external/bsd/dhcpcd/dist/crypt/hmac_md5.c

   1 #include <sys/cdefs.h>
   2  __RCSID("$NetBSD: hmac_md5.c,v 1.7 2015/03/27 11:33:47 roy Exp $");
   3
   4 /*
   5  * dhcpcd - DHCP client daemon
   6  * Copyright (c) 2006-2015 Roy Marples <roy@marples.name>
   7  * All rights reserved
   8
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #include <inttypes.h>
  32 #include <string.h>
  33
  34 #include "crypt.h"
  35
  36 #include "../config.h"
  37 #ifdef HAVE_MD5_H
  38 #  ifndef DEPGEN
  39 #    include <md5.h>
  40 #  endif
  41 #else
  42 #  include "md5.h"
  43 #endif
  44
  45 #define HMAC_PAD_LEN    64
  46 #define IPAD            0x36
  47 #define OPAD            0x5C
  48
  49 /* hmac_md5 as per RFC3118 */
  50 void
  51 hmac_md5(const uint8_t *text, size_t text_len,
  52     const uint8_t *key, size_t key_len,
  53     uint8_t *digest)
  54 {
  55         uint8_t k_ipad[HMAC_PAD_LEN], k_opad[HMAC_PAD_LEN];
  56         uint8_t tk[MD5_DIGEST_LENGTH];
  57         int i;
  58         MD5_CTX context;
  59
  60         /* Ensure key is no bigger than HMAC_PAD_LEN */
  61         if (key_len > HMAC_PAD_LEN) {
  62                 MD5Init(&context);
  63                 MD5Update(&context, key, (unsigned int)key_len);
  64                 MD5Final(tk, &context);
  65                 key = tk;
  66                 key_len = MD5_DIGEST_LENGTH;
  67         }
  68
  69         /* store key in pads */
  70         memcpy(k_ipad, key, key_len);
  71         memcpy(k_opad, key, key_len);
  72         memset(k_ipad + key_len, 0, sizeof(k_ipad) - key_len);
  73         memset(k_opad + key_len, 0, sizeof(k_opad) - key_len);
  74
  75         /* XOR key with ipad and opad values */
  76         for (i = 0; i < HMAC_PAD_LEN; i++) {
  77                 k_ipad[i] ^= IPAD;
  78                 k_opad[i] ^= OPAD;
  79         }
  80
  81         /* inner MD5 */
  82         MD5Init(&context);
  83         MD5Update(&context, k_ipad, HMAC_PAD_LEN);
  84         MD5Update(&context, text, (unsigned int)text_len);
  85         MD5Final(digest, &context);
  86
  87         /* outer MD5 */
  88         MD5Init(&context);
  89         MD5Update(&context, k_opad, HMAC_PAD_LEN);
  90         MD5Update(&context, digest, MD5_DIGEST_LENGTH);
  91         MD5Final(digest, &context);
  92 }