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