/*	$OpenBSD: hash.c,v 1.3 1998/11/17 11:10:11 niklas Exp $	*/
/*	$EOM: hash.c,v 1.7 1998/07/25 22:04:35 niklas Exp $	*/

/*
 * Copyright (c) 1998 Niels Provos.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Ericsson Radio Systems.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <sys/param.h>
#include <string.h>
#include <md5.h>
#include <sha1.h>

#include "hash.h"

void hmac_init (struct hash *, unsigned char *, int);
void hmac_final (unsigned char *, struct hash *);

/* Temporary hash contexts.  */
static union {
     MD5_CTX md5ctx;
     SHA1_CTX sha1ctx;
} Ctx, Ctx2;

/* Temporary hash digest.  */
static unsigned char digest[HASH_MAX];

/* Encapsulation of hash functions.  */

static struct hash hashes[] = {
  { HASH_MD5, 5, MD5_SIZE, (void *)&Ctx.md5ctx, digest,
    sizeof (MD5_CTX), (void *)&Ctx2.md5ctx,
    (void (*) (void *))MD5Init, 
    (void (*) (void *, unsigned char *, unsigned int))MD5Update, 
    (void (*) (unsigned char *, void *))MD5Final,
    hmac_init, hmac_final },
  { HASH_SHA1, 6, SHA1_SIZE, (void *)&Ctx.sha1ctx, digest,
    sizeof (SHA1_CTX), (void *)&Ctx2.sha1ctx,
    (void (*) (void *))SHA1Init, 
    (void (*) (void *, unsigned char *, unsigned int))SHA1Update, 
    (void (*) (unsigned char *, void *))SHA1Final,
    hmac_init, hmac_final },
};

struct hash *
hash_get (enum hashes hashtype)
{
  int i;

  for (i = 0; i < sizeof hashes / sizeof hashes[0]; i++)
    if (hashtype == hashes[i].type)
      return &hashes[i];

  return NULL;
}

/*
 * Initial a hash for HMAC usage this requires a special init function.
 * ctx, ctx2 hold the contexts, if you want to use the hash object for
 * something else in the meantime, be sure to store the contexts somewhere.
 */

void
hmac_init (struct hash *hash, unsigned char *okey, int len)
{
  int i, blocklen = HMAC_BLOCKLEN;
  unsigned char key[HMAC_BLOCKLEN];

  if (len > blocklen) 
    {
      /* Truncate key down to blocklen */
      hash->Init (hash->ctx);
      hash->Update (hash->ctx, okey, len);
      hash->Final (key, hash->ctx);
    }
  else
    {
      memset (key, 0, blocklen);
      memcpy (key, okey, len);
    }

  /* HMAC I and O pad computation */
  for (i=0; i < blocklen; i++)
    key[i] ^= HMAC_IPAD_VAL;

  hash->Init (hash->ctx);
  hash->Update (hash->ctx, key, blocklen);

  for (i=0; i < blocklen; i++)
    key[i] ^= (HMAC_IPAD_VAL ^ HMAC_OPAD_VAL);

  hash->Init (hash->ctx2);
  hash->Update (hash->ctx2, key, blocklen);
  
  memset (key, 0, blocklen);
}

/*
 * HMAC Final function
 */

void
hmac_final (unsigned char *digest, struct hash *hash)
{
  hash->Final (digest, hash->ctx);
  hash->Update (hash->ctx2, digest, hash->hashsize);
  hash->Final (digest, hash->ctx2);
}