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      1 /*
      2  * Author: Tatu Ylonen <ylo (at) cs.hut.fi>
      3  * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland
      4  *                    All rights reserved
      5  * This file contains various auxiliary functions related to multiple
      6  * precision integers.
      7  *
      8  * As far as I am concerned, the code I have written for this software
      9  * can be used freely for any purpose.  Any derived versions of this
     10  * software must be clearly marked as such, and if the derived work is
     11  * incompatible with the protocol description in the RFC file, it must be
     12  * called by a name other than "ssh" or "Secure Shell".
     13  */
     14 
     15 #include "includes.h"
     16 RCSID("$OpenBSD: mpaux.c,v 1.16 2001/02/08 19:30:52 itojun Exp $");
     17 
     18 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     19 
     20 #include <openssl/bn.h>
     21 #include "getput.h"
     22 #include "xmalloc.h"
     23 
     24 #include <openssl/md5.h>
     25 
     26 #include "mpaux.h"
     27 
     28 void
     29 compute_session_id(u_char session_id[16],
     30     u_char cookie[8],
     31     BIGNUM* host_key_n,
     32     BIGNUM* session_key_n)
     33 {
     34 	u_int host_key_bytes = BN_num_bytes(host_key_n);
     35 	u_int session_key_bytes = BN_num_bytes(session_key_n);
     36 	u_int bytes = host_key_bytes + session_key_bytes;
     37 	u_char *buf = xmalloc(bytes);
     38 	MD5_CTX md;
     39 
     40 	BN_bn2bin(host_key_n, buf);
     41 	BN_bn2bin(session_key_n, buf + host_key_bytes);
     42 	MD5_Init(&md);
     43 	MD5_Update(&md, buf, bytes);
     44 	MD5_Update(&md, cookie, 8);
     45 	MD5_Final(session_id, &md);
     46 	memset(buf, 0, bytes);
     47 	xfree(buf);
     48 }
     49