3 * $Id: gcipher.h,v 1.2 2000/06/17 10:56:00 mdw Exp $
5 * Generic symmetric cipher interface
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.2 2000/06/17 10:56:00 mdw
34 * New key size interface.
36 * Revision 1.1 1999/12/10 23:16:01 mdw
41 #ifndef CATACOMB_GCIPHER_H
42 #define CATACOMB_GCIPHER_H
48 /*----- Header files ------------------------------------------------------*/
52 #include <mLib/bits.h>
54 /*----- Generic symmetric cipher interface --------------------------------*/
56 typedef struct gcipher {
57 const struct gcipher_ops *ops; /* Pointer to cipher operations */
60 typedef struct gcipher_ops {
61 const struct gccipher *c; /* Pointer to cipher class */
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*/);
71 typedef struct gccipher {
72 const char *name; /* Cipher name */
73 const octet *keysz; /* Preferred key size table */
74 size_t blksz; /* Block size or zero if none */
75 gcipher *(*init)(const void */*k*/, size_t /*sz*/);
78 /*----- Key size management -----------------------------------------------*/
80 /* --- Key size type constants --- *
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
87 * * @KSZ_ANY@ means there is no restriction.
89 * * @KSZ_RANGE@ requires that %$k \ge a_1$%, %$k \equiv 0 \pmod{a_3}$%,
90 * and, if %$a_2 \ne 0$%, %$k \le a_2$%.
92 * * @KSZ_SET@ requires that %$k \in {\,a_i\,}$%.
96 KSZ_ANY, /* Allows any key at all */
97 KSZ_RANGE, /* Allows keys within a range */
98 KSZ_SET /* Allows specific sizes of keys */
103 * Arguments: @size_t sz@ = a proposed key size, or zero
104 * @const octet *ksz@ = pointer to key size table
106 * Returns: See below.
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
117 extern size_t keysz(size_t /*sz*/, const octet */*ksz*/);
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)))
123 /*----- That's all, folks -------------------------------------------------*/