summaryrefslogtreecommitdiffstats
path: root/utils/imxtools/sbtools/xorcrypt.c
blob: 5ecf9208d6a035a31a79a05352435b9bb98e0cad (plain)
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
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2012 Amaury Pouly
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "crypto.h"
#include <stdlib.h>
#include "misc.h"

static uint32_t do_round(union xorcrypt_key_t *key)
{
    uint32_t k7 = key->k[7];
    uint32_t k2 = key->k[2];
    uint32_t k5_3_1 = key->k[5] ^ key->k[3] ^ key->k[1];
    key->k[1] = k2;
    uint32_t k_11_7_5_3_1 = key->k[11] ^ k7 ^ k5_3_1;
    key->k[2] = key->k[3] ^ k2;
    key->k[3] = key->k[4];
    key->k[4] = key->k[5];
    key->k[5] = key->k[6];
    uint32_t k0 = key->k[0];
    key->k[7] = k7 ^ key->k[8];
    uint32_t k13 = key->k[13];
    key->k[8] = key->k[9];
    uint32_t k10 = key->k[10];
    key->k[6] = k7;
    key->k[9] = k10;
    uint32_t k11 = key->k[11];
    key->k[0] = k0 ^ k13 ^ k_11_7_5_3_1;
    key->k[10] = (k11 >> 1) | (k11 << 31);
    uint32_t k11_12 = k11 ^ key->k[12];
    uint32_t k14 = key->k[14];
    key->k[12] = k13;
    key->k[13] = k14;
    uint32_t k15 = key->k[15];
    key->k[15] = k0;
    key->k[11] = k11_12;
    key->k[14] = k15;
    return key->k[0];
}

static uint32_t do_unround(union xorcrypt_key_t *key)
{
    uint32_t k7 = key->k[6];
    uint32_t k2 = key->k[1];
    uint32_t k11 = key->k[10] >> 31 | key->k[10] << 1;
    uint32_t k0 = key->k[0];
    key->k[0] = key->k[15];
    key->k[15] = key->k[14];
    key->k[14] = key->k[13];
    key->k[13] = key->k[12];
    key->k[12] = key->k[11] ^ k11;
    key->k[11] = k11;
    key->k[10] = key->k[9];
    key->k[9] = key->k[8];
    key->k[8] = key->k[7] ^ k7;
    key->k[7] = key->k[6];
    key->k[6] = key->k[5];
    key->k[5] = key->k[4];
    key->k[4] = key->k[3];
    key->k[3] = key->k[2] ^ k2;
    key->k[2] = key->k[1];
    key->k[1] = k0 ^ key->k[0] ^ key->k[5] ^ key->k[3] ^ key->k[7] ^ key->k[11] ^ key->k[13];
    return 0;
}

static void test_round(union xorcrypt_key_t keys[2])
{
    union xorcrypt_key_t save[2];
    memcpy(save, keys, sizeof(save));
    do_round(keys);
    do_unround(keys);
    if(memcmp(save, keys, sizeof(save)))
    {
        printf("Mismatch\n");
        for(int i = 0; i < 16; i++)
            printf(" %s%08x", save[0].k[i] == keys[0].k[i] ? YELLOW : RED, save[0].k[i]);
        printf("\n");
        for(int i = 0; i < 16; i++)
            printf(" %s%08x", save[0].k[i] == keys[0].k[i] ? YELLOW : RED, keys[0].k[i]);
        printf("\n");
    }
}

uint32_t xor_encrypt(union xorcrypt_key_t keys[2], void *_data, int size)
{
    if(size % 4)
        bugp("xor_encrypt: size is not a multiple of 4 !\n");
    size /= 4;
    uint32_t *data = _data;
    uint32_t final_xor = 0;
    for(int i = 0; i < size; i += 4)
    {
        uint32_t x = do_round(&keys[1]);
        /* xor first key's first word with data (at most 4 words of data) */
        for(int j = i; j < i + 4 && j < size; j++)
        {
            keys[0].k[0] ^= data[j];
            data[j] ^= x;
        }
        final_xor = do_round(&keys[0]);
    }
    return final_xor ^ do_round(&keys[1]);
}

uint32_t xor_decrypt(union xorcrypt_key_t keys[2], void *_data, int size)
{
    if(size % 4)
        bugp("xor_decrypt: size is not a multiple of 4 !\n");
    size /= 4;
    uint32_t *data = _data;
    uint32_t final_xor = 0;
    for(int i = 0; i < size; i += 4)
    {
        uint32_t x = do_round(&keys[1]);
        /* xor first key's first word with data (at most 4 words of data) */
        for(int j = i; j < i + 4 && j < size; j++)
        {
            data[j] ^= x;
            keys[0].k[0] ^= data[j];
        }
        final_xor = do_round(&keys[0]);
    }
    return final_xor ^ do_round(&keys[1]);
}