1 | /* hmac-md5.c -- hashed message authentication codes |
2 | Copyright (C) 2005-2006, 2009-2012 Free Software Foundation, Inc. |
3 | |
4 | This program is free software; you can redistribute it and/or modify |
5 | it under the terms of the GNU Lesser General Public License as published by |
6 | the Free Software Foundation; either version 2.1, or (at your option) |
7 | any later version. |
8 | |
9 | This program is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | GNU Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public License |
15 | along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
16 | |
17 | /* Written by Simon Josefsson. */ |
18 | |
19 | #include <config.h> |
20 | |
21 | #include "hmac.h" |
22 | |
23 | #include "memxor.h" |
24 | #include "md5.h" |
25 | |
26 | #include <string.h> |
27 | |
28 | #define IPAD 0x36 |
29 | #define OPAD 0x5c |
30 | |
31 | int |
32 | hmac_md5 (const void *key, size_t keylen, |
33 | const void *in, size_t inlen, void *resbuf) |
34 | { |
35 | struct md5_ctx inner; |
36 | struct md5_ctx outer; |
37 | char optkeybuf[16]; |
38 | char block[64]; |
39 | char innerhash[16]; |
40 | |
41 | /* Reduce the key's size, so that it becomes <= 64 bytes large. */ |
42 | |
43 | if (keylen > 64) |
44 | { |
45 | struct md5_ctx keyhash; |
46 | |
47 | md5_init_ctx (&keyhash); |
48 | md5_process_bytes (key, keylen, &keyhash); |
49 | md5_finish_ctx (&keyhash, optkeybuf); |
50 | |
51 | key = optkeybuf; |
52 | keylen = 16; |
53 | } |
54 | |
55 | /* Compute INNERHASH from KEY and IN. */ |
56 | |
57 | md5_init_ctx (&inner); |
58 | |
59 | memset (block, IPAD, sizeof (block)); |
60 | memxor (block, key, keylen); |
61 | |
62 | md5_process_block (block, 64, &inner); |
63 | md5_process_bytes (in, inlen, &inner); |
64 | |
65 | md5_finish_ctx (&inner, innerhash); |
66 | |
67 | /* Compute result from KEY and INNERHASH. */ |
68 | |
69 | md5_init_ctx (&outer); |
70 | |
71 | memset (block, OPAD, sizeof (block)); |
72 | memxor (block, key, keylen); |
73 | |
74 | md5_process_block (block, 64, &outer); |
75 | md5_process_bytes (innerhash, 16, &outer); |
76 | |
77 | md5_finish_ctx (&outer, resbuf); |
78 | |
79 | return 0; |
80 | } |
81 | |