| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Implementation of the IDEA cipher |
| 4 | * |
| 5 | * (c) 1999 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 IDEA block cipher ------------------------------------* |
| 29 | * |
| 30 | * IDEA was invented by James Massey and Xuejia Lai. The fundamental idea |
| 31 | * underlying the cipher is combining incompatible group operations. The |
| 32 | * algorithm's main claim to fame is that it is the symmetric cipher in PGP |
| 33 | * version 2. |
| 34 | * |
| 35 | * The IDEA algorithm is allegedly patented by Ascom Tech A.G., even in the |
| 36 | * UK and Europe. Ascom are willing to grant licences for use in software |
| 37 | * which forbids commercial use, but this is not compatible with Free |
| 38 | * Software Foundation ideology. The author recommends against the use of |
| 39 | * the IDEA cipher entirely. Blowfish is conceptually simpler, appears more |
| 40 | * concervative, offers a larger keyspace, runs faster, and is in the public |
| 41 | * domain. |
| 42 | */ |
| 43 | |
| 44 | #ifndef CATACOMB_IDEA_H |
| 45 | #define CATACOMB_IDEA_H |
| 46 | |
| 47 | #ifdef __cplusplus |
| 48 | extern "C" { |
| 49 | #endif |
| 50 | |
| 51 | /*----- Header files ------------------------------------------------------*/ |
| 52 | |
| 53 | #include <stddef.h> |
| 54 | |
| 55 | #include <mLib/bits.h> |
| 56 | |
| 57 | /*----- Magical numbers ---------------------------------------------------*/ |
| 58 | |
| 59 | #define IDEA_BLKSZ 8 |
| 60 | #define IDEA_KEYSZ 16 |
| 61 | #define IDEA_CLASS (N, B, 64) |
| 62 | |
| 63 | extern const octet idea_keysz[]; |
| 64 | |
| 65 | /*----- Data structures ---------------------------------------------------*/ |
| 66 | |
| 67 | typedef struct idea_ctx { |
| 68 | uint16 e[52]; |
| 69 | uint16 d[52]; |
| 70 | } idea_ctx; |
| 71 | |
| 72 | /*----- Functions provided ------------------------------------------------*/ |
| 73 | |
| 74 | /* --- @idea_init@ --- * |
| 75 | * |
| 76 | * Arguments: @idea_ctx *k@ = pointer to key block |
| 77 | * @const void *buf@ = pointer to key buffer |
| 78 | * @size_t sz@ = size of key material |
| 79 | * |
| 80 | * Returns: --- |
| 81 | * |
| 82 | * Use: Initializes an IDEA key buffer. The buffer must be exactly |
| 83 | * 16 bytes in size, because IDEA is only defined with a key |
| 84 | * size of 128 bits. |
| 85 | */ |
| 86 | |
| 87 | extern void idea_init(idea_ctx */*k*/, const void */*buf*/, size_t /*sz*/); |
| 88 | |
| 89 | /* --- @idea_eblk@, @idea_dblk@ --- * |
| 90 | * |
| 91 | * Arguments: @const idea_ctx *k@ = pointer to a key block |
| 92 | * @const uint32 s[2]@ = pointer to source block |
| 93 | * @uint32 d[2]@ = pointer to destination block |
| 94 | * |
| 95 | * Returns: --- |
| 96 | * |
| 97 | * Use: Low-level block encryption and decryption. |
| 98 | */ |
| 99 | |
| 100 | extern void idea_eblk(const idea_ctx */*k*/, |
| 101 | const uint32 */*s*/, uint32 */*d*/); |
| 102 | extern void idea_dblk(const idea_ctx */*k*/, |
| 103 | const uint32 */*s*/, uint32 */*d*/); |
| 104 | |
| 105 | /*----- That's all, folks -------------------------------------------------*/ |
| 106 | |
| 107 | #ifdef __cplusplus |
| 108 | } |
| 109 | #endif |
| 110 | |
| 111 | #endif |