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80 lines
2.2 KiB
Python
80 lines
2.2 KiB
Python
# 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 abc
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import six
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from cryptography import utils
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives.asymmetric import rsa
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@six.add_metaclass(abc.ABCMeta)
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class AsymmetricPadding(object):
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@abc.abstractproperty
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def name(self):
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"""
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A string naming this padding (e.g. "PSS", "PKCS1").
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"""
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@utils.register_interface(AsymmetricPadding)
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class PKCS1v15(object):
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name = "EMSA-PKCS1-v1_5"
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@utils.register_interface(AsymmetricPadding)
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class PSS(object):
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MAX_LENGTH = object()
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name = "EMSA-PSS"
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def __init__(self, mgf, salt_length):
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self._mgf = mgf
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if (
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not isinstance(salt_length, six.integer_types)
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and salt_length is not self.MAX_LENGTH
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):
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raise TypeError("salt_length must be an integer.")
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if salt_length is not self.MAX_LENGTH 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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@utils.register_interface(AsymmetricPadding)
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class OAEP(object):
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name = "EME-OAEP"
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def __init__(self, mgf, algorithm, label):
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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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class MGF1(object):
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MAX_LENGTH = object()
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def __init__(self, algorithm):
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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(key, hash_algorithm):
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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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