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      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/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 #include "compat.h"
     43 
     44 u_char *
     45 kexgex_hash(
     46     char *client_version_string,
     47     char *server_version_string,
     48     char *ckexinit, int ckexinitlen,
     49     char *skexinit, int skexinitlen,
     50     u_char *serverhostkeyblob, int sbloblen,
     51     int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
     52     BIGNUM *client_dh_pub,
     53     BIGNUM *server_dh_pub,
     54     BIGNUM *shared_secret)
     55 {
     56 	Buffer b;
     57 	static u_char digest[EVP_MAX_MD_SIZE];
     58 	const EVP_MD *evp_md = EVP_sha1();
     59 	EVP_MD_CTX md;
     60 
     61 	buffer_init(&b);
     62 	buffer_put_cstring(&b, client_version_string);
     63 	buffer_put_cstring(&b, server_version_string);
     64 
     65 	/* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
     66 	buffer_put_int(&b, ckexinitlen+1);
     67 	buffer_put_char(&b, SSH2_MSG_KEXINIT);
     68 	buffer_append(&b, ckexinit, ckexinitlen);
     69 	buffer_put_int(&b, skexinitlen+1);
     70 	buffer_put_char(&b, SSH2_MSG_KEXINIT);
     71 	buffer_append(&b, skexinit, skexinitlen);
     72 
     73 	buffer_put_string(&b, serverhostkeyblob, sbloblen);
     74 	if (min == -1 || max == -1)
     75 		buffer_put_int(&b, wantbits);
     76 	else {
     77 		buffer_put_int(&b, min);
     78 		buffer_put_int(&b, wantbits);
     79 		buffer_put_int(&b, max);
     80 	}
     81 	buffer_put_bignum2(&b, prime);
     82 	buffer_put_bignum2(&b, gen);
     83 	buffer_put_bignum2(&b, client_dh_pub);
     84 	buffer_put_bignum2(&b, server_dh_pub);
     85 	buffer_put_bignum2(&b, shared_secret);
     86 
     87 #ifdef DEBUG_KEXDH
     88 	buffer_dump(&b);
     89 #endif
     90 	EVP_DigestInit(&md, evp_md);
     91 	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
     92 	EVP_DigestFinal(&md, digest, NULL);
     93 
     94 	buffer_free(&b);
     95 
     96 #ifdef DEBUG_KEXDH
     97 	dump_digest("hash", digest, EVP_MD_size(evp_md));
     98 #endif
     99 	return digest;
    100 }
    101