306 lines
8.6 KiB
Go
306 lines
8.6 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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/*
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This key store behaves as KeyStorePlain with the difference that
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the private key is encrypted and on disk uses another JSON encoding.
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The crypto is documented at https://github.com/ethereum/wiki/wiki/Web3-Secret-Storage-Definition
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*/
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package accounts
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import (
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"bytes"
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"crypto/aes"
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"crypto/sha256"
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"encoding/hex"
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"encoding/json"
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"fmt"
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"io/ioutil"
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"path/filepath"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/randentropy"
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"github.com/pborman/uuid"
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"golang.org/x/crypto/pbkdf2"
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"golang.org/x/crypto/scrypt"
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)
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const (
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keyHeaderKDF = "scrypt"
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// StandardScryptN is the N parameter of Scrypt encryption algorithm, using 256MB
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// memory and taking approximately 1s CPU time on a modern processor.
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StandardScryptN = 1 << 18
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// StandardScryptP is the P parameter of Scrypt encryption algorithm, using 256MB
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// memory and taking approximately 1s CPU time on a modern processor.
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StandardScryptP = 1
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// LightScryptN is the N parameter of Scrypt encryption algorithm, using 4MB
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// memory and taking approximately 100ms CPU time on a modern processor.
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LightScryptN = 1 << 12
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// LightScryptP is the P parameter of Scrypt encryption algorithm, using 4MB
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// memory and taking approximately 100ms CPU time on a modern processor.
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LightScryptP = 6
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scryptR = 8
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scryptDKLen = 32
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)
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type keyStorePassphrase struct {
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keysDirPath string
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scryptN int
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scryptP int
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}
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func (ks keyStorePassphrase) GetKey(addr common.Address, filename, auth string) (*Key, error) {
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// Load the key from the keystore and decrypt its contents
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keyjson, err := ioutil.ReadFile(filename)
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if err != nil {
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return nil, err
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}
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key, err := DecryptKey(keyjson, auth)
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if err != nil {
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return nil, err
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}
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// Make sure we're really operating on the requested key (no swap attacks)
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if key.Address != addr {
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return nil, fmt.Errorf("key content mismatch: have account %x, want %x", key.Address, addr)
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}
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return key, nil
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}
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func (ks keyStorePassphrase) StoreKey(filename string, key *Key, auth string) error {
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keyjson, err := EncryptKey(key, auth, ks.scryptN, ks.scryptP)
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if err != nil {
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return err
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}
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return writeKeyFile(filename, keyjson)
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}
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func (ks keyStorePassphrase) JoinPath(filename string) string {
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if filepath.IsAbs(filename) {
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return filename
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} else {
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return filepath.Join(ks.keysDirPath, filename)
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}
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}
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// EncryptKey encrypts a key using the specified scrypt parameters into a json
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// blob that can be decrypted later on.
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func EncryptKey(key *Key, auth string, scryptN, scryptP int) ([]byte, error) {
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authArray := []byte(auth)
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salt := randentropy.GetEntropyCSPRNG(32)
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derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptR, scryptP, scryptDKLen)
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if err != nil {
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return nil, err
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}
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encryptKey := derivedKey[:16]
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keyBytes0 := crypto.FromECDSA(key.PrivateKey)
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keyBytes := common.LeftPadBytes(keyBytes0, 32)
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iv := randentropy.GetEntropyCSPRNG(aes.BlockSize) // 16
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cipherText, err := aesCTRXOR(encryptKey, keyBytes, iv)
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if err != nil {
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return nil, err
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}
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mac := crypto.Keccak256(derivedKey[16:32], cipherText)
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scryptParamsJSON := make(map[string]interface{}, 5)
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scryptParamsJSON["n"] = scryptN
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scryptParamsJSON["r"] = scryptR
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scryptParamsJSON["p"] = scryptP
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scryptParamsJSON["dklen"] = scryptDKLen
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scryptParamsJSON["salt"] = hex.EncodeToString(salt)
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cipherParamsJSON := cipherparamsJSON{
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IV: hex.EncodeToString(iv),
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}
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cryptoStruct := cryptoJSON{
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Cipher: "aes-128-ctr",
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CipherText: hex.EncodeToString(cipherText),
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CipherParams: cipherParamsJSON,
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KDF: "scrypt",
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KDFParams: scryptParamsJSON,
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MAC: hex.EncodeToString(mac),
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}
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encryptedKeyJSONV3 := encryptedKeyJSONV3{
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hex.EncodeToString(key.Address[:]),
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cryptoStruct,
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key.Id.String(),
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version,
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}
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return json.Marshal(encryptedKeyJSONV3)
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}
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// DecryptKey decrypts a key from a json blob, returning the private key itself.
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func DecryptKey(keyjson []byte, auth string) (*Key, error) {
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// Parse the json into a simple map to fetch the key version
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m := make(map[string]interface{})
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if err := json.Unmarshal(keyjson, &m); err != nil {
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return nil, err
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}
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// Depending on the version try to parse one way or another
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var (
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keyBytes, keyId []byte
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err error
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)
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if version, ok := m["version"].(string); ok && version == "1" {
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k := new(encryptedKeyJSONV1)
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if err := json.Unmarshal(keyjson, k); err != nil {
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return nil, err
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}
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keyBytes, keyId, err = decryptKeyV1(k, auth)
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} else {
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k := new(encryptedKeyJSONV3)
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if err := json.Unmarshal(keyjson, k); err != nil {
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return nil, err
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}
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keyBytes, keyId, err = decryptKeyV3(k, auth)
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}
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// Handle any decryption errors and return the key
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if err != nil {
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return nil, err
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}
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key := crypto.ToECDSA(keyBytes)
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return &Key{
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Id: uuid.UUID(keyId),
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Address: crypto.PubkeyToAddress(key.PublicKey),
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PrivateKey: key,
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}, nil
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}
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func decryptKeyV3(keyProtected *encryptedKeyJSONV3, auth string) (keyBytes []byte, keyId []byte, err error) {
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if keyProtected.Version != version {
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return nil, nil, fmt.Errorf("Version not supported: %v", keyProtected.Version)
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}
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if keyProtected.Crypto.Cipher != "aes-128-ctr" {
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return nil, nil, fmt.Errorf("Cipher not supported: %v", keyProtected.Crypto.Cipher)
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}
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keyId = uuid.Parse(keyProtected.Id)
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mac, err := hex.DecodeString(keyProtected.Crypto.MAC)
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if err != nil {
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return nil, nil, err
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}
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iv, err := hex.DecodeString(keyProtected.Crypto.CipherParams.IV)
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if err != nil {
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return nil, nil, err
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}
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cipherText, err := hex.DecodeString(keyProtected.Crypto.CipherText)
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if err != nil {
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return nil, nil, err
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}
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derivedKey, err := getKDFKey(keyProtected.Crypto, auth)
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if err != nil {
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return nil, nil, err
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}
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calculatedMAC := crypto.Keccak256(derivedKey[16:32], cipherText)
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if !bytes.Equal(calculatedMAC, mac) {
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return nil, nil, ErrDecrypt
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}
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plainText, err := aesCTRXOR(derivedKey[:16], cipherText, iv)
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if err != nil {
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return nil, nil, err
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}
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return plainText, keyId, err
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}
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func decryptKeyV1(keyProtected *encryptedKeyJSONV1, auth string) (keyBytes []byte, keyId []byte, err error) {
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keyId = uuid.Parse(keyProtected.Id)
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mac, err := hex.DecodeString(keyProtected.Crypto.MAC)
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if err != nil {
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return nil, nil, err
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}
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iv, err := hex.DecodeString(keyProtected.Crypto.CipherParams.IV)
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if err != nil {
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return nil, nil, err
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}
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cipherText, err := hex.DecodeString(keyProtected.Crypto.CipherText)
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if err != nil {
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return nil, nil, err
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}
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derivedKey, err := getKDFKey(keyProtected.Crypto, auth)
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if err != nil {
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return nil, nil, err
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}
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calculatedMAC := crypto.Keccak256(derivedKey[16:32], cipherText)
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if !bytes.Equal(calculatedMAC, mac) {
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return nil, nil, ErrDecrypt
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}
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plainText, err := aesCBCDecrypt(crypto.Keccak256(derivedKey[:16])[:16], cipherText, iv)
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if err != nil {
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return nil, nil, err
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}
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return plainText, keyId, err
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}
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func getKDFKey(cryptoJSON cryptoJSON, auth string) ([]byte, error) {
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authArray := []byte(auth)
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salt, err := hex.DecodeString(cryptoJSON.KDFParams["salt"].(string))
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if err != nil {
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return nil, err
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}
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dkLen := ensureInt(cryptoJSON.KDFParams["dklen"])
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if cryptoJSON.KDF == "scrypt" {
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n := ensureInt(cryptoJSON.KDFParams["n"])
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r := ensureInt(cryptoJSON.KDFParams["r"])
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p := ensureInt(cryptoJSON.KDFParams["p"])
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return scrypt.Key(authArray, salt, n, r, p, dkLen)
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} else if cryptoJSON.KDF == "pbkdf2" {
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c := ensureInt(cryptoJSON.KDFParams["c"])
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prf := cryptoJSON.KDFParams["prf"].(string)
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if prf != "hmac-sha256" {
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return nil, fmt.Errorf("Unsupported PBKDF2 PRF: %s", prf)
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}
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key := pbkdf2.Key(authArray, salt, c, dkLen, sha256.New)
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return key, nil
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}
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return nil, fmt.Errorf("Unsupported KDF: %s", cryptoJSON.KDF)
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}
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// TODO: can we do without this when unmarshalling dynamic JSON?
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// why do integers in KDF params end up as float64 and not int after
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// unmarshal?
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func ensureInt(x interface{}) int {
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res, ok := x.(int)
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if !ok {
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res = int(x.(float64))
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}
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return res
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}
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