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- # 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.
- import typing
- 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: bytes) -> typing.Tuple[int, int]:
- 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: int, s: int) -> bytes:
- 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: hashes.HashAlgorithm):
- 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")
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