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des.py
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des.py
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import os
import binascii
import sys
__author__ = 'jadeszek'
B_SIZE = 64 # block size
# The 64 bits of the input block to be enciphered are first subjected to the following permutation,
# called the initial permutation IP:
IP = [i - 1 for i in [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]
]
IP_INV = [i - 1 for i in [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]
]
# Let E denote a function which takes a block of 32 bits as input and yields a block of 48 bits as
# output. Let E be such that the 48 bits of its output, written as 8 blocks of 6 bits each, are
# obtained by selecting the bits in its inputs in order according to the following table:
E = [i - 1 for i in [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]
]
S = [
[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]
]
P = [i - 1 for i in [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]
]
PC = [
[i - 1 for i in [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]
],
[i - 1 for i in [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
]
]
]
KEY_SHIFT = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
def log(bin_list, width=8):
s = ""
i = 0
for b in bin_list:
s += str(b)
i += 1
if i % width == 0:
s += " "
return s
def apply_permutation(byte_block, perm):
result = [0] * len(perm)
i = 0
for p in perm:
result[i] = byte_block[p]
i += 1
return result
def init(byte_block):
return apply_permutation(byte_block, IP)
def split_block(byte_block):
half = len(byte_block) / 2
return [byte_block[:half], byte_block[half:]]
def left_shift(block, step):
return block[step:] + block[:step]
def right_shift(block, step):
return left_shift(block, -step)
def generate_keys(base_key): # key in byte form
KP = apply_permutation(base_key, PC[0])
# # print "K_PC1", log(permuted, 6)
C, D = split_block(KP)
keys = []
for i in range(16):
shift = KEY_SHIFT[i]
C = left_shift(C, shift)
D = left_shift(D, shift)
# # print "C", i+1, log(C, 6)
# # print "D", i+1, log(D, 6)
CD = unite(C, D)
# print "CD[%s]: " % str(i + 1), log(CD, 7)
K = apply_permutation(CD, PC[1])
# print "KS[%s]: " % str(i + 1), log(K, 6)
keys.append(K)
return keys
def dec2bin(decimal, width=4):
return [int(d) for d in bin(decimal)[2:].zfill(width)]
def bin2dec(bin_list):
# print ">>", reduce(lambda x, y: str(x) + str(y), bin_list)
# print ">>", int(reduce(lambda x, y: str(x) + str(y), bin_list), 2)
return int(reduce(lambda x, y: str(x) + str(y), bin_list), 2)
def get_sbox_coordinates(six_byte_chunk):
row_bin = [six_byte_chunk[0]] + [six_byte_chunk[-1]]
column_bin = six_byte_chunk[1:-1]
# # print(row_bin, column_bin)
return bin2dec(row_bin), bin2dec(column_bin)
def apply_sbox(chunk, sbox):
row, col = get_sbox_coordinates(chunk)
number = sbox[row * 16 + col]
# # print "(", row, ",", col, ") ->", number
return dec2bin(number)
def xor(A, B):
return [a ^ b for a, b in zip(A, B)]
def unite(left_block, right_block):
return left_block + right_block
def string2bin(text):
result = []
for c in text:
result += dec2bin(ord(c), 8)
return result
def bin2hex(bin_list):
result = hex(bin2dec(bin_list))
# print ">>", result
if result[-1] == 'L':
result = result[:-1] # without L
result = "0x" + result[2:].zfill(16)
return result
def final(byte_block):
return apply_permutation(byte_block, IP_INV)
test = [0, 0, 0, 1, 0, 1, 1, 0,
1, 0, 1, 1, 1, 1, 0, 1,
0, 1, 0, 0, 0, 0, 0, 1,
1, 0, 0, 1, 0, 1, 0, 0,
1, 0, 1, 1, 0, 1, 0, 0,
0, 1, 0, 1, 0, 0, 1, 1,
1, 0, 0, 0, 1, 0, 1, 0,
0, 1, 1, 1, 1, 0, 1, 0, ]
key = [1, 1, 1, 1, 0, 1, 1, 0,
1, 0, 1, 1, 1, 1, 0, 1,
0, 1, 0, 0, 0, 0, 0, 1,
1, 0, 0, 1, 0, 1, 0, 0,
1, 0, 1, 1, 0, 1, 0, 0,
0, 1, 0, 1, 0, 1, 1, 1,
1, 0, 0, 0, 1, 0, 1, 0,
0, 1, 1, 1, 1, 0, 1, 1, ]
# t = 0x0123456789ABCDEF # "01234567"
def encode_des(block, key):
# print "block", len(block), log(block)
# print "key", len(key), log(key)
keys = generate_keys(key)
des = DES(block, keys)
res = bin2hex(des)
# print "DEBUG: "
# print log(des, 8)
# print res
return res
def decode_des(block, key):
# print "block", len(block), log(block)
# print "key", len(key), log(key)
keys = generate_keys(key)[::-1]
return bin2hex(DES(block, keys))
def f(right_block, key, iter):
# print "\n >>> round", iter + 1, "\n"
permuted = apply_permutation(right_block, E)
# print "E", len(permuted), log(permuted, 6)
# print "KS", iter + 1, len(key), log(key, 6)
# assert len(permuted) == len(key)
xored = xor(permuted, key)
# print "E ^ KS", len(xored), log(xored, 6)
six_byte_chunks = [xored[i:i + 6] for i in range(0, len(xored), 6)]
# # print "six_byte_chunks ", log(six_byte_chunks)
sbox_out = [apply_sbox(chunk, sbox) for chunk, sbox in zip(six_byte_chunks, S)]
sbox_out = reduce(lambda c1, c2: c1 + c2, sbox_out)
# print "Sbox", len(sbox_out), log(sbox_out, 4)
return apply_permutation(sbox_out, P)
def DES(block, keys):
permuted = init(block)
# print "permuted", len(permuted), log(permuted)
L, R = split_block(permuted)
# print "L", 0, len(L), log(L)
# print "R", 0, len(R), log(R)
for i in range(16):
Rf = f(R, keys[i], i)
# print "Rf", i + 1, log(Rf)
L, R = R, xor(Rf, L)
# print "L", i + 1, len(L), log(L)
# print "R", i + 1, len(R), log(R)
united = unite(R, L)
# print "united", len(united), log(united)
result = final(united)
# print "result", len(result), log(result)
return result
def padd(block):
size = len(block)
block += "\x10"
block += (8 - size - 1) * "\x00"
return block
def read_in_blocks(file):
while True:
block = file.read(8)
if block:
# print "p", block,
if len(block) < 8:
block = padd(block)
# print "x",
# print block
yield binascii.hexlify(block)
else:
return
def trunc(file):
BYTES = 8
file.seek(-BYTES, os.SEEK_END)
block = file.read(BYTES)
h = binascii.hexlify(block)
# print h
# print h[::-1]
trunc_counter = 0
for b in h[::-1]:
if b == "1":
break
trunc_counter += 1
if trunc_counter == 0: # no trailing zeros
return file
# print "tc:", trunc_counter
if h[::-1][trunc_counter] == "1":
# print "ciach"
file.seek(-(trunc_counter + 1) / 2,
os.SEEK_END) # some magic here, should be fixed later, but deadline is tomorrow
file.truncate()
return file
def get_fake_block():
print binascii.hexlify("\x10" + "\x00" * 7)
return binascii.hexlify("\x10" + "\x00" * 7)
def des_file(file, key, encode=True):
size = os.path.getsize(file)
input = open(file, 'rb')
output = open(file + '.out', 'w+b')
should_be_padded = (size % 8 != 0)
proc = 0
i = 0
for block in read_in_blocks(input):
# print ":", block, "->",
if encode:
e = encode_des(dec2bin(int(block, 16), 64), dec2bin(key, 64))[2:]
else:
e = decode_des(dec2bin(int(block, 16), 64), dec2bin(key, 64))[2:]
# print binascii.unhexlify(e[2:])
output.write(binascii.unhexlify(e))
new_proc = int(100 * (1.0 * i / size))
if proc != new_proc:
proc = new_proc
sys.stderr.write(str(proc) + "% \n")
i += 8
if encode and not should_be_padded:
e = encode_des(dec2bin(int(get_fake_block(), 16), 64), dec2bin(key, 64))[2:]
output.write(binascii.unhexlify(e))
if not encode:
output = trunc(output)
input.close()
output.close()
sys.stderr.write(str(100) + "% \n")
if __name__=="__main__":
k = 0x3b3898371520f75e
if len(sys.argv) == 1:
files = ["input"]
else:
files = sys.argv[1:]
for file in files:
sys.stderr.write("Encode " + file + "\n")
des_file(file, k)
sys.stderr.write("Decode " + file + "\n")
des_file(file + ".out", k, False)