5 files changed, 43 insertions, 13 deletions
diff --git a/core/consensus.go b/core/consensus.go
index b1b1973..c8b10a0 100644
--- a/core/consensus.go
+++ b/core/consensus.go
@@ -25,8 +25,13 @@ import (
 	"github.com/dexon-foundation/dexon-consensus-core/blockdb"
 	"github.com/dexon-foundation/dexon-consensus-core/common"
 	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+	"github.com/dexon-foundation/dexon-consensus-core/crypto"
 )
 
+// SigToPubFn is a function to recover public key from signature.
+type SigToPubFn func(hash common.Hash, signature crypto.Signature) (
+	crypto.PublicKey, error)
+
 // ErrMissingBlockInfo would be reported if some information is missing when
 // calling PrepareBlock. It implements error interface.
 type ErrMissingBlockInfo struct {
@@ -39,7 +44,8 @@ func (e *ErrMissingBlockInfo) Error() string {
 
 // Errors for sanity check error.
 var (
-	ErrIncorrectHash = fmt.Errorf("hash of block is incorrect")
+	ErrIncorrectHash      = fmt.Errorf("hash of block is incorrect")
+	ErrIncorrectSignature = fmt.Errorf("signature of block is incorrect")
 )
 
 // Consensus implements DEXON Consensus algorithm.
@@ -50,6 +56,8 @@ type Consensus struct {
 	toModule *totalOrdering
 	ctModule *consensusTimestamp
 	db       blockdb.BlockDatabase
+	prvKey   crypto.PrivateKey
+	sigToPub SigToPubFn
 	lock     sync.RWMutex
 }
 
@@ -57,7 +65,9 @@ type Consensus struct {
 func NewConsensus(
 	app Application,
 	gov Governance,
-	db blockdb.BlockDatabase) *Consensus {
+	db blockdb.BlockDatabase,
+	prv crypto.PrivateKey,
+	sigToPub SigToPubFn) *Consensus {
 	validatorSet := gov.GetValidatorSet()
 
 	// Setup acking by information returned from Governace.
@@ -79,6 +89,8 @@ func NewConsensus(
 		app:      app,
 		gov:      gov,
 		db:       db,
+		prvKey:   prv,
+		sigToPub: sigToPub,
 	}
 }
 
@@ -91,6 +103,18 @@ func (con *Consensus) sanityCheck(blockConv types.BlockConverter) (err error) {
 		return ErrIncorrectHash
 	}
 
+	/* Disable these check before the implmentation of the signature for
+	 * genesis block is finished.
+	// Check the signer.
+	pubKey, err := con.sigToPub(b.Hash, b.Signature)
+	if err != nil {
+		return err
+	}
+	if !b.ProposerID.Equal(crypto.Keccak256Hash(pubKey.Bytes())) {
+		return ErrIncorrectSignature
+	}
+	*/
+
 	return nil
 }
 
@@ -166,6 +190,13 @@ func (con *Consensus) PrepareBlock(blockConv types.BlockConverter,
 	con.rbModule.prepareBlock(b)
 	b.Timestamps[b.ProposerID] = proposeTime
 	b.Hash, err = hashBlock(b)
+	if err != nil {
+		return
+	}
+	b.Signature, err = con.prvKey.Sign(b.Hash)
+	if err != nil {
+		return
+	}
 	blockConv.SetBlock(b)
 	return
 }
diff --git a/core/consensus_test.go b/core/consensus_test.go
index c26e7e8..522c566 100644
--- a/core/consensus_test.go
+++ b/core/consensus_test.go
@@ -26,6 +26,7 @@ import (
 	"github.com/dexon-foundation/dexon-consensus-core/common"
 	"github.com/dexon-foundation/dexon-consensus-core/core/test"
 	"github.com/dexon-foundation/dexon-consensus-core/core/types"
+	"github.com/dexon-foundation/dexon-consensus-core/crypto/eth"
 	"github.com/stretchr/testify/suite"
 )
 
@@ -60,7 +61,9 @@ func (s *ConsensusTestSuite) prepareConsensus(gov *test.Governance) (
 	app := test.NewApp()
 	db, err := blockdb.NewMemBackedBlockDB()
 	s.Require().Nil(err)
-	con := NewConsensus(app, gov, db)
+	prv, err := eth.NewPrivateKey()
+	s.Require().Nil(err)
+	con := NewConsensus(app, gov, db, prv, eth.SigToPub)
 	return app, con
 }
 
diff --git a/core/crypto.go b/core/crypto.go
index abfc8fb..564ad38 100644
--- a/core/crypto.go
+++ b/core/crypto.go
@@ -101,15 +101,6 @@ func hashBlock(blockConv types.BlockConverter) (common.Hash, error) {
 	return hash, nil
 }
 
-func signBlock(blockConv types.BlockConverter,
-	prv crypto.PrivateKey) (crypto.Signature, error) {
-	hash, err := hashBlock(blockConv)
-	if err != nil {
-		return crypto.Signature{}, err
-	}
-	return prv.Sign(hash)
-}
-
 func verifyBlockSignature(pubkey crypto.PublicKey,
 	blockConv types.BlockConverter, sig crypto.Signature) (bool, error) {
 	hash, err := hashBlock(blockConv)
diff --git a/core/crypto_test.go b/core/crypto_test.go
index 06f4905..595d0e9 100644
--- a/core/crypto_test.go
+++ b/core/crypto_test.go
@@ -154,7 +154,7 @@ func (s *CryptoTestSuite) generateBlockChain(
 		block := s.newBlock(prevBlock)
 		blocks[idx] = block
 		var err error
-		block.Signature, err = signBlock(&simpleBlock{block: block}, prv)
+		block.Signature, err = prv.Sign(block.Hash)
 		s.Require().Nil(err)
 	}
 	return blocks
diff --git a/core/types/validator.go b/core/types/validator.go
index 27a9acd..5151a6d 100644
--- a/core/types/validator.go
+++ b/core/types/validator.go
@@ -35,6 +35,11 @@ func NewValidatorID(pubKey crypto.PublicKey) ValidatorID {
 	return ValidatorID{Hash: crypto.Keccak256Hash(pubKey.Bytes())}
 }
 
+// Equal checks if the hash representation is the same ValidatorID.
+func (v ValidatorID) Equal(hash common.Hash) bool {
+	return v.Hash == hash
+}
+
 // ValidatorIDs implements sort.Interface for ValidatorID.
 type ValidatorIDs []ValidatorID