// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
/*
This key store behaves as KeyStorePlain with the difference that
the private key is encrypted and on disk uses another JSON encoding.
The crypto is documented at https://github.com/ethereum/wiki/wiki/Web3-Secret-Storage-Definition
*/
package crypto
import (
"bytes"
"crypto/aes"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"io"
"reflect"
"code.google.com/p/go-uuid/uuid"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto/randentropy"
"golang.org/x/crypto/pbkdf2"
"golang.org/x/crypto/scrypt"
)
const (
keyHeaderKDF = "scrypt"
// 2^18 / 8 / 1 uses 256MB memory and approx 1s CPU time on a modern CPU.
scryptN = 1 << 18
scryptr = 8
scryptp = 1
scryptdkLen = 32
)
type keyStorePassphrase struct {
keysDirPath string
}
func NewKeyStorePassphrase(path string) KeyStore {
return &keyStorePassphrase{path}
}
func (ks keyStorePassphrase) GenerateNewKey(rand io.Reader, auth string) (key *Key, err error) {
return GenerateNewKeyDefault(ks, rand, auth)
}
func (ks keyStorePassphrase) GetKey(keyAddr common.Address, auth string) (key *Key, err error) {
keyBytes, keyId, err := decryptKeyFromFile(ks.keysDirPath, keyAddr, auth)
if err == nil {
key = &Key{
Id: uuid.UUID(keyId),
Address: keyAddr,
PrivateKey: ToECDSA(keyBytes),
}
}
return
}
func (ks keyStorePassphrase) Cleanup(keyAddr common.Address) (err error) {
return cleanup(ks.keysDirPath, keyAddr)
}
func (ks keyStorePassphrase) GetKeyAddresses() (addresses []common.Address, err error) {
return getKeyAddresses(ks.keysDirPath)
}
func (ks keyStorePassphrase) StoreKey(key *Key, auth string) (err error) {
authArray := []byte(auth)
salt := randentropy.GetEntropyCSPRNG(32)
derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptr, scryptp, scryptdkLen)
if err != nil {
return err
}
encryptKey := derivedKey[:16]
keyBytes := FromECDSA(key.PrivateKey)
iv := randentropy.GetEntropyCSPRNG(aes.BlockSize) // 16
cipherText, err := aesCTRXOR(encryptKey, keyBytes, iv)
if err != nil {
return err
}
mac := Sha3(derivedKey[16:32], cipherText)
scryptParamsJSON := make(map[string]interface{}, 5)
scryptParamsJSON["n"] = scryptN
scryptParamsJSON["r"] = scryptr
scryptParamsJSON["p"] = scryptp
scryptParamsJSON["dklen"] = scryptdkLen
scryptParamsJSON["salt"] = hex.EncodeToString(salt)
cipherParamsJSON := cipherparamsJSON{
IV: hex.EncodeToString(iv),
}
cryptoStruct := cryptoJSON{
Cipher: "aes-128-ctr",
CipherText: hex.EncodeToString(cipherText),
CipherParams: cipherParamsJSON,
KDF: "scrypt",
KDFParams: scryptParamsJSON,
MAC: hex.EncodeToString(mac),
}
encryptedKeyJSONV3 := encryptedKeyJSONV3{
hex.EncodeToString(key.Address[:]),
cryptoStruct,
key.Id.String(),
version,
}
keyJSON, err := json.Marshal(encryptedKeyJSONV3)
if err != nil {
return err
}
return writeKeyFile(key.Address, ks.keysDirPath, keyJSON)
}
func (ks keyStorePassphrase) DeleteKey(keyAddr common.Address, auth string) (err error) {
// only delete if correct passphrase is given
_, _, err = decryptKeyFromFile(ks.keysDirPath, keyAddr, auth)
if err != nil {
return err
}
return deleteKey(ks.keysDirPath, keyAddr)
}
func decryptKeyFromFile(keysDirPath string, keyAddr common.Address, auth string) (keyBytes []byte, keyId []byte, err error) {
m := make(map[string]interface{})
err = getKey(keysDirPath, keyAddr, &m)
if err != nil {
return
}
v := reflect.ValueOf(m["version"])
if v.Kind() == reflect.String && v.String() == "1" {
k := new(encryptedKeyJSONV1)
err = getKey(keysDirPath, keyAddr, &k)
if err != nil {
return
}
return decryptKeyV1(k, auth)
} else {
k := new(encryptedKeyJSONV3)
err = getKey(keysDirPath, keyAddr, &k)
if err != nil {
return
}
return decryptKeyV3(k, auth)
}
}
func decryptKeyV3(keyProtected *encryptedKeyJSONV3, auth string) (keyBytes []byte, keyId []byte, err error) {
if keyProtected.Version != version {
return nil, nil, fmt.Errorf("Version not supported: %v", keyProtected.Version)
}
if keyProtected.Crypto.Cipher != "aes-128-ctr" {
return nil, nil, fmt.Errorf("Cipher not supported: %v", keyProtected.Crypto.Cipher)
}
keyId = uuid.Parse(keyProtected.Id)
mac, err := hex.DecodeString(keyProtected.Crypto.MAC)
if err != nil {
return nil, nil, err
}
iv, err := hex.DecodeString(keyProtected.Crypto.CipherParams.IV)
if err != nil {
return nil, nil, err
}
cipherText, err := hex.DecodeString(keyProtected.Crypto.CipherText)
if err != nil {
return nil, nil, err
}
derivedKey, err := getKDFKey(keyProtected.Crypto, auth)
if err != nil {
return nil, nil, err
}
calculatedMAC := Sha3(derivedKey[16:32], cipherText)
if !bytes.Equal(calculatedMAC, mac) {
return nil, nil, errors.New("Decryption failed: MAC mismatch")
}
plainText, err := aesCTRXOR(derivedKey[:16], cipherText, iv)
if err != nil {
return nil, nil, err
}
return plainText, keyId, err
}
func decryptKeyV1(keyProtected *encryptedKeyJSONV1, auth string) (keyBytes []byte, keyId []byte, err error) {
keyId = uuid.Parse(keyProtected.Id)
mac, err := hex.DecodeString(keyProtected.Crypto.MAC)
if err != nil {
return nil, nil, err
}
iv, err := hex.DecodeString(keyProtected.Crypto.CipherParams.IV)
if err != nil {
return nil, nil, err
}
cipherText, err := hex.DecodeString(keyProtected.Crypto.CipherText)
if err != nil {
return nil, nil, err
}
derivedKey, err := getKDFKey(keyProtected.Crypto, auth)
if err != nil {
return nil, nil, err
}
calculatedMAC := Sha3(derivedKey[16:32], cipherText)
if !bytes.Equal(calculatedMAC, mac) {
return nil, nil, errors.New("Decryption failed: MAC mismatch")
}
plainText, err := aesCBCDecrypt(Sha3(derivedKey[:16])[:16], cipherText, iv)
if err != nil {
return nil, nil, err
}
return plainText, keyId, err
}
func getKDFKey(cryptoJSON cryptoJSON, auth string) ([]byte, error) {
authArray := []byte(auth)
salt, err := hex.DecodeString(cryptoJSON.KDFParams["salt"].(string))
if err != nil {
return nil, err
}
dkLen := ensureInt(cryptoJSON.KDFParams["dklen"])
if cryptoJSON.KDF == "scrypt" {
n := ensureInt(cryptoJSON.KDFParams["n"])
r := ensureInt(cryptoJSON.KDFParams["r"])
p := ensureInt(cryptoJSON.KDFParams["p"])
return scrypt.Key(authArray, salt, n, r, p, dkLen)
} else if cryptoJSON.KDF == "pbkdf2" {
c := ensureInt(cryptoJSON.KDFParams["c"])
prf := cryptoJSON.KDFParams["prf"].(string)
if prf != "hmac-sha256" {
return nil, fmt.Errorf("Unsupported PBKDF2 PRF: ", prf)
}
key := pbkdf2.Key(authArray, salt, c, dkLen, sha256.New)
return key, nil
}
return nil, fmt.Errorf("Unsupported KDF: ", cryptoJSON.KDF)
}
// TODO: can we do without this when unmarshalling dynamic JSON?
// why do integers in KDF params end up as float64 and not int after
// unmarshal?
func ensureInt(x interface{}) int {
res, ok := x.(int)
if !ok {
res = int(x.(float64))
}
return res
}
