4.4BSD/usr/src/kerberosIV/des/weak_key.c

/*
 * $Source: /mit/kerberos/src/lib/des/RCS/weak_key.c,v $
 * $Author: jtkohl $
 *
 * 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.
 */

#ifndef	lint
static char rcsid_weak_key_c[] =
"$Header: weak_key.c,v 4.3 89/01/22 12:16:41 jtkohl Exp $";
#endif	lint

#include <des.h>
#include "des_internal.h"

/*
 * The following are the weak DES keys:
 */
static 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(key)
     des_cblock key;
{
    int i;
    des_cblock *weak_p = weak;

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

    return 0;
}