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8dd8c294 | 1 | /* -*-c-*- |
2 | * | |
8dd8c294 | 3 | * The SEAL pseudo-random function family |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
8dd8c294 | 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. | |
45c0fd36 | 16 | * |
8dd8c294 | 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. | |
45c0fd36 | 21 | * |
8dd8c294 | 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 | ||
8dd8c294 | 28 | /*----- Notes on the SEAL pseudo-random function family -------------------* |
29 | * | |
30 | * SEAL is a slightly odd cryptographic primitive. It was designed by Phil | |
31 | * Rogaway and Don Coppersmith at IBM, basically as an exercise in producing | |
32 | * a really fast symmetric cipher of some kind. They succeeded: SEAL is | |
33 | * faster than the much simpler RC4. | |
34 | * | |
35 | * For each key, it gives you %$2^{32}$% different output streams. This | |
36 | * implementation imposes no length limits on the size of output streams and | |
37 | * performs careful buffer handling to allow arbitrary amounts of data to be | |
38 | * extracted. In practice, extracting more than about 64K is possibly dodgy | |
39 | * from a security point of view. | |
40 | * | |
41 | * SEAL is patented. | |
42 | */ | |
43 | ||
44 | #ifndef CATACOMB_SEAL_H | |
45 | #define CATACOMB_SEAL_H | |
46 | ||
47 | #ifdef __cplusplus | |
48 | extern "C" { | |
49 | #endif | |
50 | ||
51 | /*----- Header files ------------------------------------------------------*/ | |
52 | ||
53 | #ifndef CATACOMB_GCIPHER_H | |
54 | # include "gcipher.h" | |
55 | #endif | |
56 | ||
57 | #ifndef CATACOMB_GRAND_H | |
58 | # include "grand.h" | |
59 | #endif | |
60 | ||
61 | /*----- Data structures ---------------------------------------------------*/ | |
62 | ||
63 | #define SEAL_R 256 | |
64 | ||
65 | typedef struct seal_key { | |
66 | octet k[20]; /* Copy of the 160-bit key */ | |
67 | uint32 t[512]; /* Substitution table */ | |
68 | uint32 s[256]; /* Magic for each iteration */ | |
69 | uint32 r[SEAL_R]; /* Magic for the first 64K */ | |
70 | } seal_key; | |
71 | ||
72 | typedef struct seal_ctx { | |
73 | seal_key *k; /* Pointer to the key block */ | |
74 | uint32 *r, ri; /* Pointer to current magic */ | |
75 | uint32 n, l; /* Various indices into things */ | |
76 | uint32 a, b, c, d; /* Current chaining variables */ | |
77 | uint32 n1, n2, n3, n4; /* Increments for the variables */ | |
78 | unsigned i; /* Index into current iteration */ | |
dd95e85d MW |
79 | octet buf[16]; /* Output buffer */ |
80 | unsigned off; /* Offset into the buffer */ | |
8dd8c294 | 81 | uint32 rbuf[SEAL_R]; /* Buffer for later magic */ |
82 | } seal_ctx; | |
83 | ||
84 | /*----- Functions provided ------------------------------------------------*/ | |
85 | ||
86 | /* --- @seal_initkey@ --- * | |
87 | * | |
88 | * Arguments: @seal_key *k@ = pointer to key block | |
89 | * @const void *buf@ = pointer to key material | |
90 | * @size_t sz@ = size of the key material | |
91 | * | |
92 | * Returns: --- | |
93 | * | |
94 | * Use: Initializes a SEAL key block. The key material may be any | |
95 | * size, but if it's not 20 bytes long it's passed to SHA for | |
96 | * hashing first. | |
97 | */ | |
98 | ||
99 | extern void seal_initkey(seal_key */*k*/, | |
100 | const void */*buf*/, size_t /*sz*/); | |
101 | ||
102 | /* --- @seal_initctx@ --- * | |
103 | * | |
104 | * Arguments: @seal_ctx *c@ = pointer to a SEAL context | |
105 | * @seal_key *k@ = pointer to a SEAL key | |
106 | * @uint32 n@ = integer sequence number | |
107 | * | |
108 | * Returns: --- | |
109 | * | |
110 | * Use: Initializes a SEAL context which can be used for random | |
111 | * number generation or whatever. | |
112 | */ | |
113 | ||
114 | extern void seal_initctx(seal_ctx */*c*/, seal_key */*k*/, uint32 /*n*/); | |
115 | ||
116 | /* --- @seal_encrypt@ --- * | |
117 | * | |
118 | * Arguments: @seal_ctx *c@ = pointer to a SEAL context | |
119 | * @const void *src@ = pointer to source data | |
120 | * @void *dest@ = pointer to destination data | |
121 | * @size_t sz@ = size of the data | |
122 | * | |
123 | * Returns: --- | |
124 | * | |
125 | * Use: Encrypts a block of data using SEAL. If @src@ is zero, | |
126 | * @dest@ is filled with SEAL output. If @dest@ is zero, the | |
127 | * SEAL generator is just spun around for a bit. This shouldn't | |
128 | * be necessary, because SEAL isn't RC4. | |
129 | */ | |
130 | ||
131 | extern void seal_encrypt(seal_ctx */*c*/, const void */*src*/, | |
132 | void */*dest*/, size_t /*sz*/); | |
133 | ||
134 | /*----- Generic cipher interface ------------------------------------------*/ | |
135 | ||
136 | #define SEAL_KEYSZ 20 | |
137 | extern const octet seal_keysz[]; | |
138 | ||
139 | extern const gccipher seal; | |
140 | ||
141 | /*----- Generic random number generator interface -------------------------*/ | |
142 | ||
143 | /* --- @seal_rand@ --- * | |
144 | * | |
145 | * Arguments: @const void *k@ = pointer to key material | |
146 | * @size_t sz@ = size of key material | |
147 | * @uint32 n@ = sequence number | |
148 | * | |
149 | * Returns: Pointer to generic random number generator interface. | |
150 | * | |
151 | * Use: Creates a random number interface wrapper around a SEAL | |
152 | * pseudorandom function. | |
153 | */ | |
154 | ||
155 | extern grand *seal_rand(const void */*k*/, size_t /*sz*/, uint32 /*n*/); | |
156 | ||
157 | /*----- That's all, folks -------------------------------------------------*/ | |
158 | ||
159 | #ifdef __cplusplus | |
160 | } | |
161 | #endif | |
162 | ||
163 | #endif |