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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: cast128.h,v 1.2 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * The CAST-128 block cipher |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
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18 | * |
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19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
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23 | * |
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24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
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30 | /*----- Notes on the CAST-128 block cipher --------------------------------* |
31 | * |
32 | * CAST, designed by Carlisle Adams and Stafford Tavares, is a method for |
33 | * designing block ciphers, based around the concept of `bent functions'. It |
34 | * is described in the paper `Constructing Symmetric Ciphers using the CAST |
35 | * Design Procedure' by Carlisle Adams. |
36 | * |
37 | * CAST-128, defined in RFC2144, is a particular instance of the CAST design |
38 | * procedure, The cipher seems strong and fairly quick. The design procedure |
39 | * itself is patented, although the cipher CAST-128 is free to use. |
40 | * |
41 | * Although CAST ciphers are resistant to differential and linear |
42 | * cryptanalysis, some instances have been broken by more advanced techniques |
43 | * -- the CAST procedure does not guarantee a strong cipher. However, |
44 | * CAST-128 has so far resisted all attacks against it, and has now been |
45 | * accepted by the Canadian government for protection of all `Designated' |
46 | * material. |
47 | */ |
48 | |
49 | #ifndef CATACOMB_CAST128_H |
50 | #define CATACOMB_CAST128_H |
51 | |
52 | #ifdef __cplusplus |
53 | extern "C" { |
54 | #endif |
55 | |
56 | /*----- Header files ------------------------------------------------------*/ |
57 | |
58 | #include <mLib/bits.h> |
59 | |
60 | /*----- Magic numbers -----------------------------------------------------*/ |
61 | |
62 | #define CAST128_BLKSZ 8 |
63 | #define CAST128_KEYSZ 16 |
64 | #define CAST128_CLASS (N, B, 64) |
65 | |
66 | extern const octet cast128_keysz[]; |
67 | |
68 | /*----- Data structures ---------------------------------------------------*/ |
69 | |
70 | typedef struct cast128_ctx { |
71 | unsigned r; |
72 | uint32 km[16]; |
73 | octet kr[16]; |
74 | } cast128_ctx; |
75 | |
76 | /*----- Functions provided ------------------------------------------------*/ |
77 | |
78 | /* --- @cast128_init@ --- * |
79 | * |
80 | * Arguments: @cast128_ctx *k@ = pointer to key block to fill in |
81 | * @const void *buf@ = pointer to buffer of key material |
82 | * @size_t sz@ = size of key material |
83 | * |
84 | * Returns: --- |
85 | * |
86 | * Use: Initializes a CAST-128 key buffer. CAST-128 accepts |
87 | * 128-bit keys or shorter. |
88 | */ |
89 | |
90 | extern void cast128_init(cast128_ctx */*k*/, |
91 | const void */*buf*/, size_t /*sz*/); |
92 | |
93 | /* --- @cast128_eblk@, @cast128_dblk@ --- * |
94 | * |
95 | * Arguments: @const cast128_ctx *k@ = pointer to key block |
96 | * @const uint32 s[2]@ = pointer to source block |
97 | * @uint32 d[2]@ = pointer to destination block |
98 | * |
99 | * Returns: --- |
100 | * |
101 | * Use: Low-level block encryption and decryption. |
102 | */ |
103 | |
104 | extern void cast128_eblk(const cast128_ctx */*k*/, |
105 | const uint32 */*s*/, uint32 */*d*/); |
106 | |
107 | extern void cast128_dblk(const cast128_ctx */*k*/, |
108 | const uint32 */*s*/, uint32 */*d*/); |
109 | |
110 | /*----- That's all, folks -------------------------------------------------*/ |
111 | |
112 | #ifdef __cplusplus |
113 | } |
114 | #endif |
115 | |
116 | #endif |