/* $OpenBSD: kexgex.c,v 1.32 2019/01/23 00:30:41 djm Exp $ */

/*

 * Copyright (c) 2000 Niels Provos.  All rights reserved.

 * Copyright (c) 2001 Markus Friedl.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "includes.h"

#ifdef WITH_OPENSSL

#include <sys/types.h>

#include <openssl/evp.h>

#include <signal.h>

#include "openbsd-compat/openssl-compat.h"

#include "sshkey.h"

#include "cipher.h"

#include "kex.h"

#include "ssh2.h"

#include "ssherr.h"

#include "sshbuf.h"

#include "digest.h"

int

kexgex_hash(

    int hash_alg,

    const struct sshbuf *client_version,

    const struct sshbuf *server_version,

    const struct sshbuf *client_kexinit,

    const struct sshbuf *server_kexinit,

    const struct sshbuf *server_host_key_blob,

    int min, int wantbits, int max,

    const BIGNUM *prime,

    const BIGNUM *gen,

    const BIGNUM *client_dh_pub,

    const BIGNUM *server_dh_pub,

    const u_char *shared_secret, size_t secretlen,

    u_char *hash, size_t *hashlen)

{

  struct sshbuf *b;

  int r;

  if (*hashlen < ssh_digest_bytes(SSH_DIGEST_SHA1))

    return SSH_ERR_INVALID_ARGUMENT;

  if ((b = sshbuf_new()) == NULL)

    return SSH_ERR_ALLOC_FAIL;

  if ((r = sshbuf_put_stringb(b, client_version)) < 0 ||

      (r = sshbuf_put_stringb(b, server_version)) < 0 ||

      /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */

      (r = sshbuf_put_u32(b, sshbuf_len(client_kexinit) + 1)) != 0 ||

      (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||

      (r = sshbuf_putb(b, client_kexinit)) != 0 ||

      (r = sshbuf_put_u32(b, sshbuf_len(server_kexinit) + 1)) != 0 ||

      (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||

      (r = sshbuf_putb(b, server_kexinit)) != 0 ||

      (r = sshbuf_put_stringb(b, server_host_key_blob)) != 0 ||

      (min != -1 && (r = sshbuf_put_u32(b, min)) != 0) ||

      (r = sshbuf_put_u32(b, wantbits)) != 0 ||

      (max != -1 && (r = sshbuf_put_u32(b, max)) != 0) ||

      (r = sshbuf_put_bignum2(b, prime)) != 0 ||

      (r = sshbuf_put_bignum2(b, gen)) != 0 ||

      (r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 ||

      (r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 ||

      (r = sshbuf_put(b, shared_secret, secretlen)) != 0) {

    sshbuf_free(b);

    return r;

  }

#ifdef DEBUG_KEXDH

  sshbuf_dump(b, stderr);

#endif

  if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {

    sshbuf_free(b);

    return SSH_ERR_LIBCRYPTO_ERROR;

  }

  sshbuf_free(b);

  *hashlen = ssh_digest_bytes(hash_alg);

#ifdef DEBUG_KEXDH

  dump_digest("hash", hash, *hashlen);

#endif

  return 0;

}

#endif /* WITH_OPENSSL */