Verify challenge based on aggregated commitments and public keys

consensus/consensus_leader.go

@@ -8,6 +8,7 @@ import (
 	"github.com/dedis/kyber/sign/schnorr"
 	"harmony-benchmark/blockchain"
 	"harmony-benchmark/crypto"
+	"harmony-benchmark/log"
 	"harmony-benchmark/p2p"
 	proto_consensus "harmony-benchmark/proto/consensus"
 	"time"
@@ -246,8 +247,15 @@ func getAggregatedKey(bitmap *crypto.Mask) []byte {
 }
 
 func getChallenge(aggCommitment, aggKey kyber.Point, message []byte) []byte {
-	crypto.Challenge(crypto.Ed25519Curve, aggCommitment, aggKey, message)
-	return make([]byte, 32)
+	challenge, err := crypto.Challenge(crypto.Ed25519Curve, aggCommitment, aggKey, message)
+	if err != nil {
+		log.Error("Failed to generate challenge")
+	}
+	bytes, err := challenge.MarshalBinary()
+	if err != nil {
+		log.Error("Failed to serialize challenge")
+	}
+	return bytes
 }
 
 // Processes the response message sent from validators

consensus/consensus_validator.go

@@ -243,15 +243,32 @@ func (consensus *Consensus) processChallengeMessage(payload []byte) {
 
 	// TODO: verify aggregated commitments with real schnor cosign verification
 
+	aggCommitment := crypto.Ed25519Curve.Point()
+	aggCommitment.UnmarshalBinary(aggreCommit[:32]) // TODO: figure out whether it's 33 bytes or 32 bytes
+	aggKey := crypto.Ed25519Curve.Point()
+	aggKey.UnmarshalBinary(aggreKey[:32])
+
+	reconstructedChallenge, err := crypto.Challenge(crypto.Ed25519Curve, aggCommitment, aggKey, payload[:36]) // Only consensus Id and block hash
+
+	if err != nil {
+		log.Error("Failed to reconstruct the challenge from commits and keys")
+		return
+	}
+
 	// For now, simply return the private key of this node.
-	challengeScalar := crypto.Ed25519Curve.Scalar()
-	err := challengeScalar.UnmarshalBinary(challenge)
+	receivedChallenge := crypto.Ed25519Curve.Scalar()
+	err = receivedChallenge.UnmarshalBinary(challenge)
 	if err != nil {
 		log.Error("Failed to deserialize challenge", "err", err)
 		return
 	}
 
-	response, err := crypto.Response(crypto.Ed25519Curve, consensus.priKey, consensus.secret, challengeScalar)
+	if !reconstructedChallenge.Equal(receivedChallenge) {
+		log.Error("The challenge doesn't match the commitments and keys")
+		return
+	}
+
+	response, err := crypto.Response(crypto.Ed25519Curve, consensus.priKey, consensus.secret, receivedChallenge)
 	if err != nil {
 		log.Error("Failed to generate response", "err", err)
 		return