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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@gmail.com, http://libtom.org
*/
/**
@file ocb_done_decrypt.c
OCB implementation, terminate decryption, by Tom St Denis
*/
#include "tomcrypt.h"
#ifdef LTC_OCB_MODE
/**
Terminate a decrypting OCB state
@param ocb The OCB state
@param ct The ciphertext (if any)
@param ctlen The length of the ciphertext (octets)
@param pt [out] The plaintext
@param tag The authentication tag (to compare against)
@param taglen The length of the authentication tag provided
@param stat [out] The result of the tag comparison
@return CRYPT_OK if the process was successful regardless if the tag is valid
*/
int ocb_done_decrypt(ocb_state *ocb,
const unsigned char *ct, unsigned long ctlen,
unsigned char *pt,
const unsigned char *tag, unsigned long taglen, int *stat)
{
int err;
unsigned char *tagbuf;
unsigned long tagbuflen;
LTC_ARGCHK(ocb != NULL);
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
LTC_ARGCHK(tag != NULL);
LTC_ARGCHK(stat != NULL);
/* default to failed */
*stat = 0;
/* allocate memory */
tagbuf = XMALLOC(MAXBLOCKSIZE);
if (tagbuf == NULL) {
return CRYPT_MEM;
}
tagbuflen = MAXBLOCKSIZE;
if ((err = s_ocb_done(ocb, ct, ctlen, pt, tagbuf, &tagbuflen, 1)) != CRYPT_OK) {
goto LBL_ERR;
}
if (taglen <= tagbuflen && XMEMCMP(tagbuf, tag, taglen) == 0) {
*stat = 1;
}
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(tagbuf, MAXBLOCKSIZE);
#endif
XFREE(tagbuf);
return err;
}
#endif
/* $Source$ */
/* $Revision$ */
/* $Date$ */
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