mirror of http://git.sairate.top/sairate/doc.git
81 lines
2.3 KiB
Python
81 lines
2.3 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 sys
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import typing
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from cryptography import utils
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from cryptography.exceptions import (
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AlreadyFinalized,
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InvalidKey,
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UnsupportedAlgorithm,
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)
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from cryptography.hazmat.bindings._rust import openssl as rust_openssl
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from cryptography.hazmat.primitives import constant_time
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from cryptography.hazmat.primitives.kdf import KeyDerivationFunction
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# This is used by the scrypt tests to skip tests that require more memory
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# than the MEM_LIMIT
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_MEM_LIMIT = sys.maxsize // 2
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class Scrypt(KeyDerivationFunction):
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def __init__(
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self,
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salt: bytes,
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length: int,
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n: int,
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r: int,
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p: int,
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backend: typing.Any = None,
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):
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from cryptography.hazmat.backends.openssl.backend import (
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backend as ossl,
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)
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if not ossl.scrypt_supported():
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raise UnsupportedAlgorithm(
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"This version of OpenSSL does not support scrypt"
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)
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self._length = length
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utils._check_bytes("salt", salt)
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if n < 2 or (n & (n - 1)) != 0:
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raise ValueError("n must be greater than 1 and be a power of 2.")
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if r < 1:
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raise ValueError("r must be greater than or equal to 1.")
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if p < 1:
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raise ValueError("p must be greater than or equal to 1.")
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self._used = False
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self._salt = salt
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self._n = n
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self._r = r
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self._p = p
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def derive(self, key_material: bytes) -> bytes:
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if self._used:
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raise AlreadyFinalized("Scrypt instances can only be used once.")
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self._used = True
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utils._check_byteslike("key_material", key_material)
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return rust_openssl.kdf.derive_scrypt(
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key_material,
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self._salt,
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self._n,
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self._r,
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self._p,
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_MEM_LIMIT,
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self._length,
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)
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def verify(self, key_material: bytes, expected_key: bytes) -> None:
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derived_key = self.derive(key_material)
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if not constant_time.bytes_eq(derived_key, expected_key):
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raise InvalidKey("Keys do not match.")
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