release/src/router/nettle/salsa20-set-key.c

   1 /* salsa20-set-key.c
   2  *
   3  * The Salsa20 stream cipher.
   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
  38 #include "salsa20.h"
  39
  40 #include "macros.h"
  41
  42 void
  43 salsa20_set_key(struct salsa20_ctx *ctx,
  44                 unsigned length, const uint8_t *key)
  45 {
  46   static const uint32_t sigma[4] = {
  47     /* "expand 32-byte k" */
  48     0x61707865, 0x3320646e, 0x79622d32, 0x6b206574
  49   };
  50   static const uint32_t tau[4] = {
  51     /* "expand 16-byte k" */
  52     0x61707865, 0x3120646e, 0x79622d36, 0x6b206574
  53   };
  54   const uint32_t *constants;
  55
  56   assert (length == SALSA20_MIN_KEY_SIZE || length == SALSA20_MAX_KEY_SIZE);
  57
  58   ctx->input[1] = LE_READ_UINT32(key + 0);
  59   ctx->input[2] = LE_READ_UINT32(key + 4);
  60   ctx->input[3] = LE_READ_UINT32(key + 8);
  61   ctx->input[4] = LE_READ_UINT32(key + 12);
  62   if (length == SALSA20_MAX_KEY_SIZE) { /* recommended */
  63     ctx->input[11] = LE_READ_UINT32(key + 16);
  64     ctx->input[12] = LE_READ_UINT32(key + 20);
  65     ctx->input[13] = LE_READ_UINT32(key + 24);
  66     ctx->input[14] = LE_READ_UINT32(key + 28);
  67     constants = sigma;
  68   } else { /* kbits == 128 */
  69     ctx->input[11] = ctx->input[1];
  70     ctx->input[12] = ctx->input[2];
  71     ctx->input[13] = ctx->input[3];
  72     ctx->input[14] = ctx->input[4];
  73     constants = tau;
  74   }
  75   ctx->input[0]  = constants[0];
  76   ctx->input[5]  = constants[1];
  77   ctx->input[10] = constants[2];
  78   ctx->input[15] = constants[3];
  79 }
  80
  81 void
  82 salsa20_set_iv(struct salsa20_ctx *ctx, const uint8_t *iv)
  83 {
  84   ctx->input[6] = LE_READ_UINT32(iv + 0);
  85   ctx->input[7] = LE_READ_UINT32(iv + 4);
  86   ctx->input[8] = 0;
  87   ctx->input[9] = 0;
  88 }