-
Notifications
You must be signed in to change notification settings - Fork 0
/
decrypt.c
102 lines (88 loc) · 2.27 KB
/
decrypt.c
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
/*
*
* University of Luxembourg
* Laboratory of Algorithmics, Cryptology and Security (LACS)
*
* FELICS - Fair Evaluation of Lightweight Cryptographic Systems
*
* Copyright (C) 2015 University of Luxembourg
*
* Written in 2015 by Dmitry Khovratovich <[email protected]>
*
* This file is part of FELICS.
*
* FELICS is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* FELICS is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdint.h>
#include "cipher.h"
#include "constants.h"
void Decrypt(uint8_t *block, uint8_t *roundKeys)
{
uint32_t* data = (uint32_t*) block;
uint32_t* rk = (uint32_t*) roundKeys;
uint8_t i, j;
// Go To the End of the Keys
rk = rk + (NUMBER_OF_ROUNDS << 2) + 3; // rk = rk + (NUMBER_OF_ROUNDS * 4);
j = 3;
// Add Last Key
for(i = 0; i < 4; i++) {
data[j] = data[j] ^ *rk;
rk -= 1;
j -= 1;
}
uint32_t x0, x1, x2, x3, t0, t1, t2, t3, temp;
// Rounds
for(i = 0; i < NUMBER_OF_ROUNDS - 1; i++) {
x0 = data[0];
x1 = data[1];
x2 = data[2];
x3 = data[3];
for(j = 0; j < 4; j++) {
// Row
t0 = (uint8_t)(x3);
t1 = (uint8_t)(x2 >> 8);
t2 = (uint8_t)(x1 >> 16);
t3 = (uint8_t)(x0 >> 24);
data[3-j] = (inv_T0[t0] ^ inv_T1[t1] ^ inv_T2[t2] ^ inv_T3[t3]) ^ *rk;
rk -= 1;
// Permutations for next row
temp = x3;
x3 = x2;
x2 = x1;
x1 = x0;
x0 = temp;
}
}
// Last Round
x0 = data[0];
x1 = data[1];
x2 = data[2];
x3 = data[3];
for(j = 0; j < 4; j++) {
// Row
t0 = (uint8_t)(x3);
t1 = (uint8_t)(x2 >> 8);
t2 = (uint8_t)(x1 >> 16);
t3 = (uint8_t)(x0 >> 24);
data[3-j] = (inv_Sbox[t0] | (inv_Sbox[t1] << 8) | (inv_Sbox[t2] << 16) | (inv_Sbox[t3] << 24)) ^ *rk;
rk -= 1;
// Permutations for next row
temp = x3;
x3 = x2;
x2 = x1;
x1 = x0;
x0 = temp;
}
}