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1 | /* -*-c-*- |
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2 | * |
3 | * The CAST-128 block cipher |
4 | * |
5 | * (c) 2000 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 CAST-256 block cipher --------------------------------* |
29 | * |
30 | * CAST, designed by Carlisle Adams and Stafford Tavares, is a method for |
31 | * designing block ciphers, based around the concept of `bent functions'. It |
32 | * is described in the paper `Constructing Symmetric Ciphers using the CAST |
33 | * Design Procedure' by Carlisle Adams. |
34 | * |
35 | * CAST-256, defined in RFC2612, is a particular instance of the CAST design |
36 | * procedure. It is an `incomplete' Feistel network. It uses the same |
37 | * S-boxes and round functions as CAST-128. |
38 | * |
39 | * CAST-256 was submitted to the AES contest, but was not selected as one of |
40 | * the five `finalist' algorithms. |
41 | */ |
42 | |
43 | #ifndef CATACOMB_CAST256_H |
44 | #define CATACOMB_CAST256_H |
45 | |
46 | #ifdef __cplusplus |
47 | extern "C" { |
48 | #endif |
49 | |
50 | /*----- Header files ------------------------------------------------------*/ |
51 | |
52 | #include <mLib/bits.h> |
53 | |
54 | /*----- Magic numbers -----------------------------------------------------*/ |
55 | |
56 | #define CAST256_BLKSZ 16 |
57 | #define CAST256_KEYSZ 32 |
58 | #define CAST256_CLASS (N, B, 128) |
59 | |
60 | extern const octet cast256_keysz[]; |
61 | |
62 | /*----- Data structures ---------------------------------------------------*/ |
63 | |
64 | typedef struct cast256_ctx { |
65 | uint32 km[48]; |
66 | octet kr[48]; |
67 | } cast256_ctx; |
68 | |
69 | /*----- Functions provided ------------------------------------------------*/ |
70 | |
71 | /* --- @cast256_init@ --- * |
72 | * |
73 | * Arguments: @cast256_ctx *k@ = pointer to key block to fill in |
74 | * @const void *buf@ = pointer to buffer of key material |
75 | * @size_t sz@ = size of key material |
76 | * |
77 | * Returns: --- |
78 | * |
79 | * Use: Initializes a CAST-256 key buffer. CAST-256 accepts |
80 | * 256-bit keys or shorter. |
81 | */ |
82 | |
83 | extern void cast256_init(cast256_ctx */*k*/, |
84 | const void */*buf*/, size_t /*sz*/); |
85 | |
86 | /* --- @cast256_eblk@, @cast256_dblk@ --- * |
87 | * |
88 | * Arguments: @const cast256_ctx *k@ = pointer to key block |
89 | * @const uint32 s[2]@ = pointer to source block |
90 | * @uint32 d[2]@ = pointer to destination block |
91 | * |
92 | * Returns: --- |
93 | * |
94 | * Use: Low-level block encryption and decryption. |
95 | */ |
96 | |
97 | extern void cast256_eblk(const cast256_ctx */*k*/, |
98 | const uint32 */*s*/, uint32 */*d*/); |
99 | |
100 | extern void cast256_dblk(const cast256_ctx */*k*/, |
101 | const uint32 */*s*/, uint32 */*d*/); |
102 | |
103 | /*----- That's all, folks -------------------------------------------------*/ |
104 | |
105 | #ifdef __cplusplus |
106 | } |
107 | #endif |
108 | |
109 | #endif |