release/src/router/nettle/salsa20-core-internal.c

   1 /* salsa20-core-internal.c
   2  *
   3  * Internal interface to the Salsa20 core function.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2012 Simon Josefsson, Niels Möller
   9  *
  10  * The nettle library is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or (at your
  13  * option) any later version.
  14  *
  15  * The nettle library is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  17  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  18  * License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  22  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  23  * MA 02111-1301, USA.
  24  */
  25
  26 /* Based on:
  27    salsa20-ref.c version 20051118
  28    D. J. Bernstein
  29    Public domain.
  30 */
  31
  32 #if HAVE_CONFIG_H
  33 # include "config.h"
  34 #endif
  35
  36 #include <assert.h>
  37 #include <string.h>
  38
  39 #include "salsa20.h"
  40
  41 #include "macros.h"
  42
  43 #ifndef SALSA20_DEBUG
  44 # define SALSA20_DEBUG 0
  45 #endif
  46
  47 #if SALSA20_DEBUG
  48 # include <stdio.h>
  49 # define DEBUG(i) do {                          \
  50     unsigned debug_j;                           \
  51     for (debug_j = 0; debug_j < 16; debug_j++)  \
  52       {                                         \
  53         if (debug_j == 0)                       \
  54           fprintf(stderr, "%2d:", (i));         \
  55         else if (debug_j % 4 == 0)              \
  56           fprintf(stderr, "\n   ");             \
  57         fprintf(stderr, " %8x", x[debug_j]);    \
  58       }                                         \
  59     fprintf(stderr, "\n");                      \
  60   } while (0)
  61 #else
  62 # define DEBUG(i)
  63 #endif
  64
  65 #ifdef WORDS_BIGENDIAN
  66 #define LE_SWAP32(v)                            \
  67   ((ROTL32(8,  v) & 0x00FF00FFUL) |             \
  68    (ROTL32(24, v) & 0xFF00FF00UL))
  69 #else
  70 #define LE_SWAP32(v) (v)
  71 #endif
  72
  73 #define QROUND(x0, x1, x2, x3) do { \
  74   x1 ^= ROTL32(7, x0 + x3);         \
  75   x2 ^= ROTL32(9, x1 + x0);         \
  76   x3 ^= ROTL32(13, x2 + x1);        \
  77   x0 ^= ROTL32(18, x3 + x2);        \
  78   } while(0)
  79
  80 void
  81 _salsa20_core(uint32_t *dst, const uint32_t *src, unsigned rounds)
  82 {
  83   uint32_t x[_SALSA20_INPUT_LENGTH];
  84   unsigned i;
  85
  86   assert ( (rounds & 1) == 0);
  87
  88   memcpy (x, src, sizeof(x));
  89   for (i = 0; i < rounds;i += 2)
  90     {
  91       DEBUG (i);
  92       QROUND(x[0], x[4], x[8], x[12]);
  93       QROUND(x[5], x[9], x[13], x[1]);
  94       QROUND(x[10], x[14], x[2], x[6]);
  95       QROUND(x[15], x[3], x[7], x[11]);
  96
  97       DEBUG (i+1);
  98       QROUND(x[0], x[1], x[2], x[3]);
  99       QROUND(x[5], x[6], x[7], x[4]);
 100       QROUND(x[10], x[11], x[8], x[9]);
 101       QROUND(x[15], x[12], x[13], x[14]);
 102     }
 103   DEBUG (i);
 104
 105   for (i = 0; i < _SALSA20_INPUT_LENGTH; i++)
 106     {
 107       uint32_t t = x[i] + src[i];
 108       dst[i] = LE_SWAP32 (t);
 109     }
 110 }