116 lines
4.1 KiB
Python
116 lines
4.1 KiB
Python
|
# -*- coding: utf-8 -*-
|
||
|
|
#
|
||
|
|
# 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.
|
||
|
|
# ===================================================================
|
||
|
|
"""AES symmetric cipher
|
||
|
|
|
||
|
|
AES `(Advanced Encryption Standard)`__ is a symmetric block cipher standardized
|
||
|
|
by NIST_ . It has a fixed data block size of 16 bytes.
|
||
|
|
Its keys can be 128, 192, or 256 bits long.
|
||
|
|
|
||
|
|
AES is very fast and secure, and it is the de facto standard for symmetric
|
||
|
|
encryption.
|
||
|
|
|
||
|
|
As an example, encryption can be done as follows:
|
||
|
|
|
||
|
|
>>> from Crypto.Cipher import AES
|
||
|
|
>>> from Crypto import Random
|
||
|
|
>>>
|
||
|
|
>>> key = b'Sixteen byte key'
|
||
|
|
>>> iv = Random.new().read(AES.block_size)
|
||
|
|
>>> cipher = AES.new(key, AES.MODE_CFB, iv)
|
||
|
|
>>> msg = iv + cipher.encrypt(b'Attack at dawn')
|
||
|
|
|
||
|
|
.. __: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
|
||
|
|
.. _NIST: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
|
||
|
|
|
||
|
|
:undocumented: __revision__, __package__
|
||
|
|
"""
|
||
|
|
|
||
|
|
__revision__ = "$Id$"
|
||
|
|
|
||
|
|
from Crypto.Cipher import blockalgo
|
||
|
|
from Crypto.Cipher import _AES
|
||
|
|
|
||
|
|
class AESCipher (blockalgo.BlockAlgo):
|
||
|
|
"""AES cipher object"""
|
||
|
|
|
||
|
|
def __init__(self, key, *args, **kwargs):
|
||
|
|
"""Initialize an AES cipher object
|
||
|
|
|
||
|
|
See also `new()` at the module level."""
|
||
|
|
blockalgo.BlockAlgo.__init__(self, _AES, key, *args, **kwargs)
|
||
|
|
|
||
|
|
def new(key, *args, **kwargs):
|
||
|
|
"""Create a new AES cipher
|
||
|
|
|
||
|
|
:Parameters:
|
||
|
|
key : byte string
|
||
|
|
The secret key to use in the symmetric cipher.
|
||
|
|
It must be 16 (*AES-128*), 24 (*AES-192*), or 32 (*AES-256*) bytes long.
|
||
|
|
:Keywords:
|
||
|
|
mode : a *MODE_** constant
|
||
|
|
The chaining mode to use for encryption or decryption.
|
||
|
|
Default is `MODE_ECB`.
|
||
|
|
IV : byte string
|
||
|
|
The initialization vector to use for encryption or decryption.
|
||
|
|
|
||
|
|
It is ignored for `MODE_ECB` and `MODE_CTR`.
|
||
|
|
|
||
|
|
For `MODE_OPENPGP`, IV must be `block_size` bytes long for encryption
|
||
|
|
and `block_size` +2 bytes for decryption (in the latter case, it is
|
||
|
|
actually the *encrypted* IV which was prefixed to the ciphertext).
|
||
|
|
It is mandatory.
|
||
|
|
|
||
|
|
For all other modes, it must be `block_size` bytes longs. It is optional and
|
||
|
|
when not present it will be given a default value of all zeroes.
|
||
|
|
counter : callable
|
||
|
|
(*Only* `MODE_CTR`). A stateful function that returns the next
|
||
|
|
*counter block*, which is a byte string of `block_size` bytes.
|
||
|
|
For better performance, use `Crypto.Util.Counter`.
|
||
|
|
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 0 or not specified, it will be assumed to be 8.
|
||
|
|
|
||
|
|
:Return: an `AESCipher` object
|
||
|
|
"""
|
||
|
|
return AESCipher(key, *args, **kwargs)
|
||
|
|
|
||
|
|
#: Electronic Code Book (ECB). See `blockalgo.MODE_ECB`.
|
||
|
|
MODE_ECB = 1
|
||
|
|
#: Cipher-Block Chaining (CBC). See `blockalgo.MODE_CBC`.
|
||
|
|
MODE_CBC = 2
|
||
|
|
#: Cipher FeedBack (CFB). See `blockalgo.MODE_CFB`.
|
||
|
|
MODE_CFB = 3
|
||
|
|
#: This mode should not be used.
|
||
|
|
MODE_PGP = 4
|
||
|
|
#: Output FeedBack (OFB). See `blockalgo.MODE_OFB`.
|
||
|
|
MODE_OFB = 5
|
||
|
|
#: CounTer Mode (CTR). See `blockalgo.MODE_CTR`.
|
||
|
|
MODE_CTR = 6
|
||
|
|
#: OpenPGP Mode. See `blockalgo.MODE_OPENPGP`.
|
||
|
|
MODE_OPENPGP = 7
|
||
|
|
#: Size of a data block (in bytes)
|
||
|
|
block_size = 16
|
||
|
|
#: Size of a key (in bytes)
|
||
|
|
key_size = ( 16, 24, 32 )
|
||
|
|
|