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__pycache__	[ DIR ]	drwxr-xr-x	2025-04-10 17:07
AES.py	4.03 KB	-rw-r--r--	2016-12-28 11:45
ARC2.py	4.71 KB	-rw-r--r--	2016-12-28 11:45
ARC4.py	4.17 KB	-rw-r--r--	2016-12-28 11:45
Blowfish.py	4.26 KB	-rw-r--r--	2016-12-28 11:45
CAST.py	4.3 KB	-rw-r--r--	2016-12-28 11:45
DES.py	4.21 KB	-rw-r--r--	2016-12-28 11:45
DES3.py	4.92 KB	-rw-r--r--	2016-12-28 11:45
PKCS1_OAEP.py	9.12 KB	-rw-r--r--	2016-12-28 11:45
PKCS1_v1_5.py	8.9 KB	-rw-r--r--	2016-12-28 11:45
XOR.py	2.67 KB	-rw-r--r--	2016-12-28 11:45
_AES.cpython-35m-x86_64-linux-gnu.so	35.17 KB	-rw-r--r--	2016-12-28 11:45
_ARC2.cpython-35m-x86_64-linux-gnu.so	19.17 KB	-rw-r--r--	2016-12-28 11:45
_ARC4.cpython-35m-x86_64-linux-gnu.so	15.11 KB	-rw-r--r--	2016-12-28 11:45
_Blowfish.cpython-35m-x86_64-linux-gnu.so	31.2 KB	-rw-r--r--	2016-12-28 11:45
_CAST.cpython-35m-x86_64-linux-gnu.so	31.17 KB	-rw-r--r--	2016-12-28 11:45
_DES.cpython-35m-x86_64-linux-gnu.so	55.17 KB	-rw-r--r--	2016-12-28 11:45
_DES3.cpython-35m-x86_64-linux-gnu.so	55.17 KB	-rw-r--r--	2016-12-28 11:45
_XOR.cpython-35m-x86_64-linux-gnu.so	11.11 KB	-rw-r--r--	2016-12-28 11:45
__init__.py	3.36 KB	-rw-r--r--	2012-05-24 14:55
blockalgo.py	12.3 KB	-rw-r--r--	2013-10-14 23:38

Rename

# -*- coding: utf-8 -*-
#
#  Cipher/DES3.py : DES3
#
# ===================================================================
# 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.
# ===================================================================
"""Triple DES symmetric cipher

`Triple DES`__ (or TDES or TDEA or 3DES) is a symmetric block cipher standardized by NIST_.
It has a fixed data block size of 8 bytes. Its keys are 128 (*Option 1*) or 192
bits (*Option 2*) long.
However, 1 out of 8 bits is used for redundancy and do not contribute to
security. The effective key length is respectively 112 or 168 bits.

TDES consists of the concatenation of 3 simple `DES` ciphers.

The plaintext is first DES encrypted with *K1*, then decrypted with *K2*,
and finally encrypted again with *K3*.  The ciphertext is decrypted in the reverse manner.

The 192 bit key is a bundle of three 64 bit independent subkeys: *K1*, *K2*, and *K3*.

The 128 bit key is split into *K1* and *K2*, whereas *K1=K3*.

It is important that all subkeys are different, otherwise TDES would degrade to
single `DES`.

TDES is cryptographically secure, even though it is neither as secure nor as fast
as `AES`.

As an example, encryption can be done as follows:

>>> from Crypto.Cipher import DES
    >>> from Crypto import Random
    >>> from Crypto.Util import Counter
    >>>
    >>> key = b'-8B key-'
    >>> nonce = Random.new().read(DES.block_size/2)
    >>> ctr = Counter.new(DES.block_size*8/2, prefix=nonce)
    >>> cipher = DES.new(key, DES.MODE_CTR, counter=ctr)
    >>> plaintext = b'We are no longer the knights who say ni!'
    >>> msg = nonce + cipher.encrypt(plaintext)

.. __: http://en.wikipedia.org/wiki/Triple_DES
.. _NIST: http://csrc.nist.gov/publications/nistpubs/800-67/SP800-67.pdf

:undocumented: __revision__, __package__
"""

__revision__ = "$Id$"

from Crypto.Cipher import blockalgo
from Crypto.Cipher import _DES3

class DES3Cipher(blockalgo.BlockAlgo):
    """TDES cipher object"""

def __init__(self, key, *args, **kwargs):
        """Initialize a TDES cipher object
        
        See also `new()` at the module level."""
        blockalgo.BlockAlgo.__init__(self, _DES3, key, *args, **kwargs)

def new(key, *args, **kwargs):
    """Create a new TDES cipher

:Parameters:
      key : byte string
        The secret key to use in the symmetric cipher.
        It must be 16 or 24 bytes long. The parity bits will be ignored.
    :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.

:Attention: it is important that all 8 byte subkeys are different,
      otherwise TDES would degrade to single `DES`.
    :Return: an `DES3Cipher` object
    """
    return DES3Cipher(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 = 8
#: Size of a key (in bytes)
key_size = ( 16, 24 )