57 lines
1.3 KiB
C
57 lines
1.3 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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*/
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/* EAX Implementation by Tom St Denis */
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#include "mycrypt.h"
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#ifdef EAX_MODE
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int eax_done(eax_state *eax, unsigned char *tag, unsigned long *taglen)
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{
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int err;
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unsigned char headermac[MAXBLOCKSIZE], ctmac[MAXBLOCKSIZE];
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unsigned long x, len;
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_ARGCHK(eax != NULL);
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_ARGCHK(tag != NULL);
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_ARGCHK(taglen != NULL);
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/* finish ctomac */
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len = sizeof(ctmac);
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if ((err = omac_done(&eax->ctomac, ctmac, &len)) != CRYPT_OK) {
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return err;
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}
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/* finish headeromac */
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/* note we specifically don't reset len so the two lens are minimal */
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if ((err = omac_done(&eax->headeromac, headermac, &len)) != CRYPT_OK) {
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return err;
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}
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/* compute N xor H xor C */
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for (x = 0; x < len && x < *taglen; x++) {
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tag[x] = eax->N[x] ^ headermac[x] ^ ctmac[x];
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}
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*taglen = x;
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#ifdef CLEAN_STACK
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zeromem(ctmac, sizeof(ctmac));
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zeromem(headermac, sizeof(headermac));
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zeromem(eax, sizeof(*eax));
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#endif
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return CRYPT_OK;
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}
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#endif
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