path: root/lib/x509/mpi.c

/*
 * Copyright (C) 2003-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS 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 3 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 program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <gnutls_global.h>
#include <libtasn1.h>
#include <gnutls_datum.h>
#include "common.h"
#include "x509_int.h"
#include <gnutls_num.h>

/* Reads an Integer from the DER encoded data
 */

int
_gnutls_x509_read_der_int (uint8_t * der, int dersize, bigint_t * out)
{
  int result;
  ASN1_TYPE spk = ASN1_TYPE_EMPTY;

  /* == INTEGER */
  if ((result = asn1_create_element
       (_gnutls_get_gnutls_asn (), "GNUTLS.DSAPublicKey",
        &spk)) != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  result = asn1_der_decoding (&spk, der, dersize, NULL);

  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      asn1_delete_structure (&spk);
      return _gnutls_asn2err (result);
    }

  /* Read Y */

  if ((result = _gnutls_x509_read_int (spk, "", out)) < 0)
    {
      gnutls_assert ();
      asn1_delete_structure (&spk);
      return _gnutls_asn2err (result);
    }

  asn1_delete_structure (&spk);

  return 0;

}


/* Extracts DSA and RSA parameters from a certificate.
 */
int
_gnutls_get_asn_mpis (ASN1_TYPE asn, const char *root,
                      gnutls_pk_params_st * params)
{
  int result;
  char name[256];
  gnutls_datum_t tmp = { NULL, 0 };
  gnutls_pk_algorithm_t pk_algorithm;

  gnutls_pk_params_init(params);

  result = _gnutls_x509_get_pk_algorithm (asn, root, NULL);
  if (result < 0)
    {
      gnutls_assert ();
      return result;
    }

  pk_algorithm = result;

  /* Read the algorithm's parameters
   */
  _asnstr_append_name (name, sizeof (name), root, ".subjectPublicKey");
  result = _gnutls_x509_read_value (asn, name, &tmp);

  if (result < 0)
    {
      gnutls_assert ();
      return result;
    }

  if ((result =
       _gnutls_x509_read_pubkey (pk_algorithm, tmp.data, tmp.size, params)) < 0)
    {
      gnutls_assert ();
      goto error;
    }

  /* Now read the parameters
   */
  _gnutls_free_datum (&tmp);
 
  _asnstr_append_name (name, sizeof (name), root,
                       ".algorithm.parameters");

  /* FIXME: If the parameters are not included in the certificate
   * then the issuer's parameters should be used. This is not
   * done yet.
   */

  if (pk_algorithm != GNUTLS_PK_RSA) /* RSA doesn't use parameters */
    {
      result = _gnutls_x509_read_value (asn, name, &tmp);
      if (result < 0) 
        {
          gnutls_assert ();
          goto error;
        }

      if ((result =
           _gnutls_x509_read_pubkey_params (pk_algorithm, tmp.data, tmp.size, params)) < 0)
        {
          gnutls_assert ();
          goto error;
        }
    }

  result = 0;

error:
  _gnutls_free_datum (&tmp);
  return result;
}

/* Extracts DSA and RSA parameters from a certificate.
 */
int
_gnutls_x509_crt_get_mpis (gnutls_x509_crt_t cert,
                           gnutls_pk_params_st * params)
{
  /* Read the algorithm's OID
   */
  return _gnutls_get_asn_mpis (cert->cert,
                               "tbsCertificate.subjectPublicKeyInfo", params);
}

/* Extracts DSA and RSA parameters from a certificate.
 */
int
_gnutls_x509_crq_get_mpis (gnutls_x509_crq_t cert,
                           gnutls_pk_params_st* params)
{
  /* Read the algorithm's OID
   */
  return _gnutls_get_asn_mpis (cert->crq,
                               "certificationRequestInfo.subjectPKInfo",
                               params);
}

/*
 * This function writes and encodes the parameters for DSS or RSA keys.
 * This is the "signatureAlgorithm" fields.
 */
int
_gnutls_x509_write_sig_params (ASN1_TYPE dst, const char *dst_name,
                               gnutls_pk_algorithm_t pk_algorithm,
                               gnutls_digest_algorithm_t dig)
{
  int result;
  char name[128];
  const char *pk;

  _gnutls_str_cpy (name, sizeof (name), dst_name);
  _gnutls_str_cat (name, sizeof (name), ".algorithm");

  pk = _gnutls_x509_sign_to_oid (pk_algorithm, dig);
  if (pk == NULL)
    {
      gnutls_assert ();
      _gnutls_debug_log
        ("Cannot find OID for sign algorithm pk: %d dig: %d\n",
         (int) pk_algorithm, (int) dig);
      return GNUTLS_E_INVALID_REQUEST;
    }

  /* write the OID.
   */
  result = asn1_write_value (dst, name, pk, 1);
  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }


  _gnutls_str_cpy (name, sizeof (name), dst_name);
  _gnutls_str_cat (name, sizeof (name), ".parameters");

  if (pk_algorithm == GNUTLS_PK_RSA)
    result = asn1_write_value (dst, name, ASN1_NULL, ASN1_NULL_SIZE);
  else
    result = asn1_write_value (dst, name, NULL, 0);

  if (result != ASN1_SUCCESS && result != ASN1_ELEMENT_NOT_FOUND)
    {
      /* Here we ignore the element not found error, since this
       * may have been disabled before.
       */
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  return 0;
}

/* this function reads a (small) unsigned integer
 * from asn1 structs. Combines the read and the convertion
 * steps.
 */
int
_gnutls_x509_read_uint (ASN1_TYPE node, const char *value, unsigned int *ret)
{
  int len, result;
  uint8_t *tmpstr;

  len = 0;
  result = asn1_read_value (node, value, NULL, &len);
  if (result != ASN1_MEM_ERROR)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  tmpstr = gnutls_malloc (len);
  if (tmpstr == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  result = asn1_read_value (node, value, tmpstr, &len);

  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      gnutls_free (tmpstr);
      return _gnutls_asn2err (result);
    }

  if (len == 1)
    *ret = tmpstr[0];
  else if (len == 2)
    *ret = _gnutls_read_uint16 (tmpstr);
  else if (len == 3)
    *ret = _gnutls_read_uint24 (tmpstr);
  else if (len == 4)
    *ret = _gnutls_read_uint32 (tmpstr);
  else
    {
      gnutls_assert ();
      gnutls_free (tmpstr);
      return GNUTLS_E_INTERNAL_ERROR;
    }

  gnutls_free (tmpstr);

  return 0;
}

/* Writes the specified integer into the specified node.
 */
int
_gnutls_x509_write_uint32 (ASN1_TYPE node, const char *value, uint32_t num)
{
  uint8_t tmpstr[4];
  int result;

  _gnutls_write_uint32 (num, tmpstr);

  result = asn1_write_value (node, value, tmpstr, 4);

  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  return 0;
}