DES
Π‘Π»Π°Π±ΡΠ΅ ΠΊΠ»ΡΡΠΈ DES: E(x, key) = x (Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎ, Π½Π΅ Π΄Π»Ρ Π²ΡΠ΅Ρ
x)
=================
0101-0101-0101-0101
FEFE-FEFE-FEFE-FEFE
1F1F-1F1F-0E0E-0E0E
E0E0-E0E0-F1F1-F1F1
Π§Π°ΡΡΠΈΡΠ½ΠΎ ΡΠ»Π°Π±ΡΠ΅ ΠΊΠ»ΡΡΠΈ: E(E(x, key1), key2) = x (Π²ΡΠΎΠ΄Π΅, Π΄Π»Ρ Π²ΡΠ΅Ρ
x)
==================
key1, key2:
01FE-01FE-01FE-01FE,----FE01-FE01-FE01-FE01
1FE0-1FE0-1FE0-1FE0,----E0F1-E0F1-E0F1-E0F1
01E0-01E0-01F1-01F1,----E001-E001-F101-F101
1FFE-1FFE-0EFE-0EFE,----FE1F-FE1F-FE0E-FE0E
011F-011F-010E-010E,----1F01-1F01-0E01-0E01
E0FE-E0FE-F1FE-F1FE,----FEE0-FEE0-FEF1-FEF1
!!! ΠΠ΅ΡΠ΅ΠΌΠ΅Π½Π° sbox ΠΌΠ΅ΡΡΠ°ΠΌΠΈ Π½Π΅ Π²Π»ΠΈΡΠ΅Ρ Π½Π° ΡΠ»Π°Π±ΡΠ΅ ΠΊΠ»ΡΡΠΈ
ΠΡΠΈΠΌΠ΅Ρ DES Π½Π° python
# -*- coding: utf8 -*-
import struct
from binascii import hexlify, unhexlify
# Initial permut matrix for the datas
PI = [58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7]
# Initial permut made on the key
CP_1 = [57, 49, 41, 33, 25, 17, 9,
1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27,
19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15,
7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29,
21, 13, 5, 28, 20, 12, 4]
# Permut applied on shifted key to get Ki+1
CP_2 = [14, 17, 11, 24, 1, 5, 3, 28,
15, 6, 21, 10, 23, 19, 12, 4,
26, 8, 16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55, 30, 40,
51, 45, 33, 48, 44, 49, 39, 56,
34, 53, 46, 42, 50, 36, 29, 32]
# Expand matrix to get a 48bits matrix of datas to apply the xor with Ki
E = [32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1]
# SBOX
S_BOX = [
[[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7],
[0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8],
[4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0],
[15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13],
],
[[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10],
[3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5],
[0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15],
[13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9],
],
[[10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8],
[13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1],
[13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7],
[1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12],
],
[[7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15],
[13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9],
[10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4],
[3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14],
],
[[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9],
[14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6],
[4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14],
[11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3],
],
[[12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11],
[10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8],
[9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6],
[4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13],
],
[[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1],
[13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6],
[1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2],
[6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12],
],
[[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7],
[1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2],
[7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8],
[2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11],
]
]
# Permut made after each SBox substitution for each round
P = [16, 7, 20, 21, 29, 12, 28, 17,
1, 15, 23, 26, 5, 18, 31, 10,
2, 8, 24, 14, 32, 27, 3, 9,
19, 13, 30, 6, 22, 11, 4, 25]
# Final permut for datas after the 16 rounds
PI_1 = [40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25]
# Matrix that determine the shift for each round of keys
SHIFT = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
def Bits2Str(v):
"""Converts a vector of bits to a string."""
def Bits2Char(byte):
return struct.pack('>B', int(''.join([str(b) for b in byte]), 2))
return b''.join([Bits2Char(v[8 * i:8 * i + 8]) for i in range(len(v) // 8)])
def string_to_bit_array(text): # Convert a string into a list of bits
array = list()
for char in text:
binval = binvalue(char, 8) # Get the char value on one byte
array.extend([int(x) for x in list(binval)]) # Add the bits to the final list
return array
def bit_array_to_string(array): # Recreate the string from the bit array
return Bits2Str(array)
res = ''.join([chr(int(y, 2)) for y in [''.join([str(x) for x in bytes]) for bytes in nsplit(array, 8)]])
return res
def binvalue(val, bitsize): # Return the binary value as a string of the given size
binval = bin(val)[2:] if isinstance(val, int) else bin(ord(val))[2:]
if len(binval) > bitsize:
raise "binary value larger than the expected size"
while len(binval) < bitsize:
binval = "0" + binval # Add as many 0 as needed to get the wanted size
return binval
def nsplit(s, n): # Split a list into sublists of size "n"
return [s[k:k + n] for k in range(0, len(s), n)]
ENCRYPT = 1
DECRYPT = 0
class des():
def __init__(self):
self.password = None
self.text = None
self.keys = list()
def run(self, key, text, action=ENCRYPT, padding=False):
if len(key) < 8:
raise "Key Should be 8 bytes long"
elif len(key) > 8:
key = key[:8] # If key size is above 8bytes, cut to be 8bytes long
self.password = key
self.text = text
if padding and action == ENCRYPT:
self.addPadding()
elif len(self.text) % 8 != 0: # If not padding specified data size must be multiple of 8 bytes
raise "Data size should be multiple of 8"
print("INIT KEYS")
self.generatekeys() # Generate all the keys
print("END INIT KEYS")
text_blocks = nsplit(self.text, 8) # Split the text in blocks of 8 bytes so 64 bits
result = list()
for block in text_blocks: # Loop over all the blocks of data
block = string_to_bit_array(block) # Convert the block in bit array
block = self.permut(block, PI) # Apply the initial permutation
g, d = nsplit(block, 32) # g(LEFT), d(RIGHT)
tmp = None
for i in range(16): # Do the 16 rounds
print(hexlify(Bits2Str(g)), hexlify(Bits2Str(d)))
# step 1
print("0", hexlify(Bits2Str(d)))
d_e = self.expand(d, E) # Expand d to match Ki size (48bits)
if action == ENCRYPT:
tmp = self.xor(self.keys[i], d_e) # If encrypt use Ki
else:
tmp = self.xor(self.keys[15 - i], d_e) # If decrypt start by the last key
# step 2
print("1", hexlify(Bits2Str(tmp)))
tmp = self.substitute(tmp) # Method that will apply the SBOXes
print("2", hexlify(Bits2Str(tmp)))
# step 3
tmp = self.permut(tmp, P)
print("3", hexlify(Bits2Str(tmp)))
# step 4
tmp = self.xor(g, tmp)
g = d
d = tmp
print("4", hexlify(Bits2Str(d)))
pass
result += self.permut(d + g, PI_1) # Do the last permut and append the result to result
final_res = bit_array_to_string(result)
if padding and action == DECRYPT:
return self.removePadding(final_res) # Remove the padding if decrypt and padding is true
else:
return final_res # Return the final string of data ciphered/deciphered
def substitute(self, d_e): # Substitute bytes using SBOX
subblocks = nsplit(d_e, 6) # Split bit array into sublist of 6 bits
result = list()
for i in range(len(subblocks)): # For all the sublists
block = subblocks[i]
row = int(str(block[0]) + str(block[5]), 2) # Get the row with the first and last bit
column = int(''.join([str(x) for x in block[1:][:-1]]), 2) # Column is the 2,3,4,5th bits
val = S_BOX[i][row][column] # Take the value in the SBOX appropriated for the round (i)
bin = binvalue(val, 4) # Convert the value to binary
result += [int(x) for x in bin] # And append it to the resulting list
return result
def permut(self, block, table): # Permut the given block using the given table (so generic method)
return [block[x - 1] for x in table]
def expand(self, block, table): # Do the exact same thing than permut but for more clarity has been renamed
return [block[x - 1] for x in table]
def xor(self, t1, t2): # Apply a xor and return the resulting list
return [x ^ y for x, y in zip(t1, t2)]
def generatekeys(self): # Algorithm that generates all the keys
self.keys = []
key = string_to_bit_array(self.password)
key = self.permut(key, CP_1) # Apply the initial permut on the key
g, d = nsplit(key, 28) # Split it in to (g->LEFT),(d->RIGHT)
for i in range(16): # Apply the 16 rounds
g, d = self.shift(g, d, SHIFT[i]) # Apply the shift associated with the round (not always 1)
tmp = g + d # Merge them
kkk = self.permut(tmp, CP_2)
print(hexlify(Bits2Str(kkk)))
self.keys.append(kkk) # Apply the permut to get the Ki
def shift(self, g, d, n): # Shift a list of the given value
return g[n:] + g[:n], d[n:] + d[:n]
def addPadding(self): # Add padding to the datas using PKCS5 spec.
pad_len = 8 - (len(self.text) % 8)
self.text += pad_len * chr(pad_len)
def removePadding(self, data): # Remove the padding of the plain text (it assume there is padding)
pad_len = ord(data[-1])
return data[:-pad_len]
def encrypt(self, key, text, padding=False):
return self.run(key, text, ENCRYPT, padding)
def decrypt(self, key, text, padding=False):
return self.run(key, text, DECRYPT, padding)
def test():
k1 = unhexlify('01FE01FE01FE01FE')
k2 = unhexlify('FE01FE01FE01FE01')
d = des()
test = d.encrypt(k2, d.encrypt(k1, 'testtest'))
P = unhexlify('771DF32699DF2F2A')
notP = unhexlify('88E20CD96620D0D5')
if __name__ == '__main__':
key = "11111111"
text = "11111111"
test()
#d = des()
#r = d.encrypt(key, text)
#r2 = d.decrypt(key, r)
#print( hexlify(r))
#print("Deciphered: ", r2)
Last updated