/* openpgp-s2ks.c - OpenPGP S2K helper functions

 * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,

 *               2005, 2006 Free Software Foundation, Inc.

 * Copyright (C) 2010, 2019 g10 Code GmbH

 *

 * This file is part of GnuPG.

 *

 * This file 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.

 *

 * This file 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 a copy of the GNU General Public License

 * along with this program; if not, see <https://www.gnu.org/licenses/>.

 */

#include <config.h>

#include <stdlib.h>

#include <errno.h>

#include <ctype.h>

#include <assert.h>

#include "util.h"

#include "openpgpdefs.h"

/* Pack an s2k iteration count into the form specified in RFC-4880.

 * If we're in between valid values, round up.  */

unsigned char

encode_s2k_iterations (int iterations)

{

  unsigned char c=0;

  unsigned char result;

  unsigned int count;

  if (iterations <= 1024)

    return 0;  /* Command line arg compatibility.  */

  if (iterations >= 65011712)

    return 255;

  /* Need count to be in the range 16-31 */

  for (count=iterations>>6; count>=32; count>>=1)

    c++;

  result = (c<<4)|(count-16);

  if (S2K_DECODE_COUNT(result) < iterations)

    result++;

  return result;

}