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   1 /* -*-c-*-
   2  *
   3  * $Id: gcipher.h,v 1.3 2004/04/04 19:42:30 mdw Exp $
   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 $
  33  * Revision 1.3  2004/04/04 19:42:30  mdw
  34  * Make tables of standard encryption schemes etc.
  35  *
  36  * Revision 1.2  2000/06/17 10:56:00  mdw
  37  * New key size interface.
  38  *
  39  * Revision 1.1  1999/12/10 23:16:01  mdw
  40  * Generic interface.
  41  *
  42  */
  43
  44 #ifndef CATACOMB_GCIPHER_H
  45 #define CATACOMB_GCIPHER_H
  46
  47 #ifdef __cplusplus
  48   extern "C" {
  49 #endif
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include <stddef.h>
  54
  55 #include <mLib/bits.h>
  56
  57 /*----- Generic symmetric cipher interface --------------------------------*/
  58
  59 typedef struct gcipher {
  60   const struct gcipher_ops *ops;        /* Pointer to cipher operations */
  61 } gcipher;
  62
  63 typedef struct gcipher_ops {
  64   const struct gccipher *c;             /* Pointer to cipher class */
  65   void (*encrypt)(gcipher */*c*/, const void */*s*/,
  66                   void */*t*/, size_t /*sz*/);
  67   void (*decrypt)(gcipher */*c*/, const void */*s*/,
  68                   void */*t*/, size_t /*sz*/);
  69   void (*destroy)(gcipher */*c*/);
  70   void (*setiv)(gcipher */*c*/, const void */*iv*/);
  71   void (*bdry)(gcipher */*c*/);
  72 } gcipher_ops;
  73
  74 typedef struct gccipher {
  75   const char *name;                     /* Cipher name */
  76   const octet *keysz;                   /* Preferred key size table */
  77   size_t blksz;                         /* Block size or zero if none */
  78   gcipher *(*init)(const void */*k*/, size_t /*sz*/);
  79 } gccipher;
  80
  81 #define GC_INIT(cc, k, sz)      (cc)->init((k), (sz))
  82 #define GC_CLASS(c)             (c)->ops->c
  83 #define GC_ENCRYPT(c, s, t, sz) (c)->ops->encrypt((c), (s), (t), (sz))
  84 #define GC_DECRYPT(c, s, t, sz) (c)->ops->decrypt((c), (s), (t), (sz))
  85 #define GC_DESTROY(c)           (c)->ops->destroy((c))
  86 #define GC_SETIV(c, iv)         (c)->ops->setiv((c), (iv))
  87 #define GC_BDRY(c)              (c)->ops->bdry((c))
  88
  89 /*----- Key size management -----------------------------------------------*/
  90
  91 /* --- Key size type constants --- *
  92  *
  93  * A key size limitation is an array of bytes.  The first byte describes the
  94  * kind of limitation on the key size %$k$%; the rest are argument bytes
  95  * %$a_i$%, for %$i \ge 0$%.  In all cases, %$a_0$% is the `recommended' key
  96  * size.
  97  *
  98  *   * @KSZ_ANY@ means there is no restriction.
  99  *
 100  *   * @KSZ_RANGE@ requires that %$k \ge a_1$%, %$k \equiv 0 \pmod{a_3}$%,
 101  *     and, if %$a_2 \ne 0$%, %$k \le a_2$%.
 102  *
 103  *   * @KSZ_SET@ requires that %$k \in {\,a_i\,}$%.
 104  */
 105
 106 enum {
 107   KSZ_ANY,                              /* Allows any key at all */
 108   KSZ_RANGE,                            /* Allows keys within a range */
 109   KSZ_SET                               /* Allows specific sizes of keys */
 110 };
 111
 112 /* --- @keysz@ --- *
 113  *
 114  * Arguments:   @size_t sz@ = a proposed key size, or zero
 115  *              @const octet *ksz@ = pointer to key size table
 116  *
 117  * Returns:     See below.
 118  *
 119  * Use:         Returns a sensible key size.  If @sz@ is nonzero, it is
 120  *              interpreted as an amount (in bytes) of key material which the
 121  *              caller has available, and the return value is either the
 122  *              largest allowable key size less than or equal to the caller's
 123  *              size, or zero if there is no valid key length small enough.
 124  *              If @sz@ is zero, the function returns a `recommended' key
 125  *              size.
 126  */
 127
 128 extern size_t keysz(size_t /*sz*/, const octet */*ksz*/);
 129
 130 #define KSZ_CHECK(pre, sz) (keysz((sz), pre##_keysz) == (sz))
 131 #define KSZ_ASSERT(pre, sz)                                             \
 132   assert(((void)"Bad key size for " #pre, KSZ_CHECK(pre, sz)))
 133
 134 /*----- Tables ------------------------------------------------------------*/
 135
 136 extern const gccipher *const gciphertab[];
 137
 138 /* --- @gcipher_byname@ --- *
 139  *
 140  * Arguments:   @const char *p@ = pointer to name string
 141  *
 142  * Returns:     The named cipher class, or null.
 143  */
 144
 145 extern const gccipher *gcipher_byname(const char */*p*/);
 146
 147 /*----- That's all, folks -------------------------------------------------*/
 148
 149 #ifdef __cplusplus
 150   }
 151 #endif
 152
 153 #endif