Merge branch 'master' of git+ssh://metalzone.distorted.org.uk/~mdw/public-git/catacomb/
[u/mdw/catacomb] / skipjack.h
CommitLineData
6a0a5bdc 1/* -*-c-*-
2 *
b817bfc6 3 * $Id: skipjack.h,v 1.3 2004/04/08 01:36:15 mdw Exp $
6a0a5bdc 4 *
5 * The Skipjack block cipher
6 *
7 * (c) 2000 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of Catacomb.
13 *
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.
18 *
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.
23 *
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,
27 * MA 02111-1307, USA.
28 */
29
6a0a5bdc 30/*----- Notes on the Skipjack block cipher --------------------------------*
31 *
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
40 * force.
41 *
42 * This implementation is provided for interest's sake, and possibly for
43 * interoperability, rather than as a good cipher to use.
44 */
45
46#ifndef CATACOMB_SKIPJACK_H
47#define CATACOMB_SKIPJACK_H
48
49#ifdef __cplusplus
50 extern "C" {
51#endif
52
53/*----- Header files ------------------------------------------------------*/
54
55#include <stddef.h>
56
57#include <mLib/bits.h>
58
59/*----- Magical numbers ---------------------------------------------------*/
60
61#define SKIPJACK_BLKSZ 8
62#define SKIPJACK_KEYSZ 10
63#define SKIPJACK_CLASS (N, B, 64)
64
65extern const octet skipjack_keysz[];
66
67/*----- Data structures ---------------------------------------------------*/
68
69typedef struct skipjack_ctx {
fe371977 70 uint32 ka, kb, kc, kd, ke;
6a0a5bdc 71} skipjack_ctx;
72
73/*----- Functions provided ------------------------------------------------*/
74
75/* --- @skipjack_init@ --- *
76 *
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
80 *
81 * Returns: ---
82 *
83 * Use: Initializes a Skipjack key buffer. The key buffer must be
84 * exactly 10 bytes long.
85 */
86
87extern void skipjack_init(skipjack_ctx */*k*/,
88 const void */*buf*/, size_t /*sz*/);
89
90/* --- @skipjack_eblk@, @skipjack_dblk@ --- *
91 *
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
95 *
96 * Returns: ---
97 *
98 * Use: Low-level block encryption and decryption.
99 */
100
101extern void skipjack_eblk(const skipjack_ctx */*k*/,
102 const uint32 */*s*/, uint32 */*d*/);
103extern void skipjack_dblk(const skipjack_ctx */*k*/,
104 const uint32 */*s*/, uint32 */*d*/);
105
106/*----- That's all, folks -------------------------------------------------*/
107
108#ifdef __cplusplus
109 }
110#endif
111
112#endif