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
|
/*
* Gaim-Encryption MGF-1 Mask Generation Function (see PKCS#1 v2.1)
*
* Copyright (C) 2003 William Tompkins
*
* 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
*/
#include <pk11func.h>
/* for g_assert; PORT_Assert seems disabled... */
#include <glib.h>
#include "nss_mgf1.h"
static const SECOidTag Hash_OID = SEC_OID_SHA1;
/* Mask Generation function: From a seed, produce a variably sized mask, and */
/* XOR it with the maskee. */
/* Note- this is an inefficient implementation, as we repeatedly hash the */
/* seed. If we saved the intermediate context, we'd probably save */
/* a bunch of time. But, the NSS exported interface doesn't let us */
/* do that easily, so we don't. */
static void memxor (unsigned char* a, unsigned char* b, int len) {
while (len-- > 0) {
*a++ ^= *b++;
}
}
int mgf1(unsigned char* maskee, unsigned int maskee_len,
unsigned char* seed, unsigned seed_len) {
unsigned char* extended_seed = PORT_Alloc(seed_len + 4);
unsigned char* hash_out;
unsigned int hash_len;
unsigned long int counter = 0;
unsigned int counter_pos = seed_len;
unsigned int maskee_pos = 0;
unsigned int cur_block_size;
SECStatus rv;
hash_len = 20;
hash_out = PORT_Alloc(hash_len);
PORT_Memcpy(extended_seed, seed, seed_len);
while (maskee_pos < maskee_len) {
/* Store counter at counter_pos, msb first */
extended_seed[counter_pos] = (unsigned char) ((counter >> 24) & 0xff);
extended_seed[counter_pos+1] = (unsigned char) ((counter >> 16) & 0xff);
extended_seed[counter_pos+2] = (unsigned char) ((counter >> 8) & 0xff);
extended_seed[counter_pos+3] = (unsigned char) (counter & 0xff);
rv = PK11_HashBuf(Hash_OID, hash_out, extended_seed, seed_len + 4);
g_assert(rv == SECSuccess);
cur_block_size = (maskee_len - maskee_pos);
if (cur_block_size > hash_len) cur_block_size = hash_len;
memxor(maskee + maskee_pos, hash_out, cur_block_size);
maskee_pos += cur_block_size;
++counter;
}
PORT_ZFree(extended_seed, seed_len+4);
PORT_ZFree(hash_out, hash_len);
return 1;
}
|
