| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * The RC2 block cipher |
| 4 | * |
| 5 | * (c) 2000 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 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. |
| 16 | * |
| 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. |
| 21 | * |
| 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, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | /*----- Notes on the RC2 block cipher -------------------------------------* |
| 29 | * |
| 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 |
| 35 | * cipher. |
| 36 | * |
| 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. |
| 41 | * |
| 42 | * The key schedule allows second preimages to be computed trivially. |
| 43 | */ |
| 44 | |
| 45 | #ifndef CATACOMB_RC2_H |
| 46 | #define CATACOMB_RC2_H |
| 47 | |
| 48 | #ifdef __cplusplus |
| 49 | extern "C" { |
| 50 | #endif |
| 51 | |
| 52 | /*----- Header files ------------------------------------------------------*/ |
| 53 | |
| 54 | #include <stddef.h> |
| 55 | |
| 56 | #include <mLib/bits.h> |
| 57 | |
| 58 | /*----- Magical numbers ---------------------------------------------------*/ |
| 59 | |
| 60 | #define RC2_BLKSZ 8 |
| 61 | #define RC2_KEYSZ 16 |
| 62 | #define RC2_CLASS (N, L, 64) |
| 63 | |
| 64 | extern const octet rc2_keysz[]; |
| 65 | |
| 66 | /*----- Data structures ---------------------------------------------------*/ |
| 67 | |
| 68 | typedef struct rc2_ctx { |
| 69 | uint16 k[64]; |
| 70 | } rc2_ctx; |
| 71 | |
| 72 | /*----- Functions provided ------------------------------------------------*/ |
| 73 | |
| 74 | /* --- @rc2_braindamage@ --- * |
| 75 | * |
| 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 |
| 80 | * |
| 81 | * Returns: --- |
| 82 | * |
| 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. |
| 87 | */ |
| 88 | |
| 89 | extern void rc2_braindamage(rc2_ctx */*k*/, const void */*buf*/, |
| 90 | size_t /*sz*/, unsigned /*eb*/); |
| 91 | |
| 92 | /* --- @rc2_init@ --- * |
| 93 | * |
| 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 |
| 97 | * |
| 98 | * Returns: --- |
| 99 | * |
| 100 | * Use: Initializes an RC2 expanded key. The effective key size is |
| 101 | * set to be equal to the real key size, in bits. |
| 102 | */ |
| 103 | |
| 104 | extern void rc2_init(rc2_ctx */*k*/, const void */*buf*/, size_t /*sz*/); |
| 105 | |
| 106 | /* --- @rc2_eblk@, @rc2_dblk@ --- * |
| 107 | * |
| 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 |
| 111 | * |
| 112 | * Returns: --- |
| 113 | * |
| 114 | * Use: Low-level block encryption and decryption. |
| 115 | */ |
| 116 | |
| 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*/); |
| 121 | |
| 122 | /*----- That's all, folks -------------------------------------------------*/ |
| 123 | |
| 124 | #ifdef __cplusplus |
| 125 | } |
| 126 | #endif |
| 127 | |
| 128 | #endif |