more wiring up of drandomness

chain/beacon/beacon.go

@@ -22,43 +22,40 @@ type Response struct {
 }
 
 type DrandBeacon interface {
-	RoundTime() time.Duration
+	//RoundTime() uint64
+	//StartTime() uint64
 	LastEntry() (types.BeaconEntry, error)
 	Entry(context.Context, uint64) <-chan Response
-	VerifyEntry(types.BeaconEntry) (bool, error)
+	VerifyEntry(types.BeaconEntry, types.BeaconEntry) error
-	BeaconIndexesForEpoch(abi.ChainEpoch, int) []uint64
+	BeaconRoundsForEpoch(abi.ChainEpoch, types.BeaconEntry) []uint64
 	IsEntryForEpoch(e types.BeaconEntry, epoch abi.ChainEpoch, nulls int) (bool, error)
 }
 
-func ValidateBlockValues(b DrandBeacon, h *types.BlockHeader, nulls int) error {
+func ValidateBlockValues(b DrandBeacon, h *types.BlockHeader, prevEntry types.BeaconEntry) error {
-	for i, be := range h.BeaconEntries {
+	rounds := b.BeaconRoundsForEpoch(h.Height, prevEntry)
-		if ok, err := b.IsEntryForEpoch(be, h.Height, nulls); err != nil {
+	if len(rounds) != len(h.BeaconEntries) {
-			return xerrors.Errorf("failed to check if beacon belongs: %w")
+		return xerrors.Errorf("mismatch in number of expected beacon entries (exp %d, got %d)", len(rounds), len(h.BeaconEntries))
-		} else if !ok {
-			return xerrors.Errorf("beacon does not belong in this block: %d", i)
 	}
 
-		if ok, err := b.VerifyEntry(be); err != nil {
+	for i, e := range h.BeaconEntries {
-			return xerrors.Errorf("failed to verify beacon entry %d: %w", i, err)
+		if e.Round != rounds[i] {
-		} else if !ok {
+			return xerrors.Errorf("entry at index %d did not match expected round (exp %d, got %d)", i, rounds[i], e.Round)
-			return xerrors.Errorf("beacon entry %d was invalid", i)
-		}
 		}
 
-	// validate that block contains entry for its own epoch
+		if err := b.VerifyEntry(e, prevEntry); err != nil {
-	should := b.BeaconIndexesForEpoch(h.Height, 0)
+			return xerrors.Errorf("beacon entry %d was invalid: %w", i, err)
-	if should[len(should)-1] != h.BeaconEntries[len(h.BeaconEntries)-1].Index {
+		}
-		return xerrors.Errorf("missing beacon entry for this block")
+		prevEntry = e
 	}
 
 	return nil
 }
 
-func BeaconEntriesForBlock(ctx context.Context, beacon DrandBeacon, round abi.ChainEpoch, nulls int) ([]types.BeaconEntry, error) {
+func BeaconEntriesForBlock(ctx context.Context, beacon DrandBeacon, round abi.ChainEpoch, prev types.BeaconEntry) ([]types.BeaconEntry, error) {
 	start := time.Now()
 
 	var out []types.BeaconEntry
-	for _, ei := range beacon.BeaconIndexesForEpoch(round, nulls) {
+	for _, ei := range beacon.BeaconRoundsForEpoch(round, prev) {
 		rch := beacon.Entry(ctx, ei)
 		select {
 		case resp := <-rch:
@@ -76,6 +73,7 @@ func BeaconEntriesForBlock(ctx context.Context, beacon DrandBeacon, round abi.Ch
 	return out, nil
 }
 
+// Mock beacon assumes that filecoin rounds are 1:1 mapped with the beacon rounds
 type mockBeacon struct {
 	interval time.Duration
 }
@@ -99,7 +97,7 @@ func (mb *mockBeacon) entryForIndex(index uint64) types.BeaconEntry {
 	binary.BigEndian.PutUint64(buf, index)
 	rval := blake2b.Sum256(buf)
 	return types.BeaconEntry{
-		Index: index,
+		Round: index,
 		Data:  rval[:],
 	}
 }
@@ -111,22 +109,24 @@ func (mb *mockBeacon) Entry(ctx context.Context, index uint64) <-chan Response {
 	return out
 }
 
-func (mb *mockBeacon) VerifyEntry(e types.BeaconEntry) (bool, error) {
+func (mb *mockBeacon) VerifyEntry(from types.BeaconEntry, to types.BeaconEntry) error {
 	// TODO: cache this, especially for bls
-	oe := mb.entryForIndex(e.Index)
+	oe := mb.entryForIndex(from.Round)
-	return bytes.Equal(e.Data, oe.Data), nil
+	if !bytes.Equal(from.Data, oe.Data) {
+		return xerrors.Errorf("mock beacon entry was invalid!")
+	}
+	return nil
 }
 
 func (mb *mockBeacon) IsEntryForEpoch(e types.BeaconEntry, epoch abi.ChainEpoch, nulls int) (bool, error) {
-	return int64(e.Index) <= int64(epoch) && int64(epoch)-int64(nulls) >= int64(e.Index), nil
+	return int64(e.Round) <= int64(epoch) && int64(epoch)-int64(nulls) >= int64(e.Round), nil
 }
 
-func (mb *mockBeacon) BeaconIndexesForEpoch(epoch abi.ChainEpoch, nulls int) []uint64 {
+func (mb *mockBeacon) BeaconRoundsForEpoch(epoch abi.ChainEpoch, prevEntry types.BeaconEntry) []uint64 {
 	var out []uint64
-	for i := nulls; i > 0; i-- {
+	for i := prevEntry.Round + 1; i < uint64(epoch); i++ {
-		out = append(out, uint64(epoch)-uint64(i))
+		out = append(out, i)
 	}
-	out = append(out, uint64(epoch))
 	return out
 }
 

chain/gen/gen.go

@@ -277,7 +277,7 @@ func CarWalkFunc(nd format.Node) (out []*format.Link, err error) {
 	return out, nil
 }
 
-func (cg *ChainGen) nextBlockProof(ctx context.Context, pts *types.TipSet, m address.Address, round int64) (*types.EPostProof, *types.Ticket, error) {
+func (cg *ChainGen) nextBlockProof(ctx context.Context, pts *types.TipSet, m address.Address, round abi.ChainEpoch) ([]types.BeaconEntry, *types.Ticket, error) {
 	mc := &mca{w: cg.w, sm: cg.sm}
 
 	buf := new(bytes.Buffer)
@@ -306,20 +306,28 @@ func (cg *ChainGen) nextBlockProof(ctx context.Context, pts *types.TipSet, m add
 		VRFProof: vrfout,
 	}
 
-	// TODO beacon
+	prev, err := cg.cs.GetLatestBeaconEntry(pts)
-	eproofin, err := IsRoundWinner(ctx, pts, round, m, cg.eppProvs[m], types.BeaconEntry{}, mc)
+	if err != nil {
+		return nil, nil, xerrors.Errorf("getLatestBeaconEntry: %w", err)
+	}
+
+	entries, err := beacon.BeaconEntriesForBlock(ctx, cg.beacon, abi.ChainEpoch(round), *prev)
+	if err != nil {
+		return nil, nil, xerrors.Errorf("get beacon entries for block: %w", err)
+	}
+
+	rbase := *prev
+	if len(entries) > 0 {
+		rbase = entries[len(entries)-1]
+	}
+
+	// TODO winning post return?
+	_, err = IsRoundWinner(ctx, pts, round, m, rbase, mc)
 	if err != nil {
 		return nil, nil, xerrors.Errorf("checking round winner failed: %w", err)
 	}
-	if eproofin == nil {
-		return nil, tick, nil
-	}
-	eproof, err := ComputeProof(ctx, cg.eppProvs[m], eproofin)
-	if err != nil {
-		return nil, nil, xerrors.Errorf("computing proof: %w", err)
-	}
 
-	return eproof, tick, nil
+	return entries, tick, nil
 }
 
 type MinedTipSet struct {
@@ -345,21 +353,16 @@ func (cg *ChainGen) NextTipSetFromMiners(base *types.TipSet, miners []address.Ad
 		return nil, xerrors.Errorf("get random messages: %w", err)
 	}
 
-	for round := int64(base.Height() + 1); len(blks) == 0; round++ {
+	for round := base.Height() + 1; len(blks) == 0; round++ {
 		for _, m := range miners {
-			proof, t, err := cg.nextBlockProof(context.TODO(), base, m, round)
+			bvals, t, err := cg.nextBlockProof(context.TODO(), base, m, round)
 			if err != nil {
 				return nil, xerrors.Errorf("next block proof: %w", err)
 			}
 
-			if proof != nil {
+			if t != nil {
-				nulls := int(round) - int(base.Height()+1)
+				// TODO: winning post proof
-				bvals, err := beacon.BeaconEntriesForBlock(context.TODO(), cg.beacon, abi.ChainEpoch(round), nulls)
+				fblk, err := cg.makeBlock(base, m, nil, t, bvals, abi.ChainEpoch(round), msgs)
-				if err != nil {
-					return nil, xerrors.Errorf("failed to get beacon entries: %w", err)
-				}
-
-				fblk, err := cg.makeBlock(base, m, proof, t, bvals, abi.ChainEpoch(round), msgs)
 				if err != nil {
 					return nil, xerrors.Errorf("making a block for next tipset failed: %w", err)
 				}
@@ -475,7 +478,7 @@ func (mca mca) ChainGetRandomness(ctx context.Context, tsk types.TipSetKey, pers
 		return nil, xerrors.Errorf("loading tipset key: %w", err)
 	}
 
-	return mca.sm.ChainStore().GetRandomness(ctx, pts.Cids(), personalization, int64(randEpoch), entropy)
+	return mca.sm.ChainStore().GetRandomness(ctx, pts.Cids(), personalization, randEpoch, entropy)
 }
 
 func (mca mca) MinerGetBaseInfo(ctx context.Context, maddr address.Address, tsk types.TipSetKey) (*api.MiningBaseInfo, error) {
@@ -521,83 +524,36 @@ type ProofInput struct {
 	vrfout  []byte
 }
 
-func IsRoundWinner(ctx context.Context, ts *types.TipSet, round int64,
+func IsRoundWinner(ctx context.Context, ts *types.TipSet, round abi.ChainEpoch,
-	miner address.Address, epp ElectionPoStProver, brand types.BeaconEntry, a MiningCheckAPI) (*ProofInput, error) {
+	miner address.Address, brand types.BeaconEntry, a MiningCheckAPI) (bool, error) {
+
 	buf := new(bytes.Buffer)
-
-	_, _ = buf.Write(brand.Data) // a bit hacky, would be better if it was insidce ChainGetRanomness,
-	// but chain has no idea about the block we are in progress of producing
-
 	if err := miner.MarshalCBOR(buf); err != nil {
-		return nil, xerrors.Errorf("failed to cbor marshal address: %w")
+		return false, xerrors.Errorf("failed to cbor marshal address: %w")
 	}
 
-	epostRand, err := a.ChainGetRandomness(ctx, ts.Key(), crypto.DomainSeparationTag_ElectionPoStChallengeSeed, abi.ChainEpoch(round-build.EcRandomnessLookback), buf.Bytes())
+	electionRand, err := store.DrawRandomness(brand.Data, 17, round, buf.Bytes())
 	if err != nil {
-		return nil, xerrors.Errorf("chain get randomness: %w", err)
+		return false, xerrors.Errorf("failed to draw randomness: %w", err)
 	}
 
 	mbi, err := a.MinerGetBaseInfo(ctx, miner, ts.Key())
 	if err != nil {
-		return nil, xerrors.Errorf("failed to get mining base info: %w", err)
+		return false, xerrors.Errorf("failed to get mining base info: %w", err)
 	}
 
-	vrfout, err := ComputeVRF(ctx, a.WalletSign, mbi.Worker, epostRand)
+	vrfout, err := ComputeVRF(ctx, a.WalletSign, mbi.Worker, electionRand)
 	if err != nil {
-		return nil, xerrors.Errorf("failed to compute VRF: %w", err)
+		return false, xerrors.Errorf("failed to compute VRF: %w", err)
 	}
 
-	/*
-		if len(mbi.Sectors) == 0 {
-			return nil, nil
-		}
-
-		var sinfos []abi.SectorInfo
-		for _, s := range mbi.Sectors {
-			if s.Info.Info.RegisteredProof == 0 {
-				return nil, xerrors.Errorf("sector %d in proving set had registered type of zero", s.ID)
-			}
-			sinfos = append(sinfos, abi.SectorInfo{
-				SectorNumber:    s.ID,
-				SealedCID:       s.Info.Info.SealedCID,
-				RegisteredProof: s.Info.Info.RegisteredProof,
-			})
-		}
-
-		hvrf := blake2b.Sum256(vrfout)
-		candidates, err := epp.GenerateCandidates(ctx, sinfos, hvrf[:])
-		if err != nil {
-			return nil, xerrors.Errorf("failed to generate electionPoSt candidates: %w", err)
-		}
-
-		var winners []storage.PoStCandidateWithTicket
-		for _, c := range candidates {
-			if types.IsTicketWinner(c.Candidate.PartialTicket, mbi.SectorSize, uint64(len(sinfos)), mbi.NetworkPower) {
-				winners = append(winners, c)
-			}
-		}
-
-		// no winners, sad
-		if len(winners) == 0 {
-			return nil, nil
-		}
-	*/
 	// TODO: wire in real power
 	myPower := types.BigMul(types.NewInt(uint64(len(mbi.Sectors))), types.NewInt(uint64(mbi.SectorSize)))
-	if types.IsTicketWinner(vrfout, myPower, mbi.NetworkPower) {
+	if !types.IsTicketWinner(vrfout, myPower, mbi.NetworkPower) {
-		panic("TODO what to do when we win")
+		return false, nil
-		// yey winner
 	}
 
-	/*
+	return true, nil
-		return &ProofInput{
-			sectors: sinfos,
-			hvrf:    hvrf[:],
-			winners: winners,
-			vrfout:  vrfout,
-		}, nil
-	*/
-	return nil, nil
 }
 
 func ComputeProof(ctx context.Context, epp ElectionPoStProver, pi *ProofInput) (*types.EPostProof, error) {

chain/gen/genesis/genesis.go

@@ -266,6 +266,12 @@ func MakeGenesisBlock(ctx context.Context, bs bstore.Blockstore, sys runtime.Sys
 		BLSAggregate:          nil,
 		BlockSig:              nil,
 		Timestamp:             template.Timestamp,
+		BeaconEntries: []types.BeaconEntry{
+			types.BeaconEntry{
+				Round: 0,
+				Data:  make([]byte, 32),
+			},
+		},
 	}
 
 	sb, err := b.ToStorageBlock()

chain/gen/genesis/miners.go

@@ -264,8 +264,8 @@ func SetupStorageMiners(ctx context.Context, cs *store.ChainStore, sroot cid.Cid
 // TODO: copied from actors test harness, deduplicate or remove from here
 type fakeRand struct{}
 
-func (fr *fakeRand) GetRandomness(ctx context.Context, personalization crypto.DomainSeparationTag, randEpoch int64, entropy []byte) ([]byte, error) {
+func (fr *fakeRand) GetRandomness(ctx context.Context, personalization crypto.DomainSeparationTag, randEpoch abi.ChainEpoch, entropy []byte) ([]byte, error) {
 	out := make([]byte, 32)
-	rand.New(rand.NewSource(randEpoch)).Read(out)
+	rand.New(rand.NewSource(int64(randEpoch))).Read(out)
 	return out, nil
 }

chain/gen/mining.go

@@ -40,7 +40,7 @@ func MinerCreateBlock(ctx context.Context, sm *stmgr.StateManager, w *wallet.Wal
 		BeaconEntries: bvals,
 		Height:        height,
 		Timestamp:     timestamp,
-		EPostProof:            *proof,
+		//EPostProof:            *proof,
 		ParentStateRoot:       st,
 		ParentMessageReceipts: recpts,
 	}

chain/stmgr/stmgr.go

@@ -189,7 +189,7 @@ func (sm *StateManager) ApplyBlocks(ctx context.Context, pstate cid.Cid, bms []B
 			Miner:       b.Miner,
 			Penalty:     penalty,
 			GasReward:   gasReward,
-			TicketCount: b.TicketCount,
+			TicketCount: 1, // TODO: no longer need ticket count here.
 		})
 		if err != nil {
 			return cid.Undef, cid.Undef, xerrors.Errorf("failed to serialize award params: %w", err)

chain/store/store.go

@@ -892,12 +892,12 @@ func (cs *ChainStore) TryFillTipSet(ts *types.TipSet) (*FullTipSet, error) {
 	return NewFullTipSet(out), nil
 }
 
-func drawRandomness(t *types.Ticket, pers crypto.DomainSeparationTag, round int64, entropy []byte) ([]byte, error) {
+func DrawRandomness(rbase []byte, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
 	h := blake2b.New256()
 	if err := binary.Write(h, binary.BigEndian, int64(pers)); err != nil {
 		return nil, xerrors.Errorf("deriving randomness: %w", err)
 	}
-	VRFDigest := blake2b.Sum256(t.VRFProof)
+	VRFDigest := blake2b.Sum256(rbase)
 	h.Write(VRFDigest[:])
 	if err := binary.Write(h, binary.BigEndian, round); err != nil {
 		return nil, xerrors.Errorf("deriving randomness: %w", err)
@@ -907,10 +907,10 @@ func drawRandomness(t *types.Ticket, pers crypto.DomainSeparationTag, round int6
 	return h.Sum(nil), nil
 }
 
-func (cs *ChainStore) GetRandomness(ctx context.Context, blks []cid.Cid, pers crypto.DomainSeparationTag, round int64, entropy []byte) (out []byte, err error) {
+func (cs *ChainStore) GetRandomness(ctx context.Context, blks []cid.Cid, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) (out []byte, err error) {
 	_, span := trace.StartSpan(ctx, "store.GetRandomness")
 	defer span.End()
-	span.AddAttributes(trace.Int64Attribute("round", round))
+	span.AddAttributes(trace.Int64Attribute("round", int64(round)))
 
 	/*
 		defer func() {
@@ -927,8 +927,8 @@ func (cs *ChainStore) GetRandomness(ctx context.Context, blks []cid.Cid, pers cr
 
 		// if at (or just past -- for null epochs) appropriate epoch
 		// or at genesis (works for negative epochs)
-		if int64(nts.Height()) <= round || mtb.Height == 0 {
+		if nts.Height() <= round || mtb.Height == 0 {
-			return drawRandomness(nts.MinTicketBlock().Ticket, pers, round, entropy)
+			return DrawRandomness(nts.MinTicketBlock().Ticket.VRFProof, pers, round, entropy)
 		}
 
 		blks = mtb.Parents
@@ -1090,6 +1090,28 @@ func (cs *ChainStore) Import(r io.Reader) (*types.TipSet, error) {
 	return root, nil
 }
 
+func (cs *ChainStore) GetLatestBeaconEntry(ts *types.TipSet) (*types.BeaconEntry, error) {
+	cur := ts
+	for i := 0; i < 20; i++ {
+		cbe := cur.Blocks()[0].BeaconEntries
+		if len(cbe) > 0 {
+			return &cbe[len(cbe)-1], nil
+		}
+
+		if cur.Height() == 0 {
+			return nil, xerrors.Errorf("made it back to genesis block without finding beacon entry")
+		}
+
+		next, err := cs.LoadTipSet(cur.Parents())
+		if err != nil {
+			return nil, xerrors.Errorf("failed to load parents when searching back for latest beacon entry: %w", err)
+		}
+		cur = next
+	}
+
+	return nil, xerrors.Errorf("found NO beacon entries in the 20 blocks prior to given tipset")
+}
+
 type chainRand struct {
 	cs   *ChainStore
 	blks []cid.Cid
@@ -1104,7 +1126,7 @@ func NewChainRand(cs *ChainStore, blks []cid.Cid, bheight abi.ChainEpoch) vm.Ran
 	}
 }
 
-func (cr *chainRand) GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round int64, entropy []byte) ([]byte, error) {
+func (cr *chainRand) GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
 	return cr.cs.GetRandomness(ctx, cr.blks, pers, round, entropy)
 }
 

chain/sync.go

@@ -627,16 +627,22 @@ func (syncer *Syncer) ValidateBlock(ctx context.Context, b *types.FullBlock) err
 			return xerrors.Errorf("failed to marshal miner address to cbor: %w", err)
 		}
 
-		vrfBase, err := syncer.sm.ChainStore().GetRandomness(ctx, baseTs.Cids(), crypto.DomainSeparationTag_TicketProduction, int64(h.Height)-1, buf.Bytes())
-		if err != nil {
-			return xerrors.Errorf("failed to get randomness for verifying election proof: %w", err)
-		}
-
 		baseBeacon := prevBeacon
 		if len(h.BeaconEntries) > 0 {
 			baseBeacon = h.BeaconEntries[len(h.BeaconEntries)-1]
 		}
 
+		buf := new(bytes.Buffer)
+		if err := h.Miner.MarshalCBOR(buf); err != nil {
+			return xerrors.Errorf("failed to marshal miner address to cbor: %w", err)
+		}
+
+		// TODO: use real DST from specs actors when it lands
+		vrfBase, err := store.DrawRandomness(baseBeacon.Data, 17, int64(h.Height), buf.Bytes())
+		if err != nil {
+			return xerrors.Errorf("failed to compute vrf base for ticket: %w", err)
+		}
+
 		err = gen.VerifyVRF(ctx, waddr, vrfBase, h.Ticket.VRFProof)
 		if err != nil {
 			return xerrors.Errorf("validating block tickets failed: %w", err)

chain/types/blockheader.go

@@ -35,7 +35,7 @@ type EPostProof struct {
 }
 
 type BeaconEntry struct {
-	Index uint64
+	Round uint64
 	Data  []byte
 }
 

chain/types/cbor_gen.go

@@ -1508,7 +1508,7 @@ func (t *BeaconEntry) MarshalCBOR(w io.Writer) error {
 
 	// t.Index (uint64) (uint64)
 
-	if _, err := w.Write(cbg.CborEncodeMajorType(cbg.MajUnsignedInt, uint64(t.Index))); err != nil {
+	if _, err := w.Write(cbg.CborEncodeMajorType(cbg.MajUnsignedInt, uint64(t.Round))); err != nil {
 		return err
 	}
 
@@ -1552,7 +1552,7 @@ func (t *BeaconEntry) UnmarshalCBOR(r io.Reader) error {
 		if maj != cbg.MajUnsignedInt {
 			return fmt.Errorf("wrong type for uint64 field")
 		}
-		t.Index = uint64(extra)
+		t.Round = uint64(extra)
 
 	}
 	// t.Data ([]uint8) (slice)

chain/validation/applier.go

@@ -2,6 +2,7 @@ package validation
 
 import (
 	"context"
+
 	"golang.org/x/xerrors"
 
 	"github.com/filecoin-project/specs-actors/actors/abi"
@@ -101,15 +102,15 @@ type randWrapper struct {
 	rnd vstate.RandomnessSource
 }
 
-func (w *randWrapper) GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round int64, entropy []byte) ([]byte, error) {
+func (w *randWrapper) GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error) {
-	return w.rnd.Randomness(ctx, pers, abi.ChainEpoch(round), entropy)
+	return w.rnd.Randomness(ctx, pers, round, entropy)
 }
 
 type vmRand struct {
 	eCtx *vtypes.ExecutionContext
 }
 
-func (*vmRand) GetRandomness(ctx context.Context, dst crypto.DomainSeparationTag, h int64, input []byte) ([]byte, error) {
+func (*vmRand) GetRandomness(ctx context.Context, dst crypto.DomainSeparationTag, h abi.ChainEpoch, input []byte) ([]byte, error) {
 	panic("implement me")
 }
 

chain/vm/runtime.go

@@ -151,7 +151,7 @@ func (rs *Runtime) GetActorCodeCID(addr address.Address) (ret cid.Cid, ok bool)
 }
 
 func (rt *Runtime) GetRandomness(personalization crypto.DomainSeparationTag, randEpoch abi.ChainEpoch, entropy []byte) abi.Randomness {
-	res, err := rt.vm.rand.GetRandomness(rt.ctx, personalization, int64(randEpoch), entropy)
+	res, err := rt.vm.rand.GetRandomness(rt.ctx, personalization, randEpoch, entropy)
 	if err != nil {
 		panic(aerrors.Fatalf("could not get randomness: %s", err))
 	}

chain/vm/vm.go

@@ -188,7 +188,7 @@ func NewVM(base cid.Cid, height abi.ChainEpoch, r Rand, maddr address.Address, c
 }
 
 type Rand interface {
-	GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round int64, entropy []byte) ([]byte, error)
+	GetRandomness(ctx context.Context, pers crypto.DomainSeparationTag, round abi.ChainEpoch, entropy []byte) ([]byte, error)
 }
 
 type ApplyRet struct {

miner/miner.go

@@ -290,12 +290,40 @@ func (m *Miner) hasPower(ctx context.Context, addr address.Address, ts *types.Ti
 	return !power.MinerPower.Equals(types.NewInt(0)), nil
 }
 
+// Note: copied from the chainstore method. Maybe we should expose this over the api?
+func (m *Miner) getLatestBeaconEntry(ctx context.Context, ts *types.TipSet) (*types.BeaconEntry, error) {
+	cur := ts
+	for i := 0; i < 20; i++ {
+		cbe := cur.Blocks()[0].BeaconEntries
+		if len(cbe) > 0 {
+			return &cbe[len(cbe)-1], nil
+		}
+
+		if cur.Height() == 0 {
+			return nil, xerrors.Errorf("made it back to genesis block without finding beacon entry")
+		}
+
+		next, err := m.api.ChainGetTipSet(ctx, cur.Parents())
+		if err != nil {
+			return nil, xerrors.Errorf("failed to load parents when searching back for latest beacon entry: %w", err)
+		}
+		cur = next
+	}
+
+	return nil, xerrors.Errorf("found NO beacon entries in the 20 blocks prior to given tipset")
+}
+
 func (m *Miner) mineOne(ctx context.Context, addr address.Address, base *MiningBase) (*types.BlockMsg, error) {
 	log.Debugw("attempting to mine a block", "tipset", types.LogCids(base.ts.Cids()))
 	start := time.Now()
 
+	beaconPrev, err := m.getLatestBeaconEntry(ctx, base.ts)
+	if err != nil {
+		return nil, xerrors.Errorf("getLatestBeaconEntry: %w", err)
+	}
+
 	round := base.ts.Height() + base.nullRounds + 1
-	bvals, err := beacon.BeaconEntriesForBlock(ctx, m.beacon, round, int(base.nullRounds))
+	bvals, err := beacon.BeaconEntriesForBlock(ctx, m.beacon, round, *beaconPrev)
 	if err != nil {
 		return nil, xerrors.Errorf("get beacon entries failed: %w", err)
 	}
@@ -317,12 +345,17 @@ func (m *Miner) mineOne(ctx context.Context, addr address.Address, base *MiningB
 		return nil, xerrors.Errorf("scratching ticket failed: %w", err)
 	}
 
-	proofin, err := gen.IsRoundWinner(ctx, base.ts, int64(round), addr, m.epp, bvals[len(bvals)-1], m.api)
+	rbase := *beaconPrev
+	if len(bvals) > 0 {
+		rbase = bvals[len(bvals)-1]
+	}
+
+	winner, err := gen.IsRoundWinner(ctx, base.ts, round, addr, rbase, m.api)
 	if err != nil {
 		return nil, xerrors.Errorf("failed to check if we win next round: %w", err)
 	}
 
-	if proofin == nil {
+	if !winner {
 		base.nullRounds++
 		return nil, nil
 	}
@@ -333,12 +366,8 @@ func (m *Miner) mineOne(ctx context.Context, addr address.Address, base *MiningB
 		return nil, xerrors.Errorf("failed to get pending messages: %w", err)
 	}
 
-	proof, err := gen.ComputeProof(ctx, m.epp, proofin)
+	// TODO: winning post proof
-	if err != nil {
+	b, err := m.createBlock(base, addr, ticket, nil, bvals, pending)
-		return nil, xerrors.Errorf("computing election proof: %w", err)
-	}
-
-	b, err := m.createBlock(base, addr, ticket, proof, bvals, pending)
 	if err != nil {
 		return nil, xerrors.Errorf("failed to create block: %w", err)
 	}