/usr/lib/python2.7/dist-packages/cryptography/hazmat/backends/commoncrypto/ciphers.py is in python-cryptography 1.2.3-1ubuntu0.2.
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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 | # 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
from cryptography import utils
from cryptography.exceptions import (
InvalidTag, UnsupportedAlgorithm, _Reasons
)
from cryptography.hazmat.primitives import ciphers, constant_time
from cryptography.hazmat.primitives.ciphers import modes
from cryptography.hazmat.primitives.ciphers.modes import (
CFB, CFB8, CTR, OFB
)
@utils.register_interface(ciphers.CipherContext)
class _CipherContext(object):
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
self._cipher = cipher
self._mode = mode
self._operation = operation
# There is a bug in CommonCrypto where block ciphers do not raise
# kCCAlignmentError when finalizing if you supply non-block aligned
# data. To work around this we need to keep track of the block
# alignment ourselves, but only for alg+mode combos that require
# block alignment. OFB, CFB, and CTR make a block cipher algorithm
# into a stream cipher so we don't need to track them (and thus their
# block size is effectively 1 byte just like OpenSSL/CommonCrypto
# treat RC4 and other stream cipher block sizes).
# This bug has been filed as rdar://15589470
self._bytes_processed = 0
if (isinstance(cipher, ciphers.BlockCipherAlgorithm) and not
isinstance(mode, (OFB, CFB, CFB8, CTR))):
self._byte_block_size = cipher.block_size // 8
else:
self._byte_block_size = 1
registry = self._backend._cipher_registry
try:
cipher_enum, mode_enum = registry[type(cipher), type(mode)]
except KeyError:
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported "
"by this backend.".format(
cipher.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
ctx = self._backend._ffi.new("CCCryptorRef *")
ctx = self._backend._ffi.gc(ctx, self._backend._release_cipher_ctx)
if isinstance(mode, modes.ModeWithInitializationVector):
iv_nonce = mode.initialization_vector
elif isinstance(mode, modes.ModeWithNonce):
iv_nonce = mode.nonce
else:
iv_nonce = self._backend._ffi.NULL
if isinstance(mode, CTR):
mode_option = self._backend._lib.kCCModeOptionCTR_BE
else:
mode_option = 0
res = self._backend._lib.CCCryptorCreateWithMode(
operation,
mode_enum, cipher_enum,
self._backend._lib.ccNoPadding, iv_nonce,
cipher.key, len(cipher.key),
self._backend._ffi.NULL, 0, 0, mode_option, ctx)
self._backend._check_cipher_response(res)
self._ctx = ctx
def update(self, data):
# Count bytes processed to handle block alignment.
self._bytes_processed += len(data)
buf = self._backend._ffi.new(
"unsigned char[]", len(data) + self._byte_block_size - 1)
outlen = self._backend._ffi.new("size_t *")
res = self._backend._lib.CCCryptorUpdate(
self._ctx[0], data, len(data), buf,
len(data) + self._byte_block_size - 1, outlen)
self._backend._check_cipher_response(res)
return self._backend._ffi.buffer(buf)[:outlen[0]]
def finalize(self):
# Raise error if block alignment is wrong.
if self._bytes_processed % self._byte_block_size:
raise ValueError(
"The length of the provided data is not a multiple of "
"the block length."
)
buf = self._backend._ffi.new("unsigned char[]", self._byte_block_size)
outlen = self._backend._ffi.new("size_t *")
res = self._backend._lib.CCCryptorFinal(
self._ctx[0], buf, len(buf), outlen)
self._backend._check_cipher_response(res)
self._backend._release_cipher_ctx(self._ctx)
return self._backend._ffi.buffer(buf)[:outlen[0]]
@utils.register_interface(ciphers.AEADCipherContext)
@utils.register_interface(ciphers.AEADEncryptionContext)
class _GCMCipherContext(object):
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
self._cipher = cipher
self._mode = mode
self._operation = operation
self._tag = None
registry = self._backend._cipher_registry
try:
cipher_enum, mode_enum = registry[type(cipher), type(mode)]
except KeyError:
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported "
"by this backend.".format(
cipher.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
ctx = self._backend._ffi.new("CCCryptorRef *")
ctx = self._backend._ffi.gc(ctx, self._backend._release_cipher_ctx)
self._ctx = ctx
res = self._backend._lib.CCCryptorCreateWithMode(
operation,
mode_enum, cipher_enum,
self._backend._lib.ccNoPadding,
self._backend._ffi.NULL,
cipher.key, len(cipher.key),
self._backend._ffi.NULL, 0, 0, 0, self._ctx)
self._backend._check_cipher_response(res)
res = self._backend._lib.CCCryptorGCMAddIV(
self._ctx[0],
mode.initialization_vector,
len(mode.initialization_vector)
)
self._backend._check_cipher_response(res)
# CommonCrypto has a bug where calling update without at least one
# call to authenticate_additional_data will result in null byte output
# for ciphertext. The following empty byte string call prevents the
# issue, which is present in at least 10.8 and 10.9.
# Filed as rdar://18314544
self.authenticate_additional_data(b"")
def update(self, data):
buf = self._backend._ffi.new("unsigned char[]", len(data))
args = (self._ctx[0], data, len(data), buf)
if self._operation == self._backend._lib.kCCEncrypt:
res = self._backend._lib.CCCryptorGCMEncrypt(*args)
else:
res = self._backend._lib.CCCryptorGCMDecrypt(*args)
self._backend._check_cipher_response(res)
return self._backend._ffi.buffer(buf)[:]
def finalize(self):
# CommonCrypto has a yet another bug where you must make at least one
# call to update. If you pass just AAD and call finalize without a call
# to update you'll get null bytes for tag. The following update call
# prevents this issue, which is present in at least 10.8 and 10.9.
# Filed as rdar://18314580
self.update(b"")
tag_size = self._cipher.block_size // 8
tag_buf = self._backend._ffi.new("unsigned char[]", tag_size)
tag_len = self._backend._ffi.new("size_t *", tag_size)
res = self._backend._lib.CCCryptorGCMFinal(
self._ctx[0], tag_buf, tag_len
)
self._backend._check_cipher_response(res)
self._backend._release_cipher_ctx(self._ctx)
self._tag = self._backend._ffi.buffer(tag_buf)[:]
if (self._operation == self._backend._lib.kCCDecrypt and
not constant_time.bytes_eq(
self._tag[:len(self._mode.tag)], self._mode.tag
)):
raise InvalidTag
return b""
def authenticate_additional_data(self, data):
res = self._backend._lib.CCCryptorGCMAddAAD(
self._ctx[0], data, len(data)
)
self._backend._check_cipher_response(res)
tag = utils.read_only_property("_tag")
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