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1 | /* -*-c-*- |
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2 | * |
3 | * Implementation of the IDEA cipher |
4 | * |
5 | * (c) 1999 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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16 | * |
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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. |
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21 | * |
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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 | |
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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 | |
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44 | #ifndef CATACOMB_IDEA_H |
45 | #define CATACOMB_IDEA_H |
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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 | |
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63 | extern const octet idea_keysz[]; |
64 | |
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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 |