core: Change the lattice key from validatorID to chainID. (#83)

* Add chainID in simulation.Validator
* Change validatorid to chainID in rbModule

7 files changed, 210 insertions, 98 deletions

diff --git a/core/consensus.go b/core/consensus.go
index 6c841bf..d163686 100644
--- a/core/consensus.go
+++ b/core/consensus.go
@@ -79,6 +79,7 @@ func NewConsensus(
 
 	// Setup acking by information returned from Governace.
 	rb := newReliableBroadcast()
+	rb.setChainNum(len(validatorSet))
 	for vID := range validatorSet {
 		rb.addValidator(vID)
 	}
diff --git a/core/consensus_test.go b/core/consensus_test.go
index cd7ff02..46df8eb 100644
--- a/core/consensus_test.go
+++ b/core/consensus_test.go
@@ -36,10 +36,12 @@ type ConsensusTestSuite struct {
 
 func (s *ConsensusTestSuite) prepareGenesisBlock(
 	proposerID types.ValidatorID,
+	chainID uint64,
 	con *Consensus) *types.Block {
 
 	block := &types.Block{
 		ProposerID: proposerID,
+		ChainID:    chainID,
 	}
 	err := con.PrepareGenesisBlock(block, time.Now().UTC())
 	s.Require().Nil(err)
@@ -102,13 +104,13 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 		}
 	}
 	// Genesis blocks
-	b00 := s.prepareGenesisBlock(validators[0], objs[validators[0]].con)
+	b00 := s.prepareGenesisBlock(validators[0], 0, objs[validators[0]].con)
 	time.Sleep(minInterval)
-	b10 := s.prepareGenesisBlock(validators[1], objs[validators[1]].con)
+	b10 := s.prepareGenesisBlock(validators[1], 1, objs[validators[1]].con)
 	time.Sleep(minInterval)
-	b20 := s.prepareGenesisBlock(validators[2], objs[validators[2]].con)
+	b20 := s.prepareGenesisBlock(validators[2], 2, objs[validators[2]].con)
 	time.Sleep(minInterval)
-	b30 := s.prepareGenesisBlock(validators[3], objs[validators[3]].con)
+	b30 := s.prepareGenesisBlock(validators[3], 3, objs[validators[3]].con)
 	broadcast(b00)
 	broadcast(b10)
 	broadcast(b20)
@@ -117,6 +119,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b11 := &types.Block{
 		ProposerID: validators[1],
+		ChainID:    1,
 	}
 	b11.Hash, err = hashBlock(b11)
 	s.Require().Nil(err)
@@ -131,6 +134,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b01 := &types.Block{
 		ProposerID: validators[0],
+		ChainID:    0,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[0]].con.PrepareBlock(b01, time.Now().UTC()))
@@ -140,6 +144,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b21 := &types.Block{
 		ProposerID: validators[2],
+		ChainID:    2,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[2]].con.PrepareBlock(b21, time.Now().UTC()))
@@ -149,6 +154,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b31 := &types.Block{
 		ProposerID: validators[3],
+		ChainID:    3,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[3]].con.PrepareBlock(b31, time.Now().UTC()))
@@ -163,6 +169,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b02 := &types.Block{
 		ProposerID: validators[0],
+		ChainID:    0,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[0]].con.PrepareBlock(b02, time.Now().UTC()))
@@ -174,6 +181,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b12 := &types.Block{
 		ProposerID: validators[1],
+		ChainID:    1,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[1]].con.PrepareBlock(b12, time.Now().UTC()))
@@ -186,6 +194,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b22 := &types.Block{
 		ProposerID: validators[2],
+		ChainID:    2,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[2]].con.PrepareBlock(b22, time.Now().UTC()))
@@ -197,6 +206,7 @@ func (s *ConsensusTestSuite) TestSimpleDeliverBlock() {
 	time.Sleep(minInterval)
 	b32 := &types.Block{
 		ProposerID: validators[3],
+		ChainID:    3,
 		Hash:       common.NewRandomHash(),
 	}
 	req.Nil(objs[validators[3]].con.PrepareBlock(b32, time.Now().UTC()))
@@ -286,10 +296,10 @@ func (s *ConsensusTestSuite) TestPrepareBlock() {
 			con *Consensus
 		}{app, con}
 	}
-	b00 := s.prepareGenesisBlock(validators[0], objs[validators[0]].con)
-	b10 := s.prepareGenesisBlock(validators[1], objs[validators[1]].con)
-	b20 := s.prepareGenesisBlock(validators[2], objs[validators[2]].con)
-	b30 := s.prepareGenesisBlock(validators[3], objs[validators[3]].con)
+	b00 := s.prepareGenesisBlock(validators[0], 0, objs[validators[0]].con)
+	b10 := s.prepareGenesisBlock(validators[1], 1, objs[validators[1]].con)
+	b20 := s.prepareGenesisBlock(validators[2], 2, objs[validators[2]].con)
+	b30 := s.prepareGenesisBlock(validators[3], 3, objs[validators[3]].con)
 	for _, obj := range objs {
 		con := obj.con
 		req.Nil(con.ProcessBlock(b00))
diff --git a/core/reliable-broadcast.go b/core/reliable-broadcast.go
index d9a469a..918bad9 100644
--- a/core/reliable-broadcast.go
+++ b/core/reliable-broadcast.go
@@ -39,7 +39,7 @@ const (
 // reliableBroadcast is a module for reliable broadcast.
 type reliableBroadcast struct {
 	// lattice stores validator's blocks and other info.
-	lattice map[types.ValidatorID]*rbcValidatorStatus
+	lattice []*rbcValidatorStatus
 
 	// blockInfos stores block infos.
 	blockInfos map[common.Hash]*rbcBlockInfo
@@ -47,6 +47,9 @@ type reliableBroadcast struct {
 	// receivedBlocks stores blocks which is received but its acks are not all
 	// in lattice.
 	receivedBlocks map[common.Hash]*types.Block
+
+	// validators stores validator set.
+	validators map[types.ValidatorID]struct{}
 }
 
 type rbcValidatorStatus struct {
@@ -58,21 +61,22 @@ type rbcValidatorStatus struct {
 	// acked height + 1. Initialized to 0, when genesis blocks are still not
 	// being acked. For example, rb.lattice[vid1].NextAck[vid2] - 1 is the last
 	// acked height by vid1 acking vid2.
-	nextAck map[types.ValidatorID]uint64
+	nextAck []uint64
 
 	// nextOutput is the next output height of block, default to 0.
 	nextOutput uint64
 }
 
 type rbcBlockInfo struct {
-	block           *types.Block
-	receivedTime    time.Time
-	status          blockStatus
-	ackedValidators map[types.ValidatorID]struct{}
+	block        *types.Block
+	receivedTime time.Time
+	status       blockStatus
+	ackedChain   map[uint64]struct{}
 }
 
 // Errors for sanity check error.
 var (
+	ErrInvalidChainID     = fmt.Errorf("invalid chain id")
 	ErrInvalidProposerID  = fmt.Errorf("invalid proposer id")
 	ErrInvalidTimestamp   = fmt.Errorf("invalid timestamp")
 	ErrForkBlock          = fmt.Errorf("fork block")
@@ -85,20 +89,25 @@ var (
 // newReliableBroadcast creates a new reliableBroadcast struct.
 func newReliableBroadcast() *reliableBroadcast {
 	return &reliableBroadcast{
-		lattice:        make(map[types.ValidatorID]*rbcValidatorStatus),
 		blockInfos:     make(map[common.Hash]*rbcBlockInfo),
 		receivedBlocks: make(map[common.Hash]*types.Block),
+		validators:     make(map[types.ValidatorID]struct{}),
 	}
 }
 
 func (rb *reliableBroadcast) sanityCheck(b *types.Block) error {
+	// Check if the chain id is valid.
+	if b.ChainID >= uint64(len(rb.lattice)) {
+		return ErrInvalidChainID
+	}
+
 	// Check if its proposer is in validator set.
-	if _, exist := rb.lattice[b.ProposerID]; !exist {
+	if _, exist := rb.validators[b.ProposerID]; !exist {
 		return ErrInvalidProposerID
 	}
 
 	// Check if it forks.
-	if bInLattice, exist := rb.lattice[b.ProposerID].blocks[b.Height]; exist {
+	if bInLattice, exist := rb.lattice[b.ChainID].blocks[b.Height]; exist {
 		if b.Hash != bInLattice.Hash {
 			return ErrForkBlock
 		}
@@ -120,20 +129,24 @@ func (rb *reliableBroadcast) sanityCheck(b *types.Block) error {
 	for hash := range b.Acks {
 		if bAckStat, exist := rb.blockInfos[hash]; exist {
 			bAck := bAckStat.block
-			if bAck.Height < rb.lattice[b.ProposerID].nextAck[bAck.ProposerID] {
+			if bAck.Height < rb.lattice[b.ChainID].nextAck[bAck.ChainID] {
 				return ErrDoubleAck
 			}
 		}
 	}
 
-	// Check if its timestamp is valid.
-	for h := range rb.lattice {
-		if _, exist := b.Timestamps[h]; !exist {
-			return ErrInvalidTimestamp
+	// TODO(jimmy-dexon): verify the timestamps.
+	/*
+		// Check if its timestamp is valid.
+		for h := range rb.lattice {
+			if _, exist := b.Timestamps[h]; !exist {
+				return ErrInvalidTimestamp
+			}
 		}
-	}
-	if bParent, exist := rb.lattice[b.ProposerID].blocks[b.Height-1]; exist {
-		for hash := range rb.lattice {
+	*/
+
+	if bParent, exist := rb.lattice[b.ChainID].blocks[b.Height-1]; exist {
+		for hash := range b.Timestamps {
 			if b.Timestamps[hash].Before(bParent.Timestamps[hash]) {
 				return ErrInvalidTimestamp
 			}
@@ -154,7 +167,7 @@ func (rb *reliableBroadcast) areAllAcksInLattice(b *types.Block) bool {
 		}
 		bAck := bAckStat.block
 
-		bAckInLattice, exist := rb.lattice[bAck.ProposerID].blocks[bAck.Height]
+		bAckInLattice, exist := rb.lattice[bAck.ChainID].blocks[bAck.Height]
 		if !exist {
 			return false
 		}
@@ -173,9 +186,9 @@ func (rb *reliableBroadcast) processBlock(block *types.Block) (err error) {
 		return
 	}
 	rb.blockInfos[block.Hash] = &rbcBlockInfo{
-		block:           block,
-		receivedTime:    time.Now().UTC(),
-		ackedValidators: make(map[types.ValidatorID]struct{}),
+		block:        block,
+		receivedTime: time.Now().UTC(),
+		ackedChain:   make(map[uint64]struct{}),
 	}
 	rb.receivedBlocks[block.Hash] = block
 
@@ -206,28 +219,28 @@ func (rb *reliableBroadcast) processBlock(block *types.Block) (err error) {
 				continue
 				// TODO(mission): how to return for multiple errors?
 			}
-			rb.lattice[b.ProposerID].blocks[b.Height] = b
+			rb.lattice[b.ChainID].blocks[b.Height] = b
 			delete(rb.receivedBlocks, b.Hash)
 			for h := range b.Acks {
 				bAckStat := rb.blockInfos[h]
 				// Update nextAck only when bAckStat.block.Height + 1 is greater. A
 				// block might ack blocks proposed by same validator with different
 				// height.
-				if rb.lattice[b.ProposerID].nextAck[bAckStat.block.ProposerID] < bAckStat.block.Height+1 {
-					rb.lattice[b.ProposerID].nextAck[bAckStat.block.ProposerID] = bAckStat.block.Height + 1
+				if rb.lattice[b.ChainID].nextAck[bAckStat.block.ChainID] < bAckStat.block.Height+1 {
+					rb.lattice[b.ChainID].nextAck[bAckStat.block.ChainID] = bAckStat.block.Height + 1
 				}
-				// Update ackedValidators for each ack blocks and its parents.
+				// Update ackedChain for each ack blocks and its parents.
 				for {
-					if _, exist := bAckStat.ackedValidators[b.ProposerID]; exist {
+					if _, exist := bAckStat.ackedChain[b.ChainID]; exist {
 						break
 					}
 					if bAckStat.status > blockStatusInit {
 						break
 					}
-					bAckStat.ackedValidators[b.ProposerID] = struct{}{}
+					bAckStat.ackedChain[b.ChainID] = struct{}{}
 					// A block is strongly acked if it is acked by more than
 					// 2 * (maximum number of byzatine validators) unique validators.
-					if len(bAckStat.ackedValidators) > 2*((len(rb.lattice)-1)/3) {
+					if len(bAckStat.ackedChain) > 2*((len(rb.lattice)-1)/3) {
 						blocksToAcked[bAckStat.block.Hash] = bAckStat.block
 					}
 					if bAckStat.block.Height == 0 {
@@ -371,19 +384,19 @@ func (rb *reliableBroadcast) prepareBlock(block *types.Block) {
 	}
 	// Initial timestamps with current validator set.
 	times := make(map[types.ValidatorID]time.Time)
-	for vID := range rb.lattice {
+	for vID := range rb.validators {
 		times[vID] = time.Time{}
 	}
 	acks := make(map[common.Hash]struct{})
-	for vID := range rb.lattice {
+	for chainID := range rb.lattice {
 		// find height of the latest block for that validator.
 		var (
 			curBlock   *types.Block
-			nextHeight = rb.lattice[block.ProposerID].nextAck[vID]
+			nextHeight = rb.lattice[block.ChainID].nextAck[chainID]
 		)
 
 		for {
-			tmpBlock, exists := rb.lattice[vID].blocks[nextHeight]
+			tmpBlock, exists := rb.lattice[chainID].blocks[nextHeight]
 			if !exists {
 				break
 			}
@@ -395,7 +408,7 @@ func (rb *reliableBroadcast) prepareBlock(block *types.Block) {
 		}
 		acks[curBlock.Hash] = struct{}{}
 		accumulateTimestamps(times, curBlock)
-		if vID == block.ProposerID {
+		if uint64(chainID) == block.ChainID {
 			block.ParentHash = curBlock.Hash
 			block.Height = curBlock.Height + 1
 		}
@@ -407,17 +420,22 @@ func (rb *reliableBroadcast) prepareBlock(block *types.Block) {
 
 // addValidator adds validator in the validator set.
 func (rb *reliableBroadcast) addValidator(h types.ValidatorID) {
-	rb.lattice[h] = &rbcValidatorStatus{
-		blocks:     make(map[uint64]*types.Block),
-		nextAck:    make(map[types.ValidatorID]uint64),
-		nextOutput: 0,
-	}
+	rb.validators[h] = struct{}{}
 }
 
 // deleteValidator deletes validator in validator set.
 func (rb *reliableBroadcast) deleteValidator(h types.ValidatorID) {
-	for h := range rb.lattice {
-		delete(rb.lattice[h].nextAck, h)
+	delete(rb.validators, h)
+}
+
+// setChainNum set the number of chains.
+func (rb *reliableBroadcast) setChainNum(num int) {
+	rb.lattice = make([]*rbcValidatorStatus, num)
+	for i := range rb.lattice {
+		rb.lattice[i] = &rbcValidatorStatus{
+			blocks:     make(map[uint64]*types.Block),
+			nextAck:    make([]uint64, num),
+			nextOutput: 0,
+		}
 	}
-	delete(rb.lattice, h)
 }
diff --git a/core/reliable-broadcast_test.go b/core/reliable-broadcast_test.go
index 28edda7..0dcbb80 100644
--- a/core/reliable-broadcast_test.go
+++ b/core/reliable-broadcast_test.go
@@ -56,6 +56,12 @@ func (s *ReliableBroadcastTest) prepareGenesisBlock(
 		Acks:       make(map[common.Hash]struct{}),
 		Timestamps: genTimestamps(validatorIDs),
 	}
+	for i, vID := range validatorIDs {
+		if proposerID == vID {
+			b.ChainID = uint64(i)
+			break
+		}
+	}
 	for _, vID := range validatorIDs {
 		b.Timestamps[vID] = time.Time{}
 	}
@@ -94,6 +100,7 @@ func genTestCase1(s *ReliableBroadcastTest, rb *reliableBroadcast) []types.Valid
 		rb.addValidator(vid)
 		vids = append(vids, vid)
 	}
+	rb.setChainNum(len(vids))
 	// Add genesis blocks.
 	for _, vid := range vids {
 		b = s.prepareGenesisBlock(vid, vids)
@@ -101,13 +108,14 @@ func genTestCase1(s *ReliableBroadcastTest, rb *reliableBroadcast) []types.Valid
 	}
 
 	// Add block 0-1 which acks 0-0.
-	h = rb.lattice[vids[0]].blocks[0].Hash
+	h = rb.lattice[0].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: vids[0],
 		ParentHash: h,
 		Hash:       common.NewRandomHash(),
 		Timestamps: genTimestamps(vids),
 		Height:     1,
+		ChainID:    0,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 		},
@@ -116,33 +124,35 @@ func genTestCase1(s *ReliableBroadcastTest, rb *reliableBroadcast) []types.Valid
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
-	s.Require().NotNil(rb.lattice[vids[0]].blocks[1])
+	s.Require().NotNil(rb.lattice[0].blocks[1])
 
 	// Add block 0-2 which acks 0-1 and 1-0.
-	h = rb.lattice[vids[0]].blocks[1].Hash
+	h = rb.lattice[0].blocks[1].Hash
 	b = &types.Block{
 		ProposerID: vids[0],
 		ParentHash: h,
 		Height:     2,
+		ChainID:    0,
 		Timestamps: genTimestamps(vids),
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
-			rb.lattice[vids[1]].blocks[0].Hash: struct{}{},
+			rb.lattice[1].blocks[0].Hash: struct{}{},
 		},
 	}
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
-	s.Require().NotNil(rb.lattice[vids[0]].blocks[2])
+	s.Require().NotNil(rb.lattice[0].blocks[2])
 
 	// Add block 0-3 which acks 0-2.
-	h = rb.lattice[vids[0]].blocks[2].Hash
+	h = rb.lattice[0].blocks[2].Hash
 	b = &types.Block{
 		ProposerID: vids[0],
 		ParentHash: h,
 		Hash:       common.NewRandomHash(),
 		Timestamps: genTimestamps(vids),
 		Height:     3,
+		ChainID:    0,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 		},
@@ -150,16 +160,17 @@ func genTestCase1(s *ReliableBroadcastTest, rb *reliableBroadcast) []types.Valid
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
-	s.Require().NotNil(rb.lattice[vids[0]].blocks[3])
+	s.Require().NotNil(rb.lattice[0].blocks[3])
 
 	// Add block 3-1 which acks 3-0.
-	h = rb.lattice[vids[3]].blocks[0].Hash
+	h = rb.lattice[3].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: vids[3],
 		ParentHash: h,
 		Hash:       common.NewRandomHash(),
 		Timestamps: genTimestamps(vids),
 		Height:     1,
+		ChainID:    3,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 		},
@@ -167,7 +178,7 @@ func genTestCase1(s *ReliableBroadcastTest, rb *reliableBroadcast) []types.Valid
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
-	s.Require().NotNil(rb.lattice[vids[3]].blocks[0])
+	s.Require().NotNil(rb.lattice[3].blocks[0])
 
 	return vids
 }
@@ -195,6 +206,7 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 		ProposerID: vids[0],
 		ParentHash: common.NewRandomHash(),
 		Height:     10,
+		ChainID:    0,
 		Acks:       make(map[common.Hash]struct{}),
 	}
 	b.Hash, err = hashBlock(b)
@@ -208,8 +220,9 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 		ProposerID: vids[1],
 		ParentHash: common.NewRandomHash(),
 		Height:     1,
+		ChainID:    1,
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[2]].blocks[0].Hash: struct{}{},
+			rb.lattice[2].blocks[0].Hash: struct{}{},
 		},
 	}
 	b.Hash, err = hashBlock(b)
@@ -219,11 +232,12 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 	s.Require().Equal(ErrNotAckParent.Error(), err.Error())
 
 	// Non-genesis block which acks its parent but the height is invalid.
-	h = rb.lattice[vids[1]].blocks[0].Hash
+	h = rb.lattice[1].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: vids[1],
 		ParentHash: h,
 		Height:     2,
+		ChainID:    1,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 		},
@@ -235,7 +249,7 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 	s.Require().Equal(ErrInvalidBlockHeight.Error(), err.Error())
 
 	// Invalid proposer ID.
-	h = rb.lattice[vids[1]].blocks[0].Hash
+	h = rb.lattice[1].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: types.ValidatorID{Hash: common.NewRandomHash()},
 		ParentHash: h,
@@ -250,12 +264,30 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 	s.Require().NotNil(err)
 	s.Require().Equal(ErrInvalidProposerID.Error(), err.Error())
 
+	// Invalid chain ID.
+	h = rb.lattice[1].blocks[0].Hash
+	b = &types.Block{
+		ProposerID: vids[1],
+		ParentHash: h,
+		Height:     1,
+		ChainID:    100,
+		Acks: map[common.Hash]struct{}{
+			h: struct{}{},
+		},
+	}
+	b.Hash, err = hashBlock(b)
+	s.Require().Nil(err)
+	err = rb.sanityCheck(b)
+	s.Require().NotNil(err)
+	s.Require().Equal(ErrInvalidChainID.Error(), err.Error())
+
 	// Fork block.
-	h = rb.lattice[vids[0]].blocks[0].Hash
+	h = rb.lattice[0].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: vids[0],
 		ParentHash: h,
 		Height:     1,
+		ChainID:    0,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 		},
@@ -270,14 +302,15 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 	s.Require().Equal(ErrForkBlock.Error(), err.Error())
 
 	// Replicated ack.
-	h = rb.lattice[vids[0]].blocks[3].Hash
+	h = rb.lattice[0].blocks[3].Hash
 	b = &types.Block{
 		ProposerID: vids[0],
 		ParentHash: h,
 		Height:     4,
+		ChainID:    0,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
-			rb.lattice[vids[1]].blocks[0].Hash: struct{}{},
+			rb.lattice[1].blocks[0].Hash: struct{}{},
 		},
 	}
 	b.Hash, err = hashBlock(b)
@@ -287,11 +320,12 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 	s.Require().Equal(ErrDoubleAck.Error(), err.Error())
 
 	// Normal block.
-	h = rb.lattice[vids[1]].blocks[0].Hash
+	h = rb.lattice[1].blocks[0].Hash
 	b = &types.Block{
 		ProposerID: vids[1],
 		ParentHash: h,
 		Height:     1,
+		ChainID:    1,
 		Acks: map[common.Hash]struct{}{
 			h: struct{}{},
 			common.NewRandomHash(): struct{}{},
@@ -306,9 +340,8 @@ func (s *ReliableBroadcastTest) TestSanityCheck() {
 
 func (s *ReliableBroadcastTest) TestAreAllAcksInLattice() {
 	var b *types.Block
-	var vids []types.ValidatorID
 	rb := newReliableBroadcast()
-	vids = genTestCase1(s, rb)
+	genTestCase1(s, rb)
 
 	// Empty ack should get true, although won't pass sanity check.
 	b = &types.Block{
@@ -319,8 +352,8 @@ func (s *ReliableBroadcastTest) TestAreAllAcksInLattice() {
 	// Acks blocks in lattice
 	b = &types.Block{
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[0]].blocks[0].Hash: struct{}{},
-			rb.lattice[vids[0]].blocks[1].Hash: struct{}{},
+			rb.lattice[0].blocks[0].Hash: struct{}{},
+			rb.lattice[0].blocks[1].Hash: struct{}{},
 		},
 	}
 	s.Require().True(rb.areAllAcksInLattice(b))
@@ -343,29 +376,30 @@ func (s *ReliableBroadcastTest) TestStrongAck() {
 
 	// Check block 0-0 to 0-3 before adding 1-1 and 2-1.
 	for i := uint64(0); i < 4; i++ {
-		s.Require().Equal(blockStatusInit, rb.blockInfos[rb.lattice[vids[0]].blocks[i].Hash].status)
+		s.Require().Equal(blockStatusInit, rb.blockInfos[rb.lattice[0].blocks[i].Hash].status)
 	}
 
 	// Add block 1-1 which acks 1-0 and 0-2, and block 0-0 to 0-3 are still
 	// in blockStatusInit, because they are not strongly acked.
 	b = &types.Block{
 		ProposerID: vids[1],
-		ParentHash: rb.lattice[vids[1]].blocks[0].Hash,
+		ParentHash: rb.lattice[1].blocks[0].Hash,
 		Hash:       common.NewRandomHash(),
 		Height:     1,
+		ChainID:    1,
 		Timestamps: genTimestamps(vids),
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[0]].blocks[2].Hash: struct{}{},
-			rb.lattice[vids[1]].blocks[0].Hash: struct{}{},
+			rb.lattice[0].blocks[2].Hash: struct{}{},
+			rb.lattice[1].blocks[0].Hash: struct{}{},
 		},
 	}
 	var err error
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
-	s.Require().NotNil(rb.lattice[vids[1]].blocks[1])
+	s.Require().NotNil(rb.lattice[1].blocks[1])
 	for i := uint64(0); i < 4; i++ {
-		h := rb.lattice[vids[0]].blocks[i].Hash
+		h := rb.lattice[0].blocks[i].Hash
 		s.Require().Equal(blockStatusInit, rb.blockInfos[h].status)
 	}
 
@@ -373,23 +407,24 @@ func (s *ReliableBroadcastTest) TestStrongAck() {
 	// 0-3 is still not.
 	b = &types.Block{
 		ProposerID: vids[2],
-		ParentHash: rb.lattice[vids[2]].blocks[0].Hash,
+		ParentHash: rb.lattice[2].blocks[0].Hash,
 		Hash:       common.NewRandomHash(),
 		Height:     1,
+		ChainID:    2,
 		Timestamps: genTimestamps(vids),
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[0]].blocks[2].Hash: struct{}{},
-			rb.lattice[vids[2]].blocks[0].Hash: struct{}{},
+			rb.lattice[0].blocks[2].Hash: struct{}{},
+			rb.lattice[2].blocks[0].Hash: struct{}{},
 		},
 	}
 	b.Hash, err = hashBlock(b)
 	s.Require().Nil(err)
 	s.Require().Nil(rb.processBlock(b))
 
-	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[vids[0]].blocks[0].Hash].status)
-	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[vids[0]].blocks[1].Hash].status)
-	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[vids[0]].blocks[2].Hash].status)
-	s.Require().Equal(blockStatusInit, rb.blockInfos[rb.lattice[vids[0]].blocks[3].Hash].status)
+	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[0].blocks[0].Hash].status)
+	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[0].blocks[1].Hash].status)
+	s.Require().Equal(blockStatusAcked, rb.blockInfos[rb.lattice[0].blocks[2].Hash].status)
+	s.Require().Equal(blockStatusInit, rb.blockInfos[rb.lattice[0].blocks[3].Hash].status)
 }
 
 func (s *ReliableBroadcastTest) TestExtractBlocks() {
@@ -400,14 +435,15 @@ func (s *ReliableBroadcastTest) TestExtractBlocks() {
 	// Add block 1-1 which acks 1-0, 0-2, 3-0.
 	b = &types.Block{
 		ProposerID: vids[1],
-		ParentHash: rb.lattice[vids[1]].blocks[0].Hash,
+		ParentHash: rb.lattice[1].blocks[0].Hash,
 		Hash:       common.NewRandomHash(),
 		Height:     1,
+		ChainID:    1,
 		Timestamps: genTimestamps(vids),
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[0]].blocks[2].Hash: struct{}{},
-			rb.lattice[vids[1]].blocks[0].Hash: struct{}{},
-			rb.lattice[vids[3]].blocks[0].Hash: struct{}{},
+			rb.lattice[0].blocks[2].Hash: struct{}{},
+			rb.lattice[1].blocks[0].Hash: struct{}{},
+			rb.lattice[3].blocks[0].Hash: struct{}{},
 		},
 	}
 	var err error
@@ -418,14 +454,15 @@ func (s *ReliableBroadcastTest) TestExtractBlocks() {
 	// Add block 2-1 which acks 0-2, 2-0, 3-0.
 	b = &types.Block{
 		ProposerID: vids[2],
-		ParentHash: rb.lattice[vids[2]].blocks[0].Hash,
+		ParentHash: rb.lattice[2].blocks[0].Hash,
 		Hash:       common.NewRandomHash(),
 		Height:     1,
+		ChainID:    2,
 		Timestamps: genTimestamps(vids),
 		Acks: map[common.Hash]struct{}{
-			rb.lattice[vids[0]].blocks[2].Hash: struct{}{},
-			rb.lattice[vids[2]].blocks[0].Hash: struct{}{},
-			rb.lattice[vids[3]].blocks[0].Hash: struct{}{},
+			rb.lattice[0].blocks[2].Hash: struct{}{},
+			rb.lattice[2].blocks[0].Hash: struct{}{},
+			rb.lattice[3].blocks[0].Hash: struct{}{},
 		},
 	}
 	b.Hash, err = hashBlock(b)
@@ -433,9 +470,9 @@ func (s *ReliableBroadcastTest) TestExtractBlocks() {
 	s.Require().Nil(rb.processBlock(b))
 
 	hashes := []common.Hash{
-		rb.lattice[vids[0]].blocks[0].Hash,
-		rb.lattice[vids[0]].blocks[1].Hash,
-		rb.lattice[vids[3]].blocks[0].Hash,
+		rb.lattice[0].blocks[0].Hash,
+		rb.lattice[0].blocks[1].Hash,
+		rb.lattice[3].blocks[0].Hash,
 	}
 	hashExtracted := map[common.Hash]*types.Block{}
 	for _, b := range rb.extractBlocks() {
@@ -458,6 +495,7 @@ func (s *ReliableBroadcastTest) TestRandomIntensiveAcking() {
 	for _, vid := range vids {
 		rb.addValidator(vid)
 	}
+	rb.setChainNum(len(vids))
 	// Generate genesis blocks.
 	for _, vid := range vids {
 		b := s.prepareGenesisBlock(vid, vids)
@@ -466,13 +504,14 @@ func (s *ReliableBroadcastTest) TestRandomIntensiveAcking() {
 	}
 
 	for i := 0; i < 5000; i++ {
-		vid := vids[rand.Int()%len(vids)]
+		id := rand.Int() % len(vids)
+		vid := vids[id]
 		height := heights[vid]
 		heights[vid]++
-		parentHash := rb.lattice[vid].blocks[height-1].Hash
+		parentHash := rb.lattice[id].blocks[height-1].Hash
 		acks := map[common.Hash]struct{}{}
-		for _, vid2 := range vids {
-			if b, exist := rb.lattice[vid2].blocks[rb.lattice[vid].nextAck[vid2]]; exist {
+		for id2 := range vids {
+			if b, exist := rb.lattice[id2].blocks[rb.lattice[id].nextAck[id2]]; exist {
 				acks[b.Hash] = struct{}{}
 			}
 		}
@@ -480,6 +519,7 @@ func (s *ReliableBroadcastTest) TestRandomIntensiveAcking() {
 			ProposerID: vid,
 			ParentHash: parentHash,
 			Height:     height,
+			ChainID:    uint64(id),
 			Timestamps: genTimestamps(vids),
 			Acks:       acks,
 		}
@@ -526,6 +566,7 @@ func (s *ReliableBroadcastTest) TestRandomlyGeneratedBlocks() {
 	for i := 0; i < repeat; i++ {
 		validators := map[types.ValidatorID]struct{}{}
 		rb := newReliableBroadcast()
+		rb.setChainNum(validatorCount)
 		stronglyAckedHashes := common.Hashes{}
 		revealer.Reset()
 
@@ -580,6 +621,7 @@ func (s *ReliableBroadcastTest) TestPrepareBlock() {
 	for _, vID := range validators {
 		rb.addValidator(vID)
 	}
+	rb.setChainNum(len(validators))
 	// Setup genesis blocks.
 	b00 := s.prepareGenesisBlock(validators[0], validators)
 	time.Sleep(minInterval)
@@ -597,6 +639,7 @@ func (s *ReliableBroadcastTest) TestPrepareBlock() {
 	// prepareBlock.
 	b11 := &types.Block{
 		ProposerID: validators[1],
+		ChainID:    1,
 	}
 	rb.prepareBlock(b11)
 	var err error
@@ -620,6 +663,7 @@ func (s *ReliableBroadcastTest) TestPrepareBlock() {
 	// Propose/Process a block based on collected info.
 	b12 := &types.Block{
 		ProposerID: validators[1],
+		ChainID:    1,
 	}
 	rb.prepareBlock(b12)
 	b12.Hash, err = hashBlock(b12)
@@ -633,6 +677,7 @@ func (s *ReliableBroadcastTest) TestPrepareBlock() {
 	// get 4 blocks to ack.
 	b01 := &types.Block{
 		ProposerID: validators[0],
+		ChainID:    0,
 	}
 	rb.prepareBlock(b01)
 	b01.Hash, err = hashBlock(b01)
diff --git a/core/test/blocks-generator.go b/core/test/blocks-generator.go
index b05d08f..3485b77 100644
--- a/core/test/blocks-generator.go
+++ b/core/test/blocks-generator.go
@@ -163,6 +163,11 @@ func (vs *validatorSetStatus) proposeBlock(
 		Timestamps: ts,
 		// TODO(mission.liao): Generate timestamp.
 	}
+	for i, vID := range vs.validatorIDs {
+		if vID == proposerID {
+			newBlock.ChainID = uint64(i)
+		}
+	}
 	var err error
 	newBlock.Hash, err = vs.hashBlock(newBlock)
 	if err != nil {
diff --git a/integration_test/validator.go b/integration_test/validator.go
index 2cb7e43..60c6b1f 100644
--- a/integration_test/validator.go
+++ b/integration_test/validator.go
@@ -19,9 +19,11 @@ package integration
 
 import (
 	"fmt"
+	"sort"
 	"time"
 
 	"github.com/dexon-foundation/dexon-consensus-core/blockdb"
+	"github.com/dexon-foundation/dexon-consensus-core/common"
 	"github.com/dexon-foundation/dexon-consensus-core/core"
 	"github.com/dexon-foundation/dexon-consensus-core/core/test"
 	"github.com/dexon-foundation/dexon-consensus-core/core/types"
@@ -63,6 +65,7 @@ func NewReceiveBlockEvent(
 // Validator is designed to work with test.Scheduler.
 type Validator struct {
 	ID               types.ValidatorID
+	chainID          uint64
 	cons             *core.Consensus
 	gov              core.Governance
 	networkLatency   LatencyModel
@@ -79,8 +82,22 @@ func NewValidator(
 	networkLatency LatencyModel,
 	proposingLatency LatencyModel) *Validator {
 
+	hashes := make(common.Hashes, 0)
+	for vID := range gov.GetValidatorSet() {
+		hashes = append(hashes, vID.Hash)
+	}
+	sort.Sort(hashes)
+	chainID := uint64(0)
+	for i, hash := range hashes {
+		if hash == vID.Hash {
+			chainID = uint64(i)
+			break
+		}
+	}
+
 	return &Validator{
 		ID:               vID,
+		chainID:          chainID,
 		gov:              gov,
 		networkLatency:   networkLatency,
 		proposingLatency: proposingLatency,
@@ -106,7 +123,10 @@ func (v *Validator) Handle(e *test.Event) (events []*test.Event) {
 func (v *Validator) handleProposeBlock(when time.Time, piggyback interface{}) (
 	events []*test.Event, err error) {
 
-	b := &types.Block{ProposerID: v.ID}
+	b := &types.Block{
+		ProposerID: v.ID,
+		ChainID:    v.chainID,
+	}
 	defer types.RecycleBlock(b)
 	if err = v.cons.PrepareBlock(b, when); err != nil {
 		return
diff --git a/simulation/validator.go b/simulation/validator.go
index 24de155..302f3af 100644
--- a/simulation/validator.go
+++ b/simulation/validator.go
@@ -19,6 +19,7 @@ package simulation
 
 import (
 	"fmt"
+	"sort"
 	"time"
 
 	"github.com/dexon-foundation/dexon-consensus-core/blockdb"
@@ -41,6 +42,7 @@ type Validator struct {
 	isFinished chan struct{}
 
 	ID              types.ValidatorID
+	chainID         uint64
 	prvKey          crypto.PrivateKey
 	sigToPub        core.SigToPubFn
 	consensus       *core.Consensus
@@ -84,14 +86,24 @@ func (v *Validator) GetID() types.ValidatorID {
 func (v *Validator) Run() {
 	v.msgChannel = v.network.Join(v)
 
+	hashes := make(common.Hashes, 0, v.network.NumPeers())
 	for _, vID := range v.network.Endpoints() {
 		v.gov.addValidator(vID)
+		hashes = append(hashes, vID.Hash)
+	}
+	sort.Sort(hashes)
+	for i, hash := range hashes {
+		if hash == v.ID.Hash {
+			v.chainID = uint64(i)
+			break
+		}
 	}
 	v.consensus = core.NewConsensus(
 		v.app, v.gov, v.db, v.prvKey, v.sigToPub)
 
 	genesisBlock := &types.Block{
 		ProposerID: v.ID,
+		ChainID:    v.chainID,
 	}
 	err := v.consensus.PrepareGenesisBlock(genesisBlock, time.Now().UTC())
 	if err != nil {
@@ -188,6 +200,7 @@ ProposingBlockLoop:
 
 		block := &types.Block{
 			ProposerID: v.ID,
+			ChainID:    v.chainID,
 			Hash:       common.NewRandomHash(),
 		}
 		if err := v.consensus.PrepareBlock(block, time.Now().UTC()); err != nil {