KeyPair.py 文件源码

def PrivateKeyFromNEP2(nep2_key, passphrase):
        """
        Gets the private key from a NEP-2 encrypted private key

        Args:
            nep2_key (str): The nep-2 encrypted private key
            passphrase (str): The password to encrypt the private key with, as unicode string

        Returns:
            bytes: The private key
        """
        if not nep2_key or len(nep2_key) != 58:
            raise ValueError('Please provide a nep2_key with a length of 58 bytes (LEN: {0:d})'.format(len(nep2_key)))

        ADDRESS_HASH_SIZE = 4
        ADDRESS_HASH_OFFSET = len(NEP_FLAG) + len(NEP_HEADER)

        try:
            decoded_key = base58.b58decode_check(nep2_key)
        except Exception as e:
            raise ValueError("Invalid nep2_key")

        address_hash = decoded_key[ADDRESS_HASH_OFFSET:ADDRESS_HASH_OFFSET + ADDRESS_HASH_SIZE]
        encrypted = decoded_key[-32:]

        pwd_normalized = bytes(unicodedata.normalize('NFC', passphrase), 'utf-8')
        derived = scrypt.hash(pwd_normalized, address_hash,
                              N=SCRYPT_ITERATIONS,
                              r=SCRYPT_BLOCKSIZE,
                              p=SCRYPT_PARALLEL_FACTOR,
                              buflen=SCRYPT_KEY_LEN_BYTES)

        derived1 = derived[:32]
        derived2 = derived[32:]

        cipher = AES.new(derived2, AES.MODE_ECB)
        decrypted = cipher.decrypt(encrypted)
        private_key = xor_bytes(decrypted, derived1)

        # Now check that the address hashes match. If they don't, the password was wrong.
        kp_new = KeyPair(priv_key=private_key)
        kp_new_address = kp_new.GetAddress()
        kp_new_address_hash_tmp = hashlib.sha256(kp_new_address.encode('utf-8')).digest()
        kp_new_address_hash_tmp2 = hashlib.sha256(kp_new_address_hash_tmp).digest()
        kp_new_address_hash = kp_new_address_hash_tmp2[:4]
        if (kp_new_address_hash != address_hash):
            raise ValueError("Wrong passphrase")

        return private_key