umac64.c 3.75 KB
Newer Older
Niels Möller's avatar
Niels Möller committed
1
/* umac64.c
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

   Copyright (C) 2013 Niels Möller

   This file is part of GNU Nettle.

   GNU Nettle is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.

   GNU Nettle is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see http://www.gnu.org/licenses/.
*/
Niels Möller's avatar
Niels Möller committed
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include <assert.h>
#include <string.h>

#include "umac.h"

#include "macros.h"

void
umac64_set_key (struct umac64_ctx *ctx, const uint8_t *key)
{
  _umac_set_key (ctx->l1_key, ctx->l2_key, ctx->l3_key1, ctx->l3_key2,
		 &ctx->pdf_key, key, 2);

  /* Clear nonce */
  memset (ctx->nonce, 0, sizeof(ctx->nonce));
  ctx->nonce_low = 0;
  ctx->nonce_length = sizeof(ctx->nonce);

  /* Initialize buffer */
  ctx->count = ctx->index = 0;
}

void
umac64_set_nonce (struct umac64_ctx *ctx,
60
		  size_t nonce_length, const uint8_t *nonce)
Niels Möller's avatar
Niels Möller committed
61 62 63 64 65 66 67 68 69 70 71 72 73 74
{
  assert (nonce_length > 0);
  assert (nonce_length <= AES_BLOCK_SIZE);

  memcpy (ctx->nonce, nonce, nonce_length);
  memset (ctx->nonce + nonce_length, 0, AES_BLOCK_SIZE - nonce_length);

  ctx->nonce_low = ctx->nonce[nonce_length - 1] & 1;
  ctx->nonce[nonce_length - 1] &= ~1;
  ctx->nonce_length = nonce_length;
}

#define UMAC64_BLOCK(ctx, block) do {					\
    uint64_t __umac64_y[2];						\
75 76 77
    _umac_nh_n (__umac64_y, 2, ctx->l1_key, UMAC_BLOCK_SIZE, block);	\
    __umac64_y[0] += 8*UMAC_BLOCK_SIZE;					\
    __umac64_y[1] += 8*UMAC_BLOCK_SIZE;					\
78
    _umac_l2 (ctx->l2_key, ctx->l2_state, 2, ctx->count++, __umac64_y);	\
Niels Möller's avatar
Niels Möller committed
79 80 81 82
  } while (0)

void
umac64_update (struct umac64_ctx *ctx,
83
	       size_t length, const uint8_t *data)
Niels Möller's avatar
Niels Möller committed
84 85 86 87 88 89 90
{
  MD_UPDATE (ctx, length, data, UMAC64_BLOCK, (void)0);
}


void
umac64_digest (struct umac64_ctx *ctx,
91
	       size_t length, uint8_t *digest)
Niels Möller's avatar
Niels Möller committed
92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108
{
  uint32_t tag[2];
  uint32_t *pad;

  assert (length > 0);
  assert (length <= 8);

  if (ctx->index > 0 || ctx->count == 0)
    {
      /* Zero pad to multiple of 32 */
      uint64_t y[2];
      unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;
      memset (ctx->block + ctx->index, 0, pad);

      _umac_nh_n (y, 2, ctx->l1_key, ctx->index + pad, ctx->block);
      y[0] += 8 * ctx->index;
      y[1] += 8 * ctx->index;
109
      _umac_l2 (ctx->l2_key, ctx->l2_state, 2, ctx->count++, y);
Niels Möller's avatar
Niels Möller committed
110 111 112
    }
  assert (ctx->count > 0);
  if ( !(ctx->nonce_low & _UMAC_NONCE_CACHED))
113
    {
114 115
      aes128_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,
		      (uint8_t *) ctx->pad_cache, ctx->nonce);
116 117
      ctx->nonce_low |= _UMAC_NONCE_CACHED;
    }
Niels Möller's avatar
Niels Möller committed
118 119 120 121 122 123 124 125 126 127 128
  pad = ctx->pad_cache + 2*(ctx->nonce_low & 1);

  /* Increment nonce */
  ctx->nonce_low++;
  if ( !(ctx->nonce_low & 1))
    {
      unsigned i = ctx->nonce_length - 1;

      ctx->nonce_low = 0;
      ctx->nonce[i] += 2;

Niels Möller's avatar
Niels Möller committed
129 130
      if (ctx->nonce[i] == 0 && i > 0)
	INCREMENT (i, ctx->nonce);
Niels Möller's avatar
Niels Möller committed
131 132
    }

133
  _umac_l2_final (ctx->l2_key, ctx->l2_state, 2, ctx->count);
134 135 136 137
  tag[0] = pad[0] ^ ctx->l3_key2[0] ^ _umac_l3 (ctx->l3_key1,
						ctx->l2_state);
  tag[1] = pad[1] ^ ctx->l3_key2[1] ^ _umac_l3 (ctx->l3_key1 + 8,
						ctx->l2_state + 2);
Niels Möller's avatar
Niels Möller committed
138 139 140 141 142
  memcpy (digest, tag, length);

  /* Reinitialize */
  ctx->count = ctx->index = 0;
}