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