Overlay from eth addr (#281)

pkg/crypto/crypto.go

@@ -18,10 +18,10 @@ import (
 
 // NewOverlayAddress constructs a Swarm Address from ECDSA private key.
 func NewOverlayAddress(p ecdsa.PublicKey, networkID uint64) swarm.Address {
-	data := make([]byte, 28)
-	copy(data, elliptic.Marshal(btcec.S256(), p.X, p.Y)[12:32])
-	binary.LittleEndian.PutUint64(data[20:28], networkID)
-	h := sha3.Sum256(data)
+	ethAddr := NewEthereumAddress(p)
+	netIDBytes := make([]byte, 8)
+	binary.LittleEndian.PutUint64(netIDBytes, networkID)
+	h := sha3.Sum256(append(ethAddr, netIDBytes...))
 	return swarm.NewAddress(h[:])
 }
 
@@ -44,3 +44,17 @@ func DecodeSecp256k1PrivateKey(data []byte) (*ecdsa.PrivateKey, error) {
 	privk, _ := btcec.PrivKeyFromBytes(btcec.S256(), data)
 	return (*ecdsa.PrivateKey)(privk), nil
 }
+
+// NewEthereumAddress returns a binary representation of ethereum blockchain address.
+// This function is based on github.com/ethereum/go-ethereum/crypto.PubkeyToAddress.
+func NewEthereumAddress(p ecdsa.PublicKey) []byte {
+	if p.X == nil || p.Y == nil {
+		return nil
+	}
+	pubBytes := elliptic.Marshal(btcec.S256(), p.X, p.Y)
+	return legacyKeccak256(pubBytes[1:])[12:]
+}
+
+func legacyKeccak256(data []byte) []byte {
+	return sha3.NewLegacyKeccak256().Sum(data)
+}

pkg/keystore/file/key.go

@@ -25,7 +25,7 @@ var _ keystore.Service = (*Service)(nil)
 
 const (
 	keyHeaderKDF = "scrypt"
-	keyVersion   = 1
+	keyVersion   = 3
 
 	scryptN     = 1 << 15
 	scryptR     = 8
@@ -33,7 +33,9 @@ const (
 	scryptDKLen = 32
 )
 
+// This format is compatible with Ethereum JSON v3 key file format.
 type encryptedKey struct {
+	Address string    `json:"address"`
 	Crypto  keyCripto `json:"crypto"`
 	Version int       `json:"version"`
 }
@@ -66,6 +68,7 @@ func encryptKey(k *ecdsa.PrivateKey, password string) ([]byte, error) {
 		return nil, err
 	}
 	return json.Marshal(encryptedKey{
+		Address: hex.EncodeToString(crypto.NewEthereumAddress(k.PublicKey)),
 		Crypto:  *kc,
 		Version: keyVersion,
 	})