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not_des.py
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not_des.py
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#!/usr/bin/env python3
import functools
import struct
KEY_SIZE = 8
BLOCK_SIZE = 8
# yapf: disable
# Note the 1-based indexing in all the following tables.
IP = [
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 = [
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,
]
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,
]
PC1_C = [
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,
]
PC1_D = [
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,
]
PC2 = [
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,
]
KS_SHIFTS = [1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1]
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,
]
S1 = [
[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],
]
S2 = [
[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],
]
S3 = [
[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],
]
S4 = [
[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],
]
S5 = [
[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],
]
S6 = [
[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],
]
S7 = [
[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],
]
S8 = [
[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],
]
# yapf: enable
SBOXES = [S6, S4, S1, S5, S3, S2, S8, S7]
def Xor(b1, b2):
"""Xors two bit vectors together."""
return [x ^ y for x, y in zip(b1, b2)]
def Concat(*vectors):
"""Concats vectors."""
return functools.reduce(lambda x, y: x + y, vectors, [])
def Str2Bits(s):
"""Converts a string to a vector of bits."""
assert (isinstance(s, bytes))
def Char2Bits(num):
bits = bin(num)[2:]
bits = '0' * (8 - len(bits)) + bits
return [int(b) for b in bits]
return Concat(* [Char2Bits(c) for c in s])
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 Expand(v):
"""Expands 32bits into 48 bits."""
assert (len(v) == 32)
return [v[E[i] - 1] for i in range(48)]
def LeftShift(v, t=1):
"""Left shitfs (rotates) a vector of bits t times."""
return v[t:] + v[:t]
def KeyScheduler(key):
"""Yields round keys."""
assert (len(key) == 64)
# Only 56 bits are used. A bit in each byte is reserved for pairity checks.
C = [key[PC1_C[i] - 1] for i in range(28)]
D = [key[PC1_D[i] - 1] for i in range(28)]
for ri in range(16):
C = LeftShift(C, KS_SHIFTS[ri])
D = LeftShift(D, KS_SHIFTS[ri])
CD = Concat(C, D)
ki = [CD[PC2[i] - 1] for i in range(48)]
yield ki
def CipherFunction(key, inp):
"""Single confusion-diffusion step."""
assert (len(key) == 48)
assert (len(inp) == 32)
# Confusion step.
res = Xor(Expand(inp), key)
sbox_out = []
for si in range(48 // 6):
sbox_inp = res[6 * si:6 * si + 6]
sbox = SBOXES[si]
row = (int(sbox_inp[0]) << 1) + int(sbox_inp[-1])
col = int(''.join([str(b) for b in sbox_inp[1:5]]), 2)
bits = bin(sbox[row][col])[2:]
bits = '0' * (4 - len(bits)) + bits
sbox_out += [int(b) for b in bits]
# Diffusion step.
res = sbox_out
res = [res[P[i] - 1] for i in range(32)]
return res
def DESEncrypt(plaintext, key):
if isinstance(key, bytes):
key = Str2Bits(key)
assert (len(key) == 64)
if isinstance(plaintext, bytes):
plaintext = Str2Bits(plaintext)
# Initial permutation.
plaintext = [plaintext[IP[i] - 1] for i in range(64)]
L, R = plaintext[:32], plaintext[32:]
# Feistel network.
for ki in KeyScheduler(key):
L, R = R, Xor(L, CipherFunction(ki, R))
# Final permutation.
ciphertext = Concat(R, L)
ciphertext = [ciphertext[IP_INV[i] - 1] for i in range(64)]
return Bits2Str(ciphertext)
def DESDecrypt(ciphertext, key):
if isinstance(key, bytes):
key = Str2Bits(key)
assert (len(key) == 64)
if isinstance(ciphertext, bytes):
ciphertext = Str2Bits(ciphertext)
# Initial permutation.
ciphertext = [ciphertext[IP[i] - 1] for i in range(64)]
L, R = ciphertext[:32], ciphertext[32:]
# Feistel network.
for ki in reversed(list(KeyScheduler(key))):
L, R = R, Xor(L, CipherFunction(ki, R))
# Final permutation.
plaintext = Concat(R, L)
plaintext = [plaintext[IP_INV[i] - 1] for i in range(64)]
return Bits2Str(plaintext)