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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: gcipher.h,v 1.5 2004/04/21 00:37:32 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 | |
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30 | #ifndef CATACOMB_GCIPHER_H |
31 | #define CATACOMB_GCIPHER_H |
32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include <stddef.h> |
40 | |
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41 | #include <mLib/bits.h> |
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42 | |
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43 | /*----- Generic symmetric cipher interface --------------------------------*/ |
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44 | |
45 | typedef struct gcipher { |
46 | const struct gcipher_ops *ops; /* Pointer to cipher operations */ |
47 | } gcipher; |
48 | |
49 | typedef struct gcipher_ops { |
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50 | const struct gccipher *c; /* Pointer to cipher class */ |
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51 | void (*encrypt)(gcipher */*c*/, const void */*s*/, |
52 | void */*t*/, size_t /*sz*/); |
53 | void (*decrypt)(gcipher */*c*/, const void */*s*/, |
54 | void */*t*/, size_t /*sz*/); |
55 | void (*destroy)(gcipher */*c*/); |
56 | void (*setiv)(gcipher */*c*/, const void */*iv*/); |
57 | void (*bdry)(gcipher */*c*/); |
58 | } gcipher_ops; |
59 | |
60 | typedef struct gccipher { |
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61 | const char *name; /* Cipher name */ |
62 | const octet *keysz; /* Preferred key size table */ |
63 | size_t blksz; /* Block size or zero if none */ |
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64 | gcipher *(*init)(const void */*k*/, size_t /*sz*/); |
65 | } gccipher; |
66 | |
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67 | #define GC_INIT(cc, k, sz) (cc)->init((k), (sz)) |
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68 | #define GC_CLASS(cc) (cc)->ops->c |
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69 | #define GC_ENCRYPT(c, s, t, sz) (c)->ops->encrypt((c), (s), (t), (sz)) |
70 | #define GC_DECRYPT(c, s, t, sz) (c)->ops->decrypt((c), (s), (t), (sz)) |
71 | #define GC_DESTROY(c) (c)->ops->destroy((c)) |
72 | #define GC_SETIV(c, iv) (c)->ops->setiv((c), (iv)) |
73 | #define GC_BDRY(c) (c)->ops->bdry((c)) |
74 | |
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75 | /*----- Key size management -----------------------------------------------*/ |
76 | |
77 | /* --- Key size type constants --- * |
78 | * |
79 | * A key size limitation is an array of bytes. The first byte describes the |
80 | * kind of limitation on the key size %$k$%; the rest are argument bytes |
81 | * %$a_i$%, for %$i \ge 0$%. In all cases, %$a_0$% is the `recommended' key |
82 | * size. |
83 | * |
84 | * * @KSZ_ANY@ means there is no restriction. |
85 | * |
86 | * * @KSZ_RANGE@ requires that %$k \ge a_1$%, %$k \equiv 0 \pmod{a_3}$%, |
87 | * and, if %$a_2 \ne 0$%, %$k \le a_2$%. |
88 | * |
89 | * * @KSZ_SET@ requires that %$k \in {\,a_i\,}$%. |
90 | */ |
91 | |
92 | enum { |
93 | KSZ_ANY, /* Allows any key at all */ |
94 | KSZ_RANGE, /* Allows keys within a range */ |
95 | KSZ_SET /* Allows specific sizes of keys */ |
96 | }; |
97 | |
98 | /* --- @keysz@ --- * |
99 | * |
100 | * Arguments: @size_t sz@ = a proposed key size, or zero |
101 | * @const octet *ksz@ = pointer to key size table |
102 | * |
103 | * Returns: See below. |
104 | * |
105 | * Use: Returns a sensible key size. If @sz@ is nonzero, it is |
106 | * interpreted as an amount (in bytes) of key material which the |
107 | * caller has available, and the return value is either the |
108 | * largest allowable key size less than or equal to the caller's |
109 | * size, or zero if there is no valid key length small enough. |
110 | * If @sz@ is zero, the function returns a `recommended' key |
111 | * size. |
112 | */ |
113 | |
114 | extern size_t keysz(size_t /*sz*/, const octet */*ksz*/); |
115 | |
116 | #define KSZ_CHECK(pre, sz) (keysz((sz), pre##_keysz) == (sz)) |
117 | #define KSZ_ASSERT(pre, sz) \ |
118 | assert(((void)"Bad key size for " #pre, KSZ_CHECK(pre, sz))) |
119 | |
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120 | /*----- Tables ------------------------------------------------------------*/ |
121 | |
122 | extern const gccipher *const gciphertab[]; |
123 | |
124 | /* --- @gcipher_byname@ --- * |
125 | * |
126 | * Arguments: @const char *p@ = pointer to name string |
127 | * |
128 | * Returns: The named cipher class, or null. |
129 | */ |
130 | |
131 | extern const gccipher *gcipher_byname(const char */*p*/); |
132 | |
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133 | /*----- That's all, folks -------------------------------------------------*/ |
134 | |
135 | #ifdef __cplusplus |
136 | } |
137 | #endif |
138 | |
139 | #endif |