/* umac96.c

   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/.

*/

#if HAVE_CONFIG_H

# include "config.h"

#endif

#include <assert.h>

#include <string.h>

#include "umac.h"

#include "umac-internal.h"

#include "macros.h"

void

umac96_set_key (struct umac96_ctx *ctx, const uint8_t *key)

{

  _nettle_umac_set_key (ctx->l1_key, ctx->l2_key, ctx->l3_key1, ctx->l3_key2,

      &ctx->pdf_key, key, 3);

  /* Clear nonce */

  memset (ctx->nonce, 0, sizeof(ctx->nonce));

  ctx->nonce_length = sizeof(ctx->nonce);

  /* Initialize buffer */

  ctx->count = ctx->index = 0;

}

void

umac96_set_nonce (struct umac96_ctx *ctx,

      size_t nonce_length, const uint8_t *nonce)

{

  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_length = nonce_length;

}

#define UMAC96_BLOCK(ctx, block) do {         \

    uint64_t __umac96_y[3];           \

    _nettle_umac_nh_n (__umac96_y, 3, ctx->l1_key, UMAC_BLOCK_SIZE, block); \

    __umac96_y[0] += 8*UMAC_BLOCK_SIZE;         \

    __umac96_y[1] += 8*UMAC_BLOCK_SIZE;         \

    __umac96_y[2] += 8*UMAC_BLOCK_SIZE;         \

    _nettle_umac_l2 (ctx->l2_key, ctx->l2_state, 3, ctx->count++, __umac96_y); \

  } while (0)

void

umac96_update (struct umac96_ctx *ctx,

         size_t length, const uint8_t *data)

{

  MD_UPDATE (ctx, length, data, UMAC96_BLOCK, (void)0);

}

void

umac96_digest (struct umac96_ctx *ctx,

         size_t length, uint8_t *digest)

{

  uint32_t tag[4];

  unsigned i;

  assert (length > 0);

  assert (length <= 12);

  if (ctx->index > 0 || ctx->count == 0)

    {

      /* Zero pad to multiple of 32 */

      uint64_t y[3];

      unsigned pad = (ctx->index > 0) ? 31 & - ctx->index : 32;

      memset (ctx->block + ctx->index, 0, pad);

      _nettle_umac_nh_n (y, 3, ctx->l1_key, ctx->index + pad, ctx->block);

      y[0] += 8 * ctx->index;

      y[1] += 8 * ctx->index;

      y[2] += 8 * ctx->index;

      _nettle_umac_l2 (ctx->l2_key, ctx->l2_state, 3, ctx->count++, y);

    }

  assert (ctx->count > 0);

  aes128_encrypt (&ctx->pdf_key, AES_BLOCK_SIZE,

      (uint8_t *) tag, ctx->nonce);

  INCREMENT (ctx->nonce_length, ctx->nonce);

  _nettle_umac_l2_final (ctx->l2_key, ctx->l2_state, 3, ctx->count);

  for (i = 0; i < 3; i++)

    tag[i] ^= ctx->l3_key2[i] ^ _nettle_umac_l3 (ctx->l3_key1 + 8*i,

             ctx->l2_state + 2*i);

  memcpy (digest, tag, length);

  /* Reinitialize */

  ctx->count = ctx->index = 0;

}