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)
}
func (ks keyStorePassphrase) StoreKey(key *Key, auth string) (err error) {
authArray := []byte(auth)
salt := randentropy.GetEntropyCSPRNG(32)
derivedKey, err := scrypt.Key(authArray, salt, ks.scryptN, ks.scryptR, ks.scryptP, ks.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"] = ks.scryptN
scryptParamsJSON["r"] = ks.scryptR
scryptParamsJSON["p"] = ks.scryptP
scryptParamsJSON["dklen"] = ks.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)
}