76 lines
1.6 KiB
C
76 lines
1.6 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.
|
|
*
|
|
* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
|
|
*/
|
|
|
|
/* EAX Implementation by Tom St Denis */
|
|
#include "mycrypt.h"
|
|
|
|
#ifdef EAX_MODE
|
|
|
|
int eax_done(eax_state *eax, unsigned char *tag, unsigned long *taglen)
|
|
{
|
|
int err;
|
|
unsigned char *headermac, *ctmac;
|
|
unsigned long x, len;
|
|
|
|
_ARGCHK(eax != NULL);
|
|
_ARGCHK(tag != NULL);
|
|
_ARGCHK(taglen != NULL);
|
|
|
|
/* allocate ram */
|
|
headermac = XMALLOC(MAXBLOCKSIZE);
|
|
ctmac = XMALLOC(MAXBLOCKSIZE);
|
|
|
|
if (headermac == NULL || ctmac == NULL) {
|
|
if (headermac != NULL) {
|
|
XFREE(headermac);
|
|
}
|
|
if (ctmac != NULL) {
|
|
XFREE(ctmac);
|
|
}
|
|
return CRYPT_MEM;
|
|
}
|
|
|
|
/* finish ctomac */
|
|
len = MAXBLOCKSIZE;
|
|
if ((err = omac_done(&eax->ctomac, ctmac, &len)) != CRYPT_OK) {
|
|
goto __ERR;
|
|
}
|
|
|
|
/* finish headeromac */
|
|
|
|
/* note we specifically don't reset len so the two lens are minimal */
|
|
|
|
if ((err = omac_done(&eax->headeromac, headermac, &len)) != CRYPT_OK) {
|
|
goto __ERR;
|
|
}
|
|
|
|
/* compute N xor H xor C */
|
|
for (x = 0; x < len && x < *taglen; x++) {
|
|
tag[x] = eax->N[x] ^ headermac[x] ^ ctmac[x];
|
|
}
|
|
*taglen = x;
|
|
|
|
err = CRYPT_OK;
|
|
__ERR:
|
|
#ifdef CLEAN_STACK
|
|
zeromem(ctmac, MAXBLOCKSIZE);
|
|
zeromem(headermac, MAXBLOCKSIZE);
|
|
zeromem(eax, sizeof(*eax));
|
|
#endif
|
|
|
|
XFREE(ctmac);
|
|
XFREE(headermac);
|
|
|
|
return err;
|
|
}
|
|
|
|
#endif
|