1/* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11
12/**
13   @file gcm_mult_h.c
14   GCM implementation, do the GF mult, by Tom St Denis
15*/
16#include "tomcrypt.h"
17
18#if defined(GCM_MODE)
19/**
20  GCM multiply by H
21  @param gcm   The GCM state which holds the H value
22  @param I     The value to multiply H by
23 */
24void gcm_mult_h(gcm_state *gcm, unsigned char *I)
25{
26   unsigned char T[16];
27#ifdef GCM_TABLES
28   int x, y;
29#ifdef GCM_TABLES_SSE2
30   asm("movdqa (%0),%%xmm0"::"r"(&gcm->PC[0][I[0]][0]));
31   for (x = 1; x < 16; x++) {
32      asm("pxor (%0),%%xmm0"::"r"(&gcm->PC[x][I[x]][0]));
33   }
34   asm("movdqa %%xmm0,(%0)"::"r"(&T));
35#else
36   XMEMCPY(T, &gcm->PC[0][I[0]][0], 16);
37   for (x = 1; x < 16; x++) {
38#ifdef LTC_FAST
39       for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
40           *((LTC_FAST_TYPE *)(T + y)) ^= *((LTC_FAST_TYPE *)(&gcm->PC[x][I[x]][y]));
41       }
42#else
43       for (y = 0; y < 16; y++) {
44           T[y] ^= gcm->PC[x][I[x]][y];
45       }
46#endif /* LTC_FAST */
47   }
48#endif /* GCM_TABLES_SSE2 */
49#else
50   gcm_gf_mult(gcm->H, I, T);
51#endif
52   XMEMCPY(I, T, 16);
53}
54#endif
55
56/* $Source: /cvs/libtom/libtomcrypt/src/encauth/gcm/gcm_mult_h.c,v $ */
57/* $Revision: 1.4 $ */
58/* $Date: 2006/08/23 20:40:23 $ */
59