/* 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://libtomcrypt.org *//**   @file eax_done.c   EAX implementation, terminate session, by Tom St Denis*/#include "tomcrypt.h"#ifdef EAX_MODE/**   Terminate an EAX session and get the tag.   @param eax       The EAX state   @param tag       [out] The destination of the authentication tag   @param taglen    [in/out] The max length and resulting length of the authentication tag   @return CRYPT_OK if successful*/int eax_done(eax_state *eax, unsigned char *tag, unsigned long *taglen){   int           err;   unsigned char *headermac, *ctmac;   unsigned long x, len;   LTC_ARGCHK(eax    != NULL);   LTC_ARGCHK(tag    != NULL);   LTC_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 LBL_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 LBL_ERR;    }   /* terminate the CTR chain */   if ((err = ctr_done(&eax->ctr)) != CRYPT_OK) {      goto LBL_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;LBL_ERR:#ifdef LTC_CLEAN_STACK   zeromem(ctmac,     MAXBLOCKSIZE);   zeromem(headermac, MAXBLOCKSIZE);   zeromem(eax,       sizeof(*eax));#endif   XFREE(ctmac);   XFREE(headermac);   return err;}#endif/* $Source: /cvs/libtom/libtomcrypt/src/encauth/eax/eax_done.c,v $ *//* $Revision: 1.4 $ *//* $Date: 2005/05/05 14:35:58 $ */