1 /*
   2  * Copyright (c) 2000 Niels Provos.  All rights reserved.
   3  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25 
  26 #include "includes.h"
  27 RCSID("$OpenBSD: kexgex.c,v 1.22 2002/03/24 17:27:03 stevesk Exp $");
  28 
  29 #pragma ident   "%Z%%M% %I%     %E% SMI"
  30 
  31 #include <openssl/opensslconf.h>
  32 #include <openssl/bn.h>
  33 
  34 #include "xmalloc.h"
  35 #include "buffer.h"
  36 #include "bufaux.h"
  37 #include "key.h"
  38 #include "kex.h"
  39 #include "log.h"
  40 #include "packet.h"
  41 #include "dh.h"
  42 #include "ssh2.h"
  43 #include "compat.h"
  44 
  45 u_char *
  46 kexgex_hash(
  47     char *client_version_string,
  48     char *server_version_string,
  49     char *ckexinit, int ckexinitlen,
  50     char *skexinit, int skexinitlen,
  51     u_char *serverhostkeyblob, int sbloblen,
  52     int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
  53     BIGNUM *client_dh_pub,
  54     BIGNUM *server_dh_pub,
  55     BIGNUM *shared_secret)
  56 {
  57         Buffer b;
  58         static u_char digest[EVP_MAX_MD_SIZE];
  59         const EVP_MD *evp_md = EVP_sha1();
  60         EVP_MD_CTX md;
  61 
  62         buffer_init(&b);
  63         buffer_put_cstring(&b, client_version_string);
  64         buffer_put_cstring(&b, server_version_string);
  65 
  66         /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
  67         buffer_put_int(&b, ckexinitlen+1);
  68         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  69         buffer_append(&b, ckexinit, ckexinitlen);
  70         buffer_put_int(&b, skexinitlen+1);
  71         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  72         buffer_append(&b, skexinit, skexinitlen);
  73 
  74         buffer_put_string(&b, serverhostkeyblob, sbloblen);
  75         if (min == -1 || max == -1)
  76                 buffer_put_int(&b, wantbits);
  77         else {
  78                 buffer_put_int(&b, min);
  79                 buffer_put_int(&b, wantbits);
  80                 buffer_put_int(&b, max);
  81         }
  82         buffer_put_bignum2(&b, prime);
  83         buffer_put_bignum2(&b, gen);
  84         buffer_put_bignum2(&b, client_dh_pub);
  85         buffer_put_bignum2(&b, server_dh_pub);
  86         buffer_put_bignum2(&b, shared_secret);
  87 
  88 #ifdef DEBUG_KEXDH
  89         buffer_dump(&b);
  90 #endif
  91         EVP_DigestInit(&md, evp_md);
  92         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
  93         EVP_DigestFinal(&md, digest, NULL);
  94 
  95         buffer_free(&b);
  96 
  97 #ifdef DEBUG_KEXDH
  98         dump_digest("hash", digest, EVP_MD_size(evp_md));
  99 #endif
 100         return digest;
 101 }