491 lines
16 KiB
Python
491 lines
16 KiB
Python
#################################################
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# Documentation #
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#################################################
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# Author: Todd Whiteman
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# Date: 16th March, 2009
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# Verion: 2.0.0
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# License: Public Domain - free to do as you wish
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# Homepage: http://twhiteman.netfirms.com/Des.html
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#
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# Modified by: Adam Varga, 2018
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#
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# A pure python implementation of the DES and Triple DES
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# encryption algorithms using CBC mode. Triple DES class is
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# implemented by utilising the DES base. Triple DES is
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# DES-EDE3 with a 24 byte key, or DES-EDE2 with a 16 byte key.
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"""
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Class initialization
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--------------------
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pyDes.Des(key, iv)
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pyDes.Python_TripleDES(key, iv)
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key -> Bytes containing the encryption key. 8 bytes for DES, 16 or 24 bytes
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for Triple DES
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iv -> Initialization Vector in bytes. Length must be 8 bytes.
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"""
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import sys
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import warnings
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# PY_VER is used to handle Python2 and Python3 differences.
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PY_VER = sys.version_info
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def new(key, iv):
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"""Operate this 3DES cipher."""
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return Python_TripleDES(key, iv)
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class _baseDes(object):
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"""The base class shared by DES and triple DES."""
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def __init__(self, iv):
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self.iv = iv
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def _guard_against_unicode(self, data):
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"""Check the data for valid datatype and return them.
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Only accept byte strings or ascii unicode values.
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Otherwise there is no way to correctly decode the data into bytes.
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"""
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if PY_VER < (3, ):
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if isinstance(data, unicode):
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raise ValueError("Only bytes, bytearray or memoryview "
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"objects of them should be passed, "
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"not Unicode strings")
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else:
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if isinstance(data, str):
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warnings.warn("Only bytes, bytearray or memoryview "
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"objects of them should be passed",
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DeprecationWarning,
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stacklevel=3)
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# Only accept ascii unicode values.
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try:
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return data.encode('ascii')
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except UnicodeEncodeError:
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raise ValueError("The Unicode string shouldn't be passed")
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return data
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#############################################
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# DES #
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#############################################
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class Des(_baseDes):
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"""DES encryption/decryption class.
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Supports CBC (Cypher Block Chaining) mode.
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"""
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# Permutation and translation tables for DES
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__pc1 = [56, 48, 40, 32, 24, 16, 8,
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0, 57, 49, 41, 33, 25, 17,
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9, 1, 58, 50, 42, 34, 26,
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18, 10, 2, 59, 51, 43, 35,
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62, 54, 46, 38, 30, 22, 14,
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6, 61, 53, 45, 37, 29, 21,
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13, 5, 60, 52, 44, 36, 28,
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20, 12, 4, 27, 19, 11, 3]
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# Number left rotations of pc1
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__left_rotations = [1, 1, 2, 2, 2, 2, 2, 2,
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1, 2, 2, 2, 2, 2, 2, 1]
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# Permuted choice key (table 2)
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__pc2 = [13, 16, 10, 23, 0, 4,
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2, 27, 14, 5, 20, 9,
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22, 18, 11, 3, 25, 7,
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15, 6, 26, 19, 12, 1,
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40, 51, 30, 36, 46, 54,
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29, 39, 50, 44, 32, 47,
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43, 48, 38, 55, 33, 52,
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45, 41, 49, 35, 28, 31]
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# Initial permutation IP
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__ip = [57, 49, 41, 33, 25, 17, 9, 1,
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59, 51, 43, 35, 27, 19, 11, 3,
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61, 53, 45, 37, 29, 21, 13, 5,
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63, 55, 47, 39, 31, 23, 15, 7,
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56, 48, 40, 32, 24, 16, 8, 0,
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58, 50, 42, 34, 26, 18, 10, 2,
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60, 52, 44, 36, 28, 20, 12, 4,
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62, 54, 46, 38, 30, 22, 14, 6]
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# Expansion table for turning 32 bit blocks into 48 bits
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__expansion_table = [31, 0, 1, 2, 3, 4,
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3, 4, 5, 6, 7, 8,
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7, 8, 9, 10, 11, 12,
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11, 12, 13, 14, 15, 16,
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15, 16, 17, 18, 19, 20,
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19, 20, 21, 22, 23, 24,
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23, 24, 25, 26, 27, 28,
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27, 28, 29, 30, 31, 0]
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# The (in)famous S-boxes
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__sbox = [ # S1
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[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
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0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
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4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
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15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13],
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# S2
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[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
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3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
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0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
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13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9],
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# S3
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[10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
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13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
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13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
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1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12],
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# S4
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[7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
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13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
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10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
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3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14],
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# S5
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[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
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14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
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4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
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11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3],
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# S6
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[12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
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10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
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9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
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4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13],
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# S7
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[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
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13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
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1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
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6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12],
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# S8
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[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
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1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
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7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
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2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11], ]
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# 32-bit permutation function P used on the output of the S-boxes
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__p = [15, 6, 19, 20, 28, 11,
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27, 16, 0, 14, 22, 25,
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4, 17, 30, 9, 1, 7,
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23, 13, 31, 26, 2, 8,
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18, 12, 29, 5, 21, 10,
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3, 24]
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# Final permutation IP^-1
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__fp = [39, 7, 47, 15, 55, 23, 63, 31,
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38, 6, 46, 14, 54, 22, 62, 30,
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37, 5, 45, 13, 53, 21, 61, 29,
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36, 4, 44, 12, 52, 20, 60, 28,
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35, 3, 43, 11, 51, 19, 59, 27,
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34, 2, 42, 10, 50, 18, 58, 26,
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33, 1, 41, 9, 49, 17, 57, 25,
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32, 0, 40, 8, 48, 16, 56, 24]
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# Type of crypting being done
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ENCRYPT = 0x00
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DECRYPT = 0x01
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# Initialisation
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def __init__(self, key, iv=None):
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# Sanity checking of arguments
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if len(key) != 8:
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raise ValueError("Invalid DES key size. Key must be exactly "
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"8 bytes long")
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super(Des, self).__init__(iv)
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self.key_size = 8
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self._l = []
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self._r = []
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self._kn = [[0] * 48] * 16 # 16 48-bit keys (K1 - K16)
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self._final = []
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self.set_key(key)
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def set_key(self, key):
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"""Set the crypting key for this object. Must be 8 bytes."""
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self.key = key
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self.__create_sub_keys()
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def __string_to_bitlist(self, data):
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"""Turn the string data into a list of bits (1, 0)'s."""
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if PY_VER < (3, ):
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# Turn the strings into integers. Python 3 uses a bytes
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# class, which already has this behaviour
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if not isinstance(data, bytearray):
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data = [ord(c) for c in data]
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len_data = len(data) * 8
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result = [0] * len_data
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pos = 0
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for ch in data:
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i = 7
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while i >= 0:
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if ch & (1 << i) != 0:
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result[pos] = 1
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else:
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result[pos] = 0
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pos += 1
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i -= 1
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return result
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def __bitlist_to_string(self, data):
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"""Turn the data as list of bits into a string."""
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result = []
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pos = 0
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c = 0
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while pos < len(data):
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c += data[pos] << (7 - (pos % 8))
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if (pos % 8) == 7:
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result.append(c)
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c = 0
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pos += 1
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if PY_VER < (3, ):
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return ''.join([chr(c) for c in result])
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else:
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return bytes(result)
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def __permutate(self, table, block):
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"""Permutate this block with the specified table."""
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return [block[x] for x in table]
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def __create_sub_keys(self):
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"""Transform the secret key for data processing.
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Create the 16 subkeys k[1] to k[16] from the given key.
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"""
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key = self.__permutate(Des.__pc1,
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self.__string_to_bitlist(self.key))
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# Split into Left and Right sections
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self._l = key[:28]
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self._r = key[28:]
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for i in range(16):
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# Perform circular left shifts
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for _ in range(Des.__left_rotations[i]):
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self._l.append(self._l[0])
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del self._l[0]
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self._r.append(self._r[0])
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del self._r[0]
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# Create one of the 16 subkeys through pc2 permutation
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self._kn[i] = self.__permutate(Des.__pc2, self._l + self._r)
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def __des_crypt(self, block, crypt_type):
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"""Crypt the block of data through DES bit-manipulation."""
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block = self.__permutate(Des.__ip, block)
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self._l = block[:32]
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self._r = block[32:]
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# Encryption starts from _kn[1] through to _kn[16]
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if crypt_type == Des.ENCRYPT:
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iteration = 0
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iteration_adjustment = 1
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# Decryption starts from _kn[16] down to _kn[1]
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else:
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iteration = 15
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iteration_adjustment = -1
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for _ in range(16):
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# Make a copy of _r[i-1], this will later become _l[i]
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temp_r = self._r[:]
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# Permutate _r[i - 1] to start creating _r[i]
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self._r = self.__permutate(Des.__expansion_table, self._r)
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# Exclusive or _r[i - 1] with k[i], create b[1] to b[8] whilst here
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self._r = [x ^ y for x, y in zip(self._r, self._kn[iteration])]
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b = [self._r[:6], self._r[6:12], self._r[12:18], self._r[18:24],
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self._r[24:30], self._r[30:36], self._r[36:42], self._r[42:]]
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# Permutate b[1] to b[8] using the S-Boxes
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bn = [0] * 32
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pos = 0
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for j in range(8):
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# Work out the offsets
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m = (b[j][0] << 1) + b[j][5]
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n = (b[j][1] << 3) + (b[j][2] << 2) + (b[j][3] << 1) + b[j][4]
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# Find the permutation value
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v = Des.__sbox[j][(m << 4) + n]
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# Turn value into bits, add it to result: bn
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bn[pos] = (v & 8) >> 3
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bn[pos + 1] = (v & 4) >> 2
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bn[pos + 2] = (v & 2) >> 1
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bn[pos + 3] = v & 1
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pos += 4
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# Permutate the concatination of b[1] to b[8] (bn)
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self._r = self.__permutate(Des.__p, bn)
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# Xor with _l[i - 1]
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self._r = [x ^ y for x, y in zip(self._r, self._l)]
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self._l = temp_r
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iteration += iteration_adjustment
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# Final permutation of _r[16]_l[16]
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self._final = self.__permutate(Des.__fp, self._r + self._l)
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return self._final
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def crypt(self, data, crypt_type):
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"""Crypt the data in blocks, running it through des_crypt()."""
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iv = self.__string_to_bitlist(self.iv)
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# Split the data into blocks, crypting each one seperately
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i = 0
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result = []
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while i < len(data):
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# Test code for caching encryption results
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block = self.__string_to_bitlist(data[i:i+8])
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# Xor with iv if using CBC mode
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if crypt_type == Des.ENCRYPT:
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block = [x ^ y for x, y in zip(block, iv)]
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processed_block = self.__des_crypt(block, crypt_type)
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if crypt_type == Des.DECRYPT:
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processed_block = [x ^ y for x, y in zip(processed_block, iv)]
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iv = block
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else:
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iv = processed_block
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# Add the resulting crypted block to our list
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result.append(self.__bitlist_to_string(processed_block))
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i += 8
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# Return the full crypted string
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return b''.join(result)
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#############################################
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# Triple DES #
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#############################################
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class Python_TripleDES(_baseDes):
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"""Triple DES encryption/decrytpion class.
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This algorithm uses the DES-EDE3 (when a 24 byte key is supplied) or
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the DES-EDE2 (when a 16 byte key is supplied) encryption methods.
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Supports CBC (Cypher Block Chaining) mode.
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"""
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def __init__(self, key, iv=None):
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self.block_size = 8
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if iv:
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if len(iv) != self.block_size:
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raise ValueError("Invalid Initialization Vector (iv) must be"
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" {0} bytes long".format(self.block_size))
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iv = self._guard_against_unicode(iv)
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else:
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raise ValueError("Initialization Vector (iv) must be supplied")
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super(Python_TripleDES, self).__init__(iv)
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# Will set crypting key for this object. Either 16/24 bytes long.
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self.key_size = len(key)
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if self.key_size not in (16, 24):
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raise ValueError("Invalid triple DES key size. "
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"Key must be either 16 or 24 bytes long")
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key = self._guard_against_unicode(key)
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self.__key1 = Des(key[:8], self.iv)
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self.__key2 = Des(key[8:16], self.iv)
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if self.key_size == 16:
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self.__key3 = Des(key[:8], self.iv)
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else:
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self.__key3 = Des(key[16:], self.iv)
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self.isAEAD = False
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self.isBlockCipher = True
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self.name = "3des"
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self.implementation = "python"
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self.__key1.iv = self.iv
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self.__key2.iv = self.iv
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self.__key3.iv = self.iv
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def encrypt(self, data):
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"""Encrypt data and return bytes.
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data : bytes to be encrypted
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The data must be a multiple of 8 bytes and will be encrypted
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with the already specified key.
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"""
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ENCRYPT = Des.ENCRYPT
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DECRYPT = Des.DECRYPT
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if not data:
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return bytearray(b'')
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data = self._guard_against_unicode(data)
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if len(data) % self.block_size:
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raise ValueError("Invalid data length, must be a multiple "
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"of {0} bytes".format(self.block_size))
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i = 0
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result = []
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while i < len(data):
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block = self.__key1.crypt(data[i:i+8], ENCRYPT)
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block = self.__key2.crypt(block, DECRYPT)
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block = self.__key3.crypt(block, ENCRYPT)
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self.__key1.iv = block
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self.__key2.iv = block
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self.__key3.iv = block
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result.append(block)
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i += 8
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return bytearray(b''.join(result))
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def decrypt(self, data):
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"""Decrypt data and return bytes.
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data : bytes to be encrypted
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The data must be a multiple of 8 bytes and will be decrypted
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with the already specified key.
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"""
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ENCRYPT = Des.ENCRYPT
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DECRYPT = Des.DECRYPT
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if not data:
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return bytearray(b'')
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data = self._guard_against_unicode(data)
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if len(data) % self.block_size:
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raise ValueError("Invalid data length, must be a multiple "
|
|
"of {0} bytes".format(self.block_size))
|
|
|
|
i = 0
|
|
result = []
|
|
while i < len(data):
|
|
iv = data[i:i+8]
|
|
block = self.__key3.crypt(iv, DECRYPT)
|
|
block = self.__key2.crypt(block, ENCRYPT)
|
|
block = self.__key1.crypt(block, DECRYPT)
|
|
self.__key1.iv = iv
|
|
self.__key2.iv = iv
|
|
self.__key3.iv = iv
|
|
result.append(block)
|
|
i += 8
|
|
data = b''.join(result)
|
|
|
|
return bytearray(data)
|