1 /* hmac-md5.c -- hashed message authentication codes
2 Copyright (C) 2005-2006, 2009-2012 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
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 General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Simon Josefsson. */
32 hmac_md5 (const void *key, size_t keylen,
33 const void *in, size_t inlen, void *resbuf)
41 /* Reduce the key's size, so that it becomes <= 64 bytes large. */
45 struct md5_ctx keyhash;
47 md5_init_ctx (&keyhash);
48 md5_process_bytes (key, keylen, &keyhash);
49 md5_finish_ctx (&keyhash, optkeybuf);
55 /* Compute INNERHASH from KEY and IN. */
57 md5_init_ctx (&inner);
59 memset (block, IPAD, sizeof (block));
60 memxor (block, key, keylen);
62 md5_process_block (block, 64, &inner);
63 md5_process_bytes (in, inlen, &inner);
65 md5_finish_ctx (&inner, innerhash);
67 /* Compute result from KEY and INNERHASH. */
69 md5_init_ctx (&outer);
71 memset (block, OPAD, sizeof (block));
72 memxor (block, key, keylen);
74 md5_process_block (block, 64, &outer);
75 md5_process_bytes (innerhash, 16, &outer);
77 md5_finish_ctx (&outer, resbuf);