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ocb_decrypt_verify_memory.c
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ocb_decrypt_verify_memory.c
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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.
*
* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
*/
/* OCB Implementation by Tom St Denis */
#include "mycrypt.h"
#ifdef OCB_MODE
int ocb_decrypt_verify_memory(int cipher,
const unsigned char *key, unsigned long keylen,
const unsigned char *nonce,
const unsigned char *ct, unsigned long ctlen,
unsigned char *pt,
const unsigned char *tag, unsigned long taglen,
int *res)
{
int err;
ocb_state *ocb;
_ARGCHK(key != NULL);
_ARGCHK(nonce != NULL);
_ARGCHK(pt != NULL);
_ARGCHK(ct != NULL);
_ARGCHK(tag != NULL);
_ARGCHK(res != NULL);
/* allocate memory */
ocb = XMALLOC(sizeof(ocb_state));
if (ocb == NULL) {
return CRYPT_MEM;
}
if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) {
goto __ERR;
}
while (ctlen > (unsigned long)ocb->block_len) {
if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) {
goto __ERR;
}
ctlen -= ocb->block_len;
pt += ocb->block_len;
ct += ocb->block_len;
}
err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, res);
__ERR:
#ifdef CLEAN_STACK
zeromem(ocb, sizeof(ocb_state));
#endif
XFREE(ocb);
return err;
}
#endif