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
|
# -*- 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__ = "$Id$"
import sys
if sys.version_info[0] == 2 and sys.version_info[1] == 1:
from Crypto.Util.py21compat import *
from Crypto.Cipher import blockalgo
from Crypto.Cipher import _AES
from Crypto.Util import cpuid
# Import _AESNI. If AES-NI is not available or _AESNI has not been built, set
# _AESNI to None.
try:
if cpuid.have_aes_ni():
from Crypto.Cipher import _AESNI
else:
_AESNI = None
except ImportError:
_AESNI = None
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."""
# Check if the use_aesni was specified.
use_aesni = True
if kwargs.has_key('use_aesni'):
use_aesni = kwargs['use_aesni']
del kwargs['use_aesni']
# Use _AESNI if the user requested AES-NI and it's available
if _AESNI is not None and use_aesni:
blockalgo.BlockAlgo.__init__(self, _AESNI, key, *args, **kwargs)
else:
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.
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.
use_aesni : boolean
Use AES-NI if available.
: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 )
|
