1 /* hmac-sha1.c -- hashed message authentication codes
2 Copyright (C) 2005, 2006 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. */
33 hmac_sha1 (const void *key
, size_t keylen
,
34 const void *in
, size_t inlen
, void *resbuf
)
36 struct sha1_ctx inner
;
37 struct sha1_ctx outer
;
42 /* Reduce the key's size, so that it becomes <= 64 bytes large. */
46 struct sha1_ctx keyhash
;
48 sha1_init_ctx (&keyhash
);
49 sha1_process_bytes (key
, keylen
, &keyhash
);
50 sha1_finish_ctx (&keyhash
, optkeybuf
);
56 /* Compute INNERHASH from KEY and IN. */
58 sha1_init_ctx (&inner
);
60 memset (block
, IPAD
, sizeof (block
));
61 memxor (block
, key
, keylen
);
63 sha1_process_block (block
, 64, &inner
);
64 sha1_process_bytes (in
, inlen
, &inner
);
66 sha1_finish_ctx (&inner
, innerhash
);
68 /* Compute result from KEY and INNERHASH. */
70 sha1_init_ctx (&outer
);
72 memset (block
, OPAD
, sizeof (block
));
73 memxor (block
, key
, keylen
);
75 sha1_process_block (block
, 64, &outer
);
76 sha1_process_bytes (innerhash
, 20, &outer
);
78 sha1_finish_ctx (&outer
, resbuf
);