271 lines
10 KiB
Python
271 lines
10 KiB
Python
# -*- coding: utf8 -*-
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import binascii
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# Initial permut matrix for the datas
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PI = [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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64, 56, 48, 40, 32, 24, 16, 8,
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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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# Initial permut made on the key
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CP_1 = [57, 49, 41, 33, 25, 17, 9,
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1, 58, 50, 42, 34, 26, 18,
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10, 2, 59, 51, 43, 35, 27,
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19, 11, 3, 60, 52, 44, 36,
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63, 55, 47, 39, 31, 23, 15,
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7, 62, 54, 46, 38, 30, 22,
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14, 6, 61, 53, 45, 37, 29,
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21, 13, 5, 28, 20, 12, 4]
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# Permut applied on shifted key to get Ki+1
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CP_2 = [14, 17, 11, 24, 1, 5, 3, 28,
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15, 6, 21, 10, 23, 19, 12, 4,
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26, 8, 16, 7, 27, 20, 13, 2,
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41, 52, 31, 37, 47, 55, 30, 40,
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51, 45, 33, 48, 44, 49, 39, 56,
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34, 53, 46, 42, 50, 36, 29, 32]
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# Expand matrix to get a 48bits matrix of datas to apply the xor with Ki
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E = [32, 1, 2, 3, 4, 5,
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4, 5, 6, 7, 8, 9,
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8, 9, 10, 11, 12, 13,
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12, 13, 14, 15, 16, 17,
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16, 17, 18, 19, 20, 21,
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20, 21, 22, 23, 24, 25,
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24, 25, 26, 27, 28, 29,
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28, 29, 30, 31, 32, 1]
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# SBOX
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S_BOX = [
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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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],
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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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],
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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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],
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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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],
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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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],
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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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],
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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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],
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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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]
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]
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# Permut made after each SBox substitution for each round
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P = [16, 7, 20, 21, 29, 12, 28, 17,
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1, 15, 23, 26, 5, 18, 31, 10,
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2, 8, 24, 14, 32, 27, 3, 9,
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19, 13, 30, 6, 22, 11, 4, 25]
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# Final permut for datas after the 16 rounds
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PI_1 = [40, 8, 48, 16, 56, 24, 64, 32,
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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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# Matrix that determine the shift for each round of keys
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SHIFT = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
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def string_to_bit_array(text): # Convert a string into a list of bits
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array = list()
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for char in text:
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binval = binvalue(char, 8) # Get the char value on one byte
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array.extend([int(x) for x in list(binval)]) # Add the bits to the final list
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return array
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def bit_array_to_string(array): # Recreate the string from the bit array
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res = ''.join([chr(int(y, 2)) for y in [''.join([str(x) for x in bytes]) for bytes in nsplit(array, 8)]])
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return res
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def binvalue(val, bitsize): # Return the binary value as a string of the given size
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binval = bin(val)[2:] if isinstance(val, int) else bin(ord(val))[2:]
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if len(binval) > bitsize:
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raise "binary value larger than the expected size"
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while len(binval) < bitsize:
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binval = "0" + binval # Add as many 0 as needed to get the wanted size
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return binval
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def nsplit(s, n): # Split a list into sublists of size "n"
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return [s[k:k + n] for k in range(0, len(s), n)]
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ENCRYPT = 1
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DECRYPT = 0
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class des():
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def __init__(self):
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self.password = None
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self.text = None
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self.keys = list()
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def run(self, key, text, action=ENCRYPT, padding=False):
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if len(key) < 8:
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raise "Key Should be 8 bytes long"
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elif len(key) > 8:
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key = key[:8] # If key size is above 8bytes, cut to be 8bytes long
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self.password = key
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self.text = text
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if padding and action == ENCRYPT:
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self.addPadding()
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elif len(self.text) % 8 != 0: # If not padding specified data size must be multiple of 8 bytes
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raise "Data size should be multiple of 8"
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self.generatekeys() # Generate all the keys
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text_blocks = nsplit(self.text, 8) # Split the text in blocks of 8 bytes so 64 bits
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result = list()
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for block in text_blocks: # Loop over all the blocks of data
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block = string_to_bit_array(block) # Convert the block in bit array
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block = self.permut(block, PI) # Apply the initial permutation
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g, d = nsplit(block, 32) # g(LEFT), d(RIGHT)
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tmp = None
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for i in range(16): # Do the 16 rounds
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d_e = self.expand(d, E) # Expand d to match Ki size (48bits)
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if action == ENCRYPT:
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tmp = self.xor(self.keys[i], d_e) # If encrypt use Ki
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else:
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tmp = self.xor(self.keys[15 - i], d_e) # If decrypt start by the last key
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tmp = self.substitute(tmp) # Method that will apply the SBOXes
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tmp = self.permut(tmp, P)
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tmp = self.xor(g, tmp)
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g = d
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d = tmp
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print(g, end="")
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print(d)
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print(hex(int("".join(str(x) for x in g+d), 2)))
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result += self.permut(d + g, PI_1) # Do the last permut and append the result to result
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print(" -------- ")
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print("Result : ",result)
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print(hex(int("".join(str(x) for x in result), 2)))
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print()
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final_res = bit_array_to_string(result)
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if padding and action == DECRYPT:
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return self.removePadding(final_res) # Remove the padding if decrypt and padding is true
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else:
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return final_res # Return the final string of data ciphered/deciphered
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def substitute(self, d_e): # Substitute bytes using SBOX
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subblocks = nsplit(d_e, 6) # Split bit array into sublist of 6 bits
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result = list()
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for i in range(len(subblocks)): # For all the sublists
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block = subblocks[i]
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row = int(str(block[0]) + str(block[5]), 2) # Get the row with the first and last bit
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column = int(''.join([str(x) for x in block[1:][:-1]]), 2) # Column is the 2,3,4,5th bits
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val = S_BOX[i][row][column] # Take the value in the SBOX appropriated for the round (i)
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bin = binvalue(val, 4) # Convert the value to binary
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result += [int(x) for x in bin] # And append it to the resulting list
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return result
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def permut(self, block, table): # Permut the given block using the given table (so generic method)
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return [block[x - 1] for x in table]
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def expand(self, block, table): # Do the exact same thing than permut but for more clarity has been renamed
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return [block[x - 1] for x in table]
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def xor(self, t1, t2): # Apply a xor and return the resulting list
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return [x ^ y for x, y in zip(t1, t2)]
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def generatekeys(self): # Algorithm that generates all the keys
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self.keys = []
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key = string_to_bit_array(self.password)
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key = self.permut(key, CP_1) # Apply the initial permut on the key
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g, d = nsplit(key, 28) # Split it in to (g->LEFT),(d->RIGHT)
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for i in range(16): # Apply the 16 rounds
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g, d = self.shift(g, d, SHIFT[i]) # Apply the shift associated with the round (not always 1)
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tmp = g + d # Merge them
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self.keys.append(self.permut(tmp, CP_2)) # Apply the permut to get the Ki
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def shift(self, g, d, n): # Shift a list of the given value
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return g[n:] + g[:n], d[n:] + d[:n]
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def addPadding(self): # Add padding to the datas using PKCS5 spec.
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pad_len = 8 - (len(self.text) % 8)
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self.text += pad_len * chr(pad_len)
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def removePadding(self, data): # Remove the padding of the plain text (it assume there is padding)
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pad_len = ord(data[-1])
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return data[:-pad_len]
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def encrypt(self, key, text, padding=False):
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return self.run(key, text, ENCRYPT, padding)
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def decrypt(self, key, text, padding=False):
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return self.run(key, text, DECRYPT, padding)
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def flip(txt, pos):
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if len(text) > pos:
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if txt[pos] == 1:
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txt[pos] = 0
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else:
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txt[pos] = 1
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if __name__ == '__main__':
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key_hex = b'02468aceeca86420'
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key = binascii.unhexlify(key_hex)
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text_hex = b'0f1571c947d9e859'
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text = binascii.unhexlify(text_hex)
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print(text)
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d = des()
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r = d.encrypt(key, text)
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r2 = d.decrypt(key, r)
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print("Ciphered: %r" % r)
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print("Ciphered: %r" % binascii.hexlify(r.encode('latin1')))
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print("Deciphered: %r" % r2)
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print("Deciphered: %r" % binascii.hexlify(r2.encode('latin1')))
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