ocb_decrypt_verify_memory.c

/* 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, tomstdenis@iahu.ca, http://libtomcrypt.org
 */

/* OCB Implementation by Tom St Denis */
#include "mycrypt.h"

#ifdef OCB_MODE

int ocb_decrypt_verify_memory(int cipher,
    const unsigned char *key,    unsigned long keylen,
    const unsigned char *nonce,  
    const unsigned char *ct,     unsigned long ctlen,
          unsigned char *pt,
    const unsigned char *tag,    unsigned long taglen,
          int           *res)
{
   int err;
   ocb_state ocb;


   _ARGCHK(key    != NULL);
   _ARGCHK(nonce  != NULL);
   _ARGCHK(pt     != NULL);
   _ARGCHK(ct     != NULL);
   _ARGCHK(tag    != NULL);
   _ARGCHK(res    != NULL);

   if ((err = ocb_init(&ocb, cipher, key, keylen, nonce)) != CRYPT_OK) {
      return err;
   }

   while (ctlen > (unsigned long)ocb.block_len) {
        if ((err = ocb_decrypt(&ocb, ct, pt)) != CRYPT_OK) {
           return err;
        }
        ctlen   -= ocb.block_len;
        pt      += ocb.block_len;
        ct      += ocb.block_len;
   }

   return ocb_done_decrypt(&ocb, ct, ctlen, pt, tag, taglen, res);
}

#endif