87 lines
2.7 KiB
Python
87 lines
2.7 KiB
Python
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# -*- coding: utf-8 -*-
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#
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# Cipher/XOR.py : XOR
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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"""XOR toy cipher
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XOR is one the simplest stream ciphers. Encryption and decryption are
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performed by XOR-ing data with a keystream made by contatenating
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the key.
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Do not use it for real applications!
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:undocumented: __revision__, __package__
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"""
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__revision__ = "$Id$"
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from Crypto.Cipher import _XOR
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class XORCipher:
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"""XOR cipher object"""
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def __init__(self, key, *args, **kwargs):
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"""Initialize a XOR cipher object
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See also `new()` at the module level."""
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self._cipher = _XOR.new(key, *args, **kwargs)
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self.block_size = self._cipher.block_size
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self.key_size = self._cipher.key_size
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def encrypt(self, plaintext):
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"""Encrypt a piece of data.
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:Parameters:
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plaintext : byte string
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The piece of data to encrypt. It can be of any size.
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:Return: the encrypted data (byte string, as long as the
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plaintext).
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"""
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return self._cipher.encrypt(plaintext)
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def decrypt(self, ciphertext):
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"""Decrypt a piece of data.
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:Parameters:
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ciphertext : byte string
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The piece of data to decrypt. It can be of any size.
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:Return: the decrypted data (byte string, as long as the
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ciphertext).
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"""
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return self._cipher.decrypt(ciphertext)
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def new(key, *args, **kwargs):
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"""Create a new XOR cipher
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:Parameters:
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key : byte string
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The secret key to use in the symmetric cipher.
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Its length may vary from 1 to 32 bytes.
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:Return: an `XORCipher` object
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"""
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return XORCipher(key, *args, **kwargs)
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#: Size of a data block (in bytes)
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block_size = 1
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#: Size of a key (in bytes)
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key_size = range(1,32+1)
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