-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathdes.py
150 lines (124 loc) · 7.84 KB
/
des.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
from itertools import accumulate, batched
from Cryptodome.Cipher import DES
class Block:
def __init__(self, string_or_bytes: str | bytes, is_binary_string: bool = False):
if is_binary_string:
bit_size = len(string_or_bytes)
block = string_or_bytes
else:
bit_size = len(string_or_bytes) * 8
block = int.from_bytes(string_or_bytes, byteorder='big')
block = bin(block)[2:].zfill(bit_size)
self.block = block
self.bit_size = bit_size
def __str__(self):
return self.block
def __xor__(self, other):
value = int(self.block, 2) ^ int(other.block, 2)
binary_string = bin(value)[2:].zfill(self.bit_size)
return Block(binary_string, is_binary_string=True)
def __getitem__(self, index):
if isinstance(index, slice):
start, stop, step = index.start, index.stop, index.step
return Block(self.block[start:stop:step], is_binary_string=True)
return self.block[index]
def __lshift__(self, n):
return self[n:] + self[:n]
def __add__(self, other):
return Block(self.block + other.block, is_binary_string=True)
def __bytes__(self):
return int(self.block, 2).to_bytes(self.bit_size // 8, byteorder='big')
def map_with_table(self, table: list[int]) -> 'Block':
binary_string = ''.join(map(lambda x: self[x - 1], table))
return Block(binary_string, is_binary_string=True)
class MyDES:
def __init__(self, key: bytes):
self.key = key
def encrypt(self, plaintext: bytes) -> bytes:
return self.encrypt_or_decrypt(plaintext)
def decrypt(self, ciphertext: bytes) -> bytes:
return self.encrypt_or_decrypt(ciphertext, is_encrypt=False)
def encrypt_or_decrypt(self, data: bytes, is_encrypt: bool = True) -> bytes:
key_block = Block(self.key)
data_block = Block(data)
round_key_blocks = MyDES.get_round_keys(key_block)
if not is_encrypt:
round_key_blocks.reverse()
L, R = MyDES.IP(data_block)
for round_key_block in round_key_blocks:
L, R = R, L ^ MyDES.f(R, round_key_block)
L, R = R, L
data_block = MyDES.IP_inverse(L + R)
return bytes(data_block)
@staticmethod
def PC1(block: Block) -> tuple[Block, Block]:
table = [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]
block = block.map_with_table(table)
half_block_size = block.bit_size // 2
return block[:half_block_size], block[half_block_size:]
@staticmethod
def PC2(block: Block) -> Block:
table = [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]
return block.map_with_table(table)
@staticmethod
def get_round_keys(key_block: Block) -> list[Block]:
table = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
L, R = MyDES.PC1(key_block)
L_R_pairs = map(lambda x: (L << x, R << x), accumulate(table))
round_keys = list(map(lambda L_R_pair: MyDES.PC2(L_R_pair[0] + L_R_pair[1]), L_R_pairs))
return round_keys
@staticmethod
def IP(block: Block) -> tuple[Block, Block]:
table = [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]
block = block.map_with_table(table)
half_block_size = block.bit_size // 2
return block[:half_block_size], block[half_block_size:]
@staticmethod
def E(block: Block) -> Block:
table = [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]
return block.map_with_table(table)
@staticmethod
def S(block: Block) -> Block:
tables = [
[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],
]
row_col_pairs = map(lambda batch: (int(batch[0] + batch[-1], 2), int(''.join(batch[1:-1]), 2)), batched(block, 6))
indexes = map(lambda row_col_pair: row_col_pair[0] * 16 + row_col_pair[1], row_col_pairs)
values = map(lambda table_output_index_pair: tables[table_output_index_pair[0]][table_output_index_pair[1]], enumerate(indexes))
binary_string = ''.join(map(lambda x: bin(x)[2:].zfill(4), values))
return Block(binary_string, is_binary_string=True)
@staticmethod
def P(block: Block) -> Block:
table = [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]
return block.map_with_table(table)
@staticmethod
def f(R: Block, round_key_block: Block) -> Block:
R = MyDES.E(R)
R ^= round_key_block
R = MyDES.S(R)
R = MyDES.P(R)
return R
@staticmethod
def IP_inverse(block: Block) -> Block:
table = [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]
return block.map_with_table(table)
if __name__ == '__main__':
key = "12345678".encode()
data = 'abcdefgh'.encode()
my_des = MyDES(key)
des = DES.new(key, DES.MODE_ECB)
encrypted_data1 = my_des.encrypt(data)
encrypted_data2 = des.encrypt(data)
print(encrypted_data1.hex())
print(encrypted_data2.hex())
decrypted_data1 = my_des.decrypt(encrypted_data1)
decrypted_data2 = des.decrypt(encrypted_data2)
print(decrypted_data1.hex())
print(decrypted_data2.hex())