# This file is dual licensed under the terms of the Apache License, Version # 2.0, and the BSD License. See the LICENSE file in the root of this repository # for complete details. from __future__ import absolute_import, division, print_function from cryptography import utils from cryptography.hazmat._der import ( DERReader, INTEGER, SEQUENCE, encode_der, encode_der_integer, ) from cryptography.hazmat.primitives import hashes def decode_dss_signature(signature): with DERReader(signature).read_single_element(SEQUENCE) as seq: r = seq.read_element(INTEGER).as_integer() s = seq.read_element(INTEGER).as_integer() return r, s def encode_dss_signature(r, s): return encode_der( SEQUENCE, encode_der(INTEGER, encode_der_integer(r)), encode_der(INTEGER, encode_der_integer(s)), ) class Prehashed(object): def __init__(self, algorithm): if not isinstance(algorithm, hashes.HashAlgorithm): raise TypeError("Expected instance of HashAlgorithm.") self._algorithm = algorithm self._digest_size = algorithm.digest_size digest_size = utils.read_only_property("_digest_size") def decode_rfc6979_signature(signature): return decode_dss_signature(signature) def encode_rfc6979_signature(r, s): return encode_dss_signature(r, s)