/* LibTomCrypt, modular cryptographic library -- Tom St Denis */

/* SPDX-License-Identifier: Unlicense */

#include "tomcrypt_private.h"

#ifdef LTC_CCM_MODE

/**

  Initialize a CCM state

  @param ccm     The CCM state to initialize

  @param cipher  The index of the cipher to use

  @param key     The secret key

  @param keylen  The length of the secret key

  @param ptlen   The length of the plain/cipher text that will be processed

  @param taglen  The max length of the MAC tag

  @param aadlen  The length of the AAD

  @return CRYPT_OK on success

 */

int ccm_init(ccm_state *ccm, int cipher,

             const unsigned char *key, int keylen, int ptlen, int taglen, int aadlen)

{

   int            err;

   LTC_ARGCHK(ccm    != NULL);

   LTC_ARGCHK(key    != NULL);

   XMEMSET(ccm, 0, sizeof(ccm_state));

   /* check cipher input */

   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {

      return err;

   }

   if (cipher_descriptor[cipher].block_length != 16) {

      return CRYPT_INVALID_CIPHER;

   }

   /* make sure the taglen is valid */

   if (taglen < 4 || taglen > 16 || (taglen % 2) == 1 || aadlen < 0 || ptlen < 0) {

      return CRYPT_INVALID_ARG;

   }

   ccm->taglen = taglen;

   /* schedule key */

   if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &ccm->K)) != CRYPT_OK) {

      return err;

   }

   ccm->cipher = cipher;

   /* let's get the L value */

   ccm->ptlen = ptlen;

   ccm->L   = 0;

   while (ptlen) {

      ++ccm->L;

      ptlen >>= 8;

   }

   if (ccm->L <= 1) {

      ccm->L = 2;

   }

   ccm->aadlen = aadlen;

   return CRYPT_OK;

}

#endif