crypto: Add crypto module. (#34)

1 files changed, 58 insertions, 0 deletions

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
+}