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/*
* Copyright (c) 2001-2007, Tom St Denis
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/* 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://libtom.org
*/
/**
@file gcm_add_iv.c
GCM implementation, add IV data to the state, by Tom St Denis
*/
#include "tomcrypt.h"
#ifdef LTC_GCM_MODE
/**
Add IV data to the GCM state
@param gcm The GCM state
@param IV The initial value data to add
@param IVlen The length of the IV
@return CRYPT_OK on success
*/
int gcm_add_iv(gcm_state *gcm,
const unsigned char *IV, unsigned long IVlen)
{
unsigned long x, y;
int err;
LTC_ARGCHK(gcm != NULL);
if (IVlen > 0) {
LTC_ARGCHK(IV != NULL);
}
/* must be in IV mode */
if (gcm->mode != LTC_GCM_MODE_IV) {
return CRYPT_INVALID_ARG;
}
if (gcm->buflen >= 16 || gcm->buflen < 0) {
return CRYPT_INVALID_ARG;
}
if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
return err;
}
/* trip the ivmode flag */
if (IVlen + gcm->buflen > 12) {
gcm->ivmode |= 1;
}
x = 0;
#ifdef LTC_FAST
if (gcm->buflen == 0) {
for (x = 0; x < (IVlen & ~15); x += 16) {
for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
*((LTC_FAST_TYPE*)(&gcm->X[y])) ^= *((LTC_FAST_TYPE*)(&IV[x + y]));
}
gcm_mult_h(gcm, gcm->X);
gcm->totlen += 128;
}
IV += x;
}
#endif
/* start adding IV data to the state */
for (; x < IVlen; x++) {
gcm->buf[gcm->buflen++] = *IV++;
if (gcm->buflen == 16) {
/* GF mult it */
for (y = 0; y < 16; y++) {
gcm->X[y] ^= gcm->buf[y];
}
gcm_mult_h(gcm, gcm->X);
gcm->buflen = 0;
gcm->totlen += 128;
}
}
return CRYPT_OK;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/encauth/gcm/gcm_add_iv.c,v $ */
/* $Revision: 1.9 $ */
/* $Date: 2007/05/12 14:32:35 $ */
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