1 /* hmac-sha1.c -- hashed message authentication codes
2 Copyright (C) 2005 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, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18 /* Written by Simon Josefsson. */
35 hmac_sha1 (const void *key, size_t keylen,
36 const void *in, size_t inlen, void *resbuf)
38 struct sha1_ctx inner;
39 struct sha1_ctx outer;
44 /* Reduce the key's size, so that it becomes <= 64 bytes large. */
48 struct sha1_ctx keyhash;
50 sha1_init_ctx (&keyhash);
51 sha1_process_bytes (key, keylen, &keyhash);
52 sha1_finish_ctx (&keyhash, optkeybuf);
58 /* Compute INNERHASH from KEY and IN. */
60 sha1_init_ctx (&inner);
62 memset (block, IPAD, sizeof (block));
63 memxor (block, key, keylen);
65 sha1_process_block (block, 64, &inner);
66 sha1_process_bytes (in, inlen, &inner);
68 sha1_finish_ctx (&inner, innerhash);
70 /* Compute result from KEY and INNERHASH. */
72 sha1_init_ctx (&outer);
74 memset (block, OPAD, sizeof (block));
75 memxor (block, key, keylen);
77 sha1_process_block (block, 64, &outer);
78 sha1_process_bytes (innerhash, 20, &outer);
80 sha1_finish_ctx (&outer, resbuf);