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/* 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.
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Add AAD to the CCM state
@param ccm The CCM state
@param adata The additional authentication data to add to the CCM state
@param adatalen The length of the AAD data.
@return CRYPT_OK on success
*/
int ccm_add_aad(ccm_state *ccm,
const unsigned char *adata, unsigned long adatalen)
{
unsigned long y;
int err;
LTC_ARGCHK(ccm != NULL);
LTC_ARGCHK(adata != NULL);
if (ccm->aadlen < ccm->current_aadlen + adatalen) {
return CRYPT_INVALID_ARG;
}
ccm->current_aadlen += adatalen;
/* now add the data */
for (y = 0; y < adatalen; y++) {
if (ccm->x == 16) {
/* full block so let's encrypt it */
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return err;
}
ccm->x = 0;
}
ccm->PAD[ccm->x++] ^= adata[y];
}
/* remainder? */
if (ccm->aadlen == ccm->current_aadlen) {
if (ccm->x != 0) {
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return err;
}
}
ccm->x = 0;
}
return CRYPT_OK;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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