1/*
2 * lib/crypto/des/weak_key.c
3 *
4 * Copyright 1989,1990 by the Massachusetts Institute of Technology.
5 * All Rights Reserved.
6 *
7 * Export of this software from the United States of America may
8 *   require a specific license from the United States Government.
9 *   It is the responsibility of any person or organization contemplating
10 *   export to obtain such a license before exporting.
11 *
12 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
13 * distribute this software and its documentation for any purpose and
14 * without fee is hereby granted, provided that the above copyright
15 * notice appear in all copies and that both that copyright notice and
16 * this permission notice appear in supporting documentation, and that
17 * the name of M.I.T. not be used in advertising or publicity pertaining
18 * to distribution of the software without specific, written prior
19 * permission.  Furthermore if you modify this software you must label
20 * your software as modified software and not distribute it in such a
21 * fashion that it might be confused with the original M.I.T. software.
22 * M.I.T. makes no representations about the suitability of
23 * this software for any purpose.  It is provided "as is" without express
24 * or implied warranty.
25 *
26 *
27 * Under U.S. law, this software may not be exported outside the US
28 * without license from the U.S. Commerce department.
29 *
30 * These routines form the library interface to the DES facilities.
31 *
32 * Originally written 8/85 by Steve Miller, MIT Project Athena.
33 */
34
35#include "k5-int.h"
36#include "des_int.h"
37
38/*
39 * The following are the weak DES keys:
40 */
41static const mit_des_cblock weak[16] = {
42    /* weak keys */
43    {0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01},
44    {0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe,0xfe},
45    {0x1f,0x1f,0x1f,0x1f,0x0e,0x0e,0x0e,0x0e},
46    {0xe0,0xe0,0xe0,0xe0,0xf1,0xf1,0xf1,0xf1},
47
48    /* semi-weak */
49    {0x01,0xfe,0x01,0xfe,0x01,0xfe,0x01,0xfe},
50    {0xfe,0x01,0xfe,0x01,0xfe,0x01,0xfe,0x01},
51
52    {0x1f,0xe0,0x1f,0xe0,0x0e,0xf1,0x0e,0xf1},
53    {0xe0,0x1f,0xe0,0x1f,0xf1,0x0e,0xf1,0x0e},
54
55    {0x01,0xe0,0x01,0xe0,0x01,0xf1,0x01,0xf1},
56    {0xe0,0x01,0xe0,0x01,0xf1,0x01,0xf1,0x01},
57
58    {0x1f,0xfe,0x1f,0xfe,0x0e,0xfe,0x0e,0xfe},
59    {0xfe,0x1f,0xfe,0x1f,0xfe,0x0e,0xfe,0x0e},
60
61    {0x01,0x1f,0x01,0x1f,0x01,0x0e,0x01,0x0e},
62    {0x1f,0x01,0x1f,0x01,0x0e,0x01,0x0e,0x01},
63
64    {0xe0,0xfe,0xe0,0xfe,0xf1,0xfe,0xf1,0xfe},
65    {0xfe,0xe0,0xfe,0xe0,0xfe,0xf1,0xfe,0xf1}
66};
67
68/*
69 * mit_des_is_weak_key: returns true iff key is a [semi-]weak des key.
70 *
71 * Requires: key has correct odd parity.
72 */
73int
74mit_des_is_weak_key(mit_des_cblock key)
75{
76    int i;
77    const mit_des_cblock *weak_p = weak;
78
79    for (i = 0; i < (sizeof(weak)/sizeof(mit_des_cblock)); i++) {
80	if (!memcmp(weak_p++,key,sizeof(mit_des_cblock)))
81	    return 1;
82    }
83
84    return 0;
85}
86