mirror of
https://github.com/Laupetin/OpenAssetTools.git
synced 2025-04-21 16:45:44 +00:00
89 lines
2.4 KiB
C
89 lines
2.4 KiB
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.
|
|
*/
|
|
#include "tomcrypt.h"
|
|
|
|
#ifdef LTC_CCM_MODE
|
|
|
|
/**
|
|
Process plaintext/ciphertext through CCM
|
|
@param ccm The CCM state
|
|
@param pt The plaintext
|
|
@param ptlen The plaintext length (ciphertext length is the same)
|
|
@param ct The ciphertext
|
|
@param direction Encrypt or Decrypt mode (CCM_ENCRYPT or CCM_DECRYPT)
|
|
@return CRYPT_OK on success
|
|
*/
|
|
int ccm_process(ccm_state *ccm,
|
|
unsigned char *pt, unsigned long ptlen,
|
|
unsigned char *ct,
|
|
int direction)
|
|
{
|
|
unsigned char z, b;
|
|
unsigned long y;
|
|
int err;
|
|
|
|
LTC_ARGCHK(ccm != NULL);
|
|
|
|
/* Check aad has been correctly added */
|
|
if (ccm->aadlen != ccm->current_aadlen) {
|
|
return CRYPT_ERROR;
|
|
}
|
|
|
|
/* Check we do not process too much data */
|
|
if (ccm->ptlen < ccm->current_ptlen + ptlen) {
|
|
return CRYPT_ERROR;
|
|
}
|
|
ccm->current_ptlen += ptlen;
|
|
|
|
/* now handle the PT */
|
|
if (ptlen > 0) {
|
|
LTC_ARGCHK(pt != NULL);
|
|
LTC_ARGCHK(ct != NULL);
|
|
|
|
for (y = 0; y < ptlen; y++) {
|
|
/* increment the ctr? */
|
|
if (ccm->CTRlen == 16) {
|
|
for (z = 15; z > 15-ccm->L; z--) {
|
|
ccm->ctr[z] = (ccm->ctr[z] + 1) & 255;
|
|
if (ccm->ctr[z]) break;
|
|
}
|
|
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
|
|
return err;
|
|
}
|
|
ccm->CTRlen = 0;
|
|
}
|
|
|
|
/* if we encrypt we add the bytes to the MAC first */
|
|
if (direction == CCM_ENCRYPT) {
|
|
b = pt[y];
|
|
ct[y] = b ^ ccm->CTRPAD[ccm->CTRlen++];
|
|
} else {
|
|
b = ct[y] ^ ccm->CTRPAD[ccm->CTRlen++];
|
|
pt[y] = b;
|
|
}
|
|
|
|
if (ccm->x == 16) {
|
|
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++] ^= b;
|
|
}
|
|
}
|
|
|
|
return CRYPT_OK;
|
|
}
|
|
|
|
#endif
|
|
|
|
/* ref: HEAD -> master, tag: v1.18.2 */
|
|
/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
|
|
/* commit time: 2018-07-01 22:49:01 +0200 */
|