JezK
Edit File: padding.py
# 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 abc import typing from cryptography.hazmat.primitives import hashes from cryptography.hazmat.primitives._asymmetric import ( AsymmetricPadding as AsymmetricPadding, ) from cryptography.hazmat.primitives.asymmetric import rsa class PKCS1v15(AsymmetricPadding): name = "EMSA-PKCS1-v1_5" class _MaxLength: "Sentinel value for `MAX_LENGTH`." class _Auto: "Sentinel value for `AUTO`." class _DigestLength: "Sentinel value for `DIGEST_LENGTH`." class PSS(AsymmetricPadding): MAX_LENGTH = _MaxLength() AUTO = _Auto() DIGEST_LENGTH = _DigestLength() name = "EMSA-PSS" _salt_length: typing.Union[int, _MaxLength, _Auto, _DigestLength] def __init__( self, mgf: "MGF", salt_length: typing.Union[int, _MaxLength, _Auto, _DigestLength], ) -> None: self._mgf = mgf if not isinstance( salt_length, (int, _MaxLength, _Auto, _DigestLength) ): raise TypeError( "salt_length must be an integer, MAX_LENGTH, " "DIGEST_LENGTH, or AUTO" ) if isinstance(salt_length, int) and salt_length < 0: raise ValueError("salt_length must be zero or greater.") self._salt_length = salt_length class OAEP(AsymmetricPadding): name = "EME-OAEP" def __init__( self, mgf: "MGF", algorithm: hashes.HashAlgorithm, label: typing.Optional[bytes], ): if not isinstance(algorithm, hashes.HashAlgorithm): raise TypeError("Expected instance of hashes.HashAlgorithm.") self._mgf = mgf self._algorithm = algorithm self._label = label class MGF(metaclass=abc.ABCMeta): _algorithm: hashes.HashAlgorithm class MGF1(MGF): MAX_LENGTH = _MaxLength() def __init__(self, algorithm: hashes.HashAlgorithm): if not isinstance(algorithm, hashes.HashAlgorithm): raise TypeError("Expected instance of hashes.HashAlgorithm.") self._algorithm = algorithm def calculate_max_pss_salt_length( key: typing.Union["rsa.RSAPrivateKey", "rsa.RSAPublicKey"], hash_algorithm: hashes.HashAlgorithm, ) -> int: if not isinstance(key, (rsa.RSAPrivateKey, rsa.RSAPublicKey)): raise TypeError("key must be an RSA public or private key") # bit length - 1 per RFC 3447 emlen = (key.key_size + 6) // 8 salt_length = emlen - hash_algorithm.digest_size - 2 assert salt_length >= 0 return salt_length