crypto: Add crypto module. (#34)

15 files changed, 534 insertions, 17 deletions

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 7611454..1f681e5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -27,6 +27,7 @@ jobs:
           key: v1-vendor-{{ .Branch }}-{{ checksum "Gopkg.lock" }}
           paths:
             - vendor
+      - run: make eth-dep
       - run: make lint
       - run: make vet
       - run: make test
diff --git a/.gitignore b/.gitignore
index 83fee03..ef110dd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,4 +20,5 @@
 vendor
 build
 simulation/kubernetes/build
+.dep
 
diff --git a/GNUmakefile b/GNUmakefile
index 1680919..ab39a5c 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -50,9 +50,22 @@ all: $(COMPONENTS)
 
 $(foreach component, $(COMPONENTS), $(eval $(call BUILD_RULE,$(component))))
 
-pre-build:
-
-pre-submit: check-format lint test vet
+pre-build: eth-dep
+
+pre-submit: eth-dep check-format lint test vet
+
+eth-dep:
+	@rm -rf vendor/github.com/ethereum/go-ethereum/crypto/secp256k1/libsecp256k1
+	@if [ ! -d .dep/libsecp256k1 ]; then \
+		git init .dep/libsecp256k1; \
+		cd .dep/libsecp256k1; \
+		git remote add origin https://github.com/ethereum/go-ethereum.git; \
+		git config core.sparsecheckout true; \
+		echo "crypto/secp256k1/libsecp256k1/*" >> .git/info/sparse-checkout; \
+		cd ../../; \
+	fi
+	@cd .dep/libsecp256k1; git pull --depth=1 origin master; cd ../../
+	@cp -r .dep/libsecp256k1/crypto/secp256k1/libsecp256k1 vendor/github.com/ethereum/go-ethereum/crypto/secp256k1
 
 format:
 	@go fmt `go list ./... | grep -v 'vendor'`
diff --git a/Gopkg.toml b/Gopkg.toml
index 708d991..7d58335 100644
--- a/Gopkg.toml
+++ b/Gopkg.toml
@@ -34,6 +34,10 @@
   version = "1.2.2"
 
 [[constraint]]
+  name = "github.com/ethereum/go-ethereum"
+  version = "1.8.13"
+
+[[constraint]]
   branch = "master"
   name = "github.com/syndtr/goleveldb"
 
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:"-"`
diff --git a/crypto/eth/eth.go b/crypto/eth/eth.go
new file mode 100644
index 0000000..cb20d7d
--- /dev/null
+++ b/crypto/eth/eth.go
@@ -0,0 +1,99 @@
+// 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 eth
+
+import (
+	"crypto/ecdsa"
+
+	ethcrypto "github.com/ethereum/go-ethereum/crypto"
+
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/dexon-foundation/dexon-consensus-core/crypto"
+)
+
+// PrivateKey represents a private key structure used in geth and implments
+// Crypto.PrivateKey interface.
+type PrivateKey struct {
+	privateKey ecdsa.PrivateKey
+	publicKey  PublicKey
+}
+
+// PublicKey represents a public key structure used in geth and implements
+// Crypto.PublicKey interface.
+type PublicKey struct {
+	publicKey []byte
+}
+
+// NewPrivateKey creates a new PrivateKey structure.
+func NewPrivateKey() (*PrivateKey, error) {
+	key, err := ethcrypto.GenerateKey()
+	if err != nil {
+		return nil, err
+	}
+	return &PrivateKey{
+		privateKey: *key,
+		publicKey:  *newPublicKey(key),
+	}, nil
+}
+
+// newPublicKey creates a new PublicKey structure.
+func newPublicKey(prvKey *ecdsa.PrivateKey) *PublicKey {
+	return &PublicKey{
+		publicKey: ethcrypto.CompressPubkey(&prvKey.PublicKey),
+	}
+}
+
+// DecompressPubkey parses a public key in the 33-byte compressed format.
+func DecompressPubkey(pubkey []byte) (PublicKey, error) {
+	_, err := ethcrypto.DecompressPubkey(pubkey)
+	return PublicKey{
+		publicKey: pubkey,
+	}, err
+}
+
+// PublicKey returns the public key associate this private key.
+func (prv *PrivateKey) PublicKey() crypto.PublicKey {
+	return prv.publicKey
+}
+
+// Sign calculates an ECDSA signature.
+//
+// This function is susceptible to chosen plaintext attacks that can leak
+// information about the private key that is used for signing. Callers must
+// be aware that the given hash cannot be chosen by an adversery. Common
+// solution is to hash any input before calculating the signature.
+//
+// The produced signature is in the [R || S || V] format where V is 0 or 1.
+func (prv *PrivateKey) Sign(hash common.Hash) (sig crypto.Signature, err error) {
+	s, err := ethcrypto.Sign(hash[:], &prv.privateKey)
+	// Magic!
+	sig = crypto.Signature(s[:64])
+	return
+}
+
+// VerifySignature checks that the given public key created signature over hash.
+// The public key should be in compressed (33 bytes) or uncompressed (65 bytes) format.
+// The signature should have the 64 byte [R || S] format.
+func (pub PublicKey) VerifySignature(hash common.Hash, signature crypto.Signature) bool {
+	return ethcrypto.VerifySignature(pub.publicKey, hash[:], signature)
+}
+
+// Compress encodes a public key to the 33-byte compressed format.
+func (pub PublicKey) Compress() []byte {
+	return pub.publicKey
+}
diff --git a/crypto/eth/eth_test.go b/crypto/eth/eth_test.go
new file mode 100644
index 0000000..b09297e
--- /dev/null
+++ b/crypto/eth/eth_test.go
@@ -0,0 +1,79 @@
+// 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 eth
+
+import (
+	"testing"
+
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+	"github.com/stretchr/testify/suite"
+)
+
+type ETHCryptoTestSuite struct {
+	suite.Suite
+}
+
+func (s *ETHCryptoTestSuite) TestSignature() {
+	prv1, err := NewPrivateKey()
+	s.Require().Nil(err)
+	hash1 := common.NewRandomHash()
+	hash2 := common.NewRandomHash()
+
+	// Test that same private key should produce same signature.
+	sig11, err := prv1.Sign(hash1)
+	s.Require().Nil(err)
+	sig112, err := prv1.Sign(hash1)
+	s.Require().Nil(err)
+	s.Equal(sig11, sig112)
+
+	// Test that different private key should produce different signature.
+	prv2, err := NewPrivateKey()
+	s.Require().Nil(err)
+	sig21, err := prv2.Sign(hash1)
+	s.Require().Nil(err)
+	s.NotEqual(sig11, sig21)
+
+	// Test that different hash should produce different signature.
+	sig12, err := prv1.Sign(hash2)
+	s.Require().Nil(err)
+	s.NotEqual(sig11, sig12)
+
+	// Test VerifySignature with correct public key.
+	pub1, ok := prv1.PublicKey().(PublicKey)
+	s.Require().True(ok)
+	s.True(pub1.VerifySignature(hash1, sig11))
+
+	// Test VerifySignature with wrong hash.
+	s.False(pub1.VerifySignature(hash2, sig11))
+	// Test VerifySignature with wrong signature.
+	s.False(pub1.VerifySignature(hash1, sig21))
+	// Test VerifySignature with wrong public key.
+	pub2 := prv2.PublicKey()
+	s.False(pub2.VerifySignature(hash1, sig11))
+
+	// Test compress and decompress of public key.
+	compressPub1 := pub1.Compress()
+	decompressPub1, err := DecompressPubkey(compressPub1)
+	s.Require().Nil(err)
+	s.Equal(pub1, decompressPub1)
+	s.True(decompressPub1.VerifySignature(hash1, sig11))
+}
+
+func TestCrypto(t *testing.T) {
+	suite.Run(t, new(ETHCryptoTestSuite))
+}
diff --git a/crypto/interfaces.go b/crypto/interfaces.go
new file mode 100644
index 0000000..015ff40
--- /dev/null
+++ b/crypto/interfaces.go
@@ -0,0 +1,42 @@
+// 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 crypto
+
+import (
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+)
+
+// Signature is the basic signature type in DEXON.
+type Signature []byte
+
+// PrivateKey describes the asymmetric cryptography interface that interacts
+// with the private key.
+type PrivateKey interface {
+	// PublicKey returns the public key associate this private key.
+	PublicKey() PublicKey
+
+	// Sign calculates a signature.
+	Sign(hash common.Hash) (sig Signature, err error)
+}
+
+// PublicKey describes the asymmetric cryptography interface that interacts
+// with the public key.
+type PublicKey interface {
+	// VerifySignature checks that the given public key created signature over hash.
+	VerifySignature(hash common.Hash, signature Signature) bool
+}
diff --git a/crypto/utils.go b/crypto/utils.go
new file mode 100644
index 0000000..5534ece
--- /dev/null
+++ b/crypto/utils.go
@@ -0,0 +1,30 @@
+// 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 crypto
+
+import (
+	"github.com/ethereum/go-ethereum/crypto"
+
+	"github.com/dexon-foundation/dexon-consensus-core/common"
+)
+
+// Keccak256Hash calculates and returns the Keccak256 hash of the input data,
+// converting it to an internal Hash data structure.
+func Keccak256Hash(data ...[]byte) (h common.Hash) {
+	return common.Hash(crypto.Keccak256Hash(data...))
+}
diff --git a/crypto/utils_test.go b/crypto/utils_test.go
new file mode 100644
index 0000000..977027a
--- /dev/null
+++ b/crypto/utils_test.go
@@ -0,0 +1,52 @@
+// 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 crypto
+
+import (
+	"encoding/hex"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type CryptoTestSuite struct {
+	suite.Suite
+}
+
+func (s *CryptoTestSuite) TestHash() {
+	cases := []struct {
+		input  string
+		output string
+	}{
+		{"DEXON ROCKS!",
+			"1a3f3a424aaa464e51b693585bba3a0c439d5f1ad3b5868e46d9f830225983bd"},
+		{"Dexon Foundation",
+			"25ed4237aa978bfe706cc11c7a46a95de1a46302faea7ff6e900b03fa2b7b480"},
+		{"INFINITELY SCALABLE AND LOW-LATENCY",
+			"ed3384c58a434fbc0bc887a85659eddf997e7da978ab66565ac865f995b77cf1"},
+	}
+	for _, testcase := range cases {
+		hash := Keccak256Hash([]byte(testcase.input))
+		output := hex.EncodeToString(hash[:])
+		s.Equal(testcase.output, output)
+	}
+}
+
+func TestCrypto(t *testing.T) {
+	suite.Run(t, new(CryptoTestSuite))
+}