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 */
gcm_mult_h(gcm_state * gcm,unsigned char * I)24 void 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