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Import code from previous AssetBuilder version
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88
thirdparty/libtomcrypt/encauth/ccm/ccm_process.c
vendored
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88
thirdparty/libtomcrypt/encauth/ccm/ccm_process.c
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/* 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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Process plaintext/ciphertext through CCM
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@param ccm The CCM state
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@param pt The plaintext
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@param ptlen The plaintext length (ciphertext length is the same)
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@param ct The ciphertext
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@param direction Encrypt or Decrypt mode (CCM_ENCRYPT or CCM_DECRYPT)
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@return CRYPT_OK on success
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*/
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int ccm_process(ccm_state *ccm,
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unsigned char *pt, unsigned long ptlen,
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unsigned char *ct,
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int direction)
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{
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unsigned char z, b;
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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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/* Check aad has been correctly added */
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if (ccm->aadlen != ccm->current_aadlen) {
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return CRYPT_ERROR;
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}
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/* Check we do not process too much data */
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if (ccm->ptlen < ccm->current_ptlen + ptlen) {
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return CRYPT_ERROR;
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}
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ccm->current_ptlen += ptlen;
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/* now handle the PT */
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if (ptlen > 0) {
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LTC_ARGCHK(pt != NULL);
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LTC_ARGCHK(ct != NULL);
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for (y = 0; y < ptlen; y++) {
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/* increment the ctr? */
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if (ccm->CTRlen == 16) {
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for (z = 15; z > 15-ccm->L; z--) {
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ccm->ctr[z] = (ccm->ctr[z] + 1) & 255;
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if (ccm->ctr[z]) break;
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}
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if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
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return err;
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}
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ccm->CTRlen = 0;
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}
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/* if we encrypt we add the bytes to the MAC first */
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if (direction == CCM_ENCRYPT) {
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b = pt[y];
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ct[y] = b ^ ccm->CTRPAD[ccm->CTRlen++];
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} else {
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b = ct[y] ^ ccm->CTRPAD[ccm->CTRlen++];
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pt[y] = b;
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}
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if (ccm->x == 16) {
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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++] ^= b;
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}
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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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