452 lines
13 KiB
C
452 lines
13 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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* gurantee 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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#include "mycrypt.h"
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#ifdef EAX_MODE
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int eax_init(eax_state *eax, int cipher, const unsigned char *key, unsigned long keylen,
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const unsigned char *nonce, unsigned long noncelen,
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const unsigned char *header, unsigned long headerlen)
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{
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unsigned char buf[MAXBLOCKSIZE];
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int err, blklen;
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omac_state omac;
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unsigned long len;
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_ARGCHK(eax != NULL);
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_ARGCHK(key != NULL);
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_ARGCHK(nonce != NULL);
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if (headerlen > 0) {
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_ARGCHK(header != NULL);
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}
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if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
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return err;
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}
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blklen = cipher_descriptor[cipher].block_length;
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/* N = OMAC_0K(nonce) */
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zeromem(buf, sizeof(buf));
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if ((err = omac_init(&omac, cipher, key, keylen)) != CRYPT_OK) {
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return err;
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}
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/* omac the [0]_n */
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if ((err = omac_process(&omac, buf, blklen)) != CRYPT_OK) {
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return err;
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}
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/* omac the nonce */
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if ((err = omac_process(&omac, nonce, noncelen)) != CRYPT_OK) {
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return err;
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}
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/* store result */
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len = sizeof(eax->N);
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if ((err = omac_done(&omac, eax->N, &len)) != CRYPT_OK) {
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return err;
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}
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/* H = OMAC_1K(header) */
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zeromem(buf, sizeof(buf));
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buf[blklen - 1] = 1;
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if ((err = omac_init(&eax->headeromac, cipher, key, keylen)) != CRYPT_OK) {
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return err;
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}
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/* omac the [1]_n */
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if ((err = omac_process(&eax->headeromac, buf, blklen)) != CRYPT_OK) {
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return err;
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}
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/* omac the header */
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if (headerlen != 0) {
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if ((err = omac_process(&eax->headeromac, header, headerlen)) != CRYPT_OK) {
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return err;
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}
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}
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/* note we don't finish the headeromac, this allows us to add more header later */
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/* setup the CTR mode */
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if ((err = ctr_start(cipher, eax->N, key, keylen, 0, &eax->ctr)) != CRYPT_OK) {
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return err;
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}
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/* use big-endian counter */
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eax->ctr.mode = 1;
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/* setup the OMAC for the ciphertext */
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if ((err = omac_init(&eax->ctomac, cipher, key, keylen)) != CRYPT_OK) {
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return err;
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}
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/* omac [2]_n */
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zeromem(buf, sizeof(buf));
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buf[blklen-1] = 2;
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if ((err = omac_process(&eax->ctomac, buf, blklen)) != CRYPT_OK) {
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return err;
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}
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#ifdef CLEAN_STACK
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zeromem(buf, sizeof(buf));
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zeromem(&omac, sizeof(omac));
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#endif
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return CRYPT_OK;
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}
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int eax_encrypt(eax_state *eax, const unsigned char *pt, unsigned char *ct, unsigned long length)
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{
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int err;
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_ARGCHK(eax != NULL);
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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/* encrypt */
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if ((err = ctr_encrypt(pt, ct, length, &eax->ctr)) != CRYPT_OK) {
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return err;
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}
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/* omac ciphertext */
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return omac_process(&eax->ctomac, ct, length);
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}
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int eax_decrypt(eax_state *eax, const unsigned char *ct, unsigned char *pt, unsigned long length)
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{
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int err;
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_ARGCHK(eax != NULL);
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_ARGCHK(pt != NULL);
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_ARGCHK(ct != NULL);
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/* omac ciphertext */
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if ((err = omac_process(&eax->ctomac, ct, length)) != CRYPT_OK) {
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return err;
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}
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/* decrypt */
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return ctr_decrypt(ct, pt, length, &eax->ctr);
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}
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/* add header (metadata) to the stream */
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int eax_addheader(eax_state *eax, const unsigned char *header, unsigned long length)
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{
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_ARGCHK(eax != NULL);
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_ARGCHK(header != NULL);
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return omac_process(&eax->headeromac, header, length);
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}
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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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#endif
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return CRYPT_OK;
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}
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int eax_encrypt_authenticate_memory(int cipher,
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const unsigned char *key, unsigned long keylen,
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const unsigned char *nonce, unsigned long noncelen,
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const unsigned char *header, unsigned long headerlen,
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const unsigned char *pt, unsigned long ptlen,
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unsigned char *ct,
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unsigned char *tag, unsigned long *taglen)
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{
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int err;
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eax_state eax;
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if ((err = eax_init(&eax, cipher, key, keylen, nonce, noncelen, header, headerlen)) != CRYPT_OK) {
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return err;
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}
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if ((err = eax_encrypt(&eax, pt, ct, ptlen)) != CRYPT_OK) {
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return err;
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}
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if ((err = eax_done(&eax, tag, taglen)) != CRYPT_OK) {
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return err;
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}
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#ifdef CLEAN_STACK
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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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int eax_decrypt_verify_memory(int cipher,
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const unsigned char *key, unsigned long keylen,
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const unsigned char *nonce, unsigned long noncelen,
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const unsigned char *header, unsigned long headerlen,
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const unsigned char *ct, unsigned long ctlen,
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unsigned char *pt,
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unsigned char *tag, unsigned long taglen,
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int *res)
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{
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int err;
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eax_state eax;
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unsigned char buf[MAXBLOCKSIZE];
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unsigned long buflen;
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_ARGCHK(res != NULL);
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/* default to zero */
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*res = 0;
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if ((err = eax_init(&eax, cipher, key, keylen, nonce, noncelen, header, headerlen)) != CRYPT_OK) {
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return err;
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}
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if ((err = eax_decrypt(&eax, ct, pt, ctlen)) != CRYPT_OK) {
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return err;
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}
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buflen = MIN(sizeof(buf), taglen);
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if ((err = eax_done(&eax, buf, &buflen)) != CRYPT_OK) {
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return err;
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}
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/* compare tags */
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if (buflen >= taglen && memcmp(buf, tag, taglen) == 0) {
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*res = 1;
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}
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#ifdef CLEAN_STACK
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zeromem(&eax, sizeof(eax));
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zeromem(buf, sizeof(buf));
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#endif
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return CRYPT_OK;
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}
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int eax_test(void)
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{
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#ifndef LTC_TEST
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return CRYPT_NOP;
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#else
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static const struct {
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int keylen,
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noncelen,
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headerlen,
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msglen;
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unsigned char key[MAXBLOCKSIZE],
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nonce[MAXBLOCKSIZE],
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header[MAXBLOCKSIZE],
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plaintext[MAXBLOCKSIZE],
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ciphertext[MAXBLOCKSIZE],
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tag[MAXBLOCKSIZE];
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} tests[] = {
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/* NULL message */
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{
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16, 0, 0, 0,
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/* key */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* nonce */
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{ 0 },
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/* header */
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{ 0 },
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/* plaintext */
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{ 0 },
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/* ciphertext */
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{ 0 },
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/* tag */
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{ 0x9a, 0xd0, 0x7e, 0x7d, 0xbf, 0xf3, 0x01, 0xf5,
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0x05, 0xde, 0x59, 0x6b, 0x96, 0x15, 0xdf, 0xff }
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},
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/* test with nonce */
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{
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16, 16, 0, 0,
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/* key */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* nonce */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* header */
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{ 0 },
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/* plaintext */
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{ 0 },
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/* ciphertext */
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{ 0 },
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/* tag */
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{ 0x1c, 0xe1, 0x0d, 0x3e, 0xff, 0xd4, 0xca, 0xdb,
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0xe2, 0xe4, 0x4b, 0x58, 0xd6, 0x0a, 0xb9, 0xec }
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},
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/* test with header [no nonce] */
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{
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16, 0, 16, 0,
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/* key */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* nonce */
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{ 0 },
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/* header */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* plaintext */
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{ 0 },
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/* ciphertext */
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{ 0 },
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/* tag */
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{ 0x3a, 0x69, 0x8f, 0x7a, 0x27, 0x0e, 0x51, 0xb0,
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0xf6, 0x5b, 0x3d, 0x3e, 0x47, 0x19, 0x3c, 0xff }
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},
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/* test with header + nonce + plaintext */
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{
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16, 16, 16, 32,
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/* key */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* nonce */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* header */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* plaintext */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f },
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/* ciphertext */
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{ 0x29, 0xd8, 0x78, 0xd1, 0xa3, 0xbe, 0x85, 0x7b,
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0x6f, 0xb8, 0xc8, 0xea, 0x59, 0x50, 0xa7, 0x78,
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0x33, 0x1f, 0xbf, 0x2c, 0xcf, 0x33, 0x98, 0x6f,
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0x35, 0xe8, 0xcf, 0x12, 0x1d, 0xcb, 0x30, 0xbc },
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/* tag */
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{ 0x4f, 0xbe, 0x03, 0x38, 0xbe, 0x1c, 0x8c, 0x7e,
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0x1d, 0x7a, 0xe7, 0xe4, 0x5b, 0x92, 0xc5, 0x87 }
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},
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/* test with header + nonce + plaintext [not even sizes!] */
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{
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16, 15, 14, 29,
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/* key */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f },
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/* nonce */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e },
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/* header */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d },
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/* plaintext */
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{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1a, 0x1b, 0x1c },
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/* ciphertext */
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{ 0xdd, 0x25, 0xc7, 0x54, 0xc5, 0xb1, 0x7c, 0x59,
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0x28, 0xb6, 0x9b, 0x73, 0x15, 0x5f, 0x7b, 0xb8,
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0x88, 0x8f, 0xaf, 0x37, 0x09, 0x1a, 0xd9, 0x2c,
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0x8a, 0x24, 0xdb, 0x86, 0x8b },
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/* tag */
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{ 0x0d, 0x1a, 0x14, 0xe5, 0x22, 0x24, 0xff, 0xd2,
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0x3a, 0x05, 0xfa, 0x02, 0xcd, 0xef, 0x52, 0xda }
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},
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};
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int err, x, idx, res;
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unsigned long len;
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unsigned char outct[MAXBLOCKSIZE], outtag[MAXBLOCKSIZE];
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/* AES can be under rijndael or aes... try to find it */
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if ((idx = find_cipher("aes")) == -1) {
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if ((idx = find_cipher("rijndael")) == -1) {
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return CRYPT_NOP;
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}
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}
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for (x = 0; x < (int)(sizeof(tests)/sizeof(tests[0])); x++) {
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len = sizeof(outtag);
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if ((err = eax_encrypt_authenticate_memory(idx, tests[x].key, tests[x].keylen,
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tests[x].nonce, tests[x].noncelen, tests[x].header, tests[x].headerlen,
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tests[x].plaintext, tests[x].msglen, outct, outtag, &len)) != CRYPT_OK) {
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return err;
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}
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if (memcmp(outct, tests[x].ciphertext, tests[x].msglen) || memcmp(outtag, tests[x].tag, len)) {
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#if 0
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unsigned long y;
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printf("\n\nFailure: \nCT:\n");
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for (y = 0; y < (unsigned long)tests[x].msglen; ) {
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printf("0x%02x", outct[y]);
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if (y < (unsigned long)(tests[x].msglen-1)) printf(", ");
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if (!(++y % 8)) printf("\n");
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}
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printf("\nTAG:\n");
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for (y = 0; y < len; ) {
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printf("0x%02x", outtag[y]);
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if (y < len-1) printf(", ");
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if (!(++y % 8)) printf("\n");
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}
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#endif
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return CRYPT_FAIL_TESTVECTOR;
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}
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/* test decrypt */
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if ((err = eax_decrypt_verify_memory(idx, tests[x].key, tests[x].keylen,
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tests[x].nonce, tests[x].noncelen, tests[x].header, tests[x].headerlen,
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outct, tests[x].msglen, outct, outtag, len, &res)) != CRYPT_OK) {
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return err;
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}
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if (res != 1 || memcmp(outct, tests[x].plaintext, tests[x].msglen)) {
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#if 0
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unsigned long y;
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printf("\n\nFailure (res == %d): \nPT:\n", res);
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for (y = 0; y < (unsigned long)tests[x].msglen; ) {
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printf("0x%02x", outct[y]);
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if (y < (unsigned long)(tests[x].msglen-1)) printf(", ");
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if (!(++y % 8)) printf("\n");
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}
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printf("\n\n");
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#endif
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return CRYPT_FAIL_TESTVECTOR;
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}
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}
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return CRYPT_OK;
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#endif /* LTC_TEST */
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}
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#endif /* EAX_MODE */
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