mirror of http://git.sairate.top/sairate/doc.git
114 lines
2.8 KiB
Python
114 lines
2.8 KiB
Python
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# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import annotations
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import abc
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives._asymmetric import (
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AsymmetricPadding as AsymmetricPadding,
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)
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from cryptography.hazmat.primitives.asymmetric import rsa
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class PKCS1v15(AsymmetricPadding):
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name = "EMSA-PKCS1-v1_5"
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class _MaxLength:
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"Sentinel value for `MAX_LENGTH`."
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class _Auto:
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"Sentinel value for `AUTO`."
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class _DigestLength:
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"Sentinel value for `DIGEST_LENGTH`."
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class PSS(AsymmetricPadding):
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MAX_LENGTH = _MaxLength()
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AUTO = _Auto()
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DIGEST_LENGTH = _DigestLength()
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name = "EMSA-PSS"
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_salt_length: int | _MaxLength | _Auto | _DigestLength
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def __init__(
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self,
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mgf: MGF,
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salt_length: int | _MaxLength | _Auto | _DigestLength,
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) -> None:
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self._mgf = mgf
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if not isinstance(
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salt_length, (int, _MaxLength, _Auto, _DigestLength)
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):
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raise TypeError(
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"salt_length must be an integer, MAX_LENGTH, "
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"DIGEST_LENGTH, or AUTO"
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)
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if isinstance(salt_length, int) and salt_length < 0:
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raise ValueError("salt_length must be zero or greater.")
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self._salt_length = salt_length
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@property
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def mgf(self) -> MGF:
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return self._mgf
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class OAEP(AsymmetricPadding):
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name = "EME-OAEP"
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def __init__(
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self,
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mgf: MGF,
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algorithm: hashes.HashAlgorithm,
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label: bytes | None,
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):
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if not isinstance(algorithm, hashes.HashAlgorithm):
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raise TypeError("Expected instance of hashes.HashAlgorithm.")
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self._mgf = mgf
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self._algorithm = algorithm
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self._label = label
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@property
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def algorithm(self) -> hashes.HashAlgorithm:
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return self._algorithm
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@property
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def mgf(self) -> MGF:
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return self._mgf
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class MGF(metaclass=abc.ABCMeta):
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_algorithm: hashes.HashAlgorithm
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class MGF1(MGF):
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MAX_LENGTH = _MaxLength()
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def __init__(self, algorithm: hashes.HashAlgorithm):
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if not isinstance(algorithm, hashes.HashAlgorithm):
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raise TypeError("Expected instance of hashes.HashAlgorithm.")
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self._algorithm = algorithm
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def calculate_max_pss_salt_length(
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key: rsa.RSAPrivateKey | rsa.RSAPublicKey,
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hash_algorithm: hashes.HashAlgorithm,
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) -> int:
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if not isinstance(key, (rsa.RSAPrivateKey, rsa.RSAPublicKey)):
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raise TypeError("key must be an RSA public or private key")
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# bit length - 1 per RFC 3447
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emlen = (key.key_size + 6) // 8
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salt_length = emlen - hash_algorithm.digest_size - 2
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assert salt_length >= 0
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return salt_length
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