mirror of
https://github.com/PiBrewing/craftbeerpi4.git
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69 lines
2.2 KiB
Python
69 lines
2.2 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 absolute_import, division, print_function
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import sys
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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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_Reasons,
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)
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from cryptography.hazmat.backends import _get_backend
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from cryptography.hazmat.backends.interfaces import ScryptBackend
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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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@utils.register_interface(KeyDerivationFunction)
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class Scrypt(object):
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def __init__(self, salt, length, n, r, p, backend=None):
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backend = _get_backend(backend)
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if not isinstance(backend, ScryptBackend):
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raise UnsupportedAlgorithm(
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"Backend object does not implement ScryptBackend.",
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_Reasons.BACKEND_MISSING_INTERFACE,
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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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self._backend = backend
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def derive(self, key_material):
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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 self._backend.derive_scrypt(
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key_material, self._salt, self._length, self._n, self._r, self._p
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)
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def verify(self, key_material, expected_key):
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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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