1 files changed, 296 insertions, 0 deletions
diff --git a/accounts/key_store_passphrase.go b/accounts/key_store_passphrase.go
new file mode 100644
index 000000000..87c7cb98f
--- /dev/null
+++ b/accounts/key_store_passphrase.go
@@ -0,0 +1,296 @@
+// 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 accounts
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/randentropy"
+	"github.com/pborman/uuid"
+	"golang.org/x/crypto/pbkdf2"
+	"golang.org/x/crypto/scrypt"
+)
+
+const (
+	keyHeaderKDF = "scrypt"
+
+	// n,r,p = 2^18, 8, 1 uses 256MB memory and approx 1s CPU time on a modern CPU.
+	StandardScryptN = 1 << 18
+	StandardScryptP = 1
+
+	// n,r,p = 2^12, 8, 6 uses 4MB memory and approx 100ms CPU time on a modern CPU.
+	LightScryptN = 1 << 12
+	LightScryptP = 6
+
+	scryptR     = 8
+	scryptDKLen = 32
+)
+
+type keyStorePassphrase struct {
+	keysDirPath string
+	scryptN     int
+	scryptP     int
+}
+
+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
+}
+
+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
+	}
+	return writeKeyFile(filename, keyjson)
+}
+
+func (ks keyStorePassphrase) JoinPath(filename string) string {
+	if filepath.IsAbs(filename) {
+		return filename
+	} else {
+		return filepath.Join(ks.keysDirPath, filename)
+	}
+}
+
+// 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) {
+	authArray := []byte(auth)
+	salt := randentropy.GetEntropyCSPRNG(32)
+	derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptR, scryptP, scryptDKLen)
+	if err != nil {
+		return nil, err
+	}
+	encryptKey := derivedKey[:16]
+	keyBytes := crypto.FromECDSA(key.PrivateKey)
+
+	iv := randentropy.GetEntropyCSPRNG(aes.BlockSize) // 16
+	cipherText, err := aesCTRXOR(encryptKey, keyBytes, iv)
+	if err != nil {
+		return nil, 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:          "scrypt",
+		KDFParams:    scryptParamsJSON,
+		MAC:          hex.EncodeToString(mac),
+	}
+	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.ToECDSA(keyBytes)
+	return &Key{
+		Id:         uuid.UUID(keyId),
+		Address:    crypto.PubkeyToAddress(key.PublicKey),
+		PrivateKey: key,
+	}, nil
+}
+
+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 := crypto.Keccak256(derivedKey[16:32], cipherText)
+	if !bytes.Equal(calculatedMAC, mac) {
+		return nil, nil, ErrDecrypt
+	}
+
+	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 := 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 == "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: %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
+}