/usr/lib/python3/dist-packages/cryptography/hazmat/primitives/ciphers/modes.py is in python3-cryptography 1.2.3-1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 | # 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.
from __future__ import absolute_import, division, print_function
import abc
import six
from cryptography import utils
@six.add_metaclass(abc.ABCMeta)
class Mode(object):
@abc.abstractproperty
def name(self):
"""
A string naming this mode (e.g. "ECB", "CBC").
"""
@abc.abstractmethod
def validate_for_algorithm(self, algorithm):
"""
Checks that all the necessary invariants of this (mode, algorithm)
combination are met.
"""
@six.add_metaclass(abc.ABCMeta)
class ModeWithInitializationVector(object):
@abc.abstractproperty
def initialization_vector(self):
"""
The value of the initialization vector for this mode as bytes.
"""
@six.add_metaclass(abc.ABCMeta)
class ModeWithNonce(object):
@abc.abstractproperty
def nonce(self):
"""
The value of the nonce for this mode as bytes.
"""
@six.add_metaclass(abc.ABCMeta)
class ModeWithAuthenticationTag(object):
@abc.abstractproperty
def tag(self):
"""
The value of the tag supplied to the constructor of this mode.
"""
def _check_iv_length(self, algorithm):
if len(self.initialization_vector) * 8 != algorithm.block_size:
raise ValueError("Invalid IV size ({0}) for {1}.".format(
len(self.initialization_vector), self.name
))
@utils.register_interface(Mode)
@utils.register_interface(ModeWithInitializationVector)
class CBC(object):
name = "CBC"
def __init__(self, initialization_vector):
self._initialization_vector = initialization_vector
initialization_vector = utils.read_only_property("_initialization_vector")
validate_for_algorithm = _check_iv_length
@utils.register_interface(Mode)
class ECB(object):
name = "ECB"
def validate_for_algorithm(self, algorithm):
pass
@utils.register_interface(Mode)
@utils.register_interface(ModeWithInitializationVector)
class OFB(object):
name = "OFB"
def __init__(self, initialization_vector):
self._initialization_vector = initialization_vector
initialization_vector = utils.read_only_property("_initialization_vector")
validate_for_algorithm = _check_iv_length
@utils.register_interface(Mode)
@utils.register_interface(ModeWithInitializationVector)
class CFB(object):
name = "CFB"
def __init__(self, initialization_vector):
self._initialization_vector = initialization_vector
initialization_vector = utils.read_only_property("_initialization_vector")
validate_for_algorithm = _check_iv_length
@utils.register_interface(Mode)
@utils.register_interface(ModeWithInitializationVector)
class CFB8(object):
name = "CFB8"
def __init__(self, initialization_vector):
self._initialization_vector = initialization_vector
initialization_vector = utils.read_only_property("_initialization_vector")
validate_for_algorithm = _check_iv_length
@utils.register_interface(Mode)
@utils.register_interface(ModeWithNonce)
class CTR(object):
name = "CTR"
def __init__(self, nonce):
self._nonce = nonce
nonce = utils.read_only_property("_nonce")
def validate_for_algorithm(self, algorithm):
if len(self.nonce) * 8 != algorithm.block_size:
raise ValueError("Invalid nonce size ({0}) for {1}.".format(
len(self.nonce), self.name
))
@utils.register_interface(Mode)
@utils.register_interface(ModeWithInitializationVector)
@utils.register_interface(ModeWithAuthenticationTag)
class GCM(object):
name = "GCM"
_MAX_ENCRYPTED_BYTES = (2 ** 39 - 256) // 8
_MAX_AAD_BYTES = (2 ** 64) // 8
def __init__(self, initialization_vector, tag=None, min_tag_length=16):
# len(initialization_vector) must in [1, 2 ** 64), but it's impossible
# to actually construct a bytes object that large, so we don't check
# for it
if min_tag_length < 4:
raise ValueError("min_tag_length must be >= 4")
if tag is not None and len(tag) < min_tag_length:
raise ValueError(
"Authentication tag must be {0} bytes or longer.".format(
min_tag_length)
)
self._initialization_vector = initialization_vector
self._tag = tag
tag = utils.read_only_property("_tag")
initialization_vector = utils.read_only_property("_initialization_vector")
def validate_for_algorithm(self, algorithm):
pass
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