release/src/router/nettle/umac-l3.c

   1 /* umac-l3.c
   2  */
   3
   4 /* nettle, low-level cryptographics library
   5  *
   6  * Copyright (C) 2013 Niels Möller
   7  *
   8  * The nettle library is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or (at your
  11  * option) any later version.
  12  *
  13  * The nettle library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16  * License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with the nettle library; see the file COPYING.LIB.  If not, write to
  20  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  21  * MA 02111-1301, USA.
  22  */
  23
  24 #if HAVE_CONFIG_H
  25 # include "config.h"
  26 #endif
  27
  28 #include "umac.h"
  29
  30 #include "macros.h"
  31
  32 /* 2^36 - 5 */
  33 #define P 0x0000000FFFFFFFFBULL
  34
  35 #if WORDS_BIGENDIAN
  36 #define BE_SWAP64(x) x
  37 #else
  38 #define BE_SWAP64(x)                            \
  39   (((x & 0xff) << 56)                           \
  40    | ((x & 0xff00) << 40)                       \
  41    | ((x & 0xff0000) << 24)                     \
  42    | ((x & 0xff000000) << 8)                    \
  43    | ((x >> 8) & 0xff000000)                    \
  44    | ((x >> 24) & 0xff0000)                     \
  45    | ((x >> 40) & 0xff00)                       \
  46    | (x >> 56) )
  47 #endif
  48
  49 void
  50 _umac_l3_init (unsigned size, uint64_t *k)
  51 {
  52   unsigned i;
  53   for (i = 0; i < size; i++)
  54     {
  55       uint64_t w = k[i];
  56       w = BE_SWAP64 (w);
  57       k[i] = w % P;
  58     }
  59 }
  60
  61 static uint64_t
  62 umac_l3_word (const uint64_t *k, uint64_t w)
  63 {
  64   unsigned i;
  65   uint64_t y;
  66
  67   /* Since it's easiest to process the input word from the low end,
  68    * loop over keys in reverse order. */
  69
  70   for (i = y = 0; i < 4; i++, w >>= 16)
  71     y += (w & 0xffff) * k[3-i];
  72
  73   return y;
  74 }
  75
  76 uint32_t
  77 _umac_l3 (const uint64_t *key, const uint64_t *m)
  78 {
  79   uint32_t y = (umac_l3_word (key, m[0])
  80                 + umac_l3_word (key + 4, m[1])) % P;
  81
  82 #if !WORDS_BIGENDIAN
  83   y = ((ROTL32(8,  y) & 0x00FF00FFUL)
  84        | (ROTL32(24, y) & 0xFF00FF00UL));
  85 #endif
  86   return y;
  87 }