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64 lines
1.6 KiB
C
64 lines
1.6 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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#include "tomcrypt.h"
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#ifdef LTC_CCM_MODE
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/**
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Add AAD to the CCM state
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@param ccm The CCM state
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@param adata The additional authentication data to add to the CCM state
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@param adatalen The length of the AAD data.
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@return CRYPT_OK on success
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*/
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int ccm_add_aad(ccm_state *ccm,
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const unsigned char *adata, unsigned long adatalen)
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{
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unsigned long y;
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int err;
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LTC_ARGCHK(ccm != NULL);
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LTC_ARGCHK(adata != NULL);
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if (ccm->aadlen < ccm->current_aadlen + adatalen) {
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return CRYPT_INVALID_ARG;
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}
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ccm->current_aadlen += adatalen;
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/* now add the data */
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for (y = 0; y < adatalen; y++) {
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if (ccm->x == 16) {
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/* full block so let's encrypt it */
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if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
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return err;
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}
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ccm->x = 0;
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}
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ccm->PAD[ccm->x++] ^= adata[y];
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}
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/* remainder? */
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if (ccm->aadlen == ccm->current_aadlen) {
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if (ccm->x != 0) {
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if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
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return err;
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}
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}
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ccm->x = 0;
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}
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return CRYPT_OK;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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