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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: gcipher.h,v 1.2 2000/06/17 10:56:00 mdw Exp $ |
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4 | * |
5 | * Generic symmetric cipher interface |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
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. |
18 | * |
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. |
23 | * |
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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: gcipher.h,v $ |
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33 | * Revision 1.2 2000/06/17 10:56:00 mdw |
34 | * New key size interface. |
35 | * |
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36 | * Revision 1.1 1999/12/10 23:16:01 mdw |
37 | * Generic interface. |
38 | * |
39 | */ |
40 | |
41 | #ifndef CATACOMB_GCIPHER_H |
42 | #define CATACOMB_GCIPHER_H |
43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <stddef.h> |
51 | |
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52 | #include <mLib/bits.h> |
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53 | |
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54 | /*----- Generic symmetric cipher interface --------------------------------*/ |
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55 | |
56 | typedef struct gcipher { |
57 | const struct gcipher_ops *ops; /* Pointer to cipher operations */ |
58 | } gcipher; |
59 | |
60 | typedef struct gcipher_ops { |
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61 | const struct gccipher *c; /* Pointer to cipher class */ |
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62 | void (*encrypt)(gcipher */*c*/, const void */*s*/, |
63 | void */*t*/, size_t /*sz*/); |
64 | void (*decrypt)(gcipher */*c*/, const void */*s*/, |
65 | void */*t*/, size_t /*sz*/); |
66 | void (*destroy)(gcipher */*c*/); |
67 | void (*setiv)(gcipher */*c*/, const void */*iv*/); |
68 | void (*bdry)(gcipher */*c*/); |
69 | } gcipher_ops; |
70 | |
71 | typedef struct gccipher { |
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72 | const char *name; /* Cipher name */ |
73 | const octet *keysz; /* Preferred key size table */ |
74 | size_t blksz; /* Block size or zero if none */ |
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75 | gcipher *(*init)(const void */*k*/, size_t /*sz*/); |
76 | } gccipher; |
77 | |
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78 | /*----- Key size management -----------------------------------------------*/ |
79 | |
80 | /* --- Key size type constants --- * |
81 | * |
82 | * A key size limitation is an array of bytes. The first byte describes the |
83 | * kind of limitation on the key size %$k$%; the rest are argument bytes |
84 | * %$a_i$%, for %$i \ge 0$%. In all cases, %$a_0$% is the `recommended' key |
85 | * size. |
86 | * |
87 | * * @KSZ_ANY@ means there is no restriction. |
88 | * |
89 | * * @KSZ_RANGE@ requires that %$k \ge a_1$%, %$k \equiv 0 \pmod{a_3}$%, |
90 | * and, if %$a_2 \ne 0$%, %$k \le a_2$%. |
91 | * |
92 | * * @KSZ_SET@ requires that %$k \in {\,a_i\,}$%. |
93 | */ |
94 | |
95 | enum { |
96 | KSZ_ANY, /* Allows any key at all */ |
97 | KSZ_RANGE, /* Allows keys within a range */ |
98 | KSZ_SET /* Allows specific sizes of keys */ |
99 | }; |
100 | |
101 | /* --- @keysz@ --- * |
102 | * |
103 | * Arguments: @size_t sz@ = a proposed key size, or zero |
104 | * @const octet *ksz@ = pointer to key size table |
105 | * |
106 | * Returns: See below. |
107 | * |
108 | * Use: Returns a sensible key size. If @sz@ is nonzero, it is |
109 | * interpreted as an amount (in bytes) of key material which the |
110 | * caller has available, and the return value is either the |
111 | * largest allowable key size less than or equal to the caller's |
112 | * size, or zero if there is no valid key length small enough. |
113 | * If @sz@ is zero, the function returns a `recommended' key |
114 | * size. |
115 | */ |
116 | |
117 | extern size_t keysz(size_t /*sz*/, const octet */*ksz*/); |
118 | |
119 | #define KSZ_CHECK(pre, sz) (keysz((sz), pre##_keysz) == (sz)) |
120 | #define KSZ_ASSERT(pre, sz) \ |
121 | assert(((void)"Bad key size for " #pre, KSZ_CHECK(pre, sz))) |
122 | |
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123 | /*----- That's all, folks -------------------------------------------------*/ |
124 | |
125 | #ifdef __cplusplus |
126 | } |
127 | #endif |
128 | |
129 | #endif |