/* minip12.c - A mini pkcs-12 implementation (modified for gnutls)
 *
 * Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.
 *
 * This file is part of GNUTLS.
 *
 * The GNUTLS 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.
 *
 * This 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA
 *
 */

#include <gnutls_int.h>

#ifdef ENABLE_PKI

#include <gcrypt.h>
#include <gc.h>
#include <gnutls_errors.h>

/* Returns 0 if the password is ok, or a negative error
 * code instead.
 */
static int
MHD_pkcs12_check_pass (const char *pass, size_t plen)
{
  const char *p = pass;
  unsigned int i;

  for (i = 0; i < plen; i++)
    {
      if (isascii (p[i]))
        continue;
      return GNUTLS_E_INVALID_PASSWORD;
    }

  return 0;
}

/* ID should be:
 * 3 for MAC
 * 2 for IV
 * 1 for encryption key
 */
int
MHD_pkcs12_string_to_key (unsigned int id, const opaque * salt,
                       unsigned int salt_size, unsigned int iter,
                       const char *pw, unsigned int req_keylen,
                       opaque * keybuf)
{
  int rc;
  unsigned int i, j;
  MHD_gc_hash_handle md;
  mpi_t num_b1 = NULL;
  unsigned int pwlen;
  opaque hash[20], buf_b[64], buf_i[128], *p;
  size_t cur_keylen;
  size_t n;

  cur_keylen = 0;

  if (pw == NULL)
    pwlen = 0;
  else
    pwlen = strlen (pw);

  if (pwlen > 63 / 2)
    {
      MHD_gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  if ((rc = MHD_pkcs12_check_pass (pw, pwlen)) < 0)
    {
      MHD_gnutls_assert ();
      return rc;
    }

  /* Store salt and password in BUF_I */
  p = buf_i;
  for (i = 0; i < 64; i++)
    *p++ = salt[i % salt_size];
  if (pw)
    {
      for (i = j = 0; i < 64; i += 2)
        {
          *p++ = 0;
          *p++ = pw[j];
          if (++j > pwlen)      /* Note, that we include the trailing zero */
            j = 0;
        }
    }
  else
    memset (p, 0, 64);

  for (;;)
    {
      rc = MHD_gc_hash_open (GC_SHA1, 0, &md);
      if (rc)
        {
          MHD_gnutls_assert ();
          return GNUTLS_E_DECRYPTION_FAILED;
        }
      for (i = 0; i < 64; i++)
        {
          unsigned char lid = id & 0xFF;
          MHD_gc_hash_write (md, 1, (const char*) &lid);
        }
      MHD_gc_hash_write (md, pw ? 128 : 64, (const char*) buf_i);
      memcpy (hash, MHD_gc_hash_read (md), 20);
      MHD_gc_hash_close (md);
      for (i = 1; i < iter; i++)
        MHD_gc_hash_buffer (GC_SHA1, hash, 20, (char*) hash);
      for (i = 0; i < 20 && cur_keylen < req_keylen; i++)
        keybuf[cur_keylen++] = hash[i];
      if (cur_keylen == req_keylen)
        {
          gcry_mpi_release (num_b1);
          return 0;             /* ready */
        }

      /* need more bytes. */
      for (i = 0; i < 64; i++)
        buf_b[i] = hash[i % 20];
      n = 64;
      rc = MHD_gtls_mpi_scan (&num_b1, buf_b, &n);
      if (rc < 0)
        {
          MHD_gnutls_assert ();
          return rc;
        }
      gcry_mpi_add_ui (num_b1, num_b1, 1);
      for (i = 0; i < 128; i += 64)
        {
          mpi_t num_ij;

          n = 64;
          rc = MHD_gtls_mpi_scan (&num_ij, buf_i + i, &n);
          if (rc < 0)
            {
              MHD_gnutls_assert ();
              return rc;
            }
          gcry_mpi_add (num_ij, num_ij, num_b1);
          gcry_mpi_clear_highbit (num_ij, 64 * 8);
          n = 64;
          rc = MHD_gtls_mpi_print (buf_i + i, &n, num_ij);
          if (rc < 0)
            {
              MHD_gnutls_assert ();
              return rc;
            }
          gcry_mpi_release (num_ij);
        }
    }
}

#endif /* ENABLE_PKI */