external/bsd/ntp/dist/lib/isc/hmacmd5.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (C) 2000, 2001  Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and/or distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  12  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  13  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  15  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  16  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  17  * PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 /* Id: hmacmd5.c,v 1.14 2007/06/19 23:47:17 tbox Exp */
  21
  22 /*! \file
  23  * This code implements the HMAC-MD5 keyed hash algorithm
  24  * described in RFC2104.
  25  */
  26
  27 #include "config.h"
  28
  29 #include <isc/assertions.h>
  30 #include <isc/hmacmd5.h>
  31 #include <isc/md5.h>
  32 #include <isc/string.h>
  33 #include <isc/types.h>
  34 #include <isc/util.h>
  35
  36 #define PADLEN 64
  37 #define IPAD 0x36
  38 #define OPAD 0x5C
  39
  40 /*!
  41  * Start HMAC-MD5 process.  Initialize an md5 context and digest the key.
  42  */
  43 void
  44 isc_hmacmd5_init(isc_hmacmd5_t *ctx, const unsigned char *key,
  45                  unsigned int len)
  46 {
  47         unsigned char ipad[PADLEN];
  48         int i;
  49
  50         memset(ctx->key, 0, sizeof(ctx->key));
  51         if (len > sizeof(ctx->key)) {
  52                 isc_md5_t md5ctx;
  53                 isc_md5_init(&md5ctx);
  54                 isc_md5_update(&md5ctx, key, len);
  55                 isc_md5_final(&md5ctx, ctx->key);
  56         } else
  57                 memcpy(ctx->key, key, len);
  58
  59         isc_md5_init(&ctx->md5ctx);
  60         memset(ipad, IPAD, sizeof(ipad));
  61         for (i = 0; i < PADLEN; i++)
  62                 ipad[i] ^= ctx->key[i];
  63         isc_md5_update(&ctx->md5ctx, ipad, sizeof(ipad));
  64 }
  65
  66 void
  67 isc_hmacmd5_invalidate(isc_hmacmd5_t *ctx) {
  68         isc_md5_invalidate(&ctx->md5ctx);
  69         memset(ctx->key, 0, sizeof(ctx->key));
  70 }
  71
  72 /*!
  73  * Update context to reflect the concatenation of another buffer full
  74  * of bytes.
  75  */
  76 void
  77 isc_hmacmd5_update(isc_hmacmd5_t *ctx, const unsigned char *buf,
  78                    unsigned int len)
  79 {
  80         isc_md5_update(&ctx->md5ctx, buf, len);
  81 }
  82
  83 /*!
  84  * Compute signature - finalize MD5 operation and reapply MD5.
  85  */
  86 void
  87 isc_hmacmd5_sign(isc_hmacmd5_t *ctx, unsigned char *digest) {
  88         unsigned char opad[PADLEN];
  89         int i;
  90
  91         isc_md5_final(&ctx->md5ctx, digest);
  92
  93         memset(opad, OPAD, sizeof(opad));
  94         for (i = 0; i < PADLEN; i++)
  95                 opad[i] ^= ctx->key[i];
  96
  97         isc_md5_init(&ctx->md5ctx);
  98         isc_md5_update(&ctx->md5ctx, opad, sizeof(opad));
  99         isc_md5_update(&ctx->md5ctx, digest, ISC_MD5_DIGESTLENGTH);
 100         isc_md5_final(&ctx->md5ctx, digest);
 101         isc_hmacmd5_invalidate(ctx);
 102 }
 103
 104 /*!
 105  * Verify signature - finalize MD5 operation and reapply MD5, then
 106  * compare to the supplied digest.
 107  */
 108 isc_boolean_t
 109 isc_hmacmd5_verify(isc_hmacmd5_t *ctx, unsigned char *digest) {
 110         return (isc_hmacmd5_verify2(ctx, digest, ISC_MD5_DIGESTLENGTH));
 111 }
 112
 113 isc_boolean_t
 114 isc_hmacmd5_verify2(isc_hmacmd5_t *ctx, unsigned char *digest, size_t len) {
 115         unsigned char newdigest[ISC_MD5_DIGESTLENGTH];
 116
 117         REQUIRE(len <= ISC_MD5_DIGESTLENGTH);
 118         isc_hmacmd5_sign(ctx, newdigest);
 119         return (ISC_TF(memcmp(digest, newdigest, len) == 0));
 120 }