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
|
/* IPSec VPN client compatible with Cisco equipment.
Copyright (C) 2004-2007 Maurice Massar
A bit reorganized in 2007 by Wolfram Sang
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 program 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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
$Id$
*/
#define _GNU_SOURCE
#include <inttypes.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <gcrypt.h>
#include "decrypt-utils.h"
static int hex2bin_c(unsigned int c)
{
if ((c >= '0')&&(c <= '9'))
return c - '0';
if ((c >= 'A')&&(c <= 'F'))
return c - 'A' + 10;
if ((c >= 'a')&&(c <= 'f'))
return c - 'a' + 10;
return -1;
}
int hex2bin(const char *str, char **bin, int *len)
{
char *p;
int i, l;
if (!bin)
return EINVAL;
for (i = 0; str[i] != '\0'; i++)
if (hex2bin_c(str[i]) == -1)
return EINVAL;
l = i;
if ((l & 1) != 0)
return EINVAL;
l /= 2;
p = malloc(l);
if (p == NULL)
return ENOMEM;
for (i = 0; i < l; i++)
p[i] = hex2bin_c(str[i*2]) << 4 | hex2bin_c(str[i*2+1]);
*bin = p;
if (len)
*len = l;
return 0;
}
int deobfuscate(char *ct, int len, const char **resp, char *reslenp)
{
const char *h1 = ct;
const char *h4 = ct + 20;
const char *enc = ct + 40;
char ht[20], h2[20], h3[20], key[24];
const char *iv = h1;
char *res;
gcry_cipher_hd_t ctx;
int reslen;
if (len < 48)
return -1;
len -= 40;
memcpy(ht, h1, 20);
ht[19]++;
gcry_md_hash_buffer(GCRY_MD_SHA1, h2, ht, 20);
ht[19] += 2;
gcry_md_hash_buffer(GCRY_MD_SHA1, h3, ht, 20);
memcpy(key, h2, 20);
memcpy(key+20, h3, 4);
/* who cares about parity anyway? */
gcry_md_hash_buffer(GCRY_MD_SHA1, ht, enc, len);
if (memcmp(h4, ht, 20) != 0)
return -1;
res = malloc(len);
if (res == NULL)
return -1;
gcry_cipher_open(&ctx, GCRY_CIPHER_3DES, GCRY_CIPHER_MODE_CBC, 0);
gcry_cipher_setkey(ctx, key, 24);
gcry_cipher_setiv(ctx, iv, 8);
gcry_cipher_decrypt(ctx, (unsigned char *)res, len, (unsigned char *)enc, len);
gcry_cipher_close(ctx);
reslen = len - res[len-1];
res[reslen] = '\0';
if (resp)
*resp = res;
if (reslenp)
*reslenp = reslen;
return 0;
}
|
