def deserialize_wrapped_key()

in src/aws_encryption_sdk/internal/formatting/deserialize.py [0:0]

• 23 lines of code
• 8 McCabe index (conditional complexity)

def deserialize_wrapped_key(wrapping_algorithm, wrapping_key_id, wrapped_encrypted_key):
    """Extracts and deserializes EncryptedData from a Wrapped EncryptedDataKey.

    :param wrapping_algorithm: Wrapping Algorithm with which to wrap plaintext_data_key
    :type wrapping_algorithm: aws_encryption_sdk.identifiers.WrappingAlgorithm
    :param bytes wrapping_key_id: Key ID of wrapping MasterKey
    :param wrapped_encrypted_key: Raw Wrapped EncryptedKey
    :type wrapped_encrypted_key: aws_encryption_sdk.structures.EncryptedDataKey
    :returns: EncryptedData of deserialized Wrapped EncryptedKey
    :rtype: aws_encryption_sdk.internal.structures.EncryptedData
    :raises SerializationError: if wrapping_key_id does not match deserialized wrapping key id
    :raises SerializationError: if wrapping_algorithm IV length does not match deserialized IV length
    """
    if wrapping_key_id == wrapped_encrypted_key.key_provider.key_info:
        encrypted_wrapped_key = EncryptedData(iv=None, ciphertext=wrapped_encrypted_key.encrypted_data_key, tag=None)
    else:
        if not wrapped_encrypted_key.key_provider.key_info.startswith(wrapping_key_id):
            raise SerializationError("Master Key mismatch for wrapped data key")
        _key_info = wrapped_encrypted_key.key_provider.key_info[len(wrapping_key_id) :]
        try:
            tag_len, iv_len = struct.unpack(">II", _key_info[:8])
        except struct.error:
            raise SerializationError("Malformed key info: key info missing data")
        tag_len //= 8  # Tag Length is stored in bits, not bytes
        if iv_len != wrapping_algorithm.algorithm.iv_len:
            raise SerializationError("Wrapping AlgorithmSuite mismatch for wrapped data key")
        iv = _key_info[8:]
        if len(iv) != iv_len:
            raise SerializationError("Malformed key info: incomplete iv")
        ciphertext = wrapped_encrypted_key.encrypted_data_key[: -1 * tag_len]
        tag = wrapped_encrypted_key.encrypted_data_key[-1 * tag_len :]
        if not ciphertext or len(tag) != tag_len:
            raise SerializationError("Malformed key info: incomplete ciphertext or tag")
        encrypted_wrapped_key = EncryptedData(iv=iv, ciphertext=ciphertext, tag=tag)
    return encrypted_wrapped_key