kexdh.c

   1 /* $OpenBSD: kexdh.c,v 1.23 2006/08/03 03:34:42 deraadt 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 <sys/types.h>
  29
  30 #include <signal.h>
  31
  32 #include <openssl/evp.h>
  33
  34 #include "buffer.h"
  35 #include "ssh2.h"
  36 #include "key.h"
  37 #include "cipher.h"
  38 #include "kex.h"
  39
  40 void
  41 kex_dh_hash(
  42     char *client_version_string,
  43     char *server_version_string,
  44     char *ckexinit, int ckexinitlen,
  45     char *skexinit, int skexinitlen,
  46     u_char *serverhostkeyblob, int sbloblen,
  47     BIGNUM *client_dh_pub,
  48     BIGNUM *server_dh_pub,
  49     BIGNUM *shared_secret,
  50     u_char **hash, u_int *hashlen)
  51 {
  52         Buffer b;
  53         static u_char digest[EVP_MAX_MD_SIZE];
  54         const EVP_MD *evp_md = EVP_sha1();
  55         EVP_MD_CTX md;
  56
  57         buffer_init(&b);
  58         buffer_put_cstring(&b, client_version_string);
  59         buffer_put_cstring(&b, server_version_string);
  60
  61         /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
  62         buffer_put_int(&b, ckexinitlen+1);
  63         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  64         buffer_append(&b, ckexinit, ckexinitlen);
  65         buffer_put_int(&b, skexinitlen+1);
  66         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  67         buffer_append(&b, skexinit, skexinitlen);
  68
  69         buffer_put_string(&b, serverhostkeyblob, sbloblen);
  70         buffer_put_bignum2(&b, client_dh_pub);
  71         buffer_put_bignum2(&b, server_dh_pub);
  72         buffer_put_bignum2(&b, shared_secret);
  73
  74 #ifdef DEBUG_KEX
  75         buffer_dump(&b);
  76 #endif
  77         EVP_DigestInit(&md, evp_md);
  78         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
  79         EVP_DigestFinal(&md, digest, NULL);
  80
  81         buffer_free(&b);
  82
  83 #ifdef DEBUG_KEX
  84         dump_digest("hash", digest, EVP_MD_size(evp_md));
  85 #endif
  86         *hash = digest;
  87         *hashlen = EVP_MD_size(evp_md);
  88 }