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/* 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_mult_h.c
GCM implementation, do the GF mult, by Tom St Denis
*/
#include "tomcrypt.h"
#if defined(LTC_GCM_MODE)
/**
GCM multiply by H
@param gcm The GCM state which holds the H value
@param I The value to multiply H by
*/
void gcm_mult_h(gcm_state *gcm, unsigned char *I)
{
unsigned char T[16];
#ifdef LTC_GCM_TABLES
int x, y;
#ifdef LTC_GCM_TABLES_SSE2
asm("movdqa (%0),%%xmm0"::"r"(&gcm->PC[0][I[0]][0]));
for (x = 1; x < 16; x++) {
asm("pxor (%0),%%xmm0"::"r"(&gcm->PC[x][I[x]][0]));
}
asm("movdqa %%xmm0,(%0)"::"r"(&T));
#else
XMEMCPY(T, &gcm->PC[0][I[0]][0], 16);
for (x = 1; x < 16; x++) {
#ifdef LTC_FAST
for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
*((LTC_FAST_TYPE *)(T + y)) ^= *((LTC_FAST_TYPE *)(&gcm->PC[x][I[x]][y]));
}
#else
for (y = 0; y < 16; y++) {
T[y] ^= gcm->PC[x][I[x]][y];
}
#endif /* LTC_FAST */
}
#endif /* LTC_GCM_TABLES_SSE2 */
#else
gcm_gf_mult(gcm->H, I, T);
#endif
XMEMCPY(I, T, 16);
}
#endif
/* $Source$ */
/* $Revision$ */
/* $Date$ */
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