/*

 * Copyright (C) 2001-2012 Free Software Foundation, Inc.

 * Copyright (C) 2017 Red Hat, 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 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 program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include "errors.h"

#include <x509_b64.h>

#include <auth/cert.h>

#include <algorithms.h>

#include <datum.h>

#include <mpi.h>

#include <global.h>

#include <pk.h>

#include <debug.h>

#include <buffers.h>

#include <tls-sig.h>

#include <kx.h>

#include <libtasn1.h>

#include <ext/signature.h>

#include <state.h>

#include <x509/common.h>

#include <abstract_int.h>

int _gnutls_check_key_usage_for_sig(gnutls_session_t session,

            unsigned key_usage, unsigned our_cert)

{

  const char *lstr;

  unsigned allow_key_usage_violation;

  if (our_cert) {

    lstr = "Local";

    allow_key_usage_violation =

        session->internals.

        priorities->allow_server_key_usage_violation;

  } else {

    lstr = "Peer's";

    allow_key_usage_violation =

        session->internals.allow_key_usage_violation;

  }

  if (key_usage != 0) {

    if (!(key_usage & GNUTLS_KEY_DIGITAL_SIGNATURE)) {

      gnutls_assert();

      if (likely(allow_key_usage_violation == 0)) {

        _gnutls_audit_log(session,

              "%s certificate does not allow digital signatures. Key usage violation detected.\n",

              lstr);

        return GNUTLS_E_KEY_USAGE_VIOLATION;

      } else {

        _gnutls_audit_log(session,

              "%s certificate does not allow digital signatures. Key usage violation detected (ignored).\n",

              lstr);

      }

    }

  }

  return 0;

}

/* Generates a signature of all the random data and the parameters.

 * Used in *DHE_* ciphersuites for TLS 1.2.

 */

static int

_gnutls_handshake_sign_data12(gnutls_session_t session,

            gnutls_pcert_st * cert, gnutls_privkey_t pkey,

            gnutls_datum_t * params,

            gnutls_datum_t * signature,

            gnutls_sign_algorithm_t sign_algo)

{

  gnutls_datum_t dconcat;

  int ret;

  _gnutls_handshake_log

      ("HSK[%p]: signing TLS 1.2 handshake data: using %s\n", session,

       gnutls_sign_algorithm_get_name(sign_algo));

  if (unlikely

      (gnutls_sign_supports_pk_algorithm(sign_algo, pkey->pk_algorithm) ==

       0))

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  dconcat.size = GNUTLS_RANDOM_SIZE * 2 + params->size;

  dconcat.data = gnutls_malloc(dconcat.size);

  if (dconcat.data == NULL)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  memcpy(dconcat.data, session->security_parameters.client_random,

         GNUTLS_RANDOM_SIZE);

  memcpy(dconcat.data + GNUTLS_RANDOM_SIZE,

         session->security_parameters.server_random, GNUTLS_RANDOM_SIZE);

  memcpy(dconcat.data + GNUTLS_RANDOM_SIZE * 2, params->data,

         params->size);

  ret = gnutls_privkey_sign_data2(pkey, sign_algo,

          0, &dconcat, signature);

  if (ret < 0) {

    gnutls_assert();

  }

  gnutls_free(dconcat.data);

  return ret;

}

static int

_gnutls_handshake_sign_data10(gnutls_session_t session,

            gnutls_pcert_st * cert, gnutls_privkey_t pkey,

            gnutls_datum_t * params,

            gnutls_datum_t * signature,

            gnutls_sign_algorithm_t sign_algo)

{

  gnutls_datum_t dconcat;

  int ret;

  digest_hd_st td_sha;

  uint8_t concat[MAX_SIG_SIZE];

  const mac_entry_st *me;

  gnutls_pk_algorithm_t pk_algo;

  pk_algo = gnutls_privkey_get_pk_algorithm(pkey, NULL);

  if (pk_algo == GNUTLS_PK_RSA)

    me = hash_to_entry(GNUTLS_DIG_MD5_SHA1);

  else

    me = hash_to_entry(gnutls_sign_get_hash_algorithm(sign_algo));

  if (me == NULL)

    return gnutls_assert_val(GNUTLS_E_UNKNOWN_HASH_ALGORITHM);

  if (unlikely

      (gnutls_sign_supports_pk_algorithm(sign_algo, pk_algo) == 0))

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  pk_algo = gnutls_sign_get_pk_algorithm(sign_algo);

  if (pk_algo == GNUTLS_PK_UNKNOWN)

    return gnutls_assert_val(GNUTLS_E_UNKNOWN_PK_ALGORITHM);

  _gnutls_handshake_log

      ("HSK[%p]: signing handshake data: using %s\n", session,

       gnutls_sign_algorithm_get_name(sign_algo));

  ret = _gnutls_hash_init(&td_sha, me);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  _gnutls_hash(&td_sha, session->security_parameters.client_random,

         GNUTLS_RANDOM_SIZE);

  _gnutls_hash(&td_sha, session->security_parameters.server_random,

         GNUTLS_RANDOM_SIZE);

  _gnutls_hash(&td_sha, params->data, params->size);

  _gnutls_hash_deinit(&td_sha, concat);

  dconcat.data = concat;

  dconcat.size = _gnutls_hash_get_algo_len(me);

  ret =

      gnutls_privkey_sign_hash(pkey, MAC_TO_DIG(me->id),

             GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA,

             &dconcat, signature);

  if (ret < 0) {

    gnutls_assert();

  }

  return ret;

}

/* Generates a signature of all the random data and the parameters.

 * Used in DHE_* ciphersuites.

 */

int

_gnutls_handshake_sign_data(gnutls_session_t session,

          gnutls_pcert_st * cert, gnutls_privkey_t pkey,

          gnutls_datum_t * params,

          gnutls_datum_t * signature,

          gnutls_sign_algorithm_t * sign_algo)

{

  const version_entry_st *ver = get_version(session);

  unsigned key_usage = 0;

  int ret;

  *sign_algo = session->security_parameters.server_sign_algo;

  if (*sign_algo == GNUTLS_SIGN_UNKNOWN) {

    gnutls_assert();

    return GNUTLS_E_UNWANTED_ALGORITHM;

  }

  gnutls_pubkey_get_key_usage(cert->pubkey, &key_usage);

  ret = _gnutls_check_key_usage_for_sig(session, key_usage, 1);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (_gnutls_version_has_selectable_sighash(ver))

    return _gnutls_handshake_sign_data12(session, cert, pkey,

                 params, signature,

                 *sign_algo);

  else

    return _gnutls_handshake_sign_data10(session, cert, pkey,

                 params, signature,

                 *sign_algo);

}

/* Generates a signature of all the random data and the parameters.

 * Used in DHE_* ciphersuites.

 */

static int

_gnutls_handshake_verify_data10(gnutls_session_t session,

        unsigned verify_flags,

        gnutls_pcert_st * cert,

        const gnutls_datum_t * params,

        gnutls_datum_t * signature,

        gnutls_sign_algorithm_t sign_algo)

{

  gnutls_datum_t dconcat;

  int ret;

  digest_hd_st td_sha;

  uint8_t concat[MAX_SIG_SIZE];

  gnutls_digest_algorithm_t hash_algo;

  const mac_entry_st *me;

  gnutls_pk_algorithm_t pk_algo;

  pk_algo = gnutls_pubkey_get_pk_algorithm(cert->pubkey, NULL);

  if (pk_algo == GNUTLS_PK_RSA) {

    hash_algo = GNUTLS_DIG_MD5_SHA1;

    verify_flags |= GNUTLS_PUBKEY_VERIFY_FLAG_TLS1_RSA;

  } else {

    hash_algo = GNUTLS_DIG_SHA1;

    if (sign_algo == GNUTLS_SIGN_UNKNOWN) {

      sign_algo = gnutls_pk_to_sign(pk_algo, hash_algo);

    }

  }

  me = hash_to_entry(hash_algo);

  ret = _gnutls_hash_init(&td_sha, me);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  _gnutls_hash(&td_sha, session->security_parameters.client_random,

         GNUTLS_RANDOM_SIZE);

  _gnutls_hash(&td_sha, session->security_parameters.server_random,

         GNUTLS_RANDOM_SIZE);

  _gnutls_hash(&td_sha, params->data, params->size);

  _gnutls_hash_deinit(&td_sha, concat);

  dconcat.data = concat;

  dconcat.size = _gnutls_hash_get_algo_len(me);

  ret = gnutls_pubkey_verify_hash2(cert->pubkey, sign_algo,

           GNUTLS_VERIFY_ALLOW_SIGN_WITH_SHA1 |

           verify_flags, &dconcat, signature);

  if (ret < 0)

    return gnutls_assert_val(ret);

  return ret;

}

static int

_gnutls_handshake_verify_data12(gnutls_session_t session,

        unsigned verify_flags,

        gnutls_pcert_st * cert,

        const gnutls_datum_t * params,

        gnutls_datum_t * signature,

        gnutls_sign_algorithm_t sign_algo)

{

  gnutls_datum_t dconcat;

  int ret;

  const version_entry_st *ver = get_version(session);

  const gnutls_sign_entry_st *se = _gnutls_sign_to_entry(sign_algo);

  _gnutls_handshake_log

      ("HSK[%p]: verify TLS 1.2 handshake data: using %s\n", session,

       se->name);

  ret =

      _gnutls_pubkey_compatible_with_sig(session,

                 cert->pubkey, ver, sign_algo);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (unlikely

      (sign_supports_cert_pk_algorithm(se, cert->pubkey->params.algo) ==

       0)) {

    _gnutls_handshake_log

        ("HSK[%p]: certificate of %s cannot be combined with %s sig\n",

         session, gnutls_pk_get_name(cert->pubkey->params.algo),

         se->name);

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  }

  ret = _gnutls_session_sign_algo_enabled(session, sign_algo);

  if (ret < 0)

    return gnutls_assert_val(ret);

  dconcat.size = GNUTLS_RANDOM_SIZE * 2 + params->size;

  dconcat.data = gnutls_malloc(dconcat.size);

  if (dconcat.data == NULL)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  memcpy(dconcat.data, session->security_parameters.client_random,

         GNUTLS_RANDOM_SIZE);

  memcpy(dconcat.data + GNUTLS_RANDOM_SIZE,

         session->security_parameters.server_random, GNUTLS_RANDOM_SIZE);

  memcpy(dconcat.data + GNUTLS_RANDOM_SIZE * 2, params->data,

         params->size);

  ret = gnutls_pubkey_verify_data2(cert->pubkey, sign_algo, verify_flags,

           &dconcat, signature);

  if (ret < 0)

    gnutls_assert();

  gnutls_free(dconcat.data);

  return ret;

}

int

_gnutls_handshake_verify_data(gnutls_session_t session,

            unsigned verify_flags,

            gnutls_pcert_st * cert,

            const gnutls_datum_t * params,

            gnutls_datum_t * signature,

            gnutls_sign_algorithm_t sign_algo)

{

  unsigned key_usage;

  int ret;

  const version_entry_st *ver = get_version(session);

  if (cert == NULL) {

    gnutls_assert();

    return GNUTLS_E_CERTIFICATE_ERROR;

  }

  gnutls_pubkey_get_key_usage(cert->pubkey, &key_usage);

  ret = _gnutls_check_key_usage_for_sig(session, key_usage, 0);

  if (ret < 0)

    return gnutls_assert_val(ret);

  gnutls_sign_algorithm_set_server(session, sign_algo);

  if (_gnutls_version_has_selectable_sighash(ver))

    return _gnutls_handshake_verify_data12(session, verify_flags,

                   cert, params, signature,

                   sign_algo);

  else

    return _gnutls_handshake_verify_data10(session, verify_flags,

                   cert, params, signature,

                   sign_algo);

}

/* Client certificate verify calculations

 */

static void _gnutls_reverse_datum(gnutls_datum_t * d)

{

  unsigned i;

  for (i = 0; i < d->size / 2; i++) {

    uint8_t t = d->data[i];

    d->data[i] = d->data[d->size - 1 - i];

    d->data[d->size - 1 - i] = t;

  }

}

static int

_gnutls_create_reverse(const gnutls_datum_t * src, gnutls_datum_t * dst)

{

  unsigned int i;

  dst->size = src->size;

  dst->data = gnutls_malloc(dst->size);

  if (!dst->data)

    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  for (i = 0; i < dst->size; i++)

    dst->data[i] = src->data[dst->size - 1 - i];

  return 0;

}

/* this is _gnutls_handshake_verify_crt_vrfy for TLS 1.2

 */

static int

_gnutls_handshake_verify_crt_vrfy12(gnutls_session_t session,

            unsigned verify_flags,

            gnutls_pcert_st * cert,

            gnutls_datum_t * signature,

            gnutls_sign_algorithm_t sign_algo)

{

  int ret;

  gnutls_datum_t dconcat;

  const gnutls_sign_entry_st *se = _gnutls_sign_to_entry(sign_algo);

  gnutls_datum_t sig_rev = { NULL, 0 };

  ret = _gnutls_session_sign_algo_enabled(session, sign_algo);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (unlikely

      (sign_supports_cert_pk_algorithm(se, cert->pubkey->params.algo) ==

       0)) {

    _gnutls_handshake_log

        ("HSK[%p]: certificate of %s cannot be combined with %s sig\n",

         session, gnutls_pk_get_name(cert->pubkey->params.algo),

         se->name);

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  }

  if (se->flags & GNUTLS_SIGN_FLAG_CRT_VRFY_REVERSE) {

    ret = _gnutls_create_reverse(signature, &sig_rev);

    if (ret < 0)

      return gnutls_assert_val(ret);

  }

  dconcat.data = session->internals.handshake_hash_buffer.data;

  dconcat.size = session->internals.handshake_hash_buffer_prev_len;

  /* Here we intentionally enable flag GNUTLS_VERIFY_ALLOW_BROKEN

   * because we have checked whether the currently used signature

   * algorithm is allowed in the session. */

  ret =

      gnutls_pubkey_verify_data2(cert->pubkey, sign_algo,

               verify_flags |

               GNUTLS_VERIFY_ALLOW_BROKEN, &dconcat,

               sig_rev.data ? &sig_rev : signature);

  _gnutls_free_datum(&sig_rev);

  if (ret < 0)

    gnutls_assert();

  return ret;

}

/* Verifies a SSL 3.0 signature (like the one in the client certificate

 * verify message).

 */

#ifdef ENABLE_SSL3

static int

_gnutls_handshake_verify_crt_vrfy3(gnutls_session_t session,

           unsigned verify_flags,

           gnutls_pcert_st * cert,

           gnutls_datum_t * signature,

           gnutls_sign_algorithm_t sign_algo)

{

  int ret;

  uint8_t concat[MAX_SIG_SIZE];

  digest_hd_st td_sha;

  gnutls_datum_t dconcat;

  gnutls_pk_algorithm_t pk =

      gnutls_pubkey_get_pk_algorithm(cert->pubkey, NULL);

  ret = _gnutls_generate_master(session, 1);

  if (ret < 0) {

    return gnutls_assert_val(ret);

  }

  dconcat.data = concat;

  dconcat.size = 0;

  if (pk == GNUTLS_PK_RSA) {

    digest_hd_st td_md5;

    ret = _gnutls_hash_init(&td_md5, hash_to_entry(GNUTLS_DIG_MD5));

    if (ret < 0)

      return gnutls_assert_val(ret);

    _gnutls_hash(&td_md5,

           session->internals.handshake_hash_buffer.data,

           session->internals.handshake_hash_buffer_prev_len);

    ret = _gnutls_mac_deinit_ssl3_handshake(&td_md5, concat,

              session->security_parameters.

              master_secret,

              GNUTLS_MASTER_SIZE);

    if (ret < 0)

      return gnutls_assert_val(ret);

    verify_flags |= GNUTLS_PUBKEY_VERIFY_FLAG_TLS1_RSA;

    dconcat.size = 16;

  }

  ret = _gnutls_hash_init(&td_sha, hash_to_entry(GNUTLS_DIG_SHA1));

  if (ret < 0) {

    gnutls_assert();

    return GNUTLS_E_HASH_FAILED;

  }

  _gnutls_hash(&td_sha,

         session->internals.handshake_hash_buffer.data,

         session->internals.handshake_hash_buffer_prev_len);

  ret =

      _gnutls_mac_deinit_ssl3_handshake(&td_sha,

                dconcat.data + dconcat.size,

                session->security_parameters.

                master_secret,

                GNUTLS_MASTER_SIZE);

  if (ret < 0) {

    return gnutls_assert_val(ret);

  }

  dconcat.size += 20;

  ret = gnutls_pubkey_verify_hash2(cert->pubkey, GNUTLS_SIGN_UNKNOWN,

           GNUTLS_VERIFY_ALLOW_SIGN_WITH_SHA1 |

           verify_flags, &dconcat, signature);

  if (ret < 0)

    return gnutls_assert_val(ret);

  return ret;

}

#endif

static int

_gnutls_handshake_verify_crt_vrfy10(gnutls_session_t session,

            unsigned verify_flags,

            gnutls_pcert_st * cert,

            gnutls_datum_t * signature,

            gnutls_sign_algorithm_t sign_algo)

{

  int ret;

  uint8_t concat[MAX_SIG_SIZE];

  digest_hd_st td_sha;

  gnutls_datum_t dconcat;

  gnutls_pk_algorithm_t pk_algo;

  const mac_entry_st *me;

  /* TLS 1.0 and TLS 1.1 */

  pk_algo = gnutls_pubkey_get_pk_algorithm(cert->pubkey, NULL);

  if (pk_algo == GNUTLS_PK_RSA) {

    me = hash_to_entry(GNUTLS_DIG_MD5_SHA1);

    verify_flags |= GNUTLS_PUBKEY_VERIFY_FLAG_TLS1_RSA;

    sign_algo = GNUTLS_SIGN_UNKNOWN;

  } else {

    me = hash_to_entry(GNUTLS_DIG_SHA1);

    sign_algo = gnutls_pk_to_sign(pk_algo, GNUTLS_DIG_SHA1);

  }

  ret = _gnutls_hash_init(&td_sha, me);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  _gnutls_hash(&td_sha,

         session->internals.handshake_hash_buffer.data,

         session->internals.handshake_hash_buffer_prev_len);

  _gnutls_hash_deinit(&td_sha, concat);

  dconcat.data = concat;

  dconcat.size = _gnutls_hash_get_algo_len(me);

  ret = gnutls_pubkey_verify_hash2(cert->pubkey, sign_algo,

           GNUTLS_VERIFY_ALLOW_SIGN_WITH_SHA1 |

           verify_flags, &dconcat, signature);

  if (ret < 0)

    gnutls_assert();

  return ret;

}

/* Verifies a TLS signature (like the one in the client certificate

 * verify message). 

 */

int

_gnutls_handshake_verify_crt_vrfy(gnutls_session_t session,

          unsigned verify_flags,

          gnutls_pcert_st * cert,

          gnutls_datum_t * signature,

          gnutls_sign_algorithm_t sign_algo)

{

  int ret;

  const version_entry_st *ver = get_version(session);

  unsigned key_usage;

  if (cert == NULL) {

    gnutls_assert();

    return GNUTLS_E_CERTIFICATE_ERROR;

  }

  gnutls_pubkey_get_key_usage(cert->pubkey, &key_usage);

  ret = _gnutls_check_key_usage_for_sig(session, key_usage, 0);

  if (ret < 0)

    return gnutls_assert_val(ret);

  _gnutls_handshake_log("HSK[%p]: verify cert vrfy: using %s\n",

            session,

            gnutls_sign_algorithm_get_name(sign_algo));

  if (unlikely(ver == NULL))

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  gnutls_sign_algorithm_set_client(session, sign_algo);

  /* TLS 1.2 */

  if (_gnutls_version_has_selectable_sighash(ver))

    return _gnutls_handshake_verify_crt_vrfy12(session,

                 verify_flags,

                 cert,

                 signature,

                 sign_algo);

#ifdef ENABLE_SSL3

  if (ver->id == GNUTLS_SSL3)

    return _gnutls_handshake_verify_crt_vrfy3(session,

                verify_flags,

                cert,

                signature, sign_algo);

#endif

  /* TLS 1.0 and TLS 1.1 */

  return _gnutls_handshake_verify_crt_vrfy10(session,

               verify_flags,

               cert, signature, sign_algo);

}

/* the same as _gnutls_handshake_sign_crt_vrfy except that it is made for TLS 1.2.

 * Returns the used signature algorithm, or a negative error code.

 */

static int

_gnutls_handshake_sign_crt_vrfy12(gnutls_session_t session,

          gnutls_pcert_st * cert,

          gnutls_privkey_t pkey,

          gnutls_datum_t * signature)

{

  gnutls_datum_t dconcat;

  gnutls_sign_algorithm_t sign_algo;

  const gnutls_sign_entry_st *se;

  int ret;

  sign_algo =

      _gnutls_session_get_sign_algo(session, cert, pkey, 1,

            GNUTLS_KX_UNKNOWN);

  if (sign_algo == GNUTLS_SIGN_UNKNOWN) {

    gnutls_assert();

    return GNUTLS_E_UNWANTED_ALGORITHM;

  }

  se = _gnutls_sign_to_entry(sign_algo);

  if (se == NULL)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  gnutls_sign_algorithm_set_client(session, sign_algo);

  if (unlikely

      (gnutls_sign_supports_pk_algorithm(sign_algo, pkey->pk_algorithm) ==

       0))

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  _gnutls_debug_log("sign handshake cert vrfy: picked %s\n",

        gnutls_sign_algorithm_get_name(sign_algo));

  dconcat.data = session->internals.handshake_hash_buffer.data;

  dconcat.size = session->internals.handshake_hash_buffer.length;

  ret = gnutls_privkey_sign_data2(pkey, sign_algo,

          0, &dconcat, signature);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  if (se->flags & GNUTLS_SIGN_FLAG_CRT_VRFY_REVERSE)

    _gnutls_reverse_datum(signature);

  return sign_algo;

}

#ifdef ENABLE_SSL3

static int

_gnutls_handshake_sign_crt_vrfy3(gnutls_session_t session,

         gnutls_pcert_st * cert,

         const version_entry_st * ver,

         gnutls_privkey_t pkey,

         gnutls_datum_t * signature)

{

  gnutls_datum_t dconcat;

  int ret;

  uint8_t concat[MAX_SIG_SIZE];

  digest_hd_st td_sha;

  gnutls_pk_algorithm_t pk = gnutls_privkey_get_pk_algorithm(pkey, NULL);

  /* ensure 1024 bit DSA keys are used */

  ret =

      _gnutls_pubkey_compatible_with_sig(session, cert->pubkey, ver,

                 GNUTLS_SIGN_UNKNOWN);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_generate_master(session, 1);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  dconcat.data = concat;

  dconcat.size = 0;

  if (pk == GNUTLS_PK_RSA) {

    digest_hd_st td_md5;

    ret = _gnutls_hash_init(&td_md5, hash_to_entry(GNUTLS_DIG_MD5));

    if (ret < 0)

      return gnutls_assert_val(ret);

    _gnutls_hash(&td_md5,

           session->internals.handshake_hash_buffer.data,

           session->internals.handshake_hash_buffer.length);

    ret = _gnutls_mac_deinit_ssl3_handshake(&td_md5,

              dconcat.data,

              session->security_parameters.

              master_secret,

              GNUTLS_MASTER_SIZE);

    if (ret < 0)

      return gnutls_assert_val(ret);

    dconcat.size = 16;

  }

  ret = _gnutls_hash_init(&td_sha, hash_to_entry(GNUTLS_DIG_SHA1));

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  _gnutls_hash(&td_sha,

         session->internals.handshake_hash_buffer.data,

         session->internals.handshake_hash_buffer.length);

  ret =

      _gnutls_mac_deinit_ssl3_handshake(&td_sha,

                dconcat.data + dconcat.size,

                session->security_parameters.

                master_secret,

                GNUTLS_MASTER_SIZE);

  if (ret < 0)

    return gnutls_assert_val(ret);

  dconcat.size += 20;

  ret = gnutls_privkey_sign_hash(pkey, GNUTLS_DIG_SHA1,

               GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA,

               &dconcat, signature);

  if (ret < 0)

    return gnutls_assert_val(ret);

  return GNUTLS_SIGN_UNKNOWN;

}

#endif

static int

_gnutls_handshake_sign_crt_vrfy10(gnutls_session_t session,

          gnutls_pcert_st * cert,

          const version_entry_st * ver,

          gnutls_privkey_t pkey,

          gnutls_datum_t * signature)

{

  gnutls_datum_t dconcat;

  int ret;

  uint8_t concat[MAX_SIG_SIZE];

  digest_hd_st td_sha;

  gnutls_pk_algorithm_t pk = gnutls_privkey_get_pk_algorithm(pkey, NULL);

  const mac_entry_st *me;

  /* ensure 1024 bit DSA keys are used */

  ret =

      _gnutls_pubkey_compatible_with_sig(session, cert->pubkey, ver,

                 GNUTLS_SIGN_UNKNOWN);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (pk == GNUTLS_PK_RSA)

    me = hash_to_entry(GNUTLS_DIG_MD5_SHA1);

  else

    me = hash_to_entry(GNUTLS_DIG_SHA1);

  ret = _gnutls_hash_init(&td_sha, me);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  _gnutls_hash(&td_sha,

         session->internals.handshake_hash_buffer.data,

         session->internals.handshake_hash_buffer.length);

  _gnutls_hash_deinit(&td_sha, concat);

  dconcat.data = concat;

  dconcat.size = _gnutls_hash_get_algo_len(me);

  ret =

      gnutls_privkey_sign_hash(pkey, MAC_TO_DIG(me->id),

             GNUTLS_PRIVKEY_SIGN_FLAG_TLS1_RSA,

             &dconcat, signature);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  return GNUTLS_SIGN_UNKNOWN;

}

/* Generates a signature of all the previous sent packets in the

 * handshake procedure.

 * 20040227: now it works for SSL 3.0 as well

 * 20091031: works for TLS 1.2 too!

 *

 * For TLS1.x, x<2 returns negative for failure and zero or unspecified for success.

 * For TLS1.2 returns the signature algorithm used on success, or a negative error code;

 *

 * Returns the used signature algorithm, or a negative error code.

 */

int

_gnutls_handshake_sign_crt_vrfy(gnutls_session_t session,

        gnutls_pcert_st * cert,

        gnutls_privkey_t pkey,

        gnutls_datum_t * signature)

{

  int ret;

  const version_entry_st *ver = get_version(session);

  unsigned key_usage = 0;

  if (unlikely(ver == NULL))

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  gnutls_pubkey_get_key_usage(cert->pubkey, &key_usage);

  ret = _gnutls_check_key_usage_for_sig(session, key_usage, 1);

  if (ret < 0)

    return gnutls_assert_val(ret);

  /* TLS 1.2 */

  if (_gnutls_version_has_selectable_sighash(ver))

    return _gnutls_handshake_sign_crt_vrfy12(session, cert,

               pkey, signature);

  /* TLS 1.1 or earlier */

#ifdef ENABLE_SSL3

  if (ver->id == GNUTLS_SSL3)

    return _gnutls_handshake_sign_crt_vrfy3(session, cert, ver,

              pkey, signature);

#endif

  return _gnutls_handshake_sign_crt_vrfy10(session, cert, ver,

             pkey, signature);

}