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#
# Cipher/DES.py : DES
#
# ===================================================================
# 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.
# ===================================================================
"""DES symmetric cipher
:undocumented: __revision__, __package__
"""
__revision__ = "$Id$"
from Crypto.Cipher import blockalgo
from blockalgo import *
from Crypto.Cipher import _DES
class DESCipher(blockalgo.BlockAlgo):
"""DES cipher object"""
def __init__(self, key, *args, **kwargs):
"""Initialize a DES cipher object
See also `new()` at the module level."""
blockalgo.BlockAlgo.__init__(self, _DES, key, *args, **kwargs)
def new(key, *args, **kwargs):
"""Create a new DES cipher
:Parameters:
key : byte string
The secret key to use in the symmetric cipher.
It must be 8 byte 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 must be `block_size` bytes longs. Ignored for `MODE_ECB`
and `MODE_CTR`. The default value is 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 `DESCipher` object
"""
return DESCipher(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
#: Size of a data block (in bytes)
block_size = 8
#: Size of a key (in bytes)
key_size = 8
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