release/src/router/nettle/camellia-set-decrypt-key.c

   1 /* camellia-set-decrypt-key.c
   2  *
   3  * Inverse key setup for the camellia block cipher.
   4  */
   5
   6 /* nettle, low-level cryptographics library
   7  *
   8  * Copyright (C) 2010 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 #if HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include "camellia.h"
  31
  32 #define SWAP(a, b) \
  33 do { uint64_t t_swap = (a); (a) = (b); (b) = t_swap; } while(0)
  34
  35 void
  36 camellia_invert_key(struct camellia_ctx *dst,
  37                     const struct camellia_ctx *src)
  38 {
  39   unsigned nkeys = src->nkeys;
  40   unsigned i;
  41   if (dst == src)
  42     {
  43       for (i = 0; i < nkeys - 1 - i; i++)
  44         SWAP(dst->keys[i], dst->keys[nkeys - 1 - i]);
  45     }
  46   else
  47     {
  48       dst->nkeys = nkeys;
  49
  50       for (i = 0; i < nkeys; i++)
  51         dst->keys[i] = src->keys[nkeys - 1 - i];
  52     }
  53 }
  54
  55 void
  56 camellia_set_decrypt_key(struct camellia_ctx *ctx,
  57                          unsigned length, const uint8_t *key)
  58 {
  59   camellia_set_encrypt_key(ctx, length, key);
  60   camellia_invert_key(ctx, ctx);
  61 }