kexgex.c

   1 /* $OpenBSD: kexgex.c,v 1.27 2006/08/03 03:34:42 deraadt 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 <sys/types.h>
  30
  31 #include <openssl/evp.h>
  32 #include <signal.h>
  33
  34 #include "buffer.h"
  35 #include "key.h"
  36 #include "cipher.h"
  37 #include "kex.h"
  38 #include "ssh2.h"
  39
  40 void
  41 kexgex_hash(
  42     const EVP_MD *evp_md,
  43     char *client_version_string,
  44     char *server_version_string,
  45     char *ckexinit, int ckexinitlen,
  46     char *skexinit, int skexinitlen,
  47     u_char *serverhostkeyblob, int sbloblen,
  48     int min, int wantbits, int max, BIGNUM *prime, BIGNUM *gen,
  49     BIGNUM *client_dh_pub,
  50     BIGNUM *server_dh_pub,
  51     BIGNUM *shared_secret,
  52     u_char **hash, u_int *hashlen)
  53 {
  54         Buffer b;
  55         static u_char digest[EVP_MAX_MD_SIZE];
  56         EVP_MD_CTX md;
  57
  58         buffer_init(&b);
  59         buffer_put_cstring(&b, client_version_string);
  60         buffer_put_cstring(&b, server_version_string);
  61
  62         /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
  63         buffer_put_int(&b, ckexinitlen+1);
  64         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  65         buffer_append(&b, ckexinit, ckexinitlen);
  66         buffer_put_int(&b, skexinitlen+1);
  67         buffer_put_char(&b, SSH2_MSG_KEXINIT);
  68         buffer_append(&b, skexinit, skexinitlen);
  69
  70         buffer_put_string(&b, serverhostkeyblob, sbloblen);
  71         if (min == -1 || max == -1)
  72                 buffer_put_int(&b, wantbits);
  73         else {
  74                 buffer_put_int(&b, min);
  75                 buffer_put_int(&b, wantbits);
  76                 buffer_put_int(&b, max);
  77         }
  78         buffer_put_bignum2(&b, prime);
  79         buffer_put_bignum2(&b, gen);
  80         buffer_put_bignum2(&b, client_dh_pub);
  81         buffer_put_bignum2(&b, server_dh_pub);
  82         buffer_put_bignum2(&b, shared_secret);
  83
  84 #ifdef DEBUG_KEXDH
  85         buffer_dump(&b);
  86 #endif
  87
  88         EVP_DigestInit(&md, evp_md);
  89         EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
  90         EVP_DigestFinal(&md, digest, NULL);
  91
  92         buffer_free(&b);
  93         *hash = digest;
  94         *hashlen = EVP_MD_size(evp_md);
  95 #ifdef DEBUG_KEXDH
  96         dump_digest("hash", digest, *hashlen);
  97 #endif
  98 }