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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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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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* The library is free for all purposes without any express
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* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.org
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OMAC1 support, terminate a stream, Tom St Denis
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Terminate an OMAC stream
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@param omac The OMAC state
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@param out [out] Destination for the authentication tag
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@param outlen [in/out] The max size and resulting size of the authentication tag
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@return CRYPT_OK if successful
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int omac_done(omac_state *omac, unsigned char *out, unsigned long *outlen)
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LTC_ARGCHK(omac != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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if ((err = cipher_is_valid(omac->cipher_idx)) != CRYPT_OK) {
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if ((omac->buflen > (int)sizeof(omac->block)) || (omac->buflen < 0) ||
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(omac->blklen > (int)sizeof(omac->block)) || (omac->buflen > omac->blklen)) {
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return CRYPT_INVALID_ARG;
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if (omac->buflen != omac->blklen) {
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/* add the 0x80 byte */
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omac->block[omac->buflen++] = 0x80;
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while (omac->buflen < omac->blklen) {
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omac->block[omac->buflen++] = 0x00;
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/* now xor prev + Lu[mode] */
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for (x = 0; x < (unsigned)omac->blklen; x++) {
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omac->block[x] ^= omac->prev[x] ^ omac->Lu[mode][x];
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cipher_descriptor[omac->cipher_idx].ecb_encrypt(omac->block, omac->block, &omac->key);
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cipher_descriptor[omac->cipher_idx].done(&omac->key);
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for (x = 0; x < (unsigned)omac->blklen && x < *outlen; x++) {
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out[x] = omac->block[x];
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#ifdef LTC_CLEAN_STACK
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zeromem(omac, sizeof(*omac));
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/* $Source: /cvs/libtom/libtomcrypt/src/mac/omac/omac_done.c,v $ */
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/* $Revision: 1.4 $ */
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/* $Date: 2005/05/05 14:35:58 $ */