diff --git a/configr/main.go b/configr/main.go
index a24c16220..da3d9ce06 100644
--- a/configr/main.go
+++ b/configr/main.go
@@ -112,11 +112,11 @@ func (configr *Configr) GetShardID(ip, port string) string {
 	return "N/A"
 }
 
-// GetPeers Gets the peer list of the node corresponding to this ip and port
+// GetPeers Gets the validator list
 func (configr *Configr) GetPeers(ip, port, shardID string) []p2p.Peer {
 	var peerList []p2p.Peer
 	for _, entry := range configr.config {
-		if entry.Role != "validator" || entry.IP == ip && entry.Port == port || entry.ShardID != shardID {
+		if entry.Role != "validator" || entry.ShardID != shardID {
 			continue
 		}
 		// Get public key deterministically based on ip and port
diff --git a/consensus/consensus.go b/consensus/consensus.go
index 4a589ddc8..832f48a9c 100644
--- a/consensus/consensus.go
+++ b/consensus/consensus.go
@@ -23,6 +23,9 @@ type Consensus struct {
 	commitments          map[uint16]kyber.Point
 	aggregatedCommitment kyber.Point
 
+	// Challenges
+	challenge [32]byte
+
 	// Commits collected from validators.
 	bitmap *crypto.Mask
 	// Responses collected from validators
@@ -31,6 +34,9 @@ type Consensus struct {
 	validators map[uint16]p2p.Peer
 	// Leader
 	leader p2p.Peer
+	// Public keys of the committee including leader and validators
+	publicKeys []kyber.Point
+
 	// private/public keys of current node
 	priKey kyber.Scalar
 	pubKey kyber.Point
@@ -101,15 +107,16 @@ func NewConsensus(ip, port, ShardID string, peers []p2p.Peer, leader p2p.Peer) *
 	}
 
 	// Initialize cosign bitmap
-	allPublics := make([]kyber.Point, 0)
+	allPublicKeys := make([]kyber.Point, 0)
 	for _, validatorPeer := range consensus.validators {
-		allPublics = append(allPublics, validatorPeer.PubKey)
+		allPublicKeys = append(allPublicKeys, validatorPeer.PubKey)
 	}
-	allPublics = append(allPublics, leader.PubKey)
-	mask, err := crypto.NewMask(crypto.Ed25519Curve, allPublics, consensus.leader.PubKey)
+	allPublicKeys = append(allPublicKeys, leader.PubKey)
+	mask, err := crypto.NewMask(crypto.Ed25519Curve, allPublicKeys, consensus.leader.PubKey)
 	if err != nil {
 		panic("Failed to create commitment mask")
 	}
+	consensus.publicKeys = allPublicKeys
 	consensus.bitmap = mask
 
 	// For now use socket address as 16 byte Id
diff --git a/consensus/consensus_leader.go b/consensus/consensus_leader.go
index 9b32a4d85..b9c6efd99 100644
--- a/consensus/consensus_leader.go
+++ b/consensus/consensus_leader.go
@@ -152,11 +152,24 @@ func (consensus *Consensus) processCommitMessage(payload []byte) {
 		return
 	}
 
-	if len(consensus.commitments) >= (2*(len(consensus.validators)+1))/3+1 && consensus.state < CHALLENGE_DONE {
-		consensus.Log.Debug("Enough commitments received with signatures", "numOfSignatures", len(consensus.commitments))
+	if len(consensus.commitments) >= len(consensus.validators)+1 && consensus.state < CHALLENGE_DONE {
+		consensus.Log.Debug("Enough commitments received with signatures", "num", len(consensus.commitments))
 
 		// Broadcast challenge
 		msgToSend := consensus.constructChallengeMessage(proto_consensus.CHALLENGE)
+
+		// Add leader's response
+		challengeScalar := crypto.Ed25519Curve.Scalar()
+		challengeScalar.UnmarshalBinary(consensus.challenge[:])
+		response, err := crypto.Response(crypto.Ed25519Curve, consensus.priKey, consensus.secret, challengeScalar)
+		if err == nil {
+			consensus.responses[consensus.nodeId] = response
+			consensus.bitmap.SetKey(consensus.pubKey, true)
+		} else {
+			log.Warn("Failed to generate response", "err", err)
+		}
+
+		// Broadcast challenge message
 		p2p.BroadcastMessage(consensus.getValidatorPeers(), msgToSend)
 
 		// Set state to CHALLENGE_DONE
@@ -230,20 +243,22 @@ func (consensus *Consensus) processResponseMessage(payload []byte) {
 	}
 
 	//consensus.Log.Debug("RECEIVED RESPONSE", "consensusId", consensusId)
-	if len(consensus.responses) >= (2*len(consensus.validators))/3+1 && consensus.state != FINISHED {
+	if len(consensus.responses) >= len(consensus.validators)+1 && consensus.state != FINISHED {
 		consensus.mutex.Lock()
-		if len(consensus.responses) >= (2*len(consensus.validators))/3+1 && consensus.state != FINISHED {
+		if len(consensus.responses) >= len(consensus.validators)+1 && consensus.state != FINISHED {
+			consensus.Log.Debug("Enough responses received with signatures", "num", len(consensus.responses))
 			// Aggregate responses
-			responses := make([]kyber.Scalar, 0)
+			responses := []kyber.Scalar{}
 			for _, val := range consensus.responses {
 				responses = append(responses, val)
 			}
-			aggResponse, err := crypto.AggregateResponses(crypto.Ed25519Curve, responses)
+
+			aggregatedResponse, err := crypto.AggregateResponses(crypto.Ed25519Curve, responses)
 			if err != nil {
 				log.Error("Failed to aggregate responses")
 				return
 			}
-			collectiveSigAndBitmap, err := crypto.Sign(crypto.Ed25519Curve, consensus.aggregatedCommitment, aggResponse, consensus.bitmap)
+			collectiveSigAndBitmap, err := crypto.Sign(crypto.Ed25519Curve, consensus.aggregatedCommitment, aggregatedResponse, consensus.bitmap)
 
 			if err != nil {
 				log.Error("Failed to create collective signature")
diff --git a/consensus/consensus_leader_msg.go b/consensus/consensus_leader_msg.go
index b31e91d77..f71f74880 100644
--- a/consensus/consensus_leader_msg.go
+++ b/consensus/consensus_leader_msg.go
@@ -65,7 +65,9 @@ func (consensus *Consensus) constructChallengeMessage(msgType proto_consensus.Me
 	buffer.Write(getAggregatedKey(consensus.bitmap))
 
 	// 32 byte challenge
-	buffer.Write(getChallenge(aggCommitment, consensus.bitmap.AggregatePublic, buffer.Bytes()[:36])) // message contains consensus id and block hash for now.
+	challenge := getChallenge(aggCommitment, consensus.bitmap.AggregatePublic, buffer.Bytes()[:36])
+	buffer.Write(challenge) // message contains consensus id and block hash for now.
+	copy(consensus.challenge[:], challenge)
 	consensus.aggregatedCommitment = aggCommitment
 
 	// 64 byte of signature on previous data
diff --git a/consensus/consensus_validator.go b/consensus/consensus_validator.go
index 142611b82..047eeb0ef 100644
--- a/consensus/consensus_validator.go
+++ b/consensus/consensus_validator.go
@@ -32,6 +32,8 @@ func (consensus *Consensus) ProcessMessageValidator(message []byte) {
 		consensus.processAnnounceMessage(payload)
 	case proto_consensus.CHALLENGE:
 		consensus.processChallengeMessage(payload)
+	case proto_consensus.COLLECTIVE_SIG:
+		consensus.processCollectiveSigMessage(payload)
 	default:
 		consensus.Log.Error("Unexpected message type", "msgType", msgType, "consensus", consensus)
 	}
@@ -230,7 +232,7 @@ func (consensus *Consensus) processChallengeMessage(payload []byte) {
 
 	response, err := crypto.Response(crypto.Ed25519Curve, consensus.priKey, consensus.secret, receivedChallenge)
 	if err != nil {
-		log.Info("Failed to generate response", "err", err)
+		log.Warn("Failed to generate response", "err", err)
 		return
 	}
 	msgToSend := consensus.constructResponseMessage(proto_consensus.RESPONSE, response)
@@ -275,3 +277,83 @@ func (consensus *Consensus) processChallengeMessage(payload []byte) {
 	}
 	consensus.mutex.Unlock()
 }
+
+// Processes the collective signature message sent from the leader
+func (consensus *Consensus) processCollectiveSigMessage(payload []byte) {
+	//#### Read payload data
+	offset := 0
+	// 4 byte consensus id
+	consensusId := binary.BigEndian.Uint32(payload[offset : offset+4])
+	offset += 4
+
+	// 32 byte block hash
+	blockHash := payload[offset : offset+32]
+	offset += 32
+
+	// 2 byte leader id
+	leaderId := binary.BigEndian.Uint16(payload[offset : offset+2])
+	offset += 2
+
+	// 64 byte of collective signature
+	collectiveSig := payload[offset : offset+64]
+	offset += 64
+
+	// N byte of bitmap
+	n := len(payload) - offset - 64 // the number means 64 signature
+	bitmap := payload[offset : offset+n]
+	offset += n
+
+	// 64 byte of signature on previous data
+	signature := payload[offset : offset+64]
+	offset += 64
+	//#### END: Read payload data
+
+	copy(consensus.blockHash[:], blockHash[:])
+
+	// Verify block data
+	// check leader Id
+	myLeaderId := utils.GetUniqueIdFromPeer(consensus.leader)
+	if leaderId != myLeaderId {
+		consensus.Log.Warn("Received message from wrong leader", "myLeaderId", myLeaderId, "receivedLeaderId", leaderId, "consensus", consensus)
+		return
+	}
+
+	// Verify signature
+	if schnorr.Verify(crypto.Ed25519Curve, consensus.leader.PubKey, payload[:offset-64], signature) != nil {
+		consensus.Log.Warn("Received message with invalid signature", "leaderKey", consensus.leader.PubKey, "consensus", consensus)
+		return
+	}
+
+	// Verify collective signature
+	err := crypto.Verify(crypto.Ed25519Curve, consensus.publicKeys, payload[:36], append(collectiveSig, bitmap...), crypto.NewThresholdPolicy(len(consensus.publicKeys)/2))
+	if err != nil {
+		consensus.Log.Warn("Failed to verify the collective sig message", "consensusId", consensusId, "err", err)
+	}
+
+	// Add attack model of IncorrectResponse.
+	if attack.GetInstance().IncorrectResponse() {
+		consensus.Log.Warn("IncorrectResponse attacked")
+		return
+	}
+
+	// check consensus Id
+	if consensusId != consensus.consensusId {
+		consensus.Log.Warn("Received message with wrong consensus Id", "myConsensusId", consensus.consensusId, "theirConsensusId", consensusId, "consensus", consensus)
+		return
+	}
+
+	// check block hash
+	if bytes.Compare(blockHash[:], consensus.blockHash[:]) != 0 {
+		consensus.Log.Warn("Block hash doesn't match", "consensus", consensus)
+		return
+	}
+
+	secret, msgToSend := consensus.constructCommitMessage(proto_consensus.FINAL_COMMIT)
+	// Store the commitment secret
+	consensus.secret = secret
+
+	p2p.SendMessage(consensus.leader, msgToSend)
+
+	// Set state to COMMIT_DONE
+	consensus.state = FINAL_COMMIT_DONE
+}
diff --git a/utils/distribution_config.go b/utils/distribution_config.go
index f16c6ec9e..4c9405c13 100644
--- a/utils/distribution_config.go
+++ b/utils/distribution_config.go
@@ -116,11 +116,11 @@ func (config *DistributionConfig) GetShardID(ip, port string) string {
 	return "N/A"
 }
 
-// GetPeers Gets the peer list of the node corresponding to this ip and port
+// GetPeers Gets the validator list
 func (config *DistributionConfig) GetPeers(ip, port, shardID string) []p2p.Peer {
 	var peerList []p2p.Peer
 	for _, entry := range config.config {
-		if entry.Role != "validator" || entry.IP == ip && entry.Port == port || entry.ShardID != shardID {
+		if entry.Role != "validator" || entry.ShardID != shardID {
 			continue
 		}
 		// Get public key deterministically based on ip and port