poly1305-aes.c

/* nettle, low-level cryptographics library
 *
 * Copyright (C) 2013 Nikos Mavrogiannopoulos
 * Copyright (C) 2014 Niels Möller
 *
 * The nettle library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at your
 * option) any later version.
 *
 * The nettle library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the nettle library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02111-1301, USA.
 */

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

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

#include "poly1305.h"
#include "macros.h"

void
poly1305_aes_set_key (struct poly1305_aes_ctx *ctx, const uint8_t * key)
{
  aes128_set_encrypt_key(&ctx->aes, (key));
  poly1305_set_key(&ctx->pctx, (key+16));
  ctx->index = 0;
}

void
poly1305_aes_set_nonce (struct poly1305_aes_ctx *ctx,
			const uint8_t * nonce)
{
  memcpy (ctx->nonce, nonce, POLY1305_AES_NONCE_SIZE);
}

#define COMPRESS(ctx, data) _poly1305_block(&(ctx)->pctx, (data), 1)

void
poly1305_aes_update (struct poly1305_aes_ctx *ctx, size_t length, const uint8_t *data)
{
  MD_UPDATE (ctx, length, data, COMPRESS, (void) 0);
}

void
poly1305_aes_digest (struct poly1305_aes_ctx *ctx,
		     size_t length, uint8_t *digest)
{
  uint8_t s[POLY1305_BLOCK_SIZE];
  /* final bytes */
  if (ctx->index > 0)
    {
      assert (ctx->index < POLY1305_BLOCK_SIZE);

      ctx->block[ctx->index] = 1;
      memset (ctx->block + ctx->index + 1,
	      0, POLY1305_BLOCK_SIZE - 1 - ctx->index);

      _poly1305_block (&ctx->pctx, ctx->block, 0);
    }
  aes128_encrypt(&ctx->aes, POLY1305_BLOCK_SIZE, s, ctx->nonce);
  
  poly1305_digest (&ctx->pctx, s);
  memcpy (digest, s, length);

  INCREMENT (16, ctx->nonce);
  ctx->index = 0;
}