libtom.libtomcrypt/ctr_setiv.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, [email protected], http://libtomcrypt.org
 */

#include "mycrypt.h"

#ifdef CTR

int ctr_setiv(const unsigned char *IV, unsigned long len, symmetric_CTR *ctr)
{
   int err;
   
   _ARGCHK(IV  != NULL);
   _ARGCHK(ctr != NULL);

   /* bad param? */
   if ((err = cipher_is_valid(ctr->cipher)) != CRYPT_OK) {
      return err;
   }
   
   if (len != (unsigned long)ctr->blocklen) {
      return CRYPT_INVALID_ARG;
   }

   /* set IV */
   XMEMCPY(ctr->ctr, IV, len);
   
   /* force next block */
   ctr->padlen = 0;
   cipher_descriptor[ctr->cipher].ecb_encrypt(IV, ctr->pad, &ctr->key);
   
   return CRYPT_OK;
}

#endif