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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: seal.h,v 1.2 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * The SEAL pseudo-random function family |
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 SEAL pseudo-random function family -------------------* |
31 | * |
32 | * SEAL is a slightly odd cryptographic primitive. It was designed by Phil |
33 | * Rogaway and Don Coppersmith at IBM, basically as an exercise in producing |
34 | * a really fast symmetric cipher of some kind. They succeeded: SEAL is |
35 | * faster than the much simpler RC4. |
36 | * |
37 | * For each key, it gives you %$2^{32}$% different output streams. This |
38 | * implementation imposes no length limits on the size of output streams and |
39 | * performs careful buffer handling to allow arbitrary amounts of data to be |
40 | * extracted. In practice, extracting more than about 64K is possibly dodgy |
41 | * from a security point of view. |
42 | * |
43 | * SEAL is patented. |
44 | */ |
45 | |
46 | #ifndef CATACOMB_SEAL_H |
47 | #define CATACOMB_SEAL_H |
48 | |
49 | #ifdef __cplusplus |
50 | extern "C" { |
51 | #endif |
52 | |
53 | /*----- Header files ------------------------------------------------------*/ |
54 | |
55 | #ifndef CATACOMB_GCIPHER_H |
56 | # include "gcipher.h" |
57 | #endif |
58 | |
59 | #ifndef CATACOMB_GRAND_H |
60 | # include "grand.h" |
61 | #endif |
62 | |
63 | /*----- Data structures ---------------------------------------------------*/ |
64 | |
65 | #define SEAL_R 256 |
66 | |
67 | typedef struct seal_key { |
68 | octet k[20]; /* Copy of the 160-bit key */ |
69 | uint32 t[512]; /* Substitution table */ |
70 | uint32 s[256]; /* Magic for each iteration */ |
71 | uint32 r[SEAL_R]; /* Magic for the first 64K */ |
72 | } seal_key; |
73 | |
74 | typedef struct seal_ctx { |
75 | seal_key *k; /* Pointer to the key block */ |
76 | uint32 *r, ri; /* Pointer to current magic */ |
77 | uint32 n, l; /* Various indices into things */ |
78 | uint32 a, b, c, d; /* Current chaining variables */ |
79 | uint32 n1, n2, n3, n4; /* Increments for the variables */ |
80 | unsigned i; /* Index into current iteration */ |
81 | octet q[16]; /* Output buffer */ |
82 | unsigned qsz; /* Number of bytes in the buffer */ |
83 | uint32 rbuf[SEAL_R]; /* Buffer for later magic */ |
84 | } seal_ctx; |
85 | |
86 | /*----- Functions provided ------------------------------------------------*/ |
87 | |
88 | /* --- @seal_initkey@ --- * |
89 | * |
90 | * Arguments: @seal_key *k@ = pointer to key block |
91 | * @const void *buf@ = pointer to key material |
92 | * @size_t sz@ = size of the key material |
93 | * |
94 | * Returns: --- |
95 | * |
96 | * Use: Initializes a SEAL key block. The key material may be any |
97 | * size, but if it's not 20 bytes long it's passed to SHA for |
98 | * hashing first. |
99 | */ |
100 | |
101 | extern void seal_initkey(seal_key */*k*/, |
102 | const void */*buf*/, size_t /*sz*/); |
103 | |
104 | /* --- @seal_initctx@ --- * |
105 | * |
106 | * Arguments: @seal_ctx *c@ = pointer to a SEAL context |
107 | * @seal_key *k@ = pointer to a SEAL key |
108 | * @uint32 n@ = integer sequence number |
109 | * |
110 | * Returns: --- |
111 | * |
112 | * Use: Initializes a SEAL context which can be used for random |
113 | * number generation or whatever. |
114 | */ |
115 | |
116 | extern void seal_initctx(seal_ctx */*c*/, seal_key */*k*/, uint32 /*n*/); |
117 | |
118 | /* --- @seal_encrypt@ --- * |
119 | * |
120 | * Arguments: @seal_ctx *c@ = pointer to a SEAL context |
121 | * @const void *src@ = pointer to source data |
122 | * @void *dest@ = pointer to destination data |
123 | * @size_t sz@ = size of the data |
124 | * |
125 | * Returns: --- |
126 | * |
127 | * Use: Encrypts a block of data using SEAL. If @src@ is zero, |
128 | * @dest@ is filled with SEAL output. If @dest@ is zero, the |
129 | * SEAL generator is just spun around for a bit. This shouldn't |
130 | * be necessary, because SEAL isn't RC4. |
131 | */ |
132 | |
133 | extern void seal_encrypt(seal_ctx */*c*/, const void */*src*/, |
134 | void */*dest*/, size_t /*sz*/); |
135 | |
136 | /*----- Generic cipher interface ------------------------------------------*/ |
137 | |
138 | #define SEAL_KEYSZ 20 |
139 | extern const octet seal_keysz[]; |
140 | |
141 | extern const gccipher seal; |
142 | |
143 | /*----- Generic random number generator interface -------------------------*/ |
144 | |
145 | /* --- @seal_rand@ --- * |
146 | * |
147 | * Arguments: @const void *k@ = pointer to key material |
148 | * @size_t sz@ = size of key material |
149 | * @uint32 n@ = sequence number |
150 | * |
151 | * Returns: Pointer to generic random number generator interface. |
152 | * |
153 | * Use: Creates a random number interface wrapper around a SEAL |
154 | * pseudorandom function. |
155 | */ |
156 | |
157 | extern grand *seal_rand(const void */*k*/, size_t /*sz*/, uint32 /*n*/); |
158 | |
159 | /*----- That's all, folks -------------------------------------------------*/ |
160 | |
161 | #ifdef __cplusplus |
162 | } |
163 | #endif |
164 | |
165 | #endif |