/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, [email protected], http://libtomcrypt.com
 */
#include "tomcrypt.h"

/** 
  @file omac_file.c
  OMAC1 support, process a file, Tom St Denis
*/

#ifdef LTC_OMAC

/**
   OMAC a file
   @param cipher   The index of the cipher desired
   @param key      The secret key
   @param keylen   The length of the secret key (octets)
   @param filename The name of the file you wish to OMAC
   @param out      [out] Where the authentication tag is to be stored
   @param outlen   [in/out] The max size and resulting size of the authentication tag
   @return CRYPT_OK if successful, CRYPT_NOP if file support has been disabled
*/
int omac_file(int cipher, 
              const unsigned char *key, unsigned long keylen,
              const char *filename, 
                    unsigned char *out, unsigned long *outlen)
{
#ifdef LTC_NO_FILE
   return CRYPT_NOP;
#else
   int err, x;
   omac_state omac;
   FILE *in;
   unsigned char buf[512];

   LTC_ARGCHK(key      != NULL);
   LTC_ARGCHK(filename != NULL);
   LTC_ARGCHK(out      != NULL);
   LTC_ARGCHK(outlen   != NULL);

   in = fopen(filename, "rb");
   if (in == NULL) {
      return CRYPT_FILE_NOTFOUND;
   }

   if ((err = omac_init(&omac, cipher, key, keylen)) != CRYPT_OK) {
      fclose(in);
      return err;
   }

   do {
      x = fread(buf, 1, sizeof(buf), in);
      if ((err = omac_process(&omac, buf, x)) != CRYPT_OK) {
         fclose(in);
         return err;
      }
   } while (x == sizeof(buf));
   fclose(in);

   if ((err = omac_done(&omac, out, outlen)) != CRYPT_OK) {
      return err;
   }

#ifdef LTC_CLEAN_STACK
   zeromem(buf, sizeof(buf));
#endif

   return CRYPT_OK;
#endif
}

#endif

/* $Source: /cvs/libtom/libtomcrypt/src/mac/omac/omac_file.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/11/03 00:39:49 $ */