mpaux.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@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 #include <openssl/bn.h>
  19 #include "getput.h"
  20 #include "xmalloc.h"
  21
  22 #include <openssl/md5.h>
  23
  24 #include "mpaux.h"
  25
  26 void
  27 compute_session_id(u_char session_id[16],
  28     u_char cookie[8],
  29     BIGNUM* host_key_n,
  30     BIGNUM* session_key_n)
  31 {
  32         u_int host_key_bytes = BN_num_bytes(host_key_n);
  33         u_int session_key_bytes = BN_num_bytes(session_key_n);
  34         u_int bytes = host_key_bytes + session_key_bytes;
  35         u_char *buf = xmalloc(bytes);
  36         MD5_CTX md;
  37
  38         BN_bn2bin(host_key_n, buf);
  39         BN_bn2bin(session_key_n, buf + host_key_bytes);
  40         MD5_Init(&md);
  41         MD5_Update(&md, buf, bytes);
  42         MD5_Update(&md, cookie, 8);
  43         MD5_Final(session_id, &md);
  44         memset(buf, 0, bytes);
  45         xfree(buf);
  46 }