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Member "vpnc-0.5.3/dh.c" (19 Nov 2008, 2786 Bytes) of package /linux/privat/old/vpnc-0.5.3.tar.gz:


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    1 /* borrowed from isakmpd-20030718 (-; */
    2 
    3 /*  $OpenBSD: dh.c,v 1.8 2003/06/03 14:28:16 ho Exp $   */
    4 /*  $EOM: dh.c,v 1.5 1999/04/17 23:20:22 niklas Exp $   */
    5 
    6 /*
    7  * Copyright (c) 1998 Niels Provos.  All rights reserved.
    8  * Copyright (c) 1999 Niklas Hallqvist.  All rights reserved.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   29  */
   30 
   31 /*
   32  * This code was written under funding by Ericsson Radio Systems.
   33  */
   34 
   35 #include "math_group.h"
   36 #include "dh.h"
   37 
   38 /*
   39  * Returns the length of our exchange value.
   40  */
   41 
   42 int dh_getlen(struct group *group)
   43 {
   44     return group->getlen(group);
   45 }
   46 
   47 /*
   48  * Creates the exchange value we are offering to the other party.
   49  * Each time this function is called a new value is created, that
   50  * means the application has to save the exchange value itself,
   51  * dh_create_exchange should only be called once.
   52  */
   53 int dh_create_exchange(struct group *group, unsigned char *buf)
   54 {
   55     if (group->setrandom(group, group->c))
   56         return -1;
   57     if (group->operation(group, group->a, group->gen, group->c))
   58         return -1;
   59     group->getraw(group, group->a, buf);
   60     return 0;
   61 }
   62 
   63 /*
   64  * Creates the Diffie-Hellman shared secret in 'secret', where 'exchange'
   65  * is the exchange value offered by the other party. No length verification
   66  * is done for the value, the application has to do that.
   67  */
   68 int dh_create_shared(struct group *group, unsigned char *secret, unsigned char *exchange)
   69 {
   70     if (group->setraw(group, group->b, exchange, group->getlen(group)))
   71         return -1;
   72     if (group->operation(group, group->a, group->b, group->c))
   73         return -1;
   74     group->getraw(group, group->a, secret);
   75     return 0;
   76 }