umac128.c

   1 /* umac128.c
   2
   3    Copyright (C) 2013 Niels Möller
   4
   5    This file is part of GNU Nettle.
   6
   7    GNU Nettle is free software: you can redistribute it and/or
   8    modify it under the terms of either:
   9
  10      * the GNU Lesser General Public License as published by the Free
  11        Software Foundation; either version 3 of the License, or (at your
  12        option) any later version.
  13
  14    or
  15
  16      * the GNU General Public License as published by the Free
  17        Software Foundation; either version 2 of the License, or (at your
  18        option) any later version.
  19
  20    or both in parallel, as here.
  21
  22    GNU Nettle is distributed in the hope that it will be useful,
  23    but WITHOUT ANY WARRANTY; without even the implied warranty of
  24    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25    General Public License for more details.
  26
  27    You should have received copies of the GNU General Public License and
  28    the GNU Lesser General Public License along with this program.  If
  29    not, see http://www.gnu.org/licenses/.
  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 "umac.h"
  40 #include "umac-internal.h"
  41
  42 #include "macros.h"
  43
  44 void
  45 umac128_set_key (struct umac128_ctx *ctx, const uint8_t *key)
  46 {
  47   _nettle_umac_set_key (ctx->l1_key, ctx->l2_key, ctx->l3_key1, ctx->l3_key2,
  48                         &ctx->pdf_key, key, 4);
  49
  50   /* Clear nonce */
  51   memset (ctx->nonce, 0, sizeof(ctx->nonce));
  52   ctx->nonce_length = sizeof(ctx->nonce);
  53
  54   /* Initialize buffer */
  55   ctx->count = ctx->index = 0;
  56 }
  57
  58 void
  59 umac128_set_nonce (struct umac128_ctx *ctx,
  60                    size_t nonce_length, const uint8_t *nonce)
  61 {
  62   assert (nonce_length > 0);
  63   assert (nonce_length <= AES_BLOCK_SIZE);
  64
  65   memcpy (ctx->nonce, nonce, nonce_length);
  66   memset (ctx->nonce + nonce_length, 0, AES_BLOCK_SIZE - nonce_length);
  67
  68   ctx->nonce_length = nonce_length;
  69 }
  70
  71 #define UMAC128_BLOCK(ctx, block) do {                                  \
  72     uint64_t __umac128_y[4];                                            \
  73     _nettle_umac_nh_n (__umac128_y, 4, ctx->l1_key, UMAC_BLOCK_SIZE, block); \
  74     __umac128_y[0] += 8*UMAC_BLOCK_SIZE;                                \
  75     __umac128_y[1] += 8*UMAC_BLOCK_SIZE;                                \
  76     __umac128_y[2] += 8*UMAC_BLOCK_SIZE;                                \
  77     __umac128_y[3] += 8*UMAC_BLOCK_SIZE;                                \
  78     _nettle_umac_l2 (ctx->l2_key, ctx->l2_state, 4, ctx->count++, __umac128_y); \
  79   } while (0)
  80
  81 void
  82 umac128_update (struct umac128_ctx *ctx,
  83                 size_t length, const uint8_t *data)
  84 {
  85   MD_UPDATE (ctx, length, data, UMAC128_BLOCK, (void)0);
  86 }
  87
  88
  89 void
  90 umac128_digest (struct umac128_ctx *ctx,
  91                 size_t length, uint8_t *digest)
  92 {
  93   uint32_t tag[4];
  94   unsigned i;
  95
  96   assert (length > 0);
  97   assert (length <= 16);
  98
  99   if (ctx->index > 0 || ctx->count == 0)
 100     {
 101       /* Zero pad to multiple of 32 */
 102       uint64_t y[4];
 103       unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;
 104       memset (ctx->block + ctx->index, 0, pad);
 105
 106       _nettle_umac_nh_n (y, 4, ctx->l1_key, ctx->index + pad, ctx->block);
 107       y[0] += 8 * ctx->index;
 108       y[1] += 8 * ctx->index;
 109       y[2] += 8 * ctx->index;
 110       y[3] += 8 * ctx->index;
 111       _nettle_umac_l2 (ctx->l2_key, ctx->l2_state, 4, ctx->count++, y);
 112     }
 113   assert (ctx->count > 0);
 114
 115   aes128_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,
 116                   (uint8_t *) tag, ctx->nonce);
 117
 118   INCREMENT (ctx->nonce_length, ctx->nonce);
 119
 120   _nettle_umac_l2_final (ctx->l2_key, ctx->l2_state, 4, ctx->count);
 121   for (i = 0; i < 4; i++)
 122     tag[i] ^= ctx->l3_key2[i] ^ _nettle_umac_l3 (ctx->l3_key1 + 8*i,
 123                                                  ctx->l2_state + 2*i);
 124
 125   memcpy (digest, tag, length);
 126
 127   /* Reinitialize */
 128   ctx->count = ctx->index = 0;
 129 }