/* hmac-md5.c -- hashed message authentication codes Copyright (C) 2005, 2006 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ /* Written by Simon Josefsson. */ #include #include "hmac.h" #include "memxor.h" #include "md5.h" #include #define IPAD 0x36 #define OPAD 0x5c int hmac_md5 (const void *key, size_t keylen, const void *in, size_t inlen, void *resbuf) { struct md5_ctx inner; struct md5_ctx outer; char optkeybuf[16]; char block[64]; char innerhash[16]; /* Reduce the key's size, so that it becomes <= 64 bytes large. */ if (keylen > 64) { struct md5_ctx keyhash; md5_init_ctx (&keyhash); md5_process_bytes (key, keylen, &keyhash); md5_finish_ctx (&keyhash, optkeybuf); key = optkeybuf; keylen = 16; } /* Compute INNERHASH from KEY and IN. */ md5_init_ctx (&inner); memset (block, IPAD, sizeof (block)); memxor (block, key, keylen); md5_process_block (block, 64, &inner); md5_process_bytes (in, inlen, &inner); md5_finish_ctx (&inner, innerhash); /* Compute result from KEY and INNERHASH. */ md5_init_ctx (&outer); memset (block, OPAD, sizeof (block)); memxor (block, key, keylen); md5_process_block (block, 64, &outer); md5_process_bytes (innerhash, 16, &outer); md5_finish_ctx (&outer, resbuf); return 0; }