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      1 /*
      2  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     14  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     15  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     16  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     17  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     18  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     19  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     20  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     22  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     23  */
     24 
     25 #include "includes.h"
     26 RCSID("$OpenBSD: kexdh.c,v 1.18 2002/03/18 17:50:31 provos Exp $");
     27 
     28 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     29 
     30 #include <openssl/crypto.h>
     31 #include <openssl/bn.h>
     32 
     33 #include "xmalloc.h"
     34 #include "buffer.h"
     35 #include "bufaux.h"
     36 #include "key.h"
     37 #include "kex.h"
     38 #include "log.h"
     39 #include "packet.h"
     40 #include "dh.h"
     41 #include "ssh2.h"
     42 
     43 u_char *
     44 kex_dh_hash(
     45     char *client_version_string,
     46     char *server_version_string,
     47     char *ckexinit, int ckexinitlen,
     48     char *skexinit, int skexinitlen,
     49     u_char *serverhostkeyblob, int sbloblen,
     50     BIGNUM *client_dh_pub,
     51     BIGNUM *server_dh_pub,
     52     BIGNUM *shared_secret)
     53 {
     54 	Buffer b;
     55 	static u_char digest[EVP_MAX_MD_SIZE];
     56 	const EVP_MD *evp_md = EVP_sha1();
     57 	EVP_MD_CTX md;
     58 
     59 	buffer_init(&b);
     60 	buffer_put_cstring(&b, client_version_string);
     61 	buffer_put_cstring(&b, server_version_string);
     62 
     63 	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
     64 	buffer_put_int(&b, ckexinitlen+1);
     65 	buffer_put_char(&b, SSH2_MSG_KEXINIT);
     66 	buffer_append(&b, ckexinit, ckexinitlen);
     67 	buffer_put_int(&b, skexinitlen+1);
     68 	buffer_put_char(&b, SSH2_MSG_KEXINIT);
     69 	buffer_append(&b, skexinit, skexinitlen);
     70 
     71 	buffer_put_string(&b, serverhostkeyblob, sbloblen);
     72 	buffer_put_bignum2(&b, client_dh_pub);
     73 	buffer_put_bignum2(&b, server_dh_pub);
     74 	buffer_put_bignum2(&b, shared_secret);
     75 
     76 #ifdef DEBUG_KEX
     77 	buffer_dump(&b);
     78 #endif
     79 	EVP_DigestInit(&md, evp_md);
     80 	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
     81 	EVP_DigestFinal(&md, digest, NULL);
     82 
     83 	buffer_free(&b);
     84 
     85 #ifdef DEBUG_KEX
     86 	dump_digest("hash", digest, EVP_MD_size(evp_md));
     87 #endif
     88 	return digest;
     89 }
     90