Internal method, for creating the Key object.

def _key_from_json(self, data):
        """
        Internal method, for creating the Key object.
        """
        key = Key()
        key.algorithm = data["Algorithm"]
        key.cipher_mode = data["CipherMode"]
        key.expiration = datetime.strptime(data["Expiration"].split(".")[0],
                                           "%Y-%m-%dT%H:%M:%S")
        key.key_id = data["ID"]
        key.key = data["Key"]
        key.size = data["KeySize"]
        key.url = data["KeyUrl"]
        return key