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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-128 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-128, defined in RFC2144, is a particular instance of the CAST design |
36 | * procedure, The cipher seems strong and fairly quick. The design procedure |
37 | * itself is patented, although the cipher CAST-128 is free to use. |
38 | * |
39 | * Although CAST ciphers are resistant to differential and linear |
40 | * cryptanalysis, some instances have been broken by more advanced techniques |
41 | * -- the CAST procedure does not guarantee a strong cipher. However, |
42 | * CAST-128 has so far resisted all attacks against it, and has now been |
43 | * accepted by the Canadian government for protection of all `Designated' |
44 | * material. |
45 | */ |
46 | |
47 | #ifndef CATACOMB_CAST128_H |
48 | #define CATACOMB_CAST128_H |
49 | |
50 | #ifdef __cplusplus |
51 | extern "C" { |
52 | #endif |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
56 | #include <mLib/bits.h> |
57 | |
58 | /*----- Magic numbers -----------------------------------------------------*/ |
59 | |
60 | #define CAST128_BLKSZ 8 |
61 | #define CAST128_KEYSZ 16 |
62 | #define CAST128_CLASS (N, B, 64) |
63 | |
64 | extern const octet cast128_keysz[]; |
65 | |
66 | /*----- Data structures ---------------------------------------------------*/ |
67 | |
68 | typedef struct cast128_ctx { |
69 | unsigned r; |
70 | uint32 km[16]; |
71 | octet kr[16]; |
72 | } cast128_ctx; |
73 | |
74 | /*----- Functions provided ------------------------------------------------*/ |
75 | |
76 | /* --- @cast128_init@ --- * |
77 | * |
78 | * Arguments: @cast128_ctx *k@ = pointer to key block to fill in |
79 | * @const void *buf@ = pointer to buffer of key material |
80 | * @size_t sz@ = size of key material |
81 | * |
82 | * Returns: --- |
83 | * |
84 | * Use: Initializes a CAST-128 key buffer. CAST-128 accepts |
85 | * 128-bit keys or shorter. |
86 | */ |
87 | |
88 | extern void cast128_init(cast128_ctx */*k*/, |
89 | const void */*buf*/, size_t /*sz*/); |
90 | |
91 | /* --- @cast128_eblk@, @cast128_dblk@ --- * |
92 | * |
93 | * Arguments: @const cast128_ctx *k@ = pointer to key block |
94 | * @const uint32 s[2]@ = pointer to source block |
95 | * @uint32 d[2]@ = pointer to destination block |
96 | * |
97 | * Returns: --- |
98 | * |
99 | * Use: Low-level block encryption and decryption. |
100 | */ |
101 | |
102 | extern void cast128_eblk(const cast128_ctx */*k*/, |
103 | const uint32 */*s*/, uint32 */*d*/); |
104 | |
105 | extern void cast128_dblk(const cast128_ctx */*k*/, |
106 | const uint32 */*s*/, uint32 */*d*/); |
107 | |
108 | /*----- That's all, folks -------------------------------------------------*/ |
109 | |
110 | #ifdef __cplusplus |
111 | } |
112 | #endif |
113 | |
114 | #endif |