3 * $Id: skipjack.h,v 1.3 2004/04/08 01:36:15 mdw Exp $
5 * The Skipjack block cipher
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Notes on the Skipjack block cipher --------------------------------*
32 * Skipjack was designed by the NSA, as a type II algorithm to be used in the
33 * Clipper system. It was initially classified, so that it couldn't be used
34 * without the key escrow feature, though a team of `respectable'
35 * cryptographers, including Dorothy Denning, had a quick look at it and
36 * pronounced it `good', as if this was meant to be convincing. It is
37 * apparently a particular parameterization of a family which includes type I
38 * algorithms. Since declassification, Biham has discovered a miss-in-the-
39 * middle attack which breaks Skipjack with 31 rounds faster than brute
42 * This implementation is provided for interest's sake, and possibly for
43 * interoperability, rather than as a good cipher to use.
46 #ifndef CATACOMB_SKIPJACK_H
47 #define CATACOMB_SKIPJACK_H
53 /*----- Header files ------------------------------------------------------*/
57 #include <mLib/bits.h>
59 /*----- Magical numbers ---------------------------------------------------*/
61 #define SKIPJACK_BLKSZ 8
62 #define SKIPJACK_KEYSZ 10
63 #define SKIPJACK_CLASS (N, B, 64)
65 extern const octet skipjack_keysz
[];
67 /*----- Data structures ---------------------------------------------------*/
69 typedef struct skipjack_ctx
{
70 uint32 ka
, kb
, kc
, kd
, ke
;
73 /*----- Functions provided ------------------------------------------------*/
75 /* --- @skipjack_init@ --- *
77 * Arguments: @skipjack_ctx *k@ = pointer to key block
78 * @const void *buf@ = pointer to key buffer
79 * @size_t sz@ = size of key material
83 * Use: Initializes a Skipjack key buffer. The key buffer must be
84 * exactly 10 bytes long.
87 extern void skipjack_init(skipjack_ctx */
*k*/
,
88 const void */
*buf*/
, size_t /*sz*/);
90 /* --- @skipjack_eblk@, @skipjack_dblk@ --- *
92 * Arguments: @const skipjack_ctx *k@ = pointer to key block
93 * @const uint32 s[2]@ = pointer to source block
94 * @uint32 d[2]@ = pointer to skipjacktination block
98 * Use: Low-level block encryption and decryption.
101 extern void skipjack_eblk(const skipjack_ctx */
*k*/
,
102 const uint32 */
*s*/
, uint32 */
*d*/
);
103 extern void skipjack_dblk(const skipjack_ctx */
*k*/
,
104 const uint32 */
*s*/
, uint32 */
*d*/
);
106 /*----- That's all, folks -------------------------------------------------*/