/usr/lib/python3/dist-packages/Cryptodome/Cipher/AES.py is in python3-pycryptodome 3.4.7-1ubuntu1.
This file is owned by root:root, with mode 0o644.
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#
# Cipher/AES.py : AES
#
# ===================================================================
# The contents of this file are dedicated to the public domain. To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# ===================================================================
"""
Module's constants for the modes of operation supported with AES:
:var MODE_ECB: Electronic Code Book (ECB)
:var MODE_CBC: Cipher-Block Chaining (CBC)
:var MODE_CFB: Cipher FeedBack (CFB)
:var MODE_OFB: Output FeedBack (OFB)
:var MODE_CTR: CounTer Mode (CTR)
:var MODE_OPENPGP: OpenPGP Mode
:var MODE_CCM: Counter with CBC-MAC (CCM) Mode
:var MODE_EAX: EAX Mode
:var MODE_SIV: Syntethic Initialization Vector (SIV)
:var MODE_GCM: Galois Counter Mode (GCM)
:var MODE_OCB: Offset Code Book (OCB)
"""
import sys
from Cryptodome.Cipher import _create_cipher
from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib,
VoidPointer, SmartPointer,
c_size_t, expect_byte_string)
_raw_cpuid_lib = load_pycryptodome_raw_lib("Cryptodome.Util._cpuid",
"int have_aes_ni(void);")
_cproto = """
int AES_start_operation(const uint8_t key[],
size_t key_len,
void **pResult);
int AES_encrypt(const void *state,
const uint8_t *in,
uint8_t *out,
size_t data_len);
int AES_decrypt(const void *state,
const uint8_t *in,
uint8_t *out,
size_t data_len);
int AES_stop_operation(void *state);
"""
_raw_aes_lib = load_pycryptodome_raw_lib("Cryptodome.Cipher._raw_aes",
_cproto)
_raw_aesni_lib = None
try:
if _raw_cpuid_lib.have_aes_ni() == 1:
_raw_aesni_lib = load_pycryptodome_raw_lib("Cryptodome.Cipher._raw_aesni",
_cproto.replace("AES",
"AESNI"))
except OSError:
pass
def _create_base_cipher(dict_parameters):
"""This method instantiates and returns a handle to a low-level
base cipher. It will absorb named parameters in the process."""
use_aesni = dict_parameters.pop("use_aesni", True)
try:
key = dict_parameters.pop("key")
except KeyError:
raise TypeError("Missing 'key' parameter")
expect_byte_string(key)
if len(key) not in key_size:
raise ValueError("Incorrect AES key length (%d bytes)" % len(key))
if use_aesni and _raw_aesni_lib:
start_operation = _raw_aesni_lib.AESNI_start_operation
stop_operation = _raw_aesni_lib.AESNI_stop_operation
else:
start_operation = _raw_aes_lib.AES_start_operation
stop_operation = _raw_aes_lib.AES_stop_operation
cipher = VoidPointer()
result = start_operation(key,
c_size_t(len(key)),
cipher.address_of())
if result:
raise ValueError("Error %X while instantiating the AES cipher"
% result)
return SmartPointer(cipher.get(), stop_operation)
def new(key, mode, *args, **kwargs):
"""Create a new AES cipher.
:param key:
The secret key to use in the symmetric cipher.
It must be 16, 24 or 32 bytes long (respectively for *AES-128*,
*AES-192* or *AES-256*).
For ``MODE_SIV`` only, it doubles to 32, 48, or 64 bytes.
:type key: byte string
:param mode:
The chaining mode to use for encryption or decryption.
If in doubt, use ``MODE_EAX``.
:type mode: One of the supported ``MODE_*`` constants
:Keyword Arguments:
* *iv* (``byte string``) --
(Only applicable for ``MODE_CBC``, ``MODE_CFB``, ``MODE_OFB``,
and ``MODE_OPENPGP`` modes).
The initialization vector to use for encryption or decryption.
For ``MODE_CBC``, ``MODE_CFB``, and ``MODE_OFB`` it must be 16 bytes long.
For ``MODE_OPENPGP`` mode only,
it must be 16 bytes long for encryption
and 18 bytes for decryption (in the latter case, it is
actually the *encrypted* IV which was prefixed to the ciphertext).
If not provided, a random byte string is generated (you must then
read its value with the :attr:`iv` attribute).
* *nonce* (``byte string``) --
(Only applicable for ``MODE_CCM``, ``MODE_EAX``, ``MODE_GCM``,
``MODE_SIV``, ``MODE_OCB``, and ``MODE_CTR``).
A value that must never be reused for any other encryption done
with this key.
For ``MODE_EAX``, ``MODE_GCM`` and ``MODE_SIV`` there are no
restrictions on its length (recommended: **16** bytes).
For ``MODE_CCM``, its length must be in the range **[7..13]**.
Bear in mind that with CCM there is a trade-off between nonce
length and maximum message size. Recommendation: **11** bytes.
For ``MODE_OCB``, its length must be in the range **[1..15]**
(recommended: **15**).
For ``MODE_CTR``, its length must be in the range **[0..15]**
(recommended: **8**).
In not provided, a random byte string of the recommended
length is used (you must then read its value with the :attr:`nonce`
attribute).
* *segment_size* (``integer``) --
(Only ``MODE_CFB``).The number of **bits** the plaintext and ciphertext
are segmented in. It must be a multiple of 8.
If not specified, it will be assumed to be 8.
* *mac_len* : (``integer``) --
(Only ``MODE_EAX``, ``MODE_GCM``, ``MODE_OCB``, ``MODE_CCM``)
Length of the authentication tag, in bytes.
It must be even and in the range **[4..16]**.
The recommended value (and the default, if not specified) is **16**.
* *msg_len* : (``integer``) --
(Only ``MODE_CCM``). Length of the message to (de)cipher.
If not specified, ``encrypt`` must be called with the entire message.
Similarly, ``decrypt`` can only be called once.
* *assoc_len* : (``integer``) --
(Only ``MODE_CCM``). Length of the associated data.
If not specified, all associated data is buffered internally,
which may represent a problem for very large messages.
* *initial_value* : (``integer``) --
(Only ``MODE_CTR``). The initial value for the counter within
the counter block. By default it is **0**.
* *use_aesni* : (``boolean``) --
Use Intel AES-NI hardware extensions (default: use if available).
:Return: an AES object, of the applicable mode.
"""
kwargs["add_aes_modes"] = True
return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs)
MODE_ECB = 1
MODE_CBC = 2
MODE_CFB = 3
MODE_OFB = 5
MODE_CTR = 6
MODE_OPENPGP = 7
MODE_CCM = 8
MODE_EAX = 9
MODE_SIV = 10
MODE_GCM = 11
MODE_OCB = 12
# Size of a data block (in bytes)
block_size = 16
# Size of a key (in bytes)
key_size = (16, 24, 32)
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