From a8ebf501e54406c7449f71dba0c9af696bbc4e21 Mon Sep 17 00:00:00 2001
From: Jimmy Hu <jimmy.hu@dexon.org>
Date: Mon, 13 Aug 2018 15:13:41 +0800
Subject: core: Sign block in Consensus.PrepareBlock. (#50)

---
 core/consensus.go | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

(limited to 'core/consensus.go')

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
 }
-- 
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