/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/ciphers.py is in python3-cryptography 1.2.3-1.
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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 | # 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
from cryptography.hazmat.primitives.ciphers import modes
@utils.register_interface(ciphers.CipherContext)
@utils.register_interface(ciphers.AEADCipherContext)
@utils.register_interface(ciphers.AEADEncryptionContext)
class _CipherContext(object):
_ENCRYPT = 1
_DECRYPT = 0
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
self._cipher = cipher
self._mode = mode
self._operation = operation
self._tag = None
if isinstance(self._cipher, ciphers.BlockCipherAlgorithm):
self._block_size = self._cipher.block_size
else:
self._block_size = 1
ctx = self._backend._lib.EVP_CIPHER_CTX_new()
ctx = self._backend._ffi.gc(
ctx, self._backend._lib.EVP_CIPHER_CTX_free
)
registry = self._backend._cipher_registry
try:
adapter = 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
)
evp_cipher = adapter(self._backend, cipher, mode)
if evp_cipher == self._backend._ffi.NULL:
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
)
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
# begin init with cipher and operation type
res = self._backend._lib.EVP_CipherInit_ex(ctx, evp_cipher,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
operation)
self._backend.openssl_assert(res != 0)
# set the key length to handle variable key ciphers
res = self._backend._lib.EVP_CIPHER_CTX_set_key_length(
ctx, len(cipher.key)
)
self._backend.openssl_assert(res != 0)
if isinstance(mode, modes.GCM):
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, self._backend._lib.EVP_CTRL_GCM_SET_IVLEN,
len(iv_nonce), self._backend._ffi.NULL
)
self._backend.openssl_assert(res != 0)
if operation == self._DECRYPT:
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
ctx, self._backend._lib.EVP_CTRL_GCM_SET_TAG,
len(mode.tag), mode.tag
)
self._backend.openssl_assert(res != 0)
# pass key/iv
res = self._backend._lib.EVP_CipherInit_ex(
ctx,
self._backend._ffi.NULL,
self._backend._ffi.NULL,
cipher.key,
iv_nonce,
operation
)
self._backend.openssl_assert(res != 0)
# We purposely disable padding here as it's handled higher up in the
# API.
self._backend._lib.EVP_CIPHER_CTX_set_padding(ctx, 0)
self._ctx = ctx
def update(self, data):
# OpenSSL 0.9.8e has an assertion in its EVP code that causes it
# to SIGABRT if you call update with an empty byte string. This can be
# removed when we drop support for 0.9.8e (CentOS/RHEL 5). This branch
# should be taken only when length is zero and mode is not GCM because
# AES GCM can return improper tag values if you don't call update
# with empty plaintext when authenticating AAD for ...reasons.
if len(data) == 0 and not isinstance(self._mode, modes.GCM):
return b""
buf = self._backend._ffi.new("unsigned char[]",
len(data) + self._block_size - 1)
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherUpdate(self._ctx, buf, outlen, data,
len(data))
self._backend.openssl_assert(res != 0)
return self._backend._ffi.buffer(buf)[:outlen[0]]
def finalize(self):
# OpenSSL 1.0.1 on Ubuntu 12.04 (and possibly other distributions)
# appears to have a bug where you must make at least one call to update
# even if you are only using authenticate_additional_data or the
# GCM tag will be wrong. An (empty) call to update resolves this
# and is harmless for all other versions of OpenSSL.
if isinstance(self._mode, modes.GCM):
self.update(b"")
buf = self._backend._ffi.new("unsigned char[]", self._block_size)
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherFinal_ex(self._ctx, buf, outlen)
if res == 0:
errors = self._backend._consume_errors()
if not errors and isinstance(self._mode, modes.GCM):
raise InvalidTag
self._backend.openssl_assert(
errors[0][1:] == (
self._backend._lib.ERR_LIB_EVP,
self._backend._lib.EVP_F_EVP_ENCRYPTFINAL_EX,
self._backend._lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
) or errors[0][1:] == (
self._backend._lib.ERR_LIB_EVP,
self._backend._lib.EVP_F_EVP_DECRYPTFINAL_EX,
self._backend._lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
)
)
raise ValueError(
"The length of the provided data is not a multiple of "
"the block length."
)
if (isinstance(self._mode, modes.GCM) and
self._operation == self._ENCRYPT):
block_byte_size = self._block_size // 8
tag_buf = self._backend._ffi.new(
"unsigned char[]", block_byte_size
)
res = self._backend._lib.EVP_CIPHER_CTX_ctrl(
self._ctx, self._backend._lib.EVP_CTRL_GCM_GET_TAG,
block_byte_size, tag_buf
)
self._backend.openssl_assert(res != 0)
self._tag = self._backend._ffi.buffer(tag_buf)[:]
res = self._backend._lib.EVP_CIPHER_CTX_cleanup(self._ctx)
self._backend.openssl_assert(res == 1)
return self._backend._ffi.buffer(buf)[:outlen[0]]
def authenticate_additional_data(self, data):
outlen = self._backend._ffi.new("int *")
res = self._backend._lib.EVP_CipherUpdate(
self._ctx, self._backend._ffi.NULL, outlen, data, len(data)
)
self._backend.openssl_assert(res != 0)
tag = utils.read_only_property("_tag")
@utils.register_interface(ciphers.CipherContext)
class _AESCTRCipherContext(object):
"""
This is needed to provide support for AES CTR mode in OpenSSL 0.9.8. It can
be removed when we drop 0.9.8 support (RHEL5 extended life ends 2020).
"""
def __init__(self, backend, cipher, mode):
self._backend = backend
self._key = self._backend._ffi.new("AES_KEY *")
res = self._backend._lib.AES_set_encrypt_key(
cipher.key, len(cipher.key) * 8, self._key
)
self._backend.openssl_assert(res == 0)
self._ecount = self._backend._ffi.new("char[]", 16)
self._nonce = self._backend._ffi.new("char[16]", mode.nonce)
self._num = self._backend._ffi.new("unsigned int *", 0)
def update(self, data):
buf = self._backend._ffi.new("unsigned char[]", len(data))
self._backend._lib.AES_ctr128_encrypt(
data, buf, len(data), self._key, self._nonce,
self._ecount, self._num
)
return self._backend._ffi.buffer(buf)[:]
def finalize(self):
self._key = None
self._ecount = None
self._nonce = None
self._num = None
return b""
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