core: Nack Complaint (#116)

2 files changed, 83 insertions, 11 deletions

diff --git a/core/dkg-tsig-protocol.go b/core/dkg-tsig-protocol.go
index c549ecb..2db18f1 100644
--- a/core/dkg-tsig-protocol.go
+++ b/core/dkg-tsig-protocol.go
@@ -67,6 +67,7 @@ type dkgProtocol struct {
 	mpkMap             map[types.ValidatorID]*dkg.PublicKeyShares
 	masterPrivateShare *dkg.PrivateKeyShares
 	prvShares          *dkg.PrivateKeyShares
+	prvSharesReceived  map[types.ValidatorID]struct{}
 }
 
 type dkgShareSecret struct {
@@ -119,6 +120,7 @@ func newDKGProtocol(
 		mpkMap:             make(map[types.ValidatorID]*dkg.PublicKeyShares),
 		masterPrivateShare: prvShare,
 		prvShares:          dkg.NewEmptyPrivateKeyShares(),
+		prvSharesReceived:  make(map[types.ValidatorID]struct{}),
 	}
 }
 
@@ -126,6 +128,7 @@ func (d *dkgProtocol) processMasterPublicKeys(
 	mpks []*types.DKGMasterPublicKey) error {
 	d.idMap = make(map[types.ValidatorID]dkg.ID, len(mpks))
 	d.mpkMap = make(map[types.ValidatorID]*dkg.PublicKeyShares, len(mpks))
+	d.prvSharesReceived = make(map[types.ValidatorID]struct{}, len(mpks))
 	ids := make(dkg.IDs, len(mpks))
 	for i := range mpks {
 		vID := mpks[i].ProposerID
@@ -148,6 +151,22 @@ func (d *dkgProtocol) processMasterPublicKeys(
 	return nil
 }
 
+func (d *dkgProtocol) proposeNackComplaints() {
+	for vID := range d.mpkMap {
+		if _, exist := d.prvSharesReceived[vID]; exist {
+			continue
+		}
+		d.recv.ProposeDKGComplaint(&types.DKGComplaint{
+			ProposerID: d.ID,
+			Round:      d.round,
+			PrivateShare: types.DKGPrivateShare{
+				ProposerID: vID,
+				Round:      d.round,
+			},
+		})
+	}
+}
+
 func (d *dkgProtocol) sanityCheck(prvShare *types.DKGPrivateShare) error {
 	if _, exist := d.idMap[prvShare.ProposerID]; !exist {
 		return ErrNotDKGParticipant
@@ -180,6 +199,7 @@ func (d *dkgProtocol) processPrivateShare(
 	if err != nil {
 		return err
 	}
+	d.prvSharesReceived[prvShare.ProposerID] = struct{}{}
 	if !ok {
 		complaint := &types.DKGComplaint{
 			ProposerID:   d.ID,
diff --git a/core/dkg-tsig-protocol_test.go b/core/dkg-tsig-protocol_test.go
index f1c0017..1ea65b2 100644
--- a/core/dkg-tsig-protocol_test.go
+++ b/core/dkg-tsig-protocol_test.go
@@ -60,7 +60,7 @@ func (r *testDKGReceiver) ProposeDKGComplaint(complaint *types.DKGComplaint) {
 	var err error
 	complaint.Signature, err = r.prvKey.Sign(hashDKGComplaint(complaint))
 	r.s.Require().NoError(err)
-	r.complaints[complaint.ProposerID] = complaint
+	r.complaints[complaint.PrivateShare.ProposerID] = complaint
 }
 
 func (r *testDKGReceiver) ProposeDKGMasterPublicKey(
@@ -95,16 +95,8 @@ func (s *DKGTSIGProtocolTestSuite) setupDKGParticipants(n int) {
 	}
 }
 
-// TestDKGTSIGProtocol will test the entire DKG+TISG protocol including
-// exchanging private shares, recovering share secret, creating partial sign and
-// recovering threshold signature.
-// All participants are good people in this test.
-func (s *DKGTSIGProtocolTestSuite) TestDKGTSIGProtocol() {
-	k := 3
-	n := 10
-	round := uint64(1)
-	gov, err := test.NewGovernance(5, 100)
-	s.Require().NoError(err)
+func (s *DKGTSIGProtocolTestSuite) newProtocols(k, n int, round uint64) (
+	map[types.ValidatorID]*testDKGReceiver, map[types.ValidatorID]*dkgProtocol) {
 	s.setupDKGParticipants(n)
 
 	receivers := make(map[types.ValidatorID]*testDKGReceiver, n)
@@ -120,6 +112,21 @@ func (s *DKGTSIGProtocolTestSuite) TestDKGTSIGProtocol() {
 		)
 		s.Require().NotNil(receivers[vID].mpk)
 	}
+	return receivers, protocols
+}
+
+// TestDKGTSIGProtocol will test the entire DKG+TISG protocol including
+// exchanging private shares, recovering share secret, creating partial sign and
+// recovering threshold signature.
+// All participants are good people in this test.
+func (s *DKGTSIGProtocolTestSuite) TestDKGTSIGProtocol() {
+	k := 3
+	n := 10
+	round := uint64(1)
+	gov, err := test.NewGovernance(5, 100)
+	s.Require().NoError(err)
+
+	receivers, protocols := s.newProtocols(k, n, round)
 
 	for _, receiver := range receivers {
 		gov.AddDKGMasterPublicKey(receiver.mpk)
@@ -137,6 +144,10 @@ func (s *DKGTSIGProtocolTestSuite) TestDKGTSIGProtocol() {
 		}
 	}
 
+	for _, protocol := range protocols {
+		protocol.proposeNackComplaints()
+	}
+
 	for _, recv := range receivers {
 		s.Require().Len(recv.complaints, 0)
 	}
@@ -186,6 +197,47 @@ func (s *DKGTSIGProtocolTestSuite) TestDKGTSIGProtocol() {
 	s.True(gpk.verifySignature(msgHash, sig))
 }
 
+func (s *DKGTSIGProtocolTestSuite) TestNackComplaint() {
+	k := 3
+	n := 10
+	round := uint64(1)
+	gov, err := test.NewGovernance(5, 100)
+	s.Require().NoError(err)
+
+	receivers, protocols := s.newProtocols(k, n, round)
+
+	byzantineID := s.vIDs[0]
+
+	for _, receiver := range receivers {
+		gov.AddDKGMasterPublicKey(receiver.mpk)
+	}
+
+	for _, protocol := range protocols {
+		s.Require().NoError(
+			protocol.processMasterPublicKeys(gov.DKGMasterPublicKeys(round)))
+	}
+
+	for senderID, receiver := range receivers {
+		s.Require().Len(receiver.prvShare, n)
+		if senderID == byzantineID {
+			continue
+		}
+		for vID, prvShare := range receiver.prvShare {
+			s.Require().NoError(protocols[vID].processPrivateShare(prvShare))
+		}
+	}
+
+	for _, protocol := range protocols {
+		protocol.proposeNackComplaints()
+	}
+
+	for _, recv := range receivers {
+		complaint, exist := recv.complaints[byzantineID]
+		s.Require().True(exist)
+		s.True(verifyDKGComplaintSignature(complaint, eth.SigToPub))
+	}
+}
+
 func TestDKGTSIGProtocol(t *testing.T) {
 	suite.Run(t, new(DKGTSIGProtocolTestSuite))
 }