crypto: Add crypto module. (#34)

6 files changed, 210 insertions, 14 deletions

diff --git a/core/blocklattice.go b/core/blocklattice.go
index f94cc9a..0f5fc11 100644
--- a/core/blocklattice.go
+++ b/core/blocklattice.go
@@ -542,7 +542,7 @@ func (l *BlockLattice) totalOrdering(b *types.Block) {
 			panic(err)
 		}
 		for _, block := range blocksReady {
-			l.app.DeliverBlock(block.Hash, block.ConsensusTime)
+			l.app.DeliverBlock(block.Hash, block.ConsensusInfo.Timestamp)
 		}
 	}
 
diff --git a/core/consensus-timestamp.go b/core/consensus-timestamp.go
index e9b5cce..ab904fb 100644
--- a/core/consensus-timestamp.go
+++ b/core/consensus-timestamp.go
@@ -72,17 +72,19 @@ func (ct *consensusTimestamp) processBlocks(blocks []*types.Block) (
 			return
 		} else if block.Hash == mainChain[idxMainChain].Hash {
 			rightMainChainIdx = idx
-			blocksWithTimestamp[idx].ConsensusTime, err = ct.getMedianTime(block)
+			blocksWithTimestamp[idx].ConsensusInfo.Timestamp, err =
+				ct.getMedianTime(block)
 			if err != nil {
 				return
 			}
 			// Process Non-MainChain blocks.
 			if rightMainChainIdx > leftMainChainIdx {
 				for idx, timestamp := range interpoTime(
-					blocksWithTimestamp[leftMainChainIdx].ConsensusTime,
-					blocksWithTimestamp[rightMainChainIdx].ConsensusTime,
+					blocksWithTimestamp[leftMainChainIdx].ConsensusInfo.Timestamp,
+					blocksWithTimestamp[rightMainChainIdx].ConsensusInfo.Timestamp,
 					rightMainChainIdx-leftMainChainIdx-1) {
-					blocksWithTimestamp[leftMainChainIdx+idx+1].ConsensusTime = timestamp
+					blocksWithTimestamp[leftMainChainIdx+idx+1].ConsensusInfo.Timestamp =
+						timestamp
 				}
 			}
 			leftMainChainIdx = idx
diff --git a/core/consensus-timestamp_test.go b/core/consensus-timestamp_test.go
index 8a82080..aeba00a 100644
--- a/core/consensus-timestamp_test.go
+++ b/core/consensus-timestamp_test.go
@@ -79,7 +79,7 @@ func fillBlocksTimestamps(blocks []*types.Block, validatorNum int,
 func extractTimestamps(blocks []*types.Block) []time.Time {
 	timestamps := make([]time.Time, len(blocks))
 	for idx, block := range blocks {
-		timestamps[idx] = block.ConsensusTime
+		timestamps[idx] = block.ConsensusInfo.Timestamp
 	}
 	return timestamps
 }
diff --git a/core/crypto.go b/core/crypto.go
new file mode 100644
index 0000000..679b045
--- /dev/null
+++ b/core/crypto.go
@@ -0,0 +1,58 @@
+// Copyright 2018 The dexon-consensus-core Authors
+// This file is part of the dexon-consensus-core library.
+//
+// The dexon-consensus-core 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-core 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-core library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"encoding/binary"
+
+	"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"
+)
+
+func hashCompactionChainAck(block *types.Block) (common.Hash, error) {
+	binaryTime, err := block.ConsensusInfo.Timestamp.MarshalBinary()
+	if err != nil {
+		return common.Hash{}, err
+	}
+	binaryHeight := make([]byte, 8)
+	binary.LittleEndian.PutUint64(binaryHeight, block.ConsensusInfo.Height)
+	hash := crypto.Keccak256Hash(
+		block.ConsensusInfoParentHash[:],
+		binaryTime,
+		binaryHeight)
+	return hash, nil
+}
+
+func signCompactionChainAck(block *types.Block,
+	prv crypto.PrivateKey) (crypto.Signature, error) {
+	hash, err := hashCompactionChainAck(block)
+	if err != nil {
+		return crypto.Signature{}, err
+	}
+	return prv.Sign(hash)
+}
+
+func verifyCompactionChainAckSignature(pubkey crypto.PublicKey,
+	ackingBlock *types.Block, sig crypto.Signature) (bool, error) {
+	hash, err := hashCompactionChainAck(ackingBlock)
+	if err != nil {
+		return false, err
+	}
+	return pubkey.VerifySignature(hash, sig), nil
+}
diff --git a/core/crypto_test.go b/core/crypto_test.go
new file mode 100644
index 0000000..0ee28e4
--- /dev/null
+++ b/core/crypto_test.go
@@ -0,0 +1,116 @@
+// Copyright 2018 The dexon-consensus-core Authors
+// This file is part of the dexon-consensus-core library.
+//
+// The dexon-consensus-core 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-core 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-core library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"testing"
+	"time"
+
+	"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"
+	"github.com/dexon-foundation/dexon-consensus-core/crypto/eth"
+	"github.com/stretchr/testify/suite"
+)
+
+type CryptoTestSuite struct {
+	suite.Suite
+}
+
+func (s *CryptoTestSuite) newBlock(prevBlock *types.Block) *types.Block {
+	if prevBlock == nil {
+		return &types.Block{
+			Hash: common.NewRandomHash(),
+			ConsensusInfo: types.ConsensusInfo{
+				Timestamp: time.Now(),
+				Height:    0,
+			},
+		}
+	}
+	parentHash, err := hashCompactionChainAck(prevBlock)
+	s.Require().Nil(err)
+	return &types.Block{
+		Hash: common.NewRandomHash(),
+		ConsensusInfoParentHash: parentHash,
+		CompactionChainAck: types.CompactionChainAck{
+			AckingBlockHash: prevBlock.Hash,
+		},
+		ConsensusInfo: types.ConsensusInfo{
+			Timestamp: time.Now(),
+			Height:    prevBlock.ConsensusInfo.Height + 1,
+		},
+	}
+}
+
+func (s *CryptoTestSuite) generateCompactionChain(
+	length int, prv crypto.PrivateKey) []*types.Block {
+	blocks := make([]*types.Block, length)
+	var prevBlock *types.Block
+	for idx := range blocks {
+		block := s.newBlock(prevBlock)
+		blocks[idx] = block
+		var err error
+		if idx > 0 {
+			block.ConsensusInfoParentHash, err = hashCompactionChainAck(blocks[idx-1])
+			s.Require().Nil(err)
+			block.CompactionChainAck.ConsensusSignature, err =
+				signCompactionChainAck(blocks[idx-1], prv)
+			s.Require().Nil(err)
+		}
+	}
+	return blocks
+}
+
+func (s *CryptoTestSuite) TestSignature() {
+	prv, err := eth.NewPrivateKey()
+	pub := prv.PublicKey()
+	s.Require().Nil(err)
+	blocks := s.generateCompactionChain(10, prv)
+	blockMap := make(map[common.Hash]*types.Block)
+	for _, block := range blocks {
+		blockMap[block.Hash] = block
+	}
+	for _, block := range blocks {
+		if block.ConsensusInfo.Height == 0 {
+			continue
+		}
+		ackingBlock, exist := blockMap[block.CompactionChainAck.AckingBlockHash]
+		s.Require().True(exist)
+		s.True(ackingBlock.ConsensusInfo.Height == block.ConsensusInfo.Height-1)
+		hash, err := hashCompactionChainAck(ackingBlock)
+		s.Require().Nil(err)
+		s.Equal(hash, block.ConsensusInfoParentHash)
+		s.True(verifyCompactionChainAckSignature(
+			pub, ackingBlock, block.CompactionChainAck.ConsensusSignature))
+	}
+	// Modify Block.ConsensusTime and verify signature again.
+	for _, block := range blocks {
+		block.ConsensusInfo.Timestamp = time.Time{}
+		if block.ConsensusInfo.Height == 0 {
+			continue
+		}
+		ackingBlock, exist := blockMap[block.CompactionChainAck.AckingBlockHash]
+		s.Require().True(exist)
+		s.False(verifyCompactionChainAckSignature(
+			pub, ackingBlock, block.CompactionChainAck.ConsensusSignature))
+	}
+}
+
+func TestCrypto(t *testing.T) {
+	suite.Run(t, new(CryptoTestSuite))
+}
diff --git a/core/types/block.go b/core/types/block.go
index 56b456c..8a27ab0 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/dexon-foundation/dexon-consensus-core/crypto"
 )
 
 // Status represents the block process state.
@@ -36,16 +37,35 @@ const (
 	BlockStatusFinal
 )
 
+// CompactionChainAck represents the acking to the compaction chain.
+type CompactionChainAck struct {
+	AckingBlockHash common.Hash `json:"acking_block_hash"`
+	// Signature is the signature of the hash value of
+	// Block.ConsensusInfoParentHash and Block.ConsensusInfo.
+	ConsensusSignature crypto.Signature `json:"consensus_signature"`
+}
+
+// ConsensusInfo represents the consensus information on the compaction chain.
+type ConsensusInfo struct {
+	Timestamp time.Time `json:"timestamp"`
+	Height    uint64    `json:"height"`
+}
+
 // Block represents a single event broadcasted on the network.
 type Block struct {
-	ProposerID      ValidatorID               `json:"proposer_id"`
-	ParentHash      common.Hash               `json:"parent_hash"`
-	Hash            common.Hash               `json:"hash"`
-	Height          uint64                    `json:"height"`
-	Timestamps      map[ValidatorID]time.Time `json:"timestamps"`
-	Acks            map[common.Hash]struct{}  `json:"acks"`
-	ConsensusTime   time.Time                 `json:"consensus_time"`
-	ConsensusHeight uint64                    `json:"consensus_height"`
+	ProposerID         ValidatorID               `json:"proposer_id"`
+	ParentHash         common.Hash               `json:"parent_hash"`
+	Hash               common.Hash               `json:"hash"`
+	Height             uint64                    `json:"height"`
+	Timestamps         map[ValidatorID]time.Time `json:"timestamps"`
+	Acks               map[common.Hash]struct{}  `json:"acks"`
+	CompactionChainAck CompactionChainAck        `json:"compaction_chain_ack"`
+
+	ConsensusInfo ConsensusInfo `json:"consensus_info"`
+	// ConsensusInfoParentHash is the hash value of Block.ConsensusInfoParentHash
+	// and Block.ConsensusInfo, where Block is the previous block on
+	// the compaction chain.
+	ConsensusInfoParentHash common.Hash `json:"consensus_info_parent_hash"`
 
 	Ackeds          map[common.Hash]struct{} `json:"-"`
 	AckedValidators map[ValidatorID]struct{} `json:"-"`