gnupg/common/compliance.c

/* compliance.c - Functions for compliance modi
 * Copyright (C) 2017 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 <gcrypt.h>

#include "openpgpdefs.h"
#include "logging.h"
#include "util.h"
#include "compliance.h"

/* Return true if ALGO with a key of KEYLENGTH is compliant to the
 * give COMPLIANCE mode.  If KEY is not NULL, various bits of
 * information will be extracted from it.  If CURVENAME is not NULL, it
 * is assumed to be the already computed.  ALGO may be either an
 * OpenPGP-style pubkey_algo_t, or a gcrypt-style enum gcry_pk_algos,
 * both are compatible from the point of view of this function.  */
int
gnupg_pk_is_compliant (enum gnupg_compliance_mode compliance, int algo,
		       gcry_mpi_t key[], unsigned int keylength, const char *curvename)
{
  enum { is_rsa, is_pgp5, is_elg_sign, is_ecc } algotype;
  int result;

  switch (algo)
    {
    case PUBKEY_ALGO_RSA:
    case PUBKEY_ALGO_RSA_E:
    case PUBKEY_ALGO_RSA_S:
      algotype = is_rsa;
      break;

    case PUBKEY_ALGO_ELGAMAL_E:
    case PUBKEY_ALGO_DSA:
      algotype = is_pgp5;
      break;

    case PUBKEY_ALGO_ECDH:
    case PUBKEY_ALGO_ECDSA:
    case PUBKEY_ALGO_EDDSA:
      algotype = is_ecc;
      break;

    case PUBKEY_ALGO_ELGAMAL:
      algotype = is_elg_sign;
      break;

    default: /* Unknown.  */
      return 0;
    }

  if (compliance == CO_DE_VS)
    {
      char *curve = NULL;

      switch (algotype)
        {
        case is_pgp5:
          result = 0;
          break;

        case is_rsa:
          result = (keylength >= 2048);
          break;

        case is_ecc:
          if (!curvename && key)
            {
              curve = openpgp_oid_to_str (key[0]);
              curvename = openpgp_oid_to_curve (curve, 0);
              if (!curvename)
                curvename = curve;
            }

          result = (curvename
                    && algo != PUBKEY_ALGO_EDDSA
                    && (!strcmp (curvename, "brainpoolP256r1")
                        || !strcmp (curvename, "brainpoolP384r1")
                        || !strcmp (curvename, "brainpoolP512r1")));
          break;

        default:
          result = 0;
        }
      xfree (curve);
    }
  else if (algotype == is_elg_sign)
    {
      /* An Elgamal signing key is only RFC-2440 compliant.  */
      result = (compliance == CO_RFC2440);
    }
  else
    {
      result = 1; /* Assume compliance.  */
    }

  return result;
}


const char *
gnupg_status_compliance_flag (enum gnupg_compliance_mode compliance)
{
  switch (compliance)
    {
    case CO_GNUPG:
      return "8";
    case CO_RFC4880:
    case CO_RFC2440:
    case CO_PGP6:
    case CO_PGP7:
    case CO_PGP8:
      log_assert (!"no status code assigned for this compliance mode");
    case CO_DE_VS:
      return "23";
    }
  log_assert (!"invalid compliance mode");
}