/*
 * $Xorg: Unwrap.c,v 1.4 2001/02/09 02:03:48 xorgcvs Exp $
 *
 * 
Copyright 1989, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
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in this Software without prior written authorization from The Open Group.
 * *
 * Author:  Keith Packard, MIT X Consortium
 */

/* $XFree86: xc/lib/Xdmcp/Unwrap.c,v 1.3 2001/01/17 19:42:44 dawes Exp $ */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <X11/Xos.h>
#include <X11/X.h>
#include <X11/Xmd.h>
#include <X11/Xdmcp.h>

#ifdef HASXDMAUTH

/*
 * The following function exists only to demonstrate the
 * desired functional interface for this routine.  You will
 * need to add the appropriate algorithm if you wish to
 * use XDM-AUTHENTICATION-1/XDM-AUTHORIZATION-1.
 *
 * The interface for this routine is quite simple.  All three
 * arguments are arrays of 8 unsigned characters, the first two
 * are 64 bits of useful data, the last is 56 bits of useful
 * data packed into 8 bytes, using the low 7 bits of each
 * byte, filling the high bit with odd parity.
 *
 * Examine the XDMCP specification for the correct algorithm
 */

#include "Wrap.h"

void
XdmcpUnwrap (
    unsigned char	*input,
    unsigned char	*wrapper,
    unsigned char	*output,
    int			bytes)
{
    int			i, j, k;
    unsigned char	tmp[8];
    unsigned char	blocks[2][8];
    unsigned char	expand_wrapper[8];
    auth_wrapper_schedule	schedule;

    _XdmcpWrapperToOddParity (wrapper, expand_wrapper);
    _XdmcpAuthSetup (expand_wrapper, schedule);

    k = 0;
    for (j = 0; j < bytes; j += 8)
    {
	if (bytes - j < 8)
	    return; /* bad input length */
	for (i = 0; i < 8; i++)
	    blocks[k][i] = input[j + i];
	_XdmcpAuthDoIt ((unsigned char *) (input + j), (unsigned char *) tmp, schedule, 0);
	/* block chaining */
	k = (k == 0) ? 1 : 0;
	for (i = 0; i < 8; i++)
	{
	    if (j == 0)
		output[j + i] = tmp[i];
	    else
		output[j + i] = tmp[i] ^ blocks[k][i];
	}
    }
}

#endif /* HASXDMAUTH */