/*
 * Copyright 1989 by the Massachusetts Institute of Technology.
 *
 * For copying and distribution information, please see the file
 * <mit-copyright.h>.
 *
 * Under U.S. law, this software may not be exported outside the US
 * without license from the U.S. Commerce department.
 *
 * These routines form the library interface to the DES facilities.
 *
 * Originally written 8/85 by Steve Miller, MIT Project Athena.
 */

#include <afsconfig.h>
#include <afs/param.h>

RCSID
    ("$Header: /cvs/openafs/src/des/weak_key.c,v 1.9 2003/07/15 23:15:00 shadow Exp $");

#ifndef KERNEL
#include <stdio.h>
#endif

#include "des.h"
#include "des_internal.h"
#include "des_prototypes.h"

#ifdef HAVE_STRING_H
#include <string.h>
#else
#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif
#endif

/*
 * The following are the weak DES keys:
 */
static const des_cblock weak[16] = {
    /* weak keys */
    {0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01},
    {0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe, 0xfe},
    {0x1f, 0x1f, 0x1f, 0x1f, 0x0e, 0x0e, 0x0e, 0x0e},
    {0xe0, 0xe0, 0xe0, 0xe0, 0xf1, 0xf1, 0xf1, 0xf1},

    /* semi-weak */
    {0x01, 0xfe, 0x01, 0xfe, 0x01, 0xfe, 0x01, 0xfe},
    {0xfe, 0x01, 0xfe, 0x01, 0xfe, 0x01, 0xfe, 0x01},

    {0x1f, 0xe0, 0x1f, 0xe0, 0x0e, 0xf1, 0x0e, 0xf1},
    {0xe0, 0x1f, 0xe0, 0x1f, 0xf1, 0x0e, 0xf1, 0x0e},

    {0x01, 0xe0, 0x01, 0xe0, 0x01, 0xf1, 0x01, 0xf1},
    {0xe0, 0x01, 0xe0, 0x01, 0xf1, 0x01, 0xf1, 0x01},

    {0x1f, 0xfe, 0x1f, 0xfe, 0x0e, 0xfe, 0x0e, 0xfe},
    {0xfe, 0x1f, 0xfe, 0x1f, 0xfe, 0x0e, 0xfe, 0x0e},

    {0x01, 0x1f, 0x01, 0x1f, 0x01, 0x0e, 0x01, 0x0e},
    {0x1f, 0x01, 0x1f, 0x01, 0x0e, 0x01, 0x0e, 0x01},

    {0xe0, 0xfe, 0xe0, 0xfe, 0xf1, 0xfe, 0xf1, 0xfe},
    {0xfe, 0xe0, 0xfe, 0xe0, 0xfe, 0xf1, 0xfe, 0xf1}
};

/*
 * des_is_weak_key: returns true iff key is a [semi-]weak des key.
 *
 * Requires: key has correct odd parity.
 */
int
des_is_weak_key(des_cblock key)
{
    int i;
    const des_cblock *weak_p = weak;

    for (i = 0; i < (sizeof(weak) / sizeof(des_cblock)); i++) {
	if (!memcmp((char *)weak_p++, (char *)key, sizeof(des_cblock)))
	    return 1;
    }

    return 0;
}
