v2.1.0.7

config/version.go

@@ -43,7 +43,7 @@ func FormatVersion(version []byte) string {
 }
 
 func GetPatchNumber() byte {
-	return 0x06
+	return 0x07
 }
 
 func GetRCNumber() byte {

consensus/consensus_committee.go

@@ -38,10 +38,7 @@ type Replicas interface {
 	// Returns the following expected errors for invalid inputs:
 	//   - model.ErrRankUnknown if no rank containing the given rank is
 	//     known
-	LeaderForRank(
+	LeaderForRank(rank uint64) (models.Identity, error)
-		rank uint64,
-		selector models.Identity,
-	) (models.Identity, error)
 
 	// QuorumThresholdForRank returns the minimum total weight for a supermajority
 	// at the given rank. This weight threshold is computed using the total weight

consensus/eventhandler/event_handler.go

@@ -496,10 +496,7 @@ func (e *EventHandler[
 		consensus.Uint64Param("current_rank", curRank),
 		consensus.IdentityParam("self", e.committee.Self()),
 	)
-	currentLeader, err := e.committee.LeaderForRank(
+	currentLeader, err := e.committee.LeaderForRank(curRank)
-		curRank,
-		e.paceMaker.LatestQuorumCertificate().Identity(),
-	)
 	if err != nil {
 		return fmt.Errorf(
 			"failed to determine primary for new rank %d: %w",
@@ -694,10 +691,7 @@ func (e *EventHandler[
 		return nil
 	}
 	// leader (node ID) for next rank
-	nextLeader, err := e.committee.LeaderForRank(
+	nextLeader, err := e.committee.LeaderForRank(curRank + 1)
-		curRank+1,
-		proposal.State.Identifier,
-	)
 	if errors.Is(err, models.ErrRankUnknown) {
 		// We are attempting process a state in an unknown rank
 		// This should never happen, because:

consensus/mocks/dynamic_committee.go

@@ -133,8 +133,8 @@ func (_m *DynamicCommittee) IdentityByState(stateID models.Identity, participant
 }
 
 // LeaderForRank provides a mock function with given fields: rank
-func (_m *DynamicCommittee) LeaderForRank(rank uint64, selector models.Identity) (models.Identity, error) {
+func (_m *DynamicCommittee) LeaderForRank(rank uint64) (models.Identity, error) {
-	ret := _m.Called(rank, selector)
+	ret := _m.Called(rank)
 
 	if len(ret) == 0 {
 		panic("no return value specified for LeaderForRank")
@@ -142,17 +142,17 @@ func (_m *DynamicCommittee) LeaderForRank(rank uint64, selector models.Identity)
 
 	var r0 models.Identity
 	var r1 error
-	if rf, ok := ret.Get(0).(func(uint64, models.Identity) (models.Identity, error)); ok {
+	if rf, ok := ret.Get(0).(func(uint64) (models.Identity, error)); ok {
-		return rf(rank, selector)
+		return rf(rank)
 	}
-	if rf, ok := ret.Get(0).(func(uint64, models.Identity) models.Identity); ok {
+	if rf, ok := ret.Get(0).(func(uint64) models.Identity); ok {
-		r0 = rf(rank, selector)
+		r0 = rf(rank)
 	} else {
 		r0 = ret.Get(0).(models.Identity)
 	}
 
-	if rf, ok := ret.Get(1).(func(uint64, models.Identity) error); ok {
+	if rf, ok := ret.Get(1).(func(uint64) error); ok {
-		r1 = rf(rank, selector)
+		r1 = rf(rank)
 	} else {
 		r1 = ret.Error(1)
 	}

consensus/mocks/replicas.go

@@ -73,8 +73,8 @@ func (_m *Replicas) IdentityByRank(rank uint64, participantID models.Identity) (
 }
 
 // LeaderForRank provides a mock function with given fields: rank
-func (_m *Replicas) LeaderForRank(rank uint64, selector models.Identity) (models.Identity, error) {
+func (_m *Replicas) LeaderForRank(rank uint64) (models.Identity, error) {
-	ret := _m.Called(rank, selector)
+	ret := _m.Called(rank)
 
 	if len(ret) == 0 {
 		panic("no return value specified for LeaderForRank")
@@ -82,17 +82,17 @@ func (_m *Replicas) LeaderForRank(rank uint64, selector models.Identity) (models
 
 	var r0 models.Identity
 	var r1 error
-	if rf, ok := ret.Get(0).(func(uint64, models.Identity) (models.Identity, error)); ok {
+	if rf, ok := ret.Get(0).(func(uint64) (models.Identity, error)); ok {
-		return rf(rank, selector)
+		return rf(rank)
 	}
-	if rf, ok := ret.Get(0).(func(uint64, models.Identity) models.Identity); ok {
+	if rf, ok := ret.Get(0).(func(uint64) models.Identity); ok {
-		r0 = rf(rank, selector)
+		r0 = rf(rank)
 	} else {
 		r0 = ret.Get(0).(models.Identity)
 	}
 
-	if rf, ok := ret.Get(1).(func(uint64, models.Identity) error); ok {
+	if rf, ok := ret.Get(1).(func(uint64) error); ok {
-		r1 = rf(rank, selector)
+		r1 = rf(rank)
 	} else {
 		r1 = ret.Error(1)
 	}

consensus/safetyrules/safety_rules.go

@@ -128,10 +128,7 @@ func (r *SafetyRules[StateT, VoteT]) produceVote(
 		)
 	}
 
-	currentLeader, err := r.committee.LeaderForRank(
+	currentLeader, err := r.committee.LeaderForRank(state.Rank)
-		state.Rank,
-		state.ParentQuorumCertificate.Identity(),
-	)
 	if err != nil {
 		return nil, fmt.Errorf(
 			"expect to have a valid leader for rank %d: %w",

consensus/validator/validator.go

@@ -333,10 +333,7 @@ func (v *Validator[StateT, VoteT]) ValidateProposal(
 	}
 
 	// check the proposer is the leader for the proposed state's rank
-	leader, err := v.committee.LeaderForRank(
+	leader, err := v.committee.LeaderForRank(state.Rank)
-		state.Rank,
-		state.ParentQuorumCertificate.Identity(),
-	)
 	if err != nil {
 		return fmt.Errorf(
 			"error determining leader for state %x: %w",

node/consensus/aggregator/consensus_signature_aggregator_wrapper.go

@@ -3,6 +3,7 @@ package aggregator
 import (
 	"github.com/pkg/errors"
 
+	"source.quilibrium.com/quilibrium/monorepo/bls48581"
 	"source.quilibrium.com/quilibrium/monorepo/consensus"
 	"source.quilibrium.com/quilibrium/monorepo/consensus/models"
 	typesconsensus "source.quilibrium.com/quilibrium/monorepo/types/consensus"
@@ -62,18 +63,32 @@ func (c *ConsensusSignatureAggregatorWrapper) Aggregate(
 		return nil, errors.Wrap(err, "aggregate")
 	}
 
-	pubs := map[string]struct{}{}
+	pubs := map[string]int{}
-	for _, p := range publicKeys {
+	for i, p := range publicKeys {
-		pubs[string(p)] = struct{}{}
+		pubs[string(p)] = i
 	}
 
 	bitmask := make([]byte, (len(provers)+7)/8)
+	extra := []byte{}
+	if len(c.filter) != 0 {
+		extra = make([]byte, 516*len(provers))
+	}
 	for i, p := range provers {
-		if _, ok := pubs[string(p.PublicKey)]; ok {
+		if j, ok := pubs[string(p.PublicKey)]; ok {
 			bitmask[i/8] |= (1 << (i % 8))
+
+			if len(c.filter) != 0 {
+				copy(extra[516*i:516*(i+1)], signatures[j][74:])
+			}
 		}
 	}
 
+	// TODO: remove direct reference
+	if len(c.filter) != 0 {
+		output.(*bls48581.BlsAggregateOutput).AggregateSignature =
+			append(output.(*bls48581.BlsAggregateOutput).AggregateSignature, extra...)
+	}
+
 	return &ConsensusAggregatedSignature{output, bitmask}, nil
 }
 

node/consensus/app/app_consensus_engine.go

@@ -127,6 +127,7 @@ type AppConsensusEngine struct {
 	quit                      chan struct{}
 	canRunStandalone          bool
 	blacklistMap              map[string]bool
+	currentRank               uint64
 	alertPublicKey            []byte
 
 	// Message queues
@@ -497,6 +498,10 @@ func NewAppConsensusEngine(
 		}
 		pending = engine.getPendingProposals(frame.Header.FrameNumber)
 	}
+	liveness, err := engine.consensusStore.GetLivenessState(appAddress)
+	if err == nil {
+		engine.currentRank = liveness.CurrentRank
+	}
 
 	engine.voteAggregator, err = voting.NewAppShardVoteAggregator[PeerID](
 		tracing.NewZapTracer(logger),
@@ -1948,7 +1953,7 @@ func (e *AppConsensusEngine) OnQuorumCertificateTriggeredRankChange(
 		return
 	}
 
-	nextLeader, err := e.LeaderForRank(newRank, frame.Identity())
+	nextLeader, err := e.LeaderForRank(newRank)
 	if err != nil {
 		e.logger.Error("could not determine next prover", zap.Error(err))
 		return
@@ -1974,8 +1979,9 @@ func (e *AppConsensusEngine) OnQuorumCertificateTriggeredRankChange(
 				return
 			}
 
+			challenge := sha3.Sum256([]byte(frame.Identity()))
 			proof := e.frameProver.CalculateMultiProof(
-				[32]byte([]byte(frame.Identity())),
+				challenge,
 				frame.Header.Difficulty,
 				ids,
 				uint32(myIndex),
@@ -1989,6 +1995,7 @@ func (e *AppConsensusEngine) OnQuorumCertificateTriggeredRankChange(
 
 // OnRankChange implements consensus.Consumer.
 func (e *AppConsensusEngine) OnRankChange(oldRank uint64, newRank uint64) {
+	e.currentRank = newRank
 	err := e.ensureGlobalClient()
 	if err != nil {
 		e.logger.Error("cannot confirm cross-shard locks", zap.Error(err))
@@ -2363,7 +2370,7 @@ func (e *AppConsensusEngine) VerifyQuorumCertificate(
 		qc.AggregateSignature.GetPubKey(),
 		qc.AggregateSignature.GetSignature(),
 		verification.MakeVoteMessage(nil, qc.Rank, qc.Identity()),
-		[]byte("appshard"),
+		slices.Concat([]byte("appshard"), e.appAddress),
 	); !valid {
 		return models.ErrInvalidSignature
 	}
@@ -2426,7 +2433,7 @@ func (e *AppConsensusEngine) VerifyTimeoutCertificate(
 			tc.Rank,
 			tc.LatestQuorumCertificate.Rank,
 		),
-		[]byte("appshardtimeout"),
+		slices.Concat([]byte("appshardtimeout"), e.appAddress),
 	); !valid {
 		return models.ErrInvalidSignature
 	}
@@ -2469,7 +2476,7 @@ func (e *AppConsensusEngine) VerifyVote(
 		pubkey,
 		(*vote).PublicKeySignatureBls48581.Signature[:74],
 		verification.MakeVoteMessage(nil, (*vote).Rank, (*vote).Source()),
-		[]byte("appshard"),
+		slices.Concat([]byte("appshard"), e.appAddress),
 	); !valid {
 		return models.ErrInvalidSignature
 	}

node/consensus/app/consensus_dynamic_committee.go

@@ -3,6 +3,7 @@ package app
 import (
 	"bytes"
 	"encoding/binary"
+	"math/big"
 	"slices"
 
 	"github.com/iden3/go-iden3-crypto/poseidon"
@@ -105,28 +106,26 @@ func (e *AppConsensusEngine) IdentityByState(
 }
 
 // LeaderForRank implements consensus.DynamicCommittee.
-func (e *AppConsensusEngine) LeaderForRank(
+func (e *AppConsensusEngine) LeaderForRank(rank uint64) (
-	rank uint64,
+	models.Identity,
-	selector models.Identity,
+	error,
-) (models.Identity, error) {
+) {
+	// TODO(2.2): revisit this
 	inputBI, err := poseidon.HashBytes(slices.Concat(
-		[]byte(selector),
+		binary.BigEndian.AppendUint64(slices.Clone(e.appAddress), rank),
-		binary.BigEndian.AppendUint64(nil, rank),
 	))
 	if err != nil {
 		return "", errors.Wrap(err, "leader for rank")
 	}
 
-	input := inputBI.FillBytes(make([]byte, 32))
+	proverSet, err := e.proverRegistry.GetActiveProvers(e.appAddress)
-	prover, err := e.proverRegistry.GetNextProver(
-		[32]byte(input),
-		e.appAddress,
-	)
 	if err != nil {
 		return "", errors.Wrap(err, "leader for rank")
 	}
 
-	return models.Identity(prover), nil
+	inputBI.Mod(inputBI, big.NewInt(int64(len(proverSet))))
+	index := inputBI.Int64()
+	return models.Identity(proverSet[int(index)].Address), nil
 }
 
 // QuorumThresholdForRank implements consensus.DynamicCommittee.

node/consensus/app/consensus_leader_provider.go

@@ -84,8 +84,57 @@ func (p *AppLeaderProvider) ProveNextState(
 		return nil, models.NewNoVoteErrorf("missing prior frame")
 	}
 
+	latestQC, qcErr := p.engine.clockStore.GetLatestQuorumCertificate(
+		p.engine.appAddress,
+	)
+	if qcErr != nil {
+		p.engine.logger.Debug(
+			"could not fetch latest quorum certificate",
+			zap.Error(qcErr),
+		)
+	}
+
 	if prior.Identity() != priorState {
 		frameProvingTotal.WithLabelValues("error").Inc()
+
+		if latestQC != nil && latestQC.Identity() == priorState {
+			switch {
+			case prior.Header.Rank < latestQC.GetRank():
+				return nil, models.NewNoVoteErrorf(
+					"needs sync: prior rank %d behind latest qc rank %d",
+					prior.Header.Rank,
+					latestQC.GetRank(),
+				)
+			case prior.Header.Rank == latestQC.GetRank() &&
+				latestQC.Identity() != prior.Identity():
+				peerID, peerErr := p.engine.getRandomProverPeerId()
+				if peerErr != nil {
+					p.engine.logger.Warn(
+						"could not determine peer for fork sync",
+						zap.Error(peerErr),
+					)
+				} else {
+					p.engine.logger.Warn(
+						"detected fork, scheduling sync",
+						zap.Uint64("frame_number", latestQC.GetFrameNumber()),
+						zap.String("peer_id", peerID.String()),
+					)
+					p.engine.syncProvider.AddState(
+						[]byte(peerID),
+						latestQC.GetFrameNumber(),
+						[]byte(latestQC.Identity()),
+					)
+				}
+
+				return nil, models.NewNoVoteErrorf(
+					"fork detected at rank %d (local: %x, qc: %x)",
+					latestQC.GetRank(),
+					prior.Identity(),
+					latestQC.Identity(),
+				)
+			}
+		}
+
 		return nil, models.NewNoVoteErrorf(
 			"building on fork or needs sync: frame %d, rank %d, parent_id: %x, asked: rank %d, id: %x",
 			prior.Header.FrameNumber,

node/consensus/app/consensus_sync_provider.go

@@ -13,6 +13,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"slices"
 	"strings"
 	"time"
 
@@ -38,6 +39,7 @@ const defaultStateQueueCapacity = 10
 type syncRequest struct {
 	frameNumber uint64
 	peerId      []byte
+	identity    []byte
 }
 
 // AppSyncProvider implements SyncProvider
@@ -81,7 +83,36 @@ func (p *AppSyncProvider) Start(
 				ctx,
 				request.frameNumber,
 				request.peerId,
+				request.identity,
 			)
+		case <-time.After(10 * time.Minute):
+			// If we got here, it means we hit a pretty strong halt. This is an act of
+			// last resort to get everyone re-aligned:
+			head, err := p.engine.appTimeReel.GetHead()
+			if err != nil {
+				p.engine.logger.Error(
+					"head frame not found for time reel",
+					zap.Error(err),
+				)
+				continue
+			}
+
+			if time.UnixMilli(head.Header.Timestamp).Before(
+				time.Now().Add(-10 * time.Minute),
+			) {
+				peer, err := p.engine.getRandomProverPeerId()
+				if err != nil {
+					p.engine.logger.Error("could not get random prover", zap.Error(err))
+					continue
+				}
+
+				p.processState(
+					ctx,
+					head.Header.FrameNumber,
+					[]byte(peer),
+					[]byte(head.Identity()),
+				)
+			}
 		}
 	}
 }
@@ -90,11 +121,13 @@ func (p *AppSyncProvider) processState(
 	ctx context.Context,
 	frameNumber uint64,
 	peerID []byte,
+	identity []byte,
 ) {
 	err := p.syncWithPeer(
 		ctx,
 		frameNumber,
 		peerID,
+		identity,
 	)
 	if err != nil {
 		p.engine.logger.Error("could not sync with peer", zap.Error(err))
@@ -320,7 +353,12 @@ func (p *AppSyncProvider) syncWithMesh(ctx context.Context) error {
 			latest = head
 		}
 
-		err = p.syncWithPeer(ctx, latest.Header.FrameNumber, []byte(peerID))
+		err = p.syncWithPeer(
+			ctx,
+			latest.Header.FrameNumber,
+			[]byte(peerID),
+			[]byte(latest.Identity()),
+		)
 		if err != nil {
 			p.engine.logger.Debug("error syncing frame", zap.Error(err))
 		}
@@ -339,6 +377,7 @@ func (p *AppSyncProvider) syncWithPeer(
 	ctx context.Context,
 	frameNumber uint64,
 	peerId []byte,
+	expectedIdentity []byte,
 ) error {
 	p.engine.logger.Info(
 		"polling peer for new frames",
@@ -465,6 +504,29 @@ func (p *AppSyncProvider) syncWithPeer(
 					p.engine.logger.Debug("received invalid response from peer")
 					return nil
 				}
+				if len(expectedIdentity) != 0 {
+					if !bytes.Equal(
+						[]byte(response.Proposal.State.Identity()),
+						expectedIdentity,
+					) {
+						p.engine.logger.Warn(
+							"aborting sync due to unexpected frame identity",
+							zap.Uint64("frame_number", frameNumber),
+							zap.String(
+								"expected",
+								hex.EncodeToString(expectedIdentity),
+							),
+							zap.String(
+								"received",
+								hex.EncodeToString(
+									[]byte(response.Proposal.State.Identity()),
+								),
+							),
+						)
+						return errors.New("sync frame identity mismatch")
+					}
+					expectedIdentity = nil
+				}
 				p.engine.logger.Info(
 					"received new leading frame",
 					zap.Uint64(
@@ -476,9 +538,25 @@ func (p *AppSyncProvider) syncWithPeer(
 						frametime.AppFrameSince(response.Proposal.State),
 					),
 				)
+				provers, err := p.engine.proverRegistry.GetActiveProvers(
+					p.engine.appAddress,
+				)
+				if err != nil {
+					p.engine.logger.Error(
+						"could not obtain active provers",
+						zap.Error(err),
+					)
+					return err
+				}
+
+				ids := [][]byte{}
+				for _, p := range provers {
+					ids = append(ids, p.Address)
+				}
 				if _, err := p.engine.frameProver.VerifyFrameHeader(
 					response.Proposal.State.Header,
 					p.engine.blsConstructor,
+					ids,
 				); err != nil {
 					return errors.Wrap(err, "sync")
 				}
@@ -499,19 +577,35 @@ func (p *AppSyncProvider) syncWithPeer(
 func (p *AppSyncProvider) AddState(
 	sourcePeerID []byte,
 	frameNumber uint64,
+	expectedIdentity []byte,
 ) {
 	// Drop if we're within the threshold
 	if frameNumber <=
-		(*p.engine.forks.FinalizedState().State).Header.FrameNumber {
+		(*p.engine.forks.FinalizedState().State).Header.FrameNumber &&
-		p.engine.logger.Debug("dropping stale state for sync")
+		frameNumber != 0 {
+		p.engine.logger.Debug(
+			"dropping stale state for sync",
+			zap.Uint64("frame_requested", frameNumber),
+			zap.Uint64(
+				"finalized_frame",
+				(*p.engine.forks.FinalizedState().State).Header.FrameNumber,
+			),
+		)
 		return
 	}
 
+	// Handle special case: we're at genesis frame on time reel
+	if frameNumber == 0 {
+		frameNumber = 1
+		expectedIdentity = []byte{}
+	}
+
 	// Enqueue if we can, otherwise drop it because we'll catch up
 	select {
 	case p.queuedStates <- syncRequest{
 		frameNumber: frameNumber,
-		peerId:      sourcePeerID,
+		peerId:      slices.Clone(sourcePeerID),
+		identity:    slices.Clone(expectedIdentity),
 	}:
 		p.engine.logger.Debug(
 			"enqueued sync request",

node/consensus/app/consensus_voting_provider.go

@@ -109,7 +109,10 @@ func (p *AppVotingProvider) SignTimeoutVote(
 		newestQuorumCertificateRank,
 	)
 
-	sig, err := signer.SignWithDomain(signatureData, []byte("appshardtimeout"))
+	sig, err := signer.SignWithDomain(
+		signatureData,
+		slices.Concat([]byte("appshardtimeout"), p.engine.appAddress),
+	)
 	if err != nil {
 		p.engine.logger.Error("could not sign vote", zap.Error(err))
 		return nil, errors.Wrap(err, "sign vote")
@@ -148,10 +151,7 @@ func (p *AppVotingProvider) SignVote(
 		)
 	}
 
-	nextLeader, err := p.engine.LeaderForRank(
+	nextLeader, err := p.engine.LeaderForRank(state.Rank)
-		state.Rank,
-		state.ParentQuorumCertificate.Identity(),
-	)
 	if err != nil {
 		p.engine.logger.Error("could not determine next prover", zap.Error(err))
 		return nil, errors.Wrap(
@@ -167,7 +167,10 @@ func (p *AppVotingProvider) SignVote(
 		p.engine.proofCacheMu.RUnlock()
 
 		if !ok {
-			return nil, errors.Wrap(errors.New("no proof ready for vote"), "sign vote")
+			return nil, errors.Wrap(
+				errors.New("no proof ready for vote"),
+				"sign vote",
+			)
 		}
 		extProof = proof[:]
 	}
@@ -178,7 +181,10 @@ func (p *AppVotingProvider) SignVote(
 		state.Rank,
 		state.Identifier,
 	)
-	sig, err := signer.SignWithDomain(signatureData, []byte("appshard"))
+	sig, err := signer.SignWithDomain(
+		signatureData,
+		slices.Concat([]byte("appshard"), p.engine.appAddress),
+	)
 	if err != nil {
 		p.engine.logger.Error("could not sign vote", zap.Error(err))
 		return nil, errors.Wrap(err, "sign vote")

node/consensus/app/message_processors.go

@@ -191,21 +191,30 @@ func (e *AppConsensusEngine) handleAppShardProposal(
 	finalized := e.forks.FinalizedState()
 	finalizedRank := finalized.Rank
 	finalizedFrameNumber := (*finalized.State).Header.FrameNumber
+	frameNumber := proposal.State.Header.FrameNumber
 
 	// drop proposals if we already processed them
-	if proposal.State.Header.FrameNumber <= finalizedFrameNumber ||
+	if frameNumber <= finalizedFrameNumber ||
 		proposal.State.Header.Rank <= finalizedRank {
 		e.logger.Debug("dropping stale proposal")
 		return
 	}
-	_, _, err := e.clockStore.GetShardClockFrame(
+	existingFrame, _, err := e.clockStore.GetShardClockFrame(
 		proposal.State.Header.Address,
-		proposal.State.Header.FrameNumber,
+		frameNumber,
 		false,
 	)
-	if err == nil {
+	if err == nil && existingFrame != nil {
-		e.logger.Debug("dropping stale proposal")
+		qc, qcErr := e.clockStore.GetQuorumCertificate(
-		return
+			proposal.State.Header.Address,
+			proposal.State.GetRank(),
+		)
+		if qcErr == nil && qc != nil &&
+			qc.GetFrameNumber() == frameNumber &&
+			qc.Identity() == proposal.State.Identity() {
+			e.logger.Debug("dropping stale proposal")
+			return
+		}
 	}
 
 	if proposal.State.Header.FrameNumber != 0 {
@@ -239,12 +248,14 @@ func (e *AppConsensusEngine) handleAppShardProposal(
 				return
 			}
 
-			e.syncProvider.AddState([]byte(peerID), head.Header.FrameNumber)
+			e.syncProvider.AddState(
+				[]byte(peerID),
+				head.Header.FrameNumber,
+				[]byte(head.Identity()),
+			)
 			return
 		}
 	}
-
-	frameNumber := proposal.State.Header.FrameNumber
 	expectedFrame, err := e.appTimeReel.GetHead()
 	if err != nil {
 		e.logger.Error("could not obtain app time reel head", zap.Error(err))
@@ -351,7 +362,13 @@ func (e *AppConsensusEngine) processProposal(
 		signedProposal.PreviousRankTimeoutCertificate = prtc
 	}
 
-	e.voteAggregator.AddState(signedProposal)
+	// IMPORTANT: we do not want to send old proposals to the vote aggregator or
+	// we risk engine shutdown if the leader selection method changed – frame
+	// validation ensures that the proposer is valid for the proposal per time
+	// reel rules.
+	if signedProposal.State.Rank >= e.currentRank {
+		e.voteAggregator.AddState(signedProposal)
+	}
 	e.consensusParticipant.SubmitProposal(signedProposal)
 	proposalProcessedTotal.WithLabelValues(e.appAddressHex, "success").Inc()
 

node/consensus/app/message_validation.go

@@ -96,8 +96,9 @@ func (e *AppConsensusEngine) validateConsensusMessage(
 			return p2p.ValidationResultReject
 		}
 
-		now := uint64(time.Now().UnixMilli())
+		// We should still accept votes for the past rank – either because a peer
-		if vote.Timestamp > now+5000 || vote.Timestamp < now-5000 {
+		// needs it, or because we need it to trump a TC
+		if e.currentRank > vote.Rank+1 {
 			voteValidationTotal.WithLabelValues(e.appAddressHex, "ignore").Inc()
 			return p2p.ValidationResultIgnore
 		}
@@ -126,8 +127,8 @@ func (e *AppConsensusEngine) validateConsensusMessage(
 			return p2p.ValidationResultReject
 		}
 
-		now := uint64(time.Now().UnixMilli())
+		// We should still accept votes for the past rank in case a peer needs it
-		if timeoutState.Timestamp > now+5000 || timeoutState.Timestamp < now-5000 {
+		if e.currentRank > timeoutState.Vote.Rank+1 {
 			timeoutStateValidationTotal.WithLabelValues(
 				e.appAddressHex,
 				"ignore",

node/consensus/global/consensus_dynamic_committee.go

@@ -3,6 +3,7 @@ package global
 import (
 	"bytes"
 	"encoding/binary"
+	"math/big"
 	"slices"
 
 	"github.com/iden3/go-iden3-crypto/poseidon"
@@ -107,23 +108,23 @@ func (e *GlobalConsensusEngine) IdentityByState(
 // LeaderForRank implements consensus.DynamicCommittee.
 func (e *GlobalConsensusEngine) LeaderForRank(
 	rank uint64,
-	selector models.Identity,
 ) (models.Identity, error) {
+	// TODO(2.2): revisit this
 	inputBI, err := poseidon.HashBytes(slices.Concat(
-		[]byte(selector),
 		binary.BigEndian.AppendUint64(nil, rank),
 	))
 	if err != nil {
 		return "", errors.Wrap(err, "leader for rank")
 	}
 
-	input := inputBI.FillBytes(make([]byte, 32))
+	proverSet, err := e.proverRegistry.GetActiveProvers(nil)
-	prover, err := e.proverRegistry.GetNextProver([32]byte(input), nil)
 	if err != nil {
 		return "", errors.Wrap(err, "leader for rank")
 	}
 
-	return models.Identity(prover), nil
+	inputBI.Mod(inputBI, big.NewInt(int64(len(proverSet))))
+	index := inputBI.Int64()
+	return models.Identity(proverSet[int(index)].Address), nil
 }
 
 // QuorumThresholdForRank implements consensus.DynamicCommittee.

node/consensus/global/consensus_leader_provider.go

@@ -90,8 +90,55 @@ func (p *GlobalLeaderProvider) ProveNextState(
 		return nil, models.NewNoVoteErrorf("missing prior frame")
 	}
 
+	latestQC, qcErr := p.engine.clockStore.GetLatestQuorumCertificate(nil)
+	if qcErr != nil {
+		p.engine.logger.Debug(
+			"could not fetch latest quorum certificate",
+			zap.Error(qcErr),
+		)
+	}
+
 	if prior.Identity() != priorState {
 		frameProvingTotal.WithLabelValues("error").Inc()
+
+		if latestQC != nil && latestQC.Identity() == priorState {
+			switch {
+			case prior.Header.Rank < latestQC.GetRank():
+				return nil, models.NewNoVoteErrorf(
+					"needs sync: prior rank %d behind latest qc rank %d",
+					prior.Header.Rank,
+					latestQC.GetRank(),
+				)
+			case prior.Header.Rank == latestQC.GetRank() &&
+				latestQC.Identity() != prior.Identity():
+				peerID, peerErr := p.engine.getRandomProverPeerId()
+				if peerErr != nil {
+					p.engine.logger.Warn(
+						"could not determine peer for fork sync",
+						zap.Error(peerErr),
+					)
+				} else {
+					p.engine.logger.Warn(
+						"detected fork, scheduling sync",
+						zap.Uint64("frame_number", latestQC.GetFrameNumber()),
+						zap.String("peer_id", peerID.String()),
+					)
+					p.engine.syncProvider.AddState(
+						[]byte(peerID),
+						latestQC.GetFrameNumber(),
+						[]byte(latestQC.Identity()),
+					)
+				}
+
+				return nil, models.NewNoVoteErrorf(
+					"fork detected at rank %d (local: %x, qc: %x)",
+					latestQC.GetRank(),
+					prior.Identity(),
+					latestQC.Identity(),
+				)
+			}
+		}
+
 		return nil, models.NewNoVoteErrorf(
 			"building on fork or needs sync: frame %d, rank %d, parent_id: %x, asked: rank %d, id: %x",
 			prior.Header.FrameNumber,

node/consensus/global/consensus_sync_provider.go

@@ -3,7 +3,9 @@ package global
 import (
 	"bytes"
 	"context"
+	"encoding/hex"
 	"fmt"
+	"slices"
 	"time"
 
 	"github.com/libp2p/go-libp2p/core/crypto"
@@ -26,6 +28,7 @@ const defaultStateQueueCapacity = 10
 type syncRequest struct {
 	frameNumber uint64
 	peerId      []byte
+	identity    []byte
 }
 
 // GlobalSyncProvider implements SyncProvider
@@ -69,6 +72,7 @@ func (p *GlobalSyncProvider) Start(
 				ctx,
 				request.frameNumber,
 				request.peerId,
+				request.identity,
 			)
 		}
 	}
@@ -78,11 +82,13 @@ func (p *GlobalSyncProvider) processState(
 	ctx context.Context,
 	frameNumber uint64,
 	peerID []byte,
+	identity []byte,
 ) {
 	err := p.syncWithPeer(
 		ctx,
 		frameNumber,
 		peerID,
+		identity,
 	)
 	if err != nil {
 		p.engine.logger.Error("could not sync with peer", zap.Error(err))
@@ -230,7 +236,12 @@ func (p *GlobalSyncProvider) syncWithMesh(ctx context.Context) error {
 			latest = head
 		}
 
-		err = p.syncWithPeer(ctx, latest.Header.FrameNumber, []byte(peerID))
+		err = p.syncWithPeer(
+			ctx,
+			latest.Header.FrameNumber,
+			[]byte(peerID),
+			nil,
+		)
 		if err != nil {
 			p.engine.logger.Debug("error syncing frame", zap.Error(err))
 		}
@@ -249,6 +260,7 @@ func (p *GlobalSyncProvider) syncWithPeer(
 	ctx context.Context,
 	frameNumber uint64,
 	peerId []byte,
+	expectedIdentity []byte,
 ) error {
 	p.engine.logger.Info(
 		"polling peer for new frames",
@@ -372,6 +384,30 @@ func (p *GlobalSyncProvider) syncWithPeer(
 				return nil
 			}
 
+			if len(expectedIdentity) != 0 {
+				if !bytes.Equal(
+					[]byte(response.Proposal.State.Identity()),
+					expectedIdentity,
+				) {
+					p.engine.logger.Warn(
+						"aborting sync due to unexpected frame identity",
+						zap.Uint64("frame_number", frameNumber),
+						zap.String(
+							"expected",
+							hex.EncodeToString(expectedIdentity),
+						),
+						zap.String(
+							"received",
+							hex.EncodeToString(
+								[]byte(response.Proposal.State.Identity()),
+							),
+						),
+					)
+					return errors.New("sync frame identity mismatch")
+				}
+				expectedIdentity = nil
+			}
+
 			p.engine.logger.Info(
 				"received new leading frame",
 				zap.Uint64("frame_number", response.Proposal.State.Header.FrameNumber),
@@ -499,19 +535,35 @@ func (p *GlobalSyncProvider) hyperSyncHyperedgeRemoves(
 func (p *GlobalSyncProvider) AddState(
 	sourcePeerID []byte,
 	frameNumber uint64,
+	expectedIdentity []byte,
 ) {
 	// Drop if we're within the threshold
 	if frameNumber <=
-		(*p.engine.forks.FinalizedState().State).Header.FrameNumber {
+		(*p.engine.forks.FinalizedState().State).Header.FrameNumber &&
-		p.engine.logger.Debug("dropping stale state for sync")
+		frameNumber != 0 {
+		p.engine.logger.Debug(
+			"dropping stale state for sync",
+			zap.Uint64("frame_requested", frameNumber),
+			zap.Uint64(
+				"finalized_frame",
+				(*p.engine.forks.FinalizedState().State).Header.FrameNumber,
+			),
+		)
 		return
 	}
 
+	// Handle special case: we're at genesis frame on time reel
+	if frameNumber == 0 {
+		frameNumber = 1
+		expectedIdentity = []byte{}
+	}
+
 	// Enqueue if we can, otherwise drop it because we'll catch up
 	select {
 	case p.queuedStates <- syncRequest{
 		frameNumber: frameNumber,
-		peerId:      sourcePeerID,
+		peerId:      slices.Clone(sourcePeerID),
+		identity:    slices.Clone(expectedIdentity),
 	}:
 		p.engine.logger.Debug(
 			"enqueued sync request",

node/consensus/global/event_distributor.go

@@ -572,18 +572,18 @@ func (e *GlobalConsensusEngine) evaluateForProposals(
 				}
 			}
 
-			e.logger.Debug(
-				"appending descriptor for allocation planning",
-				zap.String("shard_key", hex.EncodeToString(bp)),
-				zap.Uint64("size", size.Uint64()),
-				zap.Int("ring", len(above)/8),
-				zap.Int("shard_count", int(shard.DataShards)),
-			)
-
 			if allocated && pending {
 				pendingFilters = append(pendingFilters, bp)
 			}
 			if !allocated {
+				e.logger.Debug(
+					"appending descriptor for allocation planning",
+					zap.String("shard_key", hex.EncodeToString(bp)),
+					zap.Uint64("size", size.Uint64()),
+					zap.Int("ring", len(above)/8),
+					zap.Int("shard_count", int(shard.DataShards)),
+				)
+
 				proposalDescriptors = append(
 					proposalDescriptors,
 					provers.ShardDescriptor{

node/consensus/global/global_consensus_engine.go

@@ -2806,6 +2806,7 @@ func (e *GlobalConsensusEngine) OnQuorumCertificateTriggeredRankChange(
 		e.syncProvider.AddState(
 			[]byte(peer),
 			current.Header.FrameNumber,
+			[]byte(current.Identity()),
 		)
 		return
 	}
@@ -2846,6 +2847,7 @@ func (e *GlobalConsensusEngine) OnQuorumCertificateTriggeredRankChange(
 		e.syncProvider.AddState(
 			[]byte(peerID),
 			current.Header.FrameNumber,
+			[]byte(current.Identity()),
 		)
 		return
 	}

node/consensus/global/message_processors.go

@@ -869,18 +869,27 @@ func (e *GlobalConsensusEngine) handleGlobalProposal(
 	finalized := e.forks.FinalizedState()
 	finalizedRank := finalized.Rank
 	finalizedFrameNumber := (*finalized.State).Header.FrameNumber
+	frameNumber := proposal.State.Header.FrameNumber
 
 	// drop proposals if we already processed them
-	if proposal.State.Header.FrameNumber <= finalizedFrameNumber ||
+	if frameNumber <= finalizedFrameNumber ||
 		proposal.State.Header.Rank <= finalizedRank {
 		e.logger.Debug("dropping stale proposal")
 		return
 	}
 
-	_, err := e.clockStore.GetGlobalClockFrame(proposal.State.Header.FrameNumber)
+	existingFrame, err := e.clockStore.GetGlobalClockFrame(frameNumber)
-	if err == nil {
+	if err == nil && existingFrame != nil {
-		e.logger.Debug("dropping stale proposal")
+		qc, qcErr := e.clockStore.GetQuorumCertificate(
-		return
+			nil,
+			proposal.State.GetRank(),
+		)
+		if qcErr == nil && qc != nil &&
+			qc.GetFrameNumber() == frameNumber &&
+			qc.Identity() == proposal.State.Identity() {
+			e.logger.Debug("dropping stale proposal")
+			return
+		}
 	}
 
 	// if we have a parent, cache and move on
@@ -915,12 +924,12 @@ func (e *GlobalConsensusEngine) handleGlobalProposal(
 			e.syncProvider.AddState(
 				[]byte(peerID),
 				head.Header.FrameNumber,
+				[]byte(head.Identity()),
 			)
 			return
 		}
 	}
 
-	frameNumber := proposal.State.Header.FrameNumber
 	expectedFrame, err := e.globalTimeReel.GetHead()
 	if err != nil {
 		e.logger.Error("could not obtain time reel head", zap.Error(err))
@@ -1021,7 +1030,14 @@ func (e *GlobalConsensusEngine) processProposal(
 	if prtc != nil {
 		signedProposal.PreviousRankTimeoutCertificate = prtc
 	}
-	e.voteAggregator.AddState(signedProposal)
+
+	// IMPORTANT: we do not want to send old proposals to the vote aggregator or
+	// we risk engine shutdown if the leader selection method changed – frame
+	// validation ensures that the proposer is valid for the proposal per time
+	// reel rules.
+	if signedProposal.State.Rank >= e.currentRank {
+		e.voteAggregator.AddState(signedProposal)
+	}
 	e.consensusParticipant.SubmitProposal(signedProposal)
 
 	e.trySealParentWithChild(proposal)
@@ -1732,7 +1748,7 @@ func (e *GlobalConsensusEngine) handleShardVote(message *pb.Message) {
 		voterPublicKey,
 		signatureData,
 		vote.PublicKeySignatureBls48581.Signature,
-		[]byte("appshard"),
+		slices.Concat([]byte("appshard"), vote.Filter),
 	)
 
 	if err != nil || !valid {

node/consensus/global/message_validation.go

@@ -83,7 +83,9 @@ func (e *GlobalConsensusEngine) validateGlobalConsensusMessage(
 			return tp2p.ValidationResultReject
 		}
 
-		if e.currentRank > vote.Rank {
+		// We should still accept votes for the past rank – either because a peer
+		// needs it, or because we need it to trump a TC
+		if e.currentRank > vote.Rank+1 {
 			e.logger.Debug("vote is stale")
 			return tp2p.ValidationResultIgnore
 		}
@@ -110,7 +112,8 @@ func (e *GlobalConsensusEngine) validateGlobalConsensusMessage(
 			return tp2p.ValidationResultReject
 		}
 
-		if e.currentRank > timeoutState.Vote.Rank {
+		// We should still accept votes for the past rank in case a peer needs it
+		if e.currentRank > timeoutState.Vote.Rank+1 {
 			e.logger.Debug("timeout is stale")
 			return tp2p.ValidationResultIgnore
 		}

node/consensus/validator/bls_app_shard_frame_validator.go

@@ -66,7 +66,11 @@ func (b *BLSAppFrameValidator) Validate(
 		}
 	}
 
-	bits, err := b.frameProver.VerifyFrameHeader(frame.Header, b.blsConstructor)
+	bits, err := b.frameProver.VerifyFrameHeader(
+		frame.Header,
+		b.blsConstructor,
+		nil,
+	)
 	isValid := err == nil
 
 	if !isValid {

node/consensus/voting/voting_aggregator.go

@@ -1,6 +1,8 @@
 package voting
 
 import (
+	"slices"
+
 	"github.com/gammazero/workerpool"
 	"github.com/pkg/errors"
 	"source.quilibrium.com/quilibrium/monorepo/consensus"
@@ -61,7 +63,7 @@ func NewAppShardVoteAggregator[PeerIDT models.Unique](
 		](
 			voteProcessorFactory.Create,
 		),
-		[]byte("appshard"),
+		slices.Concat([]byte("appshard"), filter),
 		signatureAggregator,
 		votingProvider,
 	)
@@ -119,7 +121,7 @@ func NewAppShardTimeoutAggregator[PeerIDT models.Unique](
 		committee,
 		validator,
 		votingProvider,
-		[]byte("appshardtimeout"),
+		slices.Concat([]byte("appshardtimeout"), filter),
 	)
 
 	timeoutCollectorFactory := timeoutcollector.NewTimeoutCollectorFactory(

node/execution/intrinsics/global/global_prover_kick.go

@@ -496,6 +496,7 @@ func (p *ProverKick) verifyEquivocation(kickedPublicKey []byte) bool {
 		valid, err := p.frameProver.VerifyFrameHeaderSignature(
 			frame1,
 			p.blsConstructor,
+			nil,
 		)
 		if !valid || err != nil {
 			return false
@@ -504,6 +505,7 @@ func (p *ProverKick) verifyEquivocation(kickedPublicKey []byte) bool {
 		valid, err = p.frameProver.VerifyFrameHeaderSignature(
 			frame2,
 			p.blsConstructor,
+			nil,
 		)
 		if !valid || err != nil {
 			return false

node/execution/intrinsics/global/global_prover_shard_update.go

@@ -103,11 +103,6 @@ func (p *ProverShardUpdate) Verify(frameNumber uint64) (bool, error) {
 		return false, errors.Wrap(errors.New("invalid update"), "verify")
 	}
 
-	_, err = p.frameProver.VerifyFrameHeader(p.FrameHeader, p.blsConstructor)
-	if err != nil {
-		return false, errors.Wrap(err, "verify")
-	}
-
 	return true, nil
 }
 
@@ -267,9 +262,20 @@ func (p *ProverShardUpdate) buildContext() (*shardUpdateContext, error) {
 		return nil, errors.New("frame header missing address")
 	}
 
+	info, err := p.proverRegistry.GetActiveProvers(p.FrameHeader.Address)
+	if err != nil {
+		return nil, errors.Wrap(err, "get active provers")
+	}
+
+	ids := [][]byte{}
+	for _, p := range info {
+		ids = append(ids, p.Address)
+	}
+
 	setIndices, err := p.frameProver.VerifyFrameHeader(
 		p.FrameHeader,
 		p.blsConstructor,
+		ids,
 	)
 	if err != nil {
 		return nil, errors.Wrap(err, "verify frame header")

types/crypto/frame_prover.go

@@ -26,10 +26,12 @@ type FrameProver interface {
 	VerifyFrameHeader(
 		frame *protobufs.FrameHeader,
 		bls BlsConstructor,
+		ids [][]byte,
 	) ([]uint8, error)
 	VerifyFrameHeaderSignature(
 		frame *protobufs.FrameHeader,
 		bls BlsConstructor,
+		ids [][]byte,
 	) (bool, error)
 	GetFrameSignaturePayload(
 		frame *protobufs.FrameHeader,

vdf/wesolowski_frame_prover.go

@@ -10,6 +10,8 @@ import (
 	"go.uber.org/zap"
 	"golang.org/x/crypto/sha3"
 
+	"source.quilibrium.com/quilibrium/monorepo/consensus/models"
+	"source.quilibrium.com/quilibrium/monorepo/consensus/verification"
 	"source.quilibrium.com/quilibrium/monorepo/protobufs"
 	qcrypto "source.quilibrium.com/quilibrium/monorepo/types/crypto"
 )
@@ -264,6 +266,7 @@ func (w *WesolowskiFrameProver) GetFrameSignaturePayload(
 func (w *WesolowskiFrameProver) VerifyFrameHeader(
 	frame *protobufs.FrameHeader,
 	bls qcrypto.BlsConstructor,
+	ids [][]byte,
 ) ([]uint8, error) {
 	if len(frame.Address) == 0 {
 		return nil, errors.Wrap(
@@ -329,7 +332,7 @@ func (w *WesolowskiFrameProver) VerifyFrameHeader(
 		return nil, nil
 	}
 
-	valid, err := w.VerifyFrameHeaderSignature(frame, bls)
+	valid, err := w.VerifyFrameHeaderSignature(frame, bls, ids)
 	if err != nil {
 		return nil, errors.Wrap(err, "verify frame header")
 	}
@@ -347,17 +350,23 @@ func (w *WesolowskiFrameProver) VerifyFrameHeader(
 func (w *WesolowskiFrameProver) VerifyFrameHeaderSignature(
 	frame *protobufs.FrameHeader,
 	bls qcrypto.BlsConstructor,
+	ids [][]byte,
 ) (bool, error) {
 	// Get the signature payload
-	signaturePayload, err := w.GetFrameSignaturePayload(frame)
+	selectorBI, err := poseidon.HashBytes(frame.Output)
 	if err != nil {
 		return false, errors.Wrap(err, "verify frame header signature")
 	}
+	signaturePayload := verification.MakeVoteMessage(
+		frame.Address,
+		frame.Rank,
+		models.Identity(selectorBI.FillBytes(make([]byte, 32))),
+	)
 
-	domain := append([]byte("shard"), frame.Address...)
+	domain := append([]byte("appshard"), frame.Address...)
 	if !bls.VerifySignatureRaw(
 		frame.PublicKeySignatureBls48581.PublicKey.KeyValue,
-		frame.PublicKeySignatureBls48581.Signature,
+		frame.PublicKeySignatureBls48581.Signature[:74],
 		signaturePayload,
 		domain,
 	) {
@@ -367,7 +376,45 @@ func (w *WesolowskiFrameProver) VerifyFrameHeaderSignature(
 		)
 	}
 
-	return true, nil
+	indices := GetSetBitIndices(frame.PublicKeySignatureBls48581.Bitmask)
+	if len(frame.PublicKeySignatureBls48581.Signature) == 74 &&
+		len(indices) != 1 {
+		return false, errors.Wrap(
+			errors.New("signature missing multiproof"),
+			"verify frame header signature",
+		)
+	}
+
+	if len(frame.PublicKeySignatureBls48581.Signature) == 74 && ids == nil {
+		return true, nil
+	}
+
+	buf := bytes.NewBuffer(frame.PublicKeySignatureBls48581.Signature[74:])
+
+	var multiproofCount uint32
+	if err := binary.Read(buf, binary.BigEndian, &multiproofCount); err != nil {
+		return false, errors.Wrap(err, "verify frame header signature")
+	}
+
+	multiproofs := [][516]byte{}
+	for i := uint32(0); i < multiproofCount; i++ {
+		multiproof := [516]byte{}
+		if _, err := buf.Read(multiproof[:]); err != nil {
+			return false, errors.Wrap(err, "verify frame header signature")
+		}
+		multiproofs = append(multiproofs, multiproof)
+	}
+
+	challenge := sha3.Sum256(frame.ParentSelector)
+
+	valid, err := w.VerifyMultiProof(
+		challenge,
+		frame.Difficulty,
+		ids,
+		multiproofs,
+	)
+
+	return valid, errors.Wrap(err, "verify frame header signature")
 }
 
 func (w *WesolowskiFrameProver) ProveGlobalFrameHeader(
@@ -576,10 +623,15 @@ func (w *WesolowskiFrameProver) VerifyGlobalHeaderSignature(
 	bls qcrypto.BlsConstructor,
 ) (bool, error) {
 	// Get the signature payload
-	signaturePayload, err := w.GetGlobalFrameSignaturePayload(frame)
+	selectorBI, err := poseidon.HashBytes(frame.Output)
 	if err != nil {
-		return false, errors.Wrap(err, "verify global frame header")
+		return false, errors.Wrap(err, "verify frame header signature")
 	}
+	signaturePayload := verification.MakeVoteMessage(
+		nil,
+		frame.Rank,
+		models.Identity(selectorBI.FillBytes(make([]byte, 32))),
+	)
 
 	if !bls.VerifySignatureRaw(
 		frame.PublicKeySignatureBls48581.PublicKey.KeyValue,