kexdh.c

   1 /* $OpenBSD: kexdh.c,v 1.22 2006/03/25 13:17:02 djm Exp $ */
   2 /*
   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
  28 #include <openssl/evp.h>
  29
  30 #include "buffer.h"
  31 #include "bufaux.h"
  32 #include "ssh2.h"
  33 #include "kex.h"
  34
  35 void
  36 kex_dh_hash(
  37     char *client_version_string,
  38     char *server_version_string,
  39     char *ckexinit, int ckexinitlen,
  40     char *skexinit, int skexinitlen,
  41     u_char *serverhostkeyblob, int sbloblen,
  42     BIGNUM *client_dh_pub,
  43     BIGNUM *server_dh_pub,
  44     BIGNUM *shared_secret,
  45     u_char **hash, u_int *hashlen)
  46 {
  47         Buffer b;
  48         static u_char digest[EVP_MAX_MD_SIZE];
  49         const EVP_MD *evp_md = EVP_sha1();
  50         EVP_MD_CTX md;
  51
  52         buffer_init(&b);
  53         buffer_put_cstring(&b, client_version_string);
  54         buffer_put_cstring(&b, server_version_string);
  55
  56         /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
  57         buffer_put_int(&b, ckexinitlen+1);
  58         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  59         buffer_append(&b, ckexinit, ckexinitlen);
  60         buffer_put_int(&b, skexinitlen+1);
  61         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  62         buffer_append(&b, skexinit, skexinitlen);
  63
  64         buffer_put_string(&b, serverhostkeyblob, sbloblen);
  65         buffer_put_bignum2(&b, client_dh_pub);
  66         buffer_put_bignum2(&b, server_dh_pub);
  67         buffer_put_bignum2(&b, shared_secret);
  68
  69 #ifdef DEBUG_KEX
  70         buffer_dump(&b);
  71 #endif
  72         EVP_DigestInit(&md, evp_md);
  73         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
  74         EVP_DigestFinal(&md, digest, NULL);
  75
  76         buffer_free(&b);
  77
  78 #ifdef DEBUG_KEX
  79         dump_digest("hash", digest, EVP_MD_size(evp_md));
  80 #endif
  81         *hash = digest;
  82         *hashlen = EVP_MD_size(evp_md);
  83 }