287 lines
7.6 KiB
Go
287 lines
7.6 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 crypto
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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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"errors"
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"fmt"
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"io"
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"reflect"
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"code.google.com/p/go-uuid/uuid"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto/randentropy"
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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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// 2^18 / 8 / 1 uses 256MB memory and approx 1s CPU time on a modern CPU.
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scryptN = 1 << 18
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scryptr = 8
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scryptp = 1
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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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}
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func NewKeyStorePassphrase(path string) KeyStore {
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return &keyStorePassphrase{path}
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}
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func (ks keyStorePassphrase) GenerateNewKey(rand io.Reader, auth string) (key *Key, err error) {
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return GenerateNewKeyDefault(ks, rand, auth)
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}
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func (ks keyStorePassphrase) GetKey(keyAddr common.Address, auth string) (key *Key, err error) {
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keyBytes, keyId, err := decryptKeyFromFile(ks.keysDirPath, keyAddr, auth)
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if err == nil {
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key = &Key{
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Id: uuid.UUID(keyId),
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Address: keyAddr,
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PrivateKey: ToECDSA(keyBytes),
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}
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}
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return
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}
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func (ks keyStorePassphrase) Cleanup(keyAddr common.Address) (err error) {
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return cleanup(ks.keysDirPath, keyAddr)
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}
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func (ks keyStorePassphrase) GetKeyAddresses() (addresses []common.Address, err error) {
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return getKeyAddresses(ks.keysDirPath)
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}
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func (ks keyStorePassphrase) StoreKey(key *Key, auth string) (err 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 err
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}
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encryptKey := derivedKey[:16]
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keyBytes := FromECDSA(key.PrivateKey)
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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 err
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}
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mac := Sha3(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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keyJSON, err := json.Marshal(encryptedKeyJSONV3)
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if err != nil {
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return err
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}
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return writeKeyFile(key.Address, ks.keysDirPath, keyJSON)
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}
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func (ks keyStorePassphrase) DeleteKey(keyAddr common.Address, auth string) (err error) {
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// only delete if correct passphrase is given
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_, _, err = decryptKeyFromFile(ks.keysDirPath, keyAddr, auth)
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if err != nil {
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return err
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}
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return deleteKey(ks.keysDirPath, keyAddr)
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}
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func decryptKeyFromFile(keysDirPath string, keyAddr common.Address, auth string) (keyBytes []byte, keyId []byte, err error) {
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m := make(map[string]interface{})
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err = getKey(keysDirPath, keyAddr, &m)
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if err != nil {
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return
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}
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v := reflect.ValueOf(m["version"])
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if v.Kind() == reflect.String && v.String() == "1" {
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k := new(encryptedKeyJSONV1)
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err = getKey(keysDirPath, keyAddr, &k)
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if err != nil {
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return
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}
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return decryptKeyV1(k, auth)
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} else {
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k := new(encryptedKeyJSONV3)
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err = getKey(keysDirPath, keyAddr, &k)
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if err != nil {
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return
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}
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return decryptKeyV3(k, auth)
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}
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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 := Sha3(derivedKey[16:32], cipherText)
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if !bytes.Equal(calculatedMAC, mac) {
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return nil, nil, errors.New("Decryption failed: MAC mismatch")
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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 := Sha3(derivedKey[16:32], cipherText)
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if !bytes.Equal(calculatedMAC, mac) {
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return nil, nil, errors.New("Decryption failed: MAC mismatch")
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}
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plainText, err := aesCBCDecrypt(Sha3(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: ", 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: ", 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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