Merge current master

Cargo.toml

@@ -1,7 +1,7 @@
 [workspace]
 members = [
 	"eth2/attester",
-	"eth2/block_producer",
+	"eth2/block_proposer",
 	"eth2/fork_choice",
 	"eth2/state_processing",
 	"eth2/types",
@@ -12,6 +12,7 @@ members = [
 	"eth2/utils/int_to_bytes",
 	"eth2/utils/slot_clock",
 	"eth2/utils/ssz",
+	"eth2/utils/ssz_derive",
 	"eth2/utils/swap_or_not_shuffle",
 	"eth2/utils/fisher_yates_shuffle",
 	"beacon_node",

beacon_node/beacon_chain/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
 
 [dependencies]
-block_producer = { path = "../../eth2/block_producer" }
+block_proposer = { path = "../../eth2/block_proposer" }
 bls = { path = "../../eth2/utils/bls" }
 boolean-bitfield = { path = "../../eth2/utils/boolean-bitfield" }
 db = { path = "../db" }

beacon_node/beacon_chain/test_harness/Cargo.toml

@@ -14,7 +14,7 @@ criterion = "0.2"
 [dependencies]
 attester = { path = "../../../eth2/attester" }
 beacon_chain = { path = "../../beacon_chain" }
-block_producer = { path = "../../../eth2/block_producer" }
+block_proposer = { path = "../../../eth2/block_proposer" }
 bls = { path = "../../../eth2/utils/bls" }
 boolean-bitfield = { path = "../../../eth2/utils/boolean-bitfield" }
 db = { path = "../../db" }

beacon_node/beacon_chain/test_harness/src/validator_harness/direct_beacon_node.rs

@@ -3,7 +3,7 @@ use attester::{
     PublishOutcome as AttestationPublishOutcome,
 };
 use beacon_chain::BeaconChain;
-use block_producer::{
+use block_proposer::{
     BeaconNode as BeaconBlockNode, BeaconNodeError as BeaconBlockNodeError,
     PublishOutcome as BlockPublishOutcome,
 };

beacon_node/beacon_chain/test_harness/src/validator_harness/direct_duties.rs

@@ -2,7 +2,7 @@ use attester::{
     DutiesReader as AttesterDutiesReader, DutiesReaderError as AttesterDutiesReaderError,
 };
 use beacon_chain::BeaconChain;
-use block_producer::{
+use block_proposer::{
     DutiesReader as ProducerDutiesReader, DutiesReaderError as ProducerDutiesReaderError,
 };
 use db::ClientDB;

beacon_node/beacon_chain/test_harness/src/validator_harness/local_signer.rs

@@ -1,5 +1,5 @@
 use attester::Signer as AttesterSigner;
-use block_producer::Signer as BlockProposerSigner;
+use block_proposer::Signer as BlockProposerSigner;
 use std::sync::RwLock;
 use types::{Keypair, Signature};
 

beacon_node/beacon_chain/test_harness/src/validator_harness/mod.rs

@@ -5,8 +5,8 @@ mod local_signer;
 use attester::PollOutcome as AttestationPollOutcome;
 use attester::{Attester, Error as AttestationPollError};
 use beacon_chain::BeaconChain;
-use block_producer::PollOutcome as BlockPollOutcome;
+use block_proposer::PollOutcome as BlockPollOutcome;
-use block_producer::{BlockProducer, Error as BlockPollError};
+use block_proposer::{BlockProducer, Error as BlockPollError};
 use db::MemoryDB;
 use direct_beacon_node::DirectBeaconNode;
 use direct_duties::DirectDuties;

eth2/block_proposer/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "block_producer"
+name = "block_proposer"
 version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"

eth2/block_proposer/src/lib.rs

@@ -239,7 +239,7 @@ mod tests {
         epoch_map.map.insert(produce_epoch, produce_slot);
         let epoch_map = Arc::new(epoch_map);
 
-        let mut block_producer = BlockProducer::new(
+        let mut block_proposer = BlockProducer::new(
             spec.clone(),
             epoch_map.clone(),
             slot_clock.clone(),
@@ -254,28 +254,28 @@ mod tests {
         // One slot before production slot...
         slot_clock.set_slot(produce_slot.as_u64() - 1);
         assert_eq!(
-            block_producer.poll(),
+            block_proposer.poll(),
             Ok(PollOutcome::BlockProductionNotRequired(produce_slot - 1))
         );
 
         // On the produce slot...
         slot_clock.set_slot(produce_slot.as_u64());
         assert_eq!(
-            block_producer.poll(),
+            block_proposer.poll(),
             Ok(PollOutcome::BlockProduced(produce_slot.into()))
         );
 
         // Trying the same produce slot again...
         slot_clock.set_slot(produce_slot.as_u64());
         assert_eq!(
-            block_producer.poll(),
+            block_proposer.poll(),
             Ok(PollOutcome::SlotAlreadyProcessed(produce_slot))
         );
 
         // One slot after the produce slot...
         slot_clock.set_slot(produce_slot.as_u64() + 1);
         assert_eq!(
-            block_producer.poll(),
+            block_proposer.poll(),
             Ok(PollOutcome::BlockProductionNotRequired(produce_slot + 1))
         );
 
@@ -283,7 +283,7 @@ mod tests {
         let slot = (produce_epoch.as_u64() + 1) * spec.epoch_length;
         slot_clock.set_slot(slot);
         assert_eq!(
-            block_producer.poll(),
+            block_proposer.poll(),
             Ok(PollOutcome::ProducerDutiesUnknown(Slot::new(slot)))
         );
     }

eth2/types/Cargo.toml

@@ -18,6 +18,7 @@ serde_derive = "1.0"
 serde_json = "1.0"
 slog = "^2.2.3"
 ssz = { path = "../utils/ssz" }
+ssz_derive = { path = "../utils/ssz_derive" }
 swap_or_not_shuffle = { path = "../utils/swap_or_not_shuffle" }
 
 [dev-dependencies]

eth2/types/src/attestation.rs

@@ -2,9 +2,10 @@ use super::{AggregatePublicKey, AggregateSignature, AttestationData, Bitfield, H
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, Clone, PartialEq, Serialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Encode, Decode)]
 pub struct Attestation {
     pub aggregation_bitfield: Bitfield,
     pub data: AttestationData,
@@ -35,39 +36,13 @@ impl Attestation {
     }
 }
 
-impl Encodable for Attestation {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.aggregation_bitfield);
-        s.append(&self.data);
-        s.append(&self.custody_bitfield);
-        s.append(&self.aggregate_signature);
-    }
-}
-
-impl Decodable for Attestation {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (aggregation_bitfield, i) = Bitfield::ssz_decode(bytes, i)?;
-        let (data, i) = AttestationData::ssz_decode(bytes, i)?;
-        let (custody_bitfield, i) = Bitfield::ssz_decode(bytes, i)?;
-        let (aggregate_signature, i) = AggregateSignature::ssz_decode(bytes, i)?;
-
-        let attestation_record = Self {
-            aggregation_bitfield,
-            data,
-            custody_bitfield,
-            aggregate_signature,
-        };
-        Ok((attestation_record, i))
-    }
-}
-
 impl TreeHash for Attestation {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.aggregation_bitfield.hash_tree_root());
+        result.append(&mut self.aggregation_bitfield.hash_tree_root_internal());
-        result.append(&mut self.data.hash_tree_root());
+        result.append(&mut self.data.hash_tree_root_internal());
-        result.append(&mut self.custody_bitfield.hash_tree_root());
+        result.append(&mut self.custody_bitfield.hash_tree_root_internal());
-        result.append(&mut self.aggregate_signature.hash_tree_root());
+        result.append(&mut self.aggregate_signature.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -87,7 +62,7 @@ impl<T: RngCore> TestRandom<T> for Attestation {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -101,11 +76,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Attestation::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/attestation_data.rs

@@ -2,7 +2,8 @@ use crate::test_utils::TestRandom;
 use crate::{AttestationDataAndCustodyBit, Crosslink, Epoch, Hash256, Slot};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
 pub const SSZ_ATTESTION_DATA_LENGTH: usize = {
     8 +             // slot
@@ -15,7 +16,7 @@ pub const SSZ_ATTESTION_DATA_LENGTH: usize = {
     32 // justified_block_root
 };
 
-#[derive(Debug, Clone, PartialEq, Default, Serialize, Hash)]
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Hash, Encode, Decode)]
 pub struct AttestationData {
     pub slot: Slot,
     pub shard: u64,
@@ -43,55 +44,17 @@ impl AttestationData {
     }
 }
 
-impl Encodable for AttestationData {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slot);
-        s.append(&self.shard);
-        s.append(&self.beacon_block_root);
-        s.append(&self.epoch_boundary_root);
-        s.append(&self.shard_block_root);
-        s.append(&self.latest_crosslink);
-        s.append(&self.justified_epoch);
-        s.append(&self.justified_block_root);
-    }
-}
-
-impl Decodable for AttestationData {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-        let (shard, i) = <_>::ssz_decode(bytes, i)?;
-        let (beacon_block_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (epoch_boundary_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (shard_block_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_crosslink, i) = <_>::ssz_decode(bytes, i)?;
-        let (justified_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (justified_block_root, i) = <_>::ssz_decode(bytes, i)?;
-
-        let attestation_data = AttestationData {
-            slot,
-            shard,
-            beacon_block_root,
-            epoch_boundary_root,
-            shard_block_root,
-            latest_crosslink,
-            justified_epoch,
-            justified_block_root,
-        };
-        Ok((attestation_data, i))
-    }
-}
-
 impl TreeHash for AttestationData {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
-        result.append(&mut self.shard.hash_tree_root());
+        result.append(&mut self.shard.hash_tree_root_internal());
-        result.append(&mut self.beacon_block_root.hash_tree_root());
+        result.append(&mut self.beacon_block_root.hash_tree_root_internal());
-        result.append(&mut self.epoch_boundary_root.hash_tree_root());
+        result.append(&mut self.epoch_boundary_root.hash_tree_root_internal());
-        result.append(&mut self.shard_block_root.hash_tree_root());
+        result.append(&mut self.shard_block_root.hash_tree_root_internal());
-        result.append(&mut self.latest_crosslink.hash_tree_root());
+        result.append(&mut self.latest_crosslink.hash_tree_root_internal());
-        result.append(&mut self.justified_epoch.hash_tree_root());
+        result.append(&mut self.justified_epoch.hash_tree_root_internal());
-        result.append(&mut self.justified_block_root.hash_tree_root());
+        result.append(&mut self.justified_block_root.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -115,7 +78,7 @@ impl<T: RngCore> TestRandom<T> for AttestationData {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -129,11 +92,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = AttestationData::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/attestation_data_and_custody_bit.rs

@@ -2,38 +2,21 @@ use super::AttestationData;
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::TreeHash;
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, Clone, PartialEq, Default, Serialize)]
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Encode, Decode)]
 pub struct AttestationDataAndCustodyBit {
     pub data: AttestationData,
     pub custody_bit: bool,
 }
 
-impl Encodable for AttestationDataAndCustodyBit {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.data);
-        // TODO: deal with bools
-    }
-}
-
-impl Decodable for AttestationDataAndCustodyBit {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (data, i) = <_>::ssz_decode(bytes, i)?;
-        let custody_bit = false;
-
-        let attestation_data_and_custody_bit = AttestationDataAndCustodyBit { data, custody_bit };
-
-        Ok((attestation_data_and_custody_bit, i))
-    }
-}
-
 impl TreeHash for AttestationDataAndCustodyBit {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.data.hash_tree_root());
+        result.append(&mut self.data.hash_tree_root_internal());
         // TODO: add bool ssz
-        // result.append(custody_bit.hash_tree_root());
+        // result.append(custody_bit.hash_tree_root_internal());
         ssz::hash(&result)
     }
 }
@@ -52,7 +35,7 @@ impl<T: RngCore> TestRandom<T> for AttestationDataAndCustodyBit {
 mod test {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -68,11 +51,11 @@ mod test {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = AttestationDataAndCustodyBit::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/attester_slashing.rs

@@ -1,41 +1,20 @@
 use crate::{test_utils::TestRandom, SlashableAttestation};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct AttesterSlashing {
     pub slashable_attestation_1: SlashableAttestation,
     pub slashable_attestation_2: SlashableAttestation,
 }
 
-impl Encodable for AttesterSlashing {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slashable_attestation_1);
-        s.append(&self.slashable_attestation_2);
-    }
-}
-
-impl Decodable for AttesterSlashing {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slashable_attestation_1, i) = <_>::ssz_decode(bytes, i)?;
-        let (slashable_attestation_2, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            AttesterSlashing {
-                slashable_attestation_1,
-                slashable_attestation_2,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for AttesterSlashing {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slashable_attestation_1.hash_tree_root());
+        result.append(&mut self.slashable_attestation_1.hash_tree_root_internal());
-        result.append(&mut self.slashable_attestation_2.hash_tree_root());
+        result.append(&mut self.slashable_attestation_2.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -53,7 +32,7 @@ impl<T: RngCore> TestRandom<T> for AttesterSlashing {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -67,11 +46,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = AttesterSlashing::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/beacon_block.rs

@@ -3,9 +3,10 @@ use crate::{BeaconBlockBody, ChainSpec, Eth1Data, Hash256, ProposalSignedData, S
 use bls::Signature;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct BeaconBlock {
     pub slot: Slot,
     pub parent_root: Hash256,
@@ -59,53 +60,16 @@ impl BeaconBlock {
     }
 }
 
-impl Encodable for BeaconBlock {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slot);
-        s.append(&self.parent_root);
-        s.append(&self.state_root);
-        s.append(&self.randao_reveal);
-        s.append(&self.eth1_data);
-        s.append(&self.signature);
-        s.append(&self.body);
-    }
-}
-
-impl Decodable for BeaconBlock {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-        let (parent_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (state_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (randao_reveal, i) = <_>::ssz_decode(bytes, i)?;
-        let (eth1_data, i) = <_>::ssz_decode(bytes, i)?;
-        let (signature, i) = <_>::ssz_decode(bytes, i)?;
-        let (body, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                slot,
-                parent_root,
-                state_root,
-                randao_reveal,
-                eth1_data,
-                signature,
-                body,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for BeaconBlock {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
-        result.append(&mut self.parent_root.hash_tree_root());
+        result.append(&mut self.parent_root.hash_tree_root_internal());
-        result.append(&mut self.state_root.hash_tree_root());
+        result.append(&mut self.state_root.hash_tree_root_internal());
-        result.append(&mut self.randao_reveal.hash_tree_root());
+        result.append(&mut self.randao_reveal.hash_tree_root_internal());
-        result.append(&mut self.eth1_data.hash_tree_root());
+        result.append(&mut self.eth1_data.hash_tree_root_internal());
-        result.append(&mut self.signature.hash_tree_root());
+        result.append(&mut self.signature.hash_tree_root_internal());
-        result.append(&mut self.body.hash_tree_root());
+        result.append(&mut self.body.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -128,7 +92,7 @@ impl<T: RngCore> TestRandom<T> for BeaconBlock {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -142,11 +106,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = BeaconBlock::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/beacon_block_body.rs

@@ -2,9 +2,10 @@ use super::{Attestation, AttesterSlashing, Deposit, Exit, ProposerSlashing};
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Default, Serialize)]
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Encode, Decode)]
 pub struct BeaconBlockBody {
     pub proposer_slashings: Vec<ProposerSlashing>,
     pub attester_slashings: Vec<AttesterSlashing>,
@@ -13,45 +14,14 @@ pub struct BeaconBlockBody {
     pub exits: Vec<Exit>,
 }
 
-impl Encodable for BeaconBlockBody {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append_vec(&self.proposer_slashings);
-        s.append_vec(&self.attester_slashings);
-        s.append_vec(&self.attestations);
-        s.append_vec(&self.deposits);
-        s.append_vec(&self.exits);
-    }
-}
-
-impl Decodable for BeaconBlockBody {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (proposer_slashings, i) = <_>::ssz_decode(bytes, i)?;
-        let (attester_slashings, i) = <_>::ssz_decode(bytes, i)?;
-        let (attestations, i) = <_>::ssz_decode(bytes, i)?;
-        let (deposits, i) = <_>::ssz_decode(bytes, i)?;
-        let (exits, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                proposer_slashings,
-                attester_slashings,
-                attestations,
-                deposits,
-                exits,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for BeaconBlockBody {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.proposer_slashings.hash_tree_root());
+        result.append(&mut self.proposer_slashings.hash_tree_root_internal());
-        result.append(&mut self.attester_slashings.hash_tree_root());
+        result.append(&mut self.attester_slashings.hash_tree_root_internal());
-        result.append(&mut self.attestations.hash_tree_root());
+        result.append(&mut self.attestations.hash_tree_root_internal());
-        result.append(&mut self.deposits.hash_tree_root());
+        result.append(&mut self.deposits.hash_tree_root_internal());
-        result.append(&mut self.exits.hash_tree_root());
+        result.append(&mut self.exits.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -72,7 +42,7 @@ impl<T: RngCore> TestRandom<T> for BeaconBlockBody {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -86,11 +56,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = BeaconBlockBody::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/beacon_state.rs

@@ -9,7 +9,8 @@ use honey_badger_split::SplitExt;
 use log::trace;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 use swap_or_not_shuffle::get_permutated_index;
 
 mod tests;
@@ -51,7 +52,7 @@ macro_rules! safe_sub_assign {
     };
 }
 
-#[derive(Debug, PartialEq, Clone, Default, Serialize)]
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Encode, Decode)]
 pub struct BeaconState {
     // Misc
     pub slot: Slot,
@@ -1000,125 +1001,38 @@ impl From<AttestationParticipantsError> for InclusionError {
     }
 }
 
-impl Encodable for BeaconState {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slot);
-        s.append(&self.genesis_time);
-        s.append(&self.fork);
-        s.append(&self.validator_registry);
-        s.append(&self.validator_balances);
-        s.append(&self.validator_registry_update_epoch);
-        s.append(&self.latest_randao_mixes);
-        s.append(&self.previous_epoch_start_shard);
-        s.append(&self.current_epoch_start_shard);
-        s.append(&self.previous_calculation_epoch);
-        s.append(&self.current_calculation_epoch);
-        s.append(&self.previous_epoch_seed);
-        s.append(&self.current_epoch_seed);
-        s.append(&self.previous_justified_epoch);
-        s.append(&self.justified_epoch);
-        s.append(&self.justification_bitfield);
-        s.append(&self.finalized_epoch);
-        s.append(&self.latest_crosslinks);
-        s.append(&self.latest_block_roots);
-        s.append(&self.latest_index_roots);
-        s.append(&self.latest_penalized_balances);
-        s.append(&self.latest_attestations);
-        s.append(&self.batched_block_roots);
-        s.append(&self.latest_eth1_data);
-        s.append(&self.eth1_data_votes);
-    }
-}
-
-impl Decodable for BeaconState {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-        let (genesis_time, i) = <_>::ssz_decode(bytes, i)?;
-        let (fork, i) = <_>::ssz_decode(bytes, i)?;
-        let (validator_registry, i) = <_>::ssz_decode(bytes, i)?;
-        let (validator_balances, i) = <_>::ssz_decode(bytes, i)?;
-        let (validator_registry_update_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_randao_mixes, i) = <_>::ssz_decode(bytes, i)?;
-        let (previous_epoch_start_shard, i) = <_>::ssz_decode(bytes, i)?;
-        let (current_epoch_start_shard, i) = <_>::ssz_decode(bytes, i)?;
-        let (previous_calculation_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (current_calculation_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (previous_epoch_seed, i) = <_>::ssz_decode(bytes, i)?;
-        let (current_epoch_seed, i) = <_>::ssz_decode(bytes, i)?;
-        let (previous_justified_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (justified_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (justification_bitfield, i) = <_>::ssz_decode(bytes, i)?;
-        let (finalized_epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_crosslinks, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_block_roots, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_index_roots, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_penalized_balances, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_attestations, i) = <_>::ssz_decode(bytes, i)?;
-        let (batched_block_roots, i) = <_>::ssz_decode(bytes, i)?;
-        let (latest_eth1_data, i) = <_>::ssz_decode(bytes, i)?;
-        let (eth1_data_votes, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                slot,
-                genesis_time,
-                fork,
-                validator_registry,
-                validator_balances,
-                validator_registry_update_epoch,
-                latest_randao_mixes,
-                previous_epoch_start_shard,
-                current_epoch_start_shard,
-                previous_calculation_epoch,
-                current_calculation_epoch,
-                previous_epoch_seed,
-                current_epoch_seed,
-                previous_justified_epoch,
-                justified_epoch,
-                justification_bitfield,
-                finalized_epoch,
-                latest_crosslinks,
-                latest_block_roots,
-                latest_index_roots,
-                latest_penalized_balances,
-                latest_attestations,
-                batched_block_roots,
-                latest_eth1_data,
-                eth1_data_votes,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for BeaconState {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
-        result.append(&mut self.genesis_time.hash_tree_root());
+        result.append(&mut self.genesis_time.hash_tree_root_internal());
-        result.append(&mut self.fork.hash_tree_root());
+        result.append(&mut self.fork.hash_tree_root_internal());
-        result.append(&mut self.validator_registry.hash_tree_root());
+        result.append(&mut self.validator_registry.hash_tree_root_internal());
-        result.append(&mut self.validator_balances.hash_tree_root());
+        result.append(&mut self.validator_balances.hash_tree_root_internal());
-        result.append(&mut self.validator_registry_update_epoch.hash_tree_root());
+        result.append(
-        result.append(&mut self.latest_randao_mixes.hash_tree_root());
+            &mut self
-        result.append(&mut self.previous_epoch_start_shard.hash_tree_root());
+                .validator_registry_update_epoch
-        result.append(&mut self.current_epoch_start_shard.hash_tree_root());
+                .hash_tree_root_internal(),
-        result.append(&mut self.previous_calculation_epoch.hash_tree_root());
+        );
-        result.append(&mut self.current_calculation_epoch.hash_tree_root());
+        result.append(&mut self.latest_randao_mixes.hash_tree_root_internal());
-        result.append(&mut self.previous_epoch_seed.hash_tree_root());
+        result.append(&mut self.previous_epoch_start_shard.hash_tree_root_internal());
-        result.append(&mut self.current_epoch_seed.hash_tree_root());
+        result.append(&mut self.current_epoch_start_shard.hash_tree_root_internal());
-        result.append(&mut self.previous_justified_epoch.hash_tree_root());
+        result.append(&mut self.previous_calculation_epoch.hash_tree_root_internal());
-        result.append(&mut self.justified_epoch.hash_tree_root());
+        result.append(&mut self.current_calculation_epoch.hash_tree_root_internal());
-        result.append(&mut self.justification_bitfield.hash_tree_root());
+        result.append(&mut self.previous_epoch_seed.hash_tree_root_internal());
-        result.append(&mut self.finalized_epoch.hash_tree_root());
+        result.append(&mut self.current_epoch_seed.hash_tree_root_internal());
-        result.append(&mut self.latest_crosslinks.hash_tree_root());
+        result.append(&mut self.previous_justified_epoch.hash_tree_root_internal());
-        result.append(&mut self.latest_block_roots.hash_tree_root());
+        result.append(&mut self.justified_epoch.hash_tree_root_internal());
-        result.append(&mut self.latest_index_roots.hash_tree_root());
+        result.append(&mut self.justification_bitfield.hash_tree_root_internal());
-        result.append(&mut self.latest_penalized_balances.hash_tree_root());
+        result.append(&mut self.finalized_epoch.hash_tree_root_internal());
-        result.append(&mut self.latest_attestations.hash_tree_root());
+        result.append(&mut self.latest_crosslinks.hash_tree_root_internal());
-        result.append(&mut self.batched_block_roots.hash_tree_root());
+        result.append(&mut self.latest_block_roots.hash_tree_root_internal());
-        result.append(&mut self.latest_eth1_data.hash_tree_root());
+        result.append(&mut self.latest_index_roots.hash_tree_root_internal());
-        result.append(&mut self.eth1_data_votes.hash_tree_root());
+        result.append(&mut self.latest_penalized_balances.hash_tree_root_internal());
+        result.append(&mut self.latest_attestations.hash_tree_root_internal());
+        result.append(&mut self.batched_block_roots.hash_tree_root_internal());
+        result.append(&mut self.latest_eth1_data.hash_tree_root_internal());
+        result.append(&mut self.eth1_data_votes.hash_tree_root_internal());
         hash(&result)
     }
 }

eth2/types/src/beacon_state/tests.rs

@@ -7,7 +7,7 @@ use crate::{
     Eth1Data, Hash256, Keypair,
 };
 use bls::create_proof_of_possession;
-use ssz::ssz_encode;
+use ssz::{ssz_encode, Decodable};
 
 struct BeaconStateTestBuilder {
     pub genesis_time: u64,
@@ -85,11 +85,11 @@ pub fn test_ssz_round_trip() {
 }
 
 #[test]
-pub fn test_hash_tree_root() {
+pub fn test_hash_tree_root_internal() {
     let mut rng = XorShiftRng::from_seed([42; 16]);
     let original = BeaconState::random_for_test(&mut rng);
 
-    let result = original.hash_tree_root();
+    let result = original.hash_tree_root_internal();
 
     assert_eq!(result.len(), 32);
     // TODO: Add further tests

eth2/types/src/casper_slashing.rs

@@ -2,41 +2,20 @@ use super::SlashableVoteData;
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct CasperSlashing {
     pub slashable_vote_data_1: SlashableVoteData,
     pub slashable_vote_data_2: SlashableVoteData,
 }
 
-impl Encodable for CasperSlashing {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slashable_vote_data_1);
-        s.append(&self.slashable_vote_data_2);
-    }
-}
-
-impl Decodable for CasperSlashing {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slashable_vote_data_1, i) = <_>::ssz_decode(bytes, i)?;
-        let (slashable_vote_data_2, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            CasperSlashing {
-                slashable_vote_data_1,
-                slashable_vote_data_2,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for CasperSlashing {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slashable_vote_data_1.hash_tree_root());
+        result.append(&mut self.slashable_vote_data_1.hash_tree_root_internal());
-        result.append(&mut self.slashable_vote_data_2.hash_tree_root());
+        result.append(&mut self.slashable_vote_data_2.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -54,7 +33,7 @@ impl<T: RngCore> TestRandom<T> for CasperSlashing {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -68,11 +47,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = CasperSlashing::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/crosslink.rs

@@ -2,9 +2,10 @@ use crate::test_utils::TestRandom;
 use crate::{Epoch, Hash256};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, Clone, PartialEq, Default, Serialize, Hash)]
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Hash, Encode, Decode)]
 pub struct Crosslink {
     pub epoch: Epoch,
     pub shard_block_root: Hash256,
@@ -20,33 +21,11 @@ impl Crosslink {
     }
 }
 
-impl Encodable for Crosslink {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.epoch);
-        s.append(&self.shard_block_root);
-    }
-}
-
-impl Decodable for Crosslink {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (shard_block_root, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                epoch,
-                shard_block_root,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Crosslink {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.epoch.hash_tree_root());
+        result.append(&mut self.epoch.hash_tree_root_internal());
-        result.append(&mut self.shard_block_root.hash_tree_root());
+        result.append(&mut self.shard_block_root.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -64,7 +43,7 @@ impl<T: RngCore> TestRandom<T> for Crosslink {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -78,11 +57,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Crosslink::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/deposit.rs

@@ -2,46 +2,22 @@ use super::{DepositData, Hash256};
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct Deposit {
     pub branch: Vec<Hash256>,
     pub index: u64,
     pub deposit_data: DepositData,
 }
 
-impl Encodable for Deposit {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append_vec(&self.branch);
-        s.append(&self.index);
-        s.append(&self.deposit_data);
-    }
-}
-
-impl Decodable for Deposit {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (branch, i) = <_>::ssz_decode(bytes, i)?;
-        let (index, i) = <_>::ssz_decode(bytes, i)?;
-        let (deposit_data, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                branch,
-                index,
-                deposit_data,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Deposit {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.branch.hash_tree_root());
+        result.append(&mut self.branch.hash_tree_root_internal());
-        result.append(&mut self.index.hash_tree_root());
+        result.append(&mut self.index.hash_tree_root_internal());
-        result.append(&mut self.deposit_data.hash_tree_root());
+        result.append(&mut self.deposit_data.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -60,7 +36,7 @@ impl<T: RngCore> TestRandom<T> for Deposit {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -74,11 +50,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Deposit::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/deposit_data.rs

@@ -2,46 +2,22 @@ use super::DepositInput;
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct DepositData {
     pub amount: u64,
     pub timestamp: u64,
     pub deposit_input: DepositInput,
 }
 
-impl Encodable for DepositData {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.amount);
-        s.append(&self.timestamp);
-        s.append(&self.deposit_input);
-    }
-}
-
-impl Decodable for DepositData {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (amount, i) = <_>::ssz_decode(bytes, i)?;
-        let (timestamp, i) = <_>::ssz_decode(bytes, i)?;
-        let (deposit_input, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                amount,
-                timestamp,
-                deposit_input,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for DepositData {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.amount.hash_tree_root());
+        result.append(&mut self.amount.hash_tree_root_internal());
-        result.append(&mut self.timestamp.hash_tree_root());
+        result.append(&mut self.timestamp.hash_tree_root_internal());
-        result.append(&mut self.deposit_input.hash_tree_root());
+        result.append(&mut self.deposit_input.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -60,7 +36,7 @@ impl<T: RngCore> TestRandom<T> for DepositData {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -74,11 +50,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = DepositData::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/deposit_input.rs

@@ -3,46 +3,22 @@ use crate::test_utils::TestRandom;
 use bls::{PublicKey, Signature};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct DepositInput {
     pub pubkey: PublicKey,
     pub withdrawal_credentials: Hash256,
     pub proof_of_possession: Signature,
 }
 
-impl Encodable for DepositInput {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.pubkey);
-        s.append(&self.withdrawal_credentials);
-        s.append(&self.proof_of_possession);
-    }
-}
-
-impl Decodable for DepositInput {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (pubkey, i) = <_>::ssz_decode(bytes, i)?;
-        let (withdrawal_credentials, i) = <_>::ssz_decode(bytes, i)?;
-        let (proof_of_possession, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                pubkey,
-                withdrawal_credentials,
-                proof_of_possession,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for DepositInput {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.pubkey.hash_tree_root());
+        result.append(&mut self.pubkey.hash_tree_root_internal());
-        result.append(&mut self.withdrawal_credentials.hash_tree_root());
+        result.append(&mut self.withdrawal_credentials.hash_tree_root_internal());
-        result.append(&mut self.proof_of_possession.hash_tree_root());
+        result.append(&mut self.proof_of_possession.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -61,7 +37,7 @@ impl<T: RngCore> TestRandom<T> for DepositInput {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -75,11 +51,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = DepositInput::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/eth1_data.rs

@@ -2,42 +2,21 @@ use super::Hash256;
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
 // Note: this is refer to as DepositRootVote in specs
-#[derive(Debug, PartialEq, Clone, Default, Serialize)]
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Encode, Decode)]
 pub struct Eth1Data {
     pub deposit_root: Hash256,
     pub block_hash: Hash256,
 }
 
-impl Encodable for Eth1Data {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.deposit_root);
-        s.append(&self.block_hash);
-    }
-}
-
-impl Decodable for Eth1Data {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (deposit_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (block_hash, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                deposit_root,
-                block_hash,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Eth1Data {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.deposit_root.hash_tree_root());
+        result.append(&mut self.deposit_root.hash_tree_root_internal());
-        result.append(&mut self.block_hash.hash_tree_root());
+        result.append(&mut self.block_hash.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -55,7 +34,7 @@ impl<T: RngCore> TestRandom<T> for Eth1Data {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -69,11 +48,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Eth1Data::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/eth1_data_vote.rs

@@ -2,42 +2,21 @@ use super::Eth1Data;
 use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
 // Note: this is refer to as DepositRootVote in specs
-#[derive(Debug, PartialEq, Clone, Default, Serialize)]
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Encode, Decode)]
 pub struct Eth1DataVote {
     pub eth1_data: Eth1Data,
     pub vote_count: u64,
 }
 
-impl Encodable for Eth1DataVote {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.eth1_data);
-        s.append(&self.vote_count);
-    }
-}
-
-impl Decodable for Eth1DataVote {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (eth1_data, i) = <_>::ssz_decode(bytes, i)?;
-        let (vote_count, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                eth1_data,
-                vote_count,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Eth1DataVote {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.eth1_data.hash_tree_root());
+        result.append(&mut self.eth1_data.hash_tree_root_internal());
-        result.append(&mut self.vote_count.hash_tree_root());
+        result.append(&mut self.vote_count.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -55,7 +34,7 @@ impl<T: RngCore> TestRandom<T> for Eth1DataVote {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -69,11 +48,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Eth1DataVote::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/exit.rs

@@ -2,46 +2,22 @@ use crate::{test_utils::TestRandom, Epoch};
 use bls::Signature;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct Exit {
     pub epoch: Epoch,
     pub validator_index: u64,
     pub signature: Signature,
 }
 
-impl Encodable for Exit {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.epoch);
-        s.append(&self.validator_index);
-        s.append(&self.signature);
-    }
-}
-
-impl Decodable for Exit {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (epoch, i) = <_>::ssz_decode(bytes, i)?;
-        let (validator_index, i) = <_>::ssz_decode(bytes, i)?;
-        let (signature, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                epoch,
-                validator_index,
-                signature,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Exit {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.epoch.hash_tree_root());
+        result.append(&mut self.epoch.hash_tree_root_internal());
-        result.append(&mut self.validator_index.hash_tree_root());
+        result.append(&mut self.validator_index.hash_tree_root_internal());
-        result.append(&mut self.signature.hash_tree_root());
+        result.append(&mut self.signature.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -60,7 +36,7 @@ impl<T: RngCore> TestRandom<T> for Exit {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -74,11 +50,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Exit::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/fork.rs

@@ -1,9 +1,10 @@
 use crate::{test_utils::TestRandom, Epoch};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, Clone, PartialEq, Default, Serialize)]
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Encode, Decode)]
 pub struct Fork {
     pub previous_version: u64,
     pub current_version: u64,
@@ -26,37 +27,12 @@ impl Fork {
     }
 }
 
-impl Encodable for Fork {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.previous_version);
-        s.append(&self.current_version);
-        s.append(&self.epoch);
-    }
-}
-
-impl Decodable for Fork {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (previous_version, i) = <_>::ssz_decode(bytes, i)?;
-        let (current_version, i) = <_>::ssz_decode(bytes, i)?;
-        let (epoch, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                previous_version,
-                current_version,
-                epoch,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for Fork {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.previous_version.hash_tree_root());
+        result.append(&mut self.previous_version.hash_tree_root_internal());
-        result.append(&mut self.current_version.hash_tree_root());
+        result.append(&mut self.current_version.hash_tree_root_internal());
-        result.append(&mut self.epoch.hash_tree_root());
+        result.append(&mut self.epoch.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -75,7 +51,7 @@ impl<T: RngCore> TestRandom<T> for Fork {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -89,11 +65,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Fork::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/pending_attestation.rs

@@ -2,9 +2,10 @@ use crate::test_utils::TestRandom;
 use crate::{AttestationData, Bitfield, Slot};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, Clone, PartialEq, Serialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Encode, Decode)]
 pub struct PendingAttestation {
     pub aggregation_bitfield: Bitfield,
     pub data: AttestationData,
@@ -12,41 +13,13 @@ pub struct PendingAttestation {
     pub inclusion_slot: Slot,
 }
 
-impl Encodable for PendingAttestation {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.aggregation_bitfield);
-        s.append(&self.data);
-        s.append(&self.custody_bitfield);
-        s.append(&self.inclusion_slot);
-    }
-}
-
-impl Decodable for PendingAttestation {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (aggregation_bitfield, i) = <_>::ssz_decode(bytes, i)?;
-        let (data, i) = <_>::ssz_decode(bytes, i)?;
-        let (custody_bitfield, i) = <_>::ssz_decode(bytes, i)?;
-        let (inclusion_slot, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                data,
-                aggregation_bitfield,
-                custody_bitfield,
-                inclusion_slot,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for PendingAttestation {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.aggregation_bitfield.hash_tree_root());
+        result.append(&mut self.aggregation_bitfield.hash_tree_root_internal());
-        result.append(&mut self.data.hash_tree_root());
+        result.append(&mut self.data.hash_tree_root_internal());
-        result.append(&mut self.custody_bitfield.hash_tree_root());
+        result.append(&mut self.custody_bitfield.hash_tree_root_internal());
-        result.append(&mut self.inclusion_slot.hash_tree_root());
+        result.append(&mut self.inclusion_slot.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -66,7 +39,7 @@ impl<T: RngCore> TestRandom<T> for PendingAttestation {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -80,11 +53,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = PendingAttestation::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/proposal_signed_data.rs

@@ -2,46 +2,22 @@ use crate::test_utils::TestRandom;
 use crate::{Hash256, Slot};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Default, Serialize)]
+#[derive(Debug, PartialEq, Clone, Default, Serialize, Encode, Decode)]
 pub struct ProposalSignedData {
     pub slot: Slot,
     pub shard: u64,
     pub block_root: Hash256,
 }
 
-impl Encodable for ProposalSignedData {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.slot);
-        s.append(&self.shard);
-        s.append(&self.block_root);
-    }
-}
-
-impl Decodable for ProposalSignedData {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-        let (shard, i) = <_>::ssz_decode(bytes, i)?;
-        let (block_root, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            ProposalSignedData {
-                slot,
-                shard,
-                block_root,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for ProposalSignedData {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
-        result.append(&mut self.shard.hash_tree_root());
+        result.append(&mut self.shard.hash_tree_root_internal());
-        result.append(&mut self.block_root.hash_tree_root());
+        result.append(&mut self.block_root.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -60,7 +36,7 @@ impl<T: RngCore> TestRandom<T> for ProposalSignedData {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -74,11 +50,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = ProposalSignedData::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/proposer_slashing.rs

@@ -3,9 +3,10 @@ use crate::test_utils::TestRandom;
 use bls::Signature;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct ProposerSlashing {
     pub proposer_index: u64,
     pub proposal_data_1: ProposalSignedData,
@@ -14,45 +15,14 @@ pub struct ProposerSlashing {
     pub proposal_signature_2: Signature,
 }
 
-impl Encodable for ProposerSlashing {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.proposer_index);
-        s.append(&self.proposal_data_1);
-        s.append(&self.proposal_signature_1);
-        s.append(&self.proposal_data_2);
-        s.append(&self.proposal_signature_2);
-    }
-}
-
-impl Decodable for ProposerSlashing {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (proposer_index, i) = <_>::ssz_decode(bytes, i)?;
-        let (proposal_data_1, i) = <_>::ssz_decode(bytes, i)?;
-        let (proposal_signature_1, i) = <_>::ssz_decode(bytes, i)?;
-        let (proposal_data_2, i) = <_>::ssz_decode(bytes, i)?;
-        let (proposal_signature_2, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            ProposerSlashing {
-                proposer_index,
-                proposal_data_1,
-                proposal_signature_1,
-                proposal_data_2,
-                proposal_signature_2,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for ProposerSlashing {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.proposer_index.hash_tree_root());
+        result.append(&mut self.proposer_index.hash_tree_root_internal());
-        result.append(&mut self.proposal_data_1.hash_tree_root());
+        result.append(&mut self.proposal_data_1.hash_tree_root_internal());
-        result.append(&mut self.proposal_signature_1.hash_tree_root());
+        result.append(&mut self.proposal_signature_1.hash_tree_root_internal());
-        result.append(&mut self.proposal_data_2.hash_tree_root());
+        result.append(&mut self.proposal_data_2.hash_tree_root_internal());
-        result.append(&mut self.proposal_signature_2.hash_tree_root());
+        result.append(&mut self.proposal_signature_2.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -73,7 +43,7 @@ impl<T: RngCore> TestRandom<T> for ProposerSlashing {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -87,11 +57,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = ProposerSlashing::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/shard_reassignment_record.rs

@@ -1,46 +1,22 @@
 use crate::{test_utils::TestRandom, Slot};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct ShardReassignmentRecord {
     pub validator_index: u64,
     pub shard: u64,
     pub slot: Slot,
 }
 
-impl Encodable for ShardReassignmentRecord {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.validator_index);
-        s.append(&self.shard);
-        s.append(&self.slot);
-    }
-}
-
-impl Decodable for ShardReassignmentRecord {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (validator_index, i) = <_>::ssz_decode(bytes, i)?;
-        let (shard, i) = <_>::ssz_decode(bytes, i)?;
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                validator_index,
-                shard,
-                slot,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for ShardReassignmentRecord {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.validator_index.hash_tree_root());
+        result.append(&mut self.validator_index.hash_tree_root_internal());
-        result.append(&mut self.shard.hash_tree_root());
+        result.append(&mut self.shard.hash_tree_root_internal());
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -59,7 +35,7 @@ impl<T: RngCore> TestRandom<T> for ShardReassignmentRecord {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -73,11 +49,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = ShardReassignmentRecord::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/slashable_attestation.rs

@@ -1,9 +1,10 @@
 use crate::{test_utils::TestRandom, AggregateSignature, AttestationData, Bitfield};
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct SlashableAttestation {
     pub validator_indices: Vec<u64>,
     pub data: AttestationData,
@@ -11,41 +12,13 @@ pub struct SlashableAttestation {
     pub aggregate_signature: AggregateSignature,
 }
 
-impl Encodable for SlashableAttestation {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append_vec(&self.validator_indices);
-        s.append(&self.data);
-        s.append(&self.custody_bitfield);
-        s.append(&self.aggregate_signature);
-    }
-}
-
-impl Decodable for SlashableAttestation {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (validator_indices, i) = <_>::ssz_decode(bytes, i)?;
-        let (data, i) = <_>::ssz_decode(bytes, i)?;
-        let (custody_bitfield, i) = <_>::ssz_decode(bytes, i)?;
-        let (aggregate_signature, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            SlashableAttestation {
-                validator_indices,
-                data,
-                custody_bitfield,
-                aggregate_signature,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for SlashableAttestation {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.validator_indices.hash_tree_root());
+        result.append(&mut self.validator_indices.hash_tree_root_internal());
-        result.append(&mut self.data.hash_tree_root());
+        result.append(&mut self.data.hash_tree_root_internal());
-        result.append(&mut self.custody_bitfield.hash_tree_root());
+        result.append(&mut self.custody_bitfield.hash_tree_root_internal());
-        result.append(&mut self.aggregate_signature.hash_tree_root());
+        result.append(&mut self.aggregate_signature.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -65,7 +38,7 @@ impl<T: RngCore> TestRandom<T> for SlashableAttestation {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -79,11 +52,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = SlashableAttestation::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/slashable_vote_data.rs

@@ -1,11 +1,13 @@
 use super::AttestationData;
+use crate::chain_spec::ChainSpec;
 use crate::test_utils::TestRandom;
 use bls::AggregateSignature;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
-#[derive(Debug, PartialEq, Clone, Serialize)]
+#[derive(Debug, PartialEq, Clone, Serialize, Encode, Decode)]
 pub struct SlashableVoteData {
     pub custody_bit_0_indices: Vec<u32>,
     pub custody_bit_1_indices: Vec<u32>,
@@ -13,41 +15,34 @@ pub struct SlashableVoteData {
     pub aggregate_signature: AggregateSignature,
 }
 
-impl Encodable for SlashableVoteData {
+impl SlashableVoteData {
-    fn ssz_append(&self, s: &mut SszStream) {
+    /// Check if ``attestation_data_1`` and ``attestation_data_2`` have the same target.
-        s.append_vec(&self.custody_bit_0_indices);
+    ///
-        s.append_vec(&self.custody_bit_1_indices);
+    /// Spec v0.3.0
-        s.append(&self.data);
+    pub fn is_double_vote(&self, other: &SlashableVoteData, spec: &ChainSpec) -> bool {
-        s.append(&self.aggregate_signature);
+        self.data.slot.epoch(spec.epoch_length) == other.data.slot.epoch(spec.epoch_length)
     }
-}
 
-impl Decodable for SlashableVoteData {
+    /// Check if ``attestation_data_1`` surrounds ``attestation_data_2``.
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
+    ///
-        let (custody_bit_0_indices, i) = <_>::ssz_decode(bytes, i)?;
+    /// Spec v0.3.0
-        let (custody_bit_1_indices, i) = <_>::ssz_decode(bytes, i)?;
+    pub fn is_surround_vote(&self, other: &SlashableVoteData, spec: &ChainSpec) -> bool {
-        let (data, i) = <_>::ssz_decode(bytes, i)?;
+        let source_epoch_1 = self.data.justified_epoch;
-        let (aggregate_signature, i) = <_>::ssz_decode(bytes, i)?;
+        let source_epoch_2 = other.data.justified_epoch;
+        let target_epoch_1 = self.data.slot.epoch(spec.epoch_length);
+        let target_epoch_2 = other.data.slot.epoch(spec.epoch_length);
 
-        Ok((
+        (source_epoch_1 < source_epoch_2) && (target_epoch_2 < target_epoch_1)
-            SlashableVoteData {
-                custody_bit_0_indices,
-                custody_bit_1_indices,
-                data,
-                aggregate_signature,
-            },
-            i,
-        ))
     }
 }
 
 impl TreeHash for SlashableVoteData {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.custody_bit_0_indices.hash_tree_root());
+        result.append(&mut self.custody_bit_0_indices.hash_tree_root_internal());
-        result.append(&mut self.custody_bit_1_indices.hash_tree_root());
+        result.append(&mut self.custody_bit_1_indices.hash_tree_root_internal());
-        result.append(&mut self.data.hash_tree_root());
+        result.append(&mut self.data.hash_tree_root_internal());
-        result.append(&mut self.aggregate_signature.hash_tree_root());
+        result.append(&mut self.aggregate_signature.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -66,8 +61,82 @@ impl<T: RngCore> TestRandom<T> for SlashableVoteData {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::chain_spec::ChainSpec;
+    use crate::slot_epoch::{Epoch, Slot};
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
+
+    #[test]
+    pub fn test_is_double_vote_true() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(1, 1, &spec);
+        let slashable_vote_second = create_slashable_vote_data(1, 1, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_double_vote(&slashable_vote_second, &spec),
+            true
+        )
+    }
+
+    #[test]
+    pub fn test_is_double_vote_false() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(1, 1, &spec);
+        let slashable_vote_second = create_slashable_vote_data(2, 1, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_double_vote(&slashable_vote_second, &spec),
+            false
+        );
+    }
+
+    #[test]
+    pub fn test_is_surround_vote_true() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(2, 1, &spec);
+        let slashable_vote_second = create_slashable_vote_data(1, 2, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_surround_vote(&slashable_vote_second, &spec),
+            true
+        );
+    }
+
+    #[test]
+    pub fn test_is_surround_vote_true_realistic() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(4, 1, &spec);
+        let slashable_vote_second = create_slashable_vote_data(3, 2, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_surround_vote(&slashable_vote_second, &spec),
+            true
+        );
+    }
+
+    #[test]
+    pub fn test_is_surround_vote_false_source_epoch_fails() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(2, 2, &spec);
+        let slashable_vote_second = create_slashable_vote_data(1, 1, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_surround_vote(&slashable_vote_second, &spec),
+            false
+        );
+    }
+
+    #[test]
+    pub fn test_is_surround_vote_false_target_epoch_fails() {
+        let spec = ChainSpec::foundation();
+        let slashable_vote_first = create_slashable_vote_data(1, 1, &spec);
+        let slashable_vote_second = create_slashable_vote_data(2, 2, &spec);
+
+        assert_eq!(
+            slashable_vote_first.is_surround_vote(&slashable_vote_second, &spec),
+            false
+        );
+    }
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -81,14 +150,27 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = SlashableVoteData::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests
         // https://github.com/sigp/lighthouse/issues/170
     }
+
+    fn create_slashable_vote_data(
+        slot_factor: u64,
+        justified_epoch: u64,
+        spec: &ChainSpec,
+    ) -> SlashableVoteData {
+        let mut rng = XorShiftRng::from_seed([42; 16]);
+        let mut slashable_vote = SlashableVoteData::random_for_test(&mut rng);
+
+        slashable_vote.data.slot = Slot::new(slot_factor * spec.epoch_length);
+        slashable_vote.data.justified_epoch = Epoch::new(justified_epoch);
+        slashable_vote
+    }
 }

eth2/types/src/slot_epoch_macros.rs

@@ -224,9 +224,9 @@ macro_rules! impl_ssz {
         }
 
         impl TreeHash for $type {
-            fn hash_tree_root(&self) -> Vec<u8> {
+            fn hash_tree_root_internal(&self) -> Vec<u8> {
                 let mut result: Vec<u8> = vec![];
-                result.append(&mut self.0.hash_tree_root());
+                result.append(&mut self.0.hash_tree_root_internal());
                 hash(&result)
             }
         }
@@ -560,11 +560,11 @@ macro_rules! ssz_tests {
         }
 
         #[test]
-        pub fn test_hash_tree_root() {
+        pub fn test_hash_tree_root_internal() {
             let mut rng = XorShiftRng::from_seed([42; 16]);
             let original = $type::random_for_test(&mut rng);
 
-            let result = original.hash_tree_root();
+            let result = original.hash_tree_root_internal();
 
             assert_eq!(result.len(), 32);
             // TODO: Add further tests

eth2/types/src/validator.rs

@@ -122,15 +122,17 @@ impl Decodable for Validator {
 }
 
 impl TreeHash for Validator {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.pubkey.hash_tree_root());
+        result.append(&mut self.pubkey.hash_tree_root_internal());
-        result.append(&mut self.withdrawal_credentials.hash_tree_root());
+        result.append(&mut self.withdrawal_credentials.hash_tree_root_internal());
-        result.append(&mut self.activation_epoch.hash_tree_root());
+        result.append(&mut self.activation_epoch.hash_tree_root_internal());
-        result.append(&mut self.exit_epoch.hash_tree_root());
+        result.append(&mut self.exit_epoch.hash_tree_root_internal());
-        result.append(&mut self.withdrawal_epoch.hash_tree_root());
+        result.append(&mut self.withdrawal_epoch.hash_tree_root_internal());
-        result.append(&mut self.penalized_epoch.hash_tree_root());
+        result.append(&mut self.penalized_epoch.hash_tree_root_internal());
-        result.append(&mut u64::from(status_flag_to_byte(self.status_flags)).hash_tree_root());
+        result.append(
+            &mut u64::from(status_flag_to_byte(self.status_flags)).hash_tree_root_internal(),
+        );
         hash(&result)
     }
 }
@@ -190,11 +192,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = Validator::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/types/src/validator_registry_delta_block.rs

@@ -2,10 +2,11 @@ use crate::{test_utils::TestRandom, Hash256, Slot};
 use bls::PublicKey;
 use rand::RngCore;
 use serde_derive::Serialize;
-use ssz::{hash, Decodable, DecodeError, Encodable, SszStream, TreeHash};
+use ssz::{hash, TreeHash};
+use ssz_derive::{Decode, Encode};
 
 // The information gathered from the PoW chain validator registration function.
-#[derive(Debug, Clone, PartialEq, Serialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Encode, Decode)]
 pub struct ValidatorRegistryDeltaBlock {
     pub latest_registry_delta_root: Hash256,
     pub validator_index: u32,
@@ -27,45 +28,14 @@ impl Default for ValidatorRegistryDeltaBlock {
     }
 }
 
-impl Encodable for ValidatorRegistryDeltaBlock {
-    fn ssz_append(&self, s: &mut SszStream) {
-        s.append(&self.latest_registry_delta_root);
-        s.append(&self.validator_index);
-        s.append(&self.pubkey);
-        s.append(&self.slot);
-        s.append(&self.flag);
-    }
-}
-
-impl Decodable for ValidatorRegistryDeltaBlock {
-    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
-        let (latest_registry_delta_root, i) = <_>::ssz_decode(bytes, i)?;
-        let (validator_index, i) = <_>::ssz_decode(bytes, i)?;
-        let (pubkey, i) = <_>::ssz_decode(bytes, i)?;
-        let (slot, i) = <_>::ssz_decode(bytes, i)?;
-        let (flag, i) = <_>::ssz_decode(bytes, i)?;
-
-        Ok((
-            Self {
-                latest_registry_delta_root,
-                validator_index,
-                pubkey,
-                slot,
-                flag,
-            },
-            i,
-        ))
-    }
-}
-
 impl TreeHash for ValidatorRegistryDeltaBlock {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         let mut result: Vec<u8> = vec![];
-        result.append(&mut self.latest_registry_delta_root.hash_tree_root());
+        result.append(&mut self.latest_registry_delta_root.hash_tree_root_internal());
-        result.append(&mut self.validator_index.hash_tree_root());
+        result.append(&mut self.validator_index.hash_tree_root_internal());
-        result.append(&mut self.pubkey.hash_tree_root());
+        result.append(&mut self.pubkey.hash_tree_root_internal());
-        result.append(&mut self.slot.hash_tree_root());
+        result.append(&mut self.slot.hash_tree_root_internal());
-        result.append(&mut self.flag.hash_tree_root());
+        result.append(&mut self.flag.hash_tree_root_internal());
         hash(&result)
     }
 }
@@ -86,7 +56,7 @@ impl<T: RngCore> TestRandom<T> for ValidatorRegistryDeltaBlock {
 mod tests {
     use super::*;
     use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
-    use ssz::ssz_encode;
+    use ssz::{ssz_encode, Decodable};
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -100,11 +70,11 @@ mod tests {
     }
 
     #[test]
-    pub fn test_hash_tree_root() {
+    pub fn test_hash_tree_root_internal() {
         let mut rng = XorShiftRng::from_seed([42; 16]);
         let original = ValidatorRegistryDeltaBlock::random_for_test(&mut rng);
 
-        let result = original.hash_tree_root();
+        let result = original.hash_tree_root_internal();
 
         assert_eq!(result.len(), 32);
         // TODO: Add further tests

eth2/utils/bls/src/aggregate_signature.rs

@@ -62,7 +62,7 @@ impl Serialize for AggregateSignature {
 }
 
 impl TreeHash for AggregateSignature {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         hash(&self.0.as_bytes())
     }
 }

eth2/utils/bls/src/public_key.rs

@@ -66,7 +66,7 @@ impl Serialize for PublicKey {
 }
 
 impl TreeHash for PublicKey {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         hash(&self.0.as_bytes())
     }
 }

eth2/utils/bls/src/secret_key.rs

@@ -41,7 +41,7 @@ impl Decodable for SecretKey {
 }
 
 impl TreeHash for SecretKey {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         self.0.as_bytes().clone()
     }
 }

eth2/utils/bls/src/signature.rs

@@ -73,7 +73,7 @@ impl Decodable for Signature {
 }
 
 impl TreeHash for Signature {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         hash(&self.0.as_bytes())
     }
 }

eth2/utils/boolean-bitfield/src/lib.rs

@@ -187,8 +187,8 @@ impl Serialize for BooleanBitfield {
 }
 
 impl ssz::TreeHash for BooleanBitfield {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
-        self.to_bytes().hash_tree_root()
+        self.to_bytes().hash_tree_root_internal()
     }
 }
 

eth2/utils/ssz/src/impl_decode.rs

@@ -39,6 +39,21 @@ impl Decodable for u8 {
     }
 }
 
+impl Decodable for bool {
+    fn ssz_decode(bytes: &[u8], index: usize) -> Result<(Self, usize), DecodeError> {
+        if index >= bytes.len() {
+            Err(DecodeError::TooShort)
+        } else {
+            let result = match bytes[index] {
+                0b0000_0000 => false,
+                0b1000_0000 => true,
+                _ => return Err(DecodeError::Invalid),
+            };
+            Ok((result, index + 1))
+        }
+    }
+}
+
 impl Decodable for H256 {
     fn ssz_decode(bytes: &[u8], index: usize) -> Result<(Self, usize), DecodeError> {
         if bytes.len() < 32 || bytes.len() - 32 < index {
@@ -215,4 +230,20 @@ mod tests {
         let result: u16 = decode_ssz(&vec![0, 0, 0, 0, 1], 3).unwrap().0;
         assert_eq!(result, 1);
     }
+
+    #[test]
+    fn test_decode_ssz_bool() {
+        let ssz = vec![0b0000_0000, 0b1000_0000];
+        let (result, index): (bool, usize) = decode_ssz(&ssz, 0).unwrap();
+        assert_eq!(index, 1);
+        assert_eq!(result, false);
+
+        let (result, index): (bool, usize) = decode_ssz(&ssz, 1).unwrap();
+        assert_eq!(index, 2);
+        assert_eq!(result, true);
+
+        let ssz = vec![0b0100_0000];
+        let result: Result<(bool, usize), DecodeError> = decode_ssz(&ssz, 0);
+        assert_eq!(result, Err(DecodeError::Invalid));
+    }
 }

eth2/utils/ssz/src/impl_encode.rs

@@ -46,6 +46,13 @@ impl_encodable_for_uint!(u32, 32);
 impl_encodable_for_uint!(u64, 64);
 impl_encodable_for_uint!(usize, 64);
 
+impl Encodable for bool {
+    fn ssz_append(&self, s: &mut SszStream) {
+        let byte = if *self { 0b1000_0000 } else { 0b0000_0000 };
+        s.append_encoded_raw(&[byte]);
+    }
+}
+
 impl Encodable for H256 {
     fn ssz_append(&self, s: &mut SszStream) {
         s.append_encoded_raw(&self.to_vec());
@@ -206,4 +213,17 @@ mod tests {
         ssz.append(&x);
         assert_eq!(ssz.drain(), vec![255, 255, 255, 255, 255, 255, 255, 255]);
     }
+
+    #[test]
+    fn test_ssz_encode_bool() {
+        let x: bool = false;
+        let mut ssz = SszStream::new();
+        ssz.append(&x);
+        assert_eq!(ssz.drain(), vec![0b0000_0000]);
+
+        let x: bool = true;
+        let mut ssz = SszStream::new();
+        ssz.append(&x);
+        assert_eq!(ssz.drain(), vec![0b1000_0000]);
+    }
 }

eth2/utils/ssz/src/impl_tree_hash.rs

@@ -3,49 +3,49 @@ use super::{merkle_hash, ssz_encode, TreeHash};
 use hashing::hash;
 
 impl TreeHash for u8 {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for u16 {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for u32 {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for u64 {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for usize {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for Address {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for H256 {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         ssz_encode(self)
     }
 }
 
 impl TreeHash for [u8] {
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
         if self.len() > 32 {
             return hash(&self);
         }
@@ -57,12 +57,12 @@ impl<T> TreeHash for Vec<T>
 where
     T: TreeHash,
 {
-    /// Returns the merkle_hash of a list of hash_tree_root values created
+    /// Returns the merkle_hash of a list of hash_tree_root_internal values created
     /// from the given list.
     /// Note: A byte vector, Vec<u8>, must be converted to a slice (as_slice())
     ///       to be handled properly (i.e. hashed) as byte array.
-    fn hash_tree_root(&self) -> Vec<u8> {
+    fn hash_tree_root_internal(&self) -> Vec<u8> {
-        let mut tree_hashes = self.iter().map(|x| x.hash_tree_root()).collect();
+        let mut tree_hashes = self.iter().map(|x| x.hash_tree_root_internal()).collect();
         merkle_hash(&mut tree_hashes)
     }
 }
@@ -73,7 +73,7 @@ mod tests {
 
     #[test]
     fn test_impl_tree_hash_vec() {
-        let result = vec![1u32, 2, 3, 4, 5, 6, 7].hash_tree_root();
+        let result = vec![1u32, 2, 3, 4, 5, 6, 7].hash_tree_root_internal();
         assert_eq!(result.len(), 32);
     }
 }

eth2/utils/ssz/src/tree_hash.rs

@@ -4,7 +4,14 @@ const SSZ_CHUNK_SIZE: usize = 128;
 const HASHSIZE: usize = 32;
 
 pub trait TreeHash {
-    fn hash_tree_root(&self) -> Vec<u8>;
+    fn hash_tree_root_internal(&self) -> Vec<u8>;
+    fn hash_tree_root(&self) -> Vec<u8> {
+        let mut result = self.hash_tree_root_internal();
+        if result.len() < HASHSIZE {
+            zpad(&mut result, HASHSIZE);
+        }
+        result
+    }
 }
 
 /// Returns a 32 byte hash of 'list' - a vector of byte vectors.
@@ -14,7 +21,8 @@ pub fn merkle_hash(list: &mut Vec<Vec<u8>>) -> Vec<u8> {
     let (mut chunk_size, mut chunkz) = list_to_blob(list);
 
     // get data_len as bytes. It will hashed will the merkle root
-    let datalen = list.len().to_le_bytes();
+    let mut datalen = list.len().to_le_bytes().to_vec();
+    zpad(&mut datalen, 32);
 
     // Tree-hash
     while chunkz.len() > HASHSIZE {
@@ -36,33 +44,68 @@ pub fn merkle_hash(list: &mut Vec<Vec<u8>>) -> Vec<u8> {
         chunkz = new_chunkz;
     }
 
-    chunkz.append(&mut datalen.to_vec());
+    chunkz.append(&mut datalen);
     hash(&chunkz)
 }
 
 fn list_to_blob(list: &mut Vec<Vec<u8>>) -> (usize, Vec<u8>) {
-    let chunk_size = if list.is_empty() {
+    let chunk_size = if list.is_empty() || list[0].len() < SSZ_CHUNK_SIZE {
         SSZ_CHUNK_SIZE
-    } else if list[0].len() < SSZ_CHUNK_SIZE {
-        let items_per_chunk = SSZ_CHUNK_SIZE / list[0].len();
-        items_per_chunk * list[0].len()
     } else {
         list[0].len()
     };
 
-    let mut data = Vec::new();
+    let (items_per_chunk, chunk_count) = if list.is_empty() {
+        (1, 1)
+    } else {
+        let items_per_chunk = SSZ_CHUNK_SIZE / list[0].len();
+        let chunk_count = list.len() / items_per_chunk;
+        (items_per_chunk, chunk_count)
+    };
+
+    let mut chunkz = Vec::new();
     if list.is_empty() {
         // handle and empty list
-        data.append(&mut vec![0; SSZ_CHUNK_SIZE]);
+        chunkz.append(&mut vec![0; SSZ_CHUNK_SIZE]);
-    } else {
+    } else if list[0].len() <= SSZ_CHUNK_SIZE {
         // just create a blob here; we'll divide into
         // chunked slices when we merklize
-        data.reserve(list[0].len() * list.len());
+        let mut chunk = Vec::with_capacity(chunk_size);
+        let mut item_count_in_chunk = 0;
+        chunkz.reserve(chunk_count * chunk_size);
         for item in list.iter_mut() {
-            data.append(item);
+            item_count_in_chunk += 1;
+            chunk.append(item);
+
+            // completed chunk?
+            if item_count_in_chunk == items_per_chunk {
+                zpad(&mut chunk, chunk_size);
+                chunkz.append(&mut chunk);
+                item_count_in_chunk = 0;
+            }
+        }
+
+        // left-over uncompleted chunk?
+        if item_count_in_chunk != 0 {
+            zpad(&mut chunk, chunk_size);
+            chunkz.append(&mut chunk);
+        }
+    } else {
+        // chunks larger than SSZ_CHUNK_SIZE
+        chunkz.reserve(chunk_count * chunk_size);
+        for item in list.iter_mut() {
+            chunkz.append(item);
         }
     }
-    (chunk_size, data)
+
+    (chunk_size, chunkz)
+}
+
+/// right pads with zeros making 'bytes' 'size' in length
+fn zpad(bytes: &mut Vec<u8>, size: usize) {
+    if bytes.len() < size {
+        bytes.resize(size, 0);
+    }
 }
 
 #[cfg(test)]

eth2/utils/ssz_derive/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "ssz_derive"
+version = "0.1.0"
+authors = ["Paul Hauner <paul@paulhauner.com>"]
+edition = "2018"
+description = "Procedural derive macros for SSZ encoding and decoding."
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = "0.15"
+quote = "0.6"
+ssz = { path = "../ssz" }

eth2/utils/ssz_derive/src/lib.rs

@@ -0,0 +1,128 @@
+//! Provides the following procedural derive macros:
+//!
+//! - `#[derive(Encode)]`
+//! - `#[derive(Decode)]`
+//!
+//! These macros provide SSZ encoding/decoding for a `struct`. Fields are encoded/decoded in the
+//! order they are defined.
+//!
+//! Presently, only `structs` with named fields are supported. `enum`s and tuple-structs are
+//! unsupported.
+//!
+//! Example:
+//! ```
+//! use ssz::{ssz_encode, Decodable};
+//! use ssz_derive::{Encode, Decode};
+//!
+//! #[derive(Encode, Decode)]
+//! struct Foo {
+//!     pub bar: bool,
+//!     pub baz: u64,
+//! }
+//!
+//! fn main() {
+//!     let foo = Foo {
+//!         bar: true,
+//!         baz: 42,
+//!     };
+//!
+//!     let bytes = ssz_encode(&foo);
+//!
+//!     let (decoded_foo, _i) = Foo::ssz_decode(&bytes, 0).unwrap();
+//!
+//!     assert_eq!(foo.baz, decoded_foo.baz);
+//! }
+//! ```
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput};
+
+/// Returns a Vec of `syn::Ident` for each named field in the struct.
+///
+/// # Panics
+/// Any unnamed struct field (like in a tuple struct) will raise a panic at compile time.
+fn get_named_field_idents<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a syn::Ident> {
+    struct_data
+        .fields
+        .iter()
+        .map(|f| match &f.ident {
+            Some(ref ident) => ident,
+            _ => panic!("ssz_derive only supports named struct fields."),
+        })
+        .collect()
+}
+
+/// Implements `ssz::Encodable` for some `struct`.
+///
+/// Fields are encoded in the order they are defined.
+#[proc_macro_derive(Encode)]
+pub fn ssz_encode_derive(input: TokenStream) -> TokenStream {
+    let item = parse_macro_input!(input as DeriveInput);
+
+    let name = &item.ident;
+
+    let struct_data = match &item.data {
+        syn::Data::Struct(s) => s,
+        _ => panic!("ssz_derive only supports structs."),
+    };
+
+    let field_idents = get_named_field_idents(&struct_data);
+
+    let output = quote! {
+        impl ssz::Encodable for #name {
+            fn ssz_append(&self, s: &mut ssz::SszStream) {
+                #(
+                    s.append(&self.#field_idents);
+                )*
+            }
+        }
+    };
+    output.into()
+}
+
+/// Implements `ssz::Decodable` for some `struct`.
+///
+/// Fields are decoded in the order they are defined.
+#[proc_macro_derive(Decode)]
+pub fn ssz_decode_derive(input: TokenStream) -> TokenStream {
+    let item = parse_macro_input!(input as DeriveInput);
+
+    let name = &item.ident;
+
+    let struct_data = match &item.data {
+        syn::Data::Struct(s) => s,
+        _ => panic!("ssz_derive only supports structs."),
+    };
+
+    let field_idents = get_named_field_idents(&struct_data);
+
+    // Using a var in an iteration always consumes the var, therefore we must make a `fields_a` and
+    // a `fields_b` in order to perform two loops.
+    //
+    // https://github.com/dtolnay/quote/issues/8
+    let field_idents_a = &field_idents;
+    let field_idents_b = &field_idents;
+
+    let output = quote! {
+        impl ssz::Decodable for #name {
+            fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), ssz::DecodeError> {
+                #(
+                    let (#field_idents_a, i) = <_>::ssz_decode(bytes, i)?;
+                )*
+
+                Ok((
+                    Self {
+                        #(
+                            #field_idents_b,
+                        )*
+                    },
+                    i
+                ))
+            }
+        }
+    };
+    output.into()
+}

validator_client/Cargo.toml

@@ -5,7 +5,7 @@ authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
 
 [dependencies]
-block_producer = { path = "../eth2/block_producer" }
+block_proposer = { path = "../eth2/block_proposer" }
 bls = { path = "../eth2/utils/bls" }
 clap = "2.32.0"
 dirs = "1.0.3"

validator_client/src/block_producer_service/beacon_block_grpc_client.rs

@@ -1,4 +1,4 @@
-use block_producer::{BeaconNode, BeaconNodeError, PublishOutcome};
+use block_proposer::{BeaconNode, BeaconNodeError, PublishOutcome};
 use protos::services::{
     BeaconBlock as GrpcBeaconBlock, ProduceBeaconBlockRequest, PublishBeaconBlockRequest,
 };

validator_client/src/block_producer_service/mod.rs

@@ -1,7 +1,7 @@
 mod beacon_block_grpc_client;
 // mod block_producer_service;
 
-use block_producer::{
+use block_proposer::{
     BeaconNode, BlockProducer, DutiesReader, PollOutcome as BlockProducerPollOutcome, Signer,
 };
 use slog::{error, info, warn, Logger};

validator_client/src/duties/epoch_duties.rs

@@ -1,4 +1,4 @@
-use block_producer::{DutiesReader, DutiesReaderError};
+use block_proposer::{DutiesReader, DutiesReaderError};
 use std::collections::HashMap;
 use std::sync::RwLock;
 use types::{Epoch, Slot};

validator_client/src/main.rs

@@ -1,7 +1,7 @@
 use self::block_producer_service::{BeaconBlockGrpcClient, BlockProducerService};
 use self::duties::{DutiesManager, DutiesManagerService, EpochDutiesMap};
 use crate::config::ClientConfig;
-use block_producer::{test_utils::LocalSigner, BlockProducer};
+use block_proposer::{test_utils::LocalSigner, BlockProducer};
 use bls::Keypair;
 use clap::{App, Arg};
 use grpcio::{ChannelBuilder, EnvBuilder};