allow empty signatures

internal/consensus/state.go

@@ -1317,9 +1317,11 @@ func (cs *State) createProposalBlock(ctx context.Context) (*types.Block, error)
 		// because votes are different.
 		_, blsKey := cs.privValidatorPubKey.(*bls12381.PubKey)
 		canBeAggregated := blsKey &&
-			cs.state.Validators.AllKeysHaveSameType() &&
-			!cs.isVoteExtensionsEnabled(cs.Height)
+			cs.state.Validators.AllKeysHaveSameType()
 		if canBeAggregated {
+			if cs.isVoteExtensionsEnabled(cs.Height) {
+				panic("Wanted to aggregate LastCommit, but VoteExtensions are enabled for height " + strconv.FormatInt(cs.Height, 10))
+			}
 			if !cs.isPBTSEnabled(cs.Height) {
 				panic("Wanted to aggregate LastCommit, but PBTS is not enabled for height " + strconv.FormatInt(cs.Height, 10))
 			}

types/block.go

@@ -686,9 +686,7 @@ func (cs CommitSig) ValidateBasic() error {
 			)
 		}
 		// NOTE: Timestamp validation is subtle and handled elsewhere.
-		if len(cs.Signature) == 0 {
-			return errors.New("signature is missing")
-		}
+		// NOTE: Signature can be empty when using BLS aggregation.
 		if len(cs.Signature) > MaxSignatureSize {
 			return fmt.Errorf("signature is too big (max: %d)", MaxSignatureSize)
 		}

types/vote_set.go

@@ -730,11 +730,7 @@ func (voteSet *VoteSet) MakeBLSCommit() *ExtendedCommit {
 	sigs := make([]ExtendedCommitSig, len(voteSet.votes))
 	for i, v := range voteSet.votes {
 		cSig := v.CommitSig()
-		if cSig.BlockIDFlag != BlockIDFlagAbsent {
-			cSig.Signature = []byte{0x00} // clear the signature
-		} else {
-			cSig.Signature = []byte{} // clear the signature
-		}
+		cSig.Signature = []byte{} // clear the signature
 		sig := ExtendedCommitSig{
 			CommitSig: cSig,
 		}