5 * (c) 2000 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Notes on the RC2 block cipher -------------------------------------*
30 * RC2 was designed by Ron Rivest, and for a long time was a trade secret of
31 * RSA Data Security Inc. Like RC4, it leaked out, and has now been
32 * described in RFC2268. The RC2 key schedule is known to have some
33 * weaknesses, although I'm not aware of any major results against the cipher
34 * itself. I'm also not aware of any legal problems with using the RC2
37 * The oddest feature in the cipher is the key schedule. It expands the
38 * initial key material to 128 bytes, and then `brain-damages' it, according
39 * to a supplied `effective key-bits' parameter, before expanding the
40 * remaining key material back into the buffer.
42 * The key schedule allows second preimages to be computed trivially.
45 #ifndef CATACOMB_RC2_H
46 #define CATACOMB_RC2_H
52 /*----- Header files ------------------------------------------------------*/
56 #include <mLib/bits.h>
58 /*----- Magical numbers ---------------------------------------------------*/
62 #define RC2_CLASS (N, L, 64)
64 extern const octet rc2_keysz[];
66 /*----- Data structures ---------------------------------------------------*/
68 typedef struct rc2_ctx {
72 /*----- Functions provided ------------------------------------------------*/
74 /* --- @rc2_braindamage@ --- *
76 * Arguments: @rc2_ctx *k@ = pointer to context to initialize
77 * @const void *buf@ = pointer to key material
78 * @size_t sz@ = size of key material in bytes
79 * @unsigned eb@ = desired effective key size, in bits
83 * Use: Initializes an RC2 expanded key, and braindamages it to the
84 * requested effective key size. This is here for compatibility
85 * reasons. You should be using @rc2_init@ in normal code,
86 * which doesn't actually apply braindamage.
89 extern void rc2_braindamage(rc2_ctx */*k*/, const void */*buf*/,
90 size_t /*sz*/, unsigned /*eb*/);
92 /* --- @rc2_init@ --- *
94 * Arguments: @rc2_ctx *k@ = pointer to context to initialize
95 * @const void *buf@ = pointer to key material
96 * @size_t sz@ = size of key material in bytes
100 * Use: Initializes an RC2 expanded key. The effective key size is
101 * set to be equal to the real key size, in bits.
104 extern void rc2_init(rc2_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
106 /* --- @rc2_eblk@, @rc2_dblk@ --- *
108 * Arguments: @const rc2_ctx *k@ = pointer to RC2 context
109 * @const uint32 s[2]@ = pointer to source block
110 * @const uint32 d[2]@ = pointer to destination block
114 * Use: Low-level block encryption and decryption.
117 extern void rc2_eblk(const rc2_ctx */*k*/,
118 const uint32 */*s*/, uint32 */*dst*/);
119 extern void rc2_dblk(const rc2_ctx */*k*/,
120 const uint32 */*s*/, uint32 */*dst*/);
122 /*----- That's all, folks -------------------------------------------------*/