-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathDES.py
326 lines (276 loc) · 11.4 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
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
#DES
print("Data Encryption Standard - DES")
pc1_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]
ls_scheme = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
pc2_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]
ip_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]
e_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]
p_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]
ip_inv_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]
s_boxes = [[[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]]]
def ascii2bin(string):
binary = ''
for char in string:
bin_char = bin(ord(char))[2:]
while len(bin_char) < 8:
bin_char = "0" + bin_char
binary += bin_char
out = []
for bit in binary:
out.append(bit)
return out
def bin2ascii(binary):
out = ""
for i in range(int(len(binary) / 8)):
byte = binary[i * 8:i * 8 + 8]
out += chr(int(bin2dec(byte)))
return out
def list2string(input_list):
out = ""
for i in input_list:
out += i
return out
def string2list(string):
out = []
for char in string:
out.append(char)
return out
def hex2bin(hexa):
out = ""
for digit in hexa:
out += bin(int(digit, 16))[2:].zfill(4)
return string2list(out)
def bin2hex(binary):
out = ""
for nibble in range(int(len(binary) / 4)):
out += hex(int(binary[nibble * 4: nibble * 4 + 4], 2))[2:]
return out
def bin2dec(binary):
return str(int(binary, 2))
def dec2bin(dec):
return bin(dec)[2:].zfill(4)
def XOR(arg1, arg2):
out = []
for pos in range(len(arg1)):
if arg1[pos] == arg2[pos]:
out.append('0')
else:
out.append('1')
return out
def permute(inp, table):
output = []
for pos in table:
output.append(inp[pos - 1])
return output
def substitute(inp, s_box):
out = []
for i in range(8):
row = bin2dec(inp[i][0] + inp[i][5])
col = bin2dec(list2string(inp[i][1:5]))
cell = s_box[i][int(row)][int(col)]
out += string2list(dec2bin(cell))
return out
def left_shift(inp, num):
for i in range(num):
inp.append(inp.pop(0))
return inp
def pkcs5_pad(inp):
last_block = inp[len(inp) // 64 * 64:]
pad_length = int((64 - len(last_block)) / 8)
pad_bits = ""
for i in range(pad_length):
pad_bits += "0000" + dec2bin(pad_length)
last_block += string2list(pad_bits)
out = inp[0:len(inp) // 64 * 64] + last_block
return out
def pkcs5_unpad(inp):
last_byte = int(bin2dec(list2string(inp[len(inp) - 7:])))
if 1 <= last_byte <= 7:
out = inp[:-8 * last_byte]
return out
elif last_byte == 8:
return ""
else:
return inp
def blockify(inp, block_length):
out = []
for i in range(len(inp) // block_length + 1):
if len(inp) % block_length == 0 and i == len(inp) // block_length:
break
out.append(inp[i * block_length: i * block_length + block_length])
return out
def subkey_gen(c0, d0):
global subkeys
c = []
d = []
prev_c = c0
prev_d = d0
#1. Left shift c0 and d0 according to the LS Scheme to obtain c1 to c16 and d1 to d16
for i in range(16):
shifted = left_shift(prev_c, ls_scheme[i])
c.append(shifted[:])
for i in range(16):
shifted = left_shift(prev_d, ls_scheme[i])
d.append(shifted[:])
#2. Permute cNdN using PC-2 Table to obtain 16 subkeys:
#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
subkeys = []
for i in range(1, 17):
cd = c[i-1] + d[i-1]
subkeys.append(permute(cd, pc2_table))
def keygen(key):
#1. Permute using PC-1 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
pc1_key = permute(key, pc1_table)
#2. Split key in half
c0 = pc1_key[0:28]
d0 = pc1_key[28:56]
#3. Generate 16 subkeys
subkey_gen(c0, d0)
def DES_Round(l, r, n):
#1. Expansion using E 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
expanded_r = permute(r, e_table)
#2. XOR round key with expanded right half-block
xor_r = XOR(subkeys[n], expanded_r)
#3. Substitute XORed right half-block with S-boxes S1 to S8
pre_sub = []
for i in range(8):
pre_sub.append(xor_r[i * 6: i * 6 + 6])
sub_r = substitute(pre_sub, s_boxes)
#4. Permute substituted right half-block using P 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
permuted_r = permute(sub_r, p_table)
#5. XOR L(n-1) with permuted right half-block
ln = r
rn = XOR(l, permuted_r)
prev_lr["prev_l"] = ln
prev_lr["prev_r"] = rn
round_out = ln + rn
return round_out
def DES_Block(text):
#1. Initial permutation using IP 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
permuted_text = permute(text, ip_table)
#2. Split text in half
l0 = permuted_text[0:32]
r0 = permuted_text[32:64]
#3. Perform 16 rounds
global prev_lr
prev_lr = {"prev_l" : l0, "prev_r" : r0}
if method == "e":
for n in range(16):
final_block = DES_Round(prev_lr["prev_l"], prev_lr["prev_r"], n)
elif method == "d":
for n in range(15, -1, -1):
final_block = DES_Round(prev_lr["prev_l"], prev_lr["prev_r"], n)
#4. Switch the left and right half-blocks
final_block = final_block[32:64] + final_block[0:32]
#5. Inverse permute using IP-1 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
block_out = permute(final_block, ip_inv_table)
return block_out
def DES_encrypt(plaintext):
bin_encrypted = ""
for block in plaintext:
if block == plaintext[-1]:
bin_encrypted += list2string(DES_Block(pkcs5_pad(ascii2bin(block))))
else:
bin_encrypted += list2string(DES_Block(ascii2bin(block)))
hex_encrypted = bin2hex(bin_encrypted)
print("Binary: " + bin_encrypted)
print("Hex: " + hex_encrypted)
def DES_decrypt(ciphertext):
decrypted = ""
for block in ciphertext:
if block == ciphertext[-1]:
decrypted += list2string(pkcs5_unpad(DES_Block(hex2bin(block))))
else:
decrypted += list2string(DES_Block(hex2bin(block)))
print("Plaintext: " + bin2ascii(decrypted))
def main():
global method
method = input("(e)ncrypt or (d)ecrypt: ")
key = input("64-bit Key: ")
keygen(ascii2bin(key))
if method == "e":
plaintext = blockify(input("Plaintext (PKCS#5/#7 padding will be applied): "), 8)
DES_encrypt(plaintext)
elif method == "d":
ciphertext = blockify(input("Ciphertext (in hex): "), 16)
DES_decrypt(ciphertext)
if __name__ == "__main__":
main()