options: Complete the transition to numeric toggles (`#if') For the sake of review, this commit alters only the code; the affiliated comments within the source files also need to be updated, but doing so now would obscure the operational changes that have been made here. * All on/off options have been switched to the numeric `#if' variant; that is the only way to make this `default_options.h.in' thing work in a reasonable manner. * There is now some very minor compile-time checking of the user's choice of options. * NO_FAST_EXPTMOD doesn't seem to be used, so it has been removed. * ENABLE_USER_ALGO_LIST was supposed to be renamed DROPBEAR_USER_ALGO_LIST, and this commit completes that work. * DROPBEAR_FUZZ seems to be a relatively new, as-yet undocumented option, which was added by the following commit: commit 6e0b539e9ca0b5628c6c5a3d118ad6a2e79e8039 Author: Matt Johnston <[email protected]> Date: Tue May 23 22:29:21 2017 +0800 split out checkpubkey_line() separately It has now been added to `sysoptions.h' and defined as `0' by default. * The configuration option `DROPBEAR_PASSWORD_ENV' is no longer listed in `default_options.h.in'; it is no longer meant to be set by the user, and is instead left to be defined in `sysoptions.h' (where it was already being defined) as merely the name of the environment variable in question: DROPBEAR_PASSWORD To enable or disable use of that environment variable, the user must now toggle `DROPBEAR_USE_DROPBEAR_PASSWORD'. * The sFTP support is now toggled by setting `DROPBEAR_SFTPSERVER', and the path of the sFTP server program is set independently through the usual SFTPSERVER_PATH.

/* 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.
 */

/**
   @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;
#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
   int y;
   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_PTR_CAST(T + y)) ^= *(LTC_FAST_TYPE_PTR_CAST(&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

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