// 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 keystore
import (
"bytes"
"crypto/aes"
"crypto/rand"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/pborman/uuid"
"golang.org/x/crypto/pbkdf2"
"golang.org/x/crypto/scrypt"
)
const (
keyHeaderKDF = "scrypt"
// StandardScryptN is the N parameter of Scrypt encryption algorithm, using 256MB
// memory and taking approximately 1s CPU time on a modern processor.
StandardScryptN = 1 << 18
// StandardScryptP is the P parameter of Scrypt encryption algorithm, using 256MB
// memory and taking approximately 1s CPU time on a modern processor.
StandardScryptP = 1
// LightScryptN is the N parameter of Scrypt encryption algorithm, using 4MB
// memory and taking approximately 100ms CPU time on a modern processor.
LightScryptN = 1 << 12
// LightScryptP is the P parameter of Scrypt encryption algorithm, using 4MB
// memory and taking approximately 100ms CPU time on a modern processor.
LightScryptP = 6
scryptR = 8
scryptDKLen = 32
)
type keyStorePassphrase struct {
keysDirPath string
scryptN int
scryptP int
// skipKeyFileVerification disables the security-feature which does
// reads and decrypts any newly created keyfiles. This should be 'false' in all
// cases except tests -- setting this to 'true' is not recommended.
skipKeyFileVerification bool
}
func (ks keyStorePassphrase) GetKey(addr common.Address, filename, auth string) (*Key, error) {
// Load the key from the keystore and decrypt its contents
keyjson, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
key, err := DecryptKey(keyjson, auth)
if err != nil {
return nil, err
}
// Make sure we're really operating on the requested key (no swap attacks)
if key.Address != addr {
return nil, fmt.Errorf("key content mismatch: have account %x, want %x", key.Address, addr)
}
return key, nil
}
// StoreKey generates a key, encrypts with 'auth' and stores in the given directory
func StoreKey(dir, auth string, scryptN, scryptP int) (common.Address, error) {
_, a, err := storeNewKey(&keyStorePassphrase{dir, scryptN, scryptP, false}, rand.Reader, auth)
return a.Address, err
}
func (ks keyStorePassphrase) StoreKey(filename string, key *Key, auth string) error {
keyjson, err := EncryptKey(key, auth, ks.scryptN, ks.scryptP)
if err != nil {
return err
}
// Write into temporary file
tmpName, err := writeTemporaryKeyFile(filename, keyjson)
if err != nil {
return err
}
if !ks.skipKeyFileVerification {
// Verify that we can decrypt the file with the given password.
_, err = ks.GetKey(key.Address, tmpName, auth)
if err != nil {
msg := "An error was encountered when saving and verifying the keystore file. \n" +
"This indicates that the keystore is corrupted. \n" +
"The corrupted file is stored at \n%v\n" +
"Please file a ticket at:\n\n" +
"https://github.com/ethereum/go-ethereum/issues." +
"The error was : %s"
return fmt.Errorf(msg, tmpName, err)
}
}
return os.Rename(tmpName, filename)
}
func (ks keyStorePassphrase) JoinPath(filename string) string {
if filepath.IsAbs(filename) {
return filename
}
return filepath.Join(ks.keysDirPath, filename)
}
// Encryptdata encrypts the data given as 'data' with the password 'auth'.
func EncryptDataV3(data, auth []byte, scryptN, scryptP int) (CryptoJSON, error) {
salt := make([]byte, 32)
if _, err := io.ReadFull(rand.Reader, salt); err != nil {
panic("reading from crypto/rand failed: " + err.Error())
}
derivedKey, err := scrypt.Key(auth, salt, scryptN, scryptR, scryptP, scryptDKLen)
if err != nil {
return CryptoJSON{}, err
}
encryptKey := derivedKey[:16]
iv := make([]byte, aes.BlockSize) // 16
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
panic("reading from crypto/rand failed: " + err.Error())
}
cipherText, err := aesCTRXOR(encryptKey, data, iv)
if err != nil {
return CryptoJSON{}, err
}
mac := crypto.Keccak256(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: keyHeaderKDF,
KDFParams: scryptParamsJSON,
MAC: hex.EncodeToString(mac),
}
return cryptoStruct, nil
}
// EncryptKey encrypts a key using the specified scrypt parameters into a json
// blob that can be decrypted later on.
func EncryptKey(key *Key, auth string, scryptN, scryptP int) ([]byte, error) {
keyBytes := math.PaddedBigBytes(key.PrivateKey.D, 32)
cryptoStruct, err := EncryptDataV3(keyBytes, []byte(auth), scryptN, scryptP)
if err != nil {
return nil, err
}
encryptedKeyJSONV3 := encryptedKeyJSONV3{
hex.EncodeToString(key.Address[:]),
cryptoStruct,
key.Id.String(),
version,
}
return json.Marshal(encryptedKeyJSONV3)
}
// DecryptKey decrypts a key from a json blob, returning the private key itself.
func DecryptKey(keyjson []byte, auth string) (*Key, error) {
// Parse the json into a simple map to fetch the key version
m := make(map[string]interface{})
if err := json.Unmarshal(keyjson, &m); err != nil {
return nil, err
}
// Depending on the version try to parse one way or another
var (
keyBytes, keyId []byte
err error
)
if version, ok := m["version"].(string); ok && version == "1" {
k := new(encryptedKeyJSONV1)
if err := json.Unmarshal(keyjson, k); err != nil {
return nil, err
}
keyBytes, keyId, err = decryptKeyV1(k, auth)
} else {
k := new(encryptedKeyJSONV3)
if err := json.Unmarshal(keyjson, k); err != nil {
return nil, err
}
keyBytes, keyId, err = decryptKeyV3(k, auth)
}
// Handle any decryption errors and return the key
if err != nil {
return nil, err
}
key := crypto.ToECDSAUnsafe(keyBytes)
return &Key{
Id: uuid.UUID(keyId),
Address: crypto.PubkeyToAddress(key.PublicKey),
PrivateKey: key,
}, nil
}
func DecryptDataV3(cryptoJson CryptoJSON, auth string) ([]byte, error) {
if cryptoJson.Cipher != "aes-128-ctr" {
return nil, fmt.Errorf("Cipher not supported: %v", cryptoJson.Cipher)
}
mac, err := hex.DecodeString(cryptoJson.MAC)
if err != nil {
return nil, err
}
iv, err := hex.DecodeString(cryptoJson.CipherParams.IV)
if err != nil {
return nil, err
}
cipherText, err := hex.DecodeString(cryptoJson.CipherText)
if err != nil {
return nil, err
}
derivedKey, err := getKDFKey(cryptoJson, auth)
if err != nil {
return nil, err
}
calculatedMAC := crypto.Keccak256(derivedKey[16:32], cipherText)
if !bytes.Equal(calculatedMAC, mac) {
return nil, ErrDecrypt
}
plainText, err := aesCTRXOR(derivedKey[:16], cipherText, iv)
if err != nil {
return nil, err
}
return plainText, err
}
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)
}
keyId = uuid.Parse(keyProtected.Id)
plainText, err := DecryptDataV3(keyProtected.Crypto, auth)
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 := crypto.Keccak256(derivedKey[16:32], cipherText)
if !bytes.Equal(calculatedMAC, mac) {
return nil, nil, ErrDecrypt
}
plainText, err := aesCBCDecrypt(crypto.Keccak256(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 == keyHeaderKDF {
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: %s", prf)
}
key := pbkdf2.Key(authArray, salt, c, dkLen, sha256.New)
return key, nil
}
return nil, fmt.Errorf("Unsupported KDF: %s", 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
}
