kexgex.c

   1 /* $OpenBSD: kexgex.c,v 1.26 2006/03/25 13:17:02 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000 Niels Provos.  All rights reserved.
   4  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28
  29 #include <openssl/evp.h>
  30
  31 #include "buffer.h"
  32 #include "bufaux.h"
  33 #include "kex.h"
  34 #include "ssh2.h"
  35
  36 void
  37 kexgex_hash(
  38     const EVP_MD *evp_md,
  39     char *client_version_string,
  40     char *server_version_string,
  41     char *ckexinit, int ckexinitlen,
  42     char *skexinit, int skexinitlen,
  43     u_char *serverhostkeyblob, int sbloblen,
  44     int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
  45     BIGNUM *client_dh_pub,
  46     BIGNUM *server_dh_pub,
  47     BIGNUM *shared_secret,
  48     u_char **hash, u_int *hashlen)
  49 {
  50         Buffer b;
  51         static u_char digest[EVP_MAX_MD_SIZE];
  52         EVP_MD_CTX md;
  53
  54         buffer_init(&b);
  55         buffer_put_cstring(&b, client_version_string);
  56         buffer_put_cstring(&b, server_version_string);
  57
  58         /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
  59         buffer_put_int(&b, ckexinitlen+1);
  60         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  61         buffer_append(&b, ckexinit, ckexinitlen);
  62         buffer_put_int(&b, skexinitlen+1);
  63         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  64         buffer_append(&b, skexinit, skexinitlen);
  65
  66         buffer_put_string(&b, serverhostkeyblob, sbloblen);
  67         if (min == -1 || max == -1)
  68                 buffer_put_int(&b, wantbits);
  69         else {
  70                 buffer_put_int(&b, min);
  71                 buffer_put_int(&b, wantbits);
  72                 buffer_put_int(&b, max);
  73         }
  74         buffer_put_bignum2(&b, prime);
  75         buffer_put_bignum2(&b, gen);
  76         buffer_put_bignum2(&b, client_dh_pub);
  77         buffer_put_bignum2(&b, server_dh_pub);
  78         buffer_put_bignum2(&b, shared_secret);
  79
  80 #ifdef DEBUG_KEXDH
  81         buffer_dump(&b);
  82 #endif
  83
  84         EVP_DigestInit(&md, evp_md);
  85         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
  86         EVP_DigestFinal(&md, digest, NULL);
  87
  88         buffer_free(&b);
  89         *hash = digest;
  90         *hashlen = EVP_MD_size(evp_md);
  91 #ifdef DEBUG_KEXDH
  92         dump_digest("hash", digest, *hashlen);
  93 #endif
  94 }