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
|
/* hmac-sha256.c -- hashed message authentication codes
Copyright (C) 2005-2006, 2009-2015 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1, 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, see <http://www.gnu.org/licenses/>. */
/* Written by Simon Josefsson. */
#include <config.h>
#include "hmac.h"
#include "memxor.h"
#include "sha256.h"
#include <string.h>
#define IPAD 0x36
#define OPAD 0x5c
int
hmac_sha256 (const void *key, size_t keylen,
const void *in, size_t inlen, void *resbuf)
{
struct sha256_ctx inner;
struct sha256_ctx outer;
char optkeybuf[32];
char block[64];
char innerhash[32];
/* Reduce the key's size, so that it becomes <= 64 bytes large. */
if (keylen > 64)
{
struct sha256_ctx keyhash;
sha256_init_ctx (&keyhash);
sha256_process_bytes (key, keylen, &keyhash);
sha256_finish_ctx (&keyhash, optkeybuf);
key = optkeybuf;
keylen = 32;
}
/* Compute INNERHASH from KEY and IN. */
sha256_init_ctx (&inner);
memset (block, IPAD, sizeof (block));
memxor (block, key, keylen);
sha256_process_block (block, 64, &inner);
sha256_process_bytes (in, inlen, &inner);
sha256_finish_ctx (&inner, innerhash);
/* Compute result from KEY and INNERHASH. */
sha256_init_ctx (&outer);
memset (block, OPAD, sizeof (block));
memxor (block, key, keylen);
sha256_process_block (block, 64, &outer);
sha256_process_bytes (innerhash, 32, &outer);
sha256_finish_ctx (&outer, resbuf);
return 0;
}
|
