core/utils: Add Penalty checker and VerifyDKGComplaint (#393)

* Add Util for checking penalty

* Add VerifyDKGComplaints

* Fixup and rename

* Happy New Year!

1 files changed, 116 insertions, 0 deletions

diff --git a/core/utils/utils_test.go b/core/utils/utils_test.go
new file mode 100644
index 0000000..34336b3
--- /dev/null
+++ b/core/utils/utils_test.go
@@ -0,0 +1,116 @@
+// Copyright 2019 The dexon-consensus Authors
+// This file is part of the dexon-consensus library.
+//
+// The dexon-consensus library is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation, either version 3 of the License,
+// or (at your option) any later version.
+//
+// The dexon-consensus library is distributed in the hope that it will be
+// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
+// General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the dexon-consensus library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package utils
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+
+	"github.com/dexon-foundation/dexon-consensus/core/crypto"
+	"github.com/dexon-foundation/dexon-consensus/core/crypto/dkg"
+	"github.com/dexon-foundation/dexon-consensus/core/crypto/ecdsa"
+	"github.com/dexon-foundation/dexon-consensus/core/types"
+	typesDKG "github.com/dexon-foundation/dexon-consensus/core/types/dkg"
+)
+
+type UtilsTestSuite struct {
+	suite.Suite
+}
+
+func (s *UtilsTestSuite) TestVerifyDKGComplaint() {
+	signComplaint := func(prv crypto.PrivateKey, complaint *typesDKG.Complaint) {
+		var err error
+		complaint.Signature, err = prv.Sign(hashDKGComplaint(complaint))
+		s.Require().NoError(err)
+	}
+	prv1, err := ecdsa.NewPrivateKey()
+	s.Require().NoError(err)
+	nID1 := types.NewNodeID(prv1.PublicKey())
+
+	prv2, err := ecdsa.NewPrivateKey()
+	s.Require().NoError(err)
+	nID2 := types.NewNodeID(prv2.PublicKey())
+
+	prvShares, pubShares := dkg.NewPrivateKeyShares(3)
+	mpk := &typesDKG.MasterPublicKey{
+		ProposerID:      nID1,
+		DKGID:           typesDKG.NewID(nID1),
+		PublicKeyShares: *pubShares,
+	}
+	mpk.Signature, err = prv1.Sign(hashDKGMasterPublicKey(mpk))
+	s.Require().NoError(err)
+
+	// Valid NackComplaint.
+	complaint := &typesDKG.Complaint{
+		ProposerID: nID2,
+	}
+	signComplaint(prv2, complaint)
+	s.Require().True(complaint.IsNack())
+	ok, err := VerifyDKGComplaint(complaint, mpk)
+	s.Require().NoError(err)
+	s.True(ok)
+
+	// Correct privateShare.
+	prvShares.SetParticipants(dkg.IDs{typesDKG.NewID(nID1), typesDKG.NewID(nID2)})
+	share, exist := prvShares.Share(typesDKG.NewID(nID2))
+	s.Require().True(exist)
+	prvShare := &typesDKG.PrivateShare{
+		ProposerID:   nID1,
+		ReceiverID:   nID2,
+		PrivateShare: *share,
+	}
+	prvShare.Signature, err = prv1.Sign(hashDKGPrivateShare(prvShare))
+	s.Require().NoError(err)
+	complaint.PrivateShare = *prvShare
+	signComplaint(prv2, complaint)
+	ok, err = VerifyDKGComplaint(complaint, mpk)
+	s.Require().NoError(err)
+	s.True(ok)
+
+	// Incorrect privateShare.
+	share, exist = prvShares.Share(typesDKG.NewID(nID1))
+	s.Require().True(exist)
+	prvShare.PrivateShare = *share
+	prvShare.Signature, err = prv1.Sign(hashDKGPrivateShare(prvShare))
+	s.Require().NoError(err)
+	complaint.PrivateShare = *prvShare
+	signComplaint(prv2, complaint)
+	ok, err = VerifyDKGComplaint(complaint, mpk)
+	s.Require().NoError(err)
+	s.False(ok)
+
+	// MPK is incorrect.
+	mpk.Round++
+	ok, err = VerifyDKGComplaint(complaint, mpk)
+	s.Require().NoError(err)
+	s.False(ok)
+
+	// MPK's proposer not match with prvShares'.
+	mpk.Round--
+	mpk.ProposerID = nID2
+	mpk.Signature, err = prv1.Sign(hashDKGMasterPublicKey(mpk))
+	s.Require().NoError(err)
+	ok, err = VerifyDKGComplaint(complaint, mpk)
+	s.Require().NoError(err)
+	s.False(ok)
+}
+
+func TestUtils(t *testing.T) {
+	suite.Run(t, new(UtilsTestSuite))
+}