ) {
-        let mut builder = TestingTransferBuilder::new(from, to, amount, state.slot);
-        builder.sign::<T>(keypair, &state.fork, spec);
-
-        self.block.body.transfers.push(builder.build()).unwrap()
-    }
-
     /// Signs and returns the block, consuming the builder.
     pub fn build(mut self, sk: &SecretKey, fork: &Fork, spec: &ChainSpec) -> BeaconBlock<T> {
         self.sign(sk, fork, spec);
@@ -416,7 +391,7 @@ impl<T: EthSpec> TestingBeaconBlockBuilder<T> {
 ///
 /// Signs the message using a `BeaconChainHarness`.
 fn build_proposer_slashing<T: EthSpec>(
-    test_task: &ProposerSlashingTestTask,
+    test_task: ProposerSlashingTestTask,
     validator_index: u64,
     secret_key: &SecretKey,
     fork: &Fork,
@@ -434,7 +409,7 @@ fn build_proposer_slashing<T: EthSpec>(
 ///
 /// Signs the message using a `BeaconChainHarness`.
 fn build_double_vote_attester_slashing<T: EthSpec>(
-    test_task: &AttesterSlashingTestTask,
+    test_task: AttesterSlashingTestTask,
     validator_indices: &[u64],
     secret_keys: &[&SecretKey],
     fork: &Fork,

eth2/types/src/test_utils/builders/testing_beacon_state_builder.rs

@@ -181,8 +181,6 @@ impl<T: EthSpec> TestingBeaconStateBuilder<T> {
 
         state.slot = slot;
 
-        // NOTE: we could update the latest start shard here
-
         state.previous_justified_checkpoint.epoch = epoch - 3;
         state.current_justified_checkpoint.epoch = epoch - 2;
         state.justification_bits = BitVector::from_bytes(vec![0b0000_1111]).unwrap();
@@ -215,23 +213,23 @@ impl<T: EthSpec> TestingBeaconStateBuilder<T> {
         for slot in first_slot..=last_slot {
             let slot = Slot::from(slot);
 
-            let committees: Vec<OwnedCrosslinkCommittee> = state
+            let committees: Vec<OwnedBeaconCommittee> = state
-                .get_crosslink_committees_at_slot(slot)
+                .get_beacon_committees_at_slot(slot)
                 .unwrap()
                 .into_iter()
                 .map(|c| c.clone().into_owned())
                 .collect();
 
-            for crosslink_committee in committees {
+            for beacon_committee in committees {
                 let mut builder = TestingPendingAttestationBuilder::new(
-                    &AttestationTestTask::Valid,
+                    AttestationTestTask::Valid,
                     state,
-                    crosslink_committee.shard,
+                    beacon_committee.index,
                     slot,
                     spec,
                 );
                 // The entire committee should have signed the pending attestation.
-                let signers = vec![true; crosslink_committee.committee.len()];
+                let signers = vec![true; beacon_committee.committee.len()];
                 builder.add_committee_participation(signers);
                 let attestation = builder.build();
 

eth2/types/src/test_utils/builders/testing_deposit_builder.rs

@@ -30,7 +30,7 @@ impl TestingDepositBuilder {
     /// - `pubkey` to the signing pubkey.
     /// - `withdrawal_credentials` to the signing pubkey.
     /// - `proof_of_possession`
-    pub fn sign(&mut self, test_task: &DepositTestTask, keypair: &Keypair, spec: &ChainSpec) {
+    pub fn sign(&mut self, test_task: DepositTestTask, keypair: &Keypair, spec: &ChainSpec) {
         let new_key = Keypair::random();
         let mut pubkeybytes = PublicKeyBytes::from(keypair.pk.clone());
         let mut secret_key = keypair.sk.clone();

eth2/types/src/test_utils/builders/testing_pending_attestation_builder.rs

@@ -13,23 +13,18 @@ impl<T: EthSpec> TestingPendingAttestationBuilder<T> {
     ///
     /// The `inclusion_delay` will be set to `MIN_ATTESTATION_INCLUSION_DELAY`.
     ///
-    /// * The aggregation and custody bitfields will all be empty, they need to be set with
+    /// * The aggregation bitfield will be empty, it needs to be set with
     /// `Self::add_committee_participation`.
     pub fn new(
-        test_task: &AttestationTestTask,
+        test_task: AttestationTestTask,
         state: &BeaconState<T>,
-        shard: u64,
+        index: u64,
         slot: Slot,
         spec: &ChainSpec,
     ) -> Self {
-        let data_builder = TestingAttestationDataBuilder::new(test_task, state, shard, slot, spec);
+        let data_builder = TestingAttestationDataBuilder::new(test_task, state, index, slot, spec);
 
-        let relative_epoch =
+        let proposer_index = state.get_beacon_proposer_index(slot, spec).unwrap() as u64;
-            RelativeEpoch::from_epoch(state.current_epoch(), slot.epoch(T::slots_per_epoch()))
-                .expect("epoch out of bounds");
-        let proposer_index = state
-            .get_beacon_proposer_index(slot, relative_epoch, spec)
-            .unwrap() as u64;
 
         let pending_attestation = PendingAttestation {
             aggregation_bits: BitList::with_capacity(T::MaxValidatorsPerCommittee::to_usize())

eth2/types/src/test_utils/builders/testing_proposer_slashing_builder.rs

@@ -19,7 +19,7 @@ impl TestingProposerSlashingBuilder {
     ///
     /// Where domain is a domain "constant" (e.g., `spec.domain_attestation`).
     pub fn double_vote<T, F>(
-        test_task: &ProposerSlashingTestTask,
+        test_task: ProposerSlashingTestTask,
         mut proposer_index: u64,
         signer: F,
     ) -> ProposerSlashing
@@ -29,7 +29,7 @@ impl TestingProposerSlashingBuilder {
     {
         let slot = Slot::new(0);
         let hash_1 = Hash256::from([1; 32]);
-        let hash_2 = if *test_task == ProposerSlashingTestTask::ProposalsIdentical {
+        let hash_2 = if test_task == ProposerSlashingTestTask::ProposalsIdentical {
             hash_1.clone()
         } else {
             Hash256::from([2; 32])
@@ -43,7 +43,7 @@ impl TestingProposerSlashingBuilder {
             signature: Signature::empty_signature(),
         };
 
-        let slot_2 = if *test_task == ProposerSlashingTestTask::ProposalEpochMismatch {
+        let slot_2 = if test_task == ProposerSlashingTestTask::ProposalEpochMismatch {
             Slot::new(128)
         } else {
             Slot::new(0)
@@ -57,21 +57,21 @@ impl TestingProposerSlashingBuilder {
 
         let epoch = slot.epoch(T::slots_per_epoch());
 
-        if *test_task != ProposerSlashingTestTask::BadProposal1Signature {
+        if test_task != ProposerSlashingTestTask::BadProposal1Signature {
             header_1.signature = {
                 let message = header_1.signed_root();
                 signer(proposer_index, &message[..], epoch, Domain::BeaconProposer)
             };
         }
 
-        if *test_task != ProposerSlashingTestTask::BadProposal2Signature {
+        if test_task != ProposerSlashingTestTask::BadProposal2Signature {
             header_2.signature = {
                 let message = header_2.signed_root();
                 signer(proposer_index, &message[..], epoch, Domain::BeaconProposer)
             };
         }
 
-        if *test_task == ProposerSlashingTestTask::ProposerUnknown {
+        if test_task == ProposerSlashingTestTask::ProposerUnknown {
             proposer_index = 3_141_592;
         }
 

eth2/types/src/test_utils/builders/testing_transfer_builder.rs

@@ -1,45 +0,0 @@
-use crate::*;
-use tree_hash::SignedRoot;
-
-/// Builds a transfer to be used for testing purposes.
-///
-/// This struct should **never be used for production purposes.**
-pub struct TestingTransferBuilder {
-    transfer: Transfer,
-}
-
-impl TestingTransferBuilder {
-    /// Instantiates a new builder.
-    pub fn new(sender: u64, recipient: u64, amount: u64, slot: Slot) -> Self {
-        let keypair = Keypair::random();
-
-        let transfer = Transfer {
-            sender,
-            recipient,
-            amount,
-            fee: 0,
-            slot,
-            pubkey: keypair.pk,
-            signature: Signature::empty_signature(),
-        };
-
-        Self { transfer }
-    }
-
-    /// Signs the transfer.
-    ///
-    /// The keypair must match that of the `from` validator index.
-    pub fn sign<T: EthSpec>(&mut self, keypair: Keypair, fork: &Fork, spec: &ChainSpec) {
-        self.transfer.pubkey = keypair.pk;
-        let message = self.transfer.signed_root();
-        let epoch = self.transfer.slot.epoch(T::slots_per_epoch());
-        let domain = spec.get_domain(epoch, Domain::Transfer, fork);
-
-        self.transfer.signature = Signature::new(&message, domain, &keypair.sk);
-    }
-
-    /// Builds the transfer, consuming the builder.
-    pub fn build(self) -> Transfer {
-        self.transfer
-    }
-}

eth2/types/src/transfer.rs

@@ -1,45 +0,0 @@
-use super::Slot;
-use crate::test_utils::TestRandom;
-use bls::{PublicKey, Signature};
-use derivative::Derivative;
-
-use serde_derive::{Deserialize, Serialize};
-use ssz_derive::{Decode, Encode};
-use test_random_derive::TestRandom;
-use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
-
-/// The data submitted to the deposit contract.
-///
-/// Spec v0.8.0
-#[derive(
-    Debug,
-    Clone,
-    Serialize,
-    Deserialize,
-    Encode,
-    Decode,
-    TreeHash,
-    TestRandom,
-    SignedRoot,
-    Derivative,
-)]
-#[derivative(PartialEq, Eq, Hash)]
-pub struct Transfer {
-    pub sender: u64,
-    pub recipient: u64,
-    pub amount: u64,
-    pub fee: u64,
-    pub slot: Slot,
-    pub pubkey: PublicKey,
-    #[derivative(Hash = "ignore")]
-    #[signed_root(skip_hashing)]
-    pub signature: Signature,
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    ssz_tests!(Transfer);
-}

eth2/types/src/validator.rs

@@ -7,7 +7,7 @@ use tree_hash_derive::TreeHash;
 
 /// Information about a `BeaconChain` validator.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
 pub struct Validator {
     pub pubkey: PublicKey,

eth2/types/src/voluntary_exit.rs

@@ -9,7 +9,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
 
 /// An exit voluntarily submitted a validator who wishes to withdraw.
 ///
-/// Spec v0.8.0
+/// Spec v0.9.1
 #[derive(
     Debug,
     PartialEq,

eth2/utils/swap_or_not_shuffle/src/shuffle_list.rs

@@ -19,7 +19,17 @@ const TOTAL_SIZE: usize = SEED_SIZE + ROUND_SIZE + POSITION_WINDOW_SIZE;
 /// It holds that: shuffle_list(shuffle_list(l, r, s, true), r, s, false) == l
 ///           and: shuffle_list(shuffle_list(l, r, s, false), r, s, true) == l
 ///
-/// TODO forwards is around the wrong way - denote?
+/// The Eth2.0 spec mostly uses shuffling with `forwards == false`, because backwards
+/// shuffled lists are slightly easier to specify, and slightly easier to compute.
+///
+/// The forwards shuffling of a list is equivalent to:
+///
+/// `[indices[x] for i in 0..n, where compute_shuffled_index(x) = i]`
+///
+/// Whereas the backwards shuffling of a list is:
+///
+/// `[indices[compute_shuffled_index(i)] for i in 0..n]`
+///
 /// Returns `None` under any of the following conditions:
 ///  - `list_size == 0`
 ///  - `list_size > 2**24`

tests/ef_tests/Makefile

@@ -1,5 +1,5 @@
 # Bump the test tag here and in .gitlab-ci.yml and CI will take care of updating the cached tarballs
-TESTS_TAG := v0.8.3
+TESTS_TAG := v0.9.1
 TESTS = general minimal mainnet
 TARBALLS = $(patsubst %,%-$(TESTS_TAG).tar.gz,$(TESTS))
 

tests/ef_tests/src/cases/epoch_processing.rs

@@ -6,8 +6,8 @@ use crate::type_name;
 use crate::type_name::TypeName;
 use serde_derive::Deserialize;
 use state_processing::per_epoch_processing::{
-    errors::EpochProcessingError, process_crosslinks, process_final_updates,
+    errors::EpochProcessingError, process_final_updates, process_justification_and_finalization,
-    process_justification_and_finalization, process_registry_updates, process_slashings,
+    process_registry_updates, process_rewards_and_penalties, process_slashings,
     validator_statuses::ValidatorStatuses,
 };
 use std::marker::PhantomData;
@@ -38,7 +38,7 @@ pub trait EpochTransition<E: EthSpec>: TypeName + Debug + Sync {
 #[derive(Debug)]
 pub struct JustificationAndFinalization;
 #[derive(Debug)]
-pub struct Crosslinks;
+pub struct RewardsAndPenalties;
 #[derive(Debug)]
 pub struct RegistryUpdates;
 #[derive(Debug)]
@@ -50,7 +50,7 @@ type_name!(
     JustificationAndFinalization,
     "justification_and_finalization"
 );
-type_name!(Crosslinks, "crosslinks");
+type_name!(RewardsAndPenalties, "rewards_and_penalties");
 type_name!(RegistryUpdates, "registry_updates");
 type_name!(Slashings, "slashings");
 type_name!(FinalUpdates, "final_updates");
@@ -63,10 +63,11 @@ impl<E: EthSpec> EpochTransition<E> for JustificationAndFinalization {
     }
 }
 
-impl<E: EthSpec> EpochTransition<E> for Crosslinks {
+impl<E: EthSpec> EpochTransition<E> for RewardsAndPenalties {
     fn run(state: &mut BeaconState<E>, spec: &ChainSpec) -> Result<(), EpochProcessingError> {
-        process_crosslinks(state, spec)?;
+        let mut validator_statuses = ValidatorStatuses::new(state, spec)?;
-        Ok(())
+        validator_statuses.process_attestations(state, spec)?;
+        process_rewards_and_penalties(state, &mut validator_statuses, spec)
     }
 }
 

tests/ef_tests/src/cases/operations.rs

@@ -8,13 +8,13 @@ use ssz::Decode;
 use state_processing::per_block_processing::{
     errors::BlockProcessingError, process_attestations, process_attester_slashings,
     process_block_header, process_deposits, process_exits, process_proposer_slashings,
-    process_transfers, VerifySignatures,
+    VerifySignatures,
 };
 use std::fmt::Debug;
 use std::path::Path;
 use types::{
     Attestation, AttesterSlashing, BeaconBlock, BeaconState, ChainSpec, Deposit, EthSpec,
-    ProposerSlashing, Transfer, VoluntaryExit,
+    ProposerSlashing, VoluntaryExit,
 };
 
 #[derive(Debug, Clone, Default, Deserialize)]
@@ -95,16 +95,6 @@ impl<E: EthSpec> Operation<E> for ProposerSlashing {
     }
 }
 
-impl<E: EthSpec> Operation<E> for Transfer {
-    fn apply_to(
-        &self,
-        state: &mut BeaconState<E>,
-        spec: &ChainSpec,
-    ) -> Result<(), BlockProcessingError> {
-        process_transfers(state, &[self.clone()], VerifySignatures::True, spec)
-    }
-}
-
 impl<E: EthSpec> Operation<E> for VoluntaryExit {
     fn handler_name() -> String {
         "voluntary_exit".into()

tests/ef_tests/src/lib.rs

@@ -3,7 +3,7 @@ use types::EthSpec;
 pub use case_result::CaseResult;
 pub use cases::Case;
 pub use cases::{
-    Crosslinks, FinalUpdates, JustificationAndFinalization, RegistryUpdates, Slashings,
+    FinalUpdates, JustificationAndFinalization, RegistryUpdates, RewardsAndPenalties, Slashings,
 };
 pub use error::Error;
 pub use handler::*;

tests/ef_tests/src/type_name.rs

@@ -38,15 +38,12 @@ type_name!(MainnetEthSpec, "mainnet");
 
 type_name_generic!(Attestation);
 type_name!(AttestationData);
-type_name!(AttestationDataAndCustodyBit);
 type_name_generic!(AttesterSlashing);
 type_name_generic!(BeaconBlock);
 type_name_generic!(BeaconBlockBody);
 type_name!(BeaconBlockHeader);
 type_name_generic!(BeaconState);
 type_name!(Checkpoint);
-type_name_generic!(CompactCommittee);
-type_name!(Crosslink);
 type_name!(Deposit);
 type_name!(DepositData);
 type_name!(Eth1Data);
@@ -55,6 +52,5 @@ type_name_generic!(HistoricalBatch);
 type_name_generic!(IndexedAttestation);
 type_name_generic!(PendingAttestation);
 type_name!(ProposerSlashing);
-type_name!(Transfer);
 type_name!(Validator);
 type_name!(VoluntaryExit);

tests/ef_tests/tests/tests.rs

@@ -15,12 +15,6 @@ fn operations_deposit() {
     OperationsHandler::<MainnetEthSpec, Deposit>::run();
 }
 
-#[test]
-fn operations_transfer() {
-    OperationsHandler::<MinimalEthSpec, Transfer>::run();
-    // Note: there are no transfer tests for mainnet
-}
-
 #[test]
 fn operations_exit() {
     OperationsHandler::<MinimalEthSpec, VoluntaryExit>::run();
@@ -139,10 +133,6 @@ mod ssz_static {
 
     ssz_static_test!(attestation, Attestation<_>, SR);
     ssz_static_test!(attestation_data, AttestationData);
-    ssz_static_test!(
-        attestation_data_and_custody_bit,
-        AttestationDataAndCustodyBit
-    );
     ssz_static_test!(attester_slashing, AttesterSlashing<_>);
     ssz_static_test!(beacon_block, BeaconBlock<_>, SR);
     ssz_static_test!(beacon_block_body, BeaconBlockBody<_>);
@@ -155,8 +145,6 @@ mod ssz_static {
         }
     );
     ssz_static_test!(checkpoint, Checkpoint);
-    ssz_static_test!(compact_committee, CompactCommittee<_>);
-    ssz_static_test!(crosslink, Crosslink);
     ssz_static_test!(deposit, Deposit);
     ssz_static_test!(deposit_data, DepositData, SR);
     ssz_static_test!(eth1_data, Eth1Data);
@@ -165,7 +153,6 @@ mod ssz_static {
     ssz_static_test!(indexed_attestation, IndexedAttestation<_>, SR);
     ssz_static_test!(pending_attestation, PendingAttestation<_>);
     ssz_static_test!(proposer_slashing, ProposerSlashing);
-    ssz_static_test!(transfer, Transfer, SR);
     ssz_static_test!(validator, Validator);
     ssz_static_test!(voluntary_exit, VoluntaryExit, SR);
 }
@@ -187,9 +174,9 @@ fn epoch_processing_justification_and_finalization() {
 }
 
 #[test]
-fn epoch_processing_crosslinks() {
+fn epoch_processing_rewards_and_penalties() {
-    EpochProcessingHandler::<MinimalEthSpec, Crosslinks>::run();
+    EpochProcessingHandler::<MinimalEthSpec, RewardsAndPenalties>::run();
-    EpochProcessingHandler::<MainnetEthSpec, Crosslinks>::run();
+    // Note: there are no reward and penalty tests for mainnet yet
 }
 
 #[test]

validator_client/README.md

@@ -8,11 +8,11 @@ Node (BN) and fulfils the roles of a validator.
 The VC is responsible for the following tasks:
 
 - Requesting validator duties (a.k.a. shuffling) from the BN.
-- Prompting the BN to produce a new block, when a validators block production
+- Prompting the BN to produce a new block, when a validator's block production
 	duties require.
 - Completing all the fields on a new block (e.g., RANDAO reveal, signature) and
 	publishing the block to a BN.
-- Prompting the BN to produce a new shard attestation as per a validators
+- Prompting the BN to produce a new attestation as per a validator's
 	duties.
 - Ensuring that no slashable messages are signed by a validator private key.
 - Keeping track of the system clock and how it relates to slots/epochs.