git.distorted.org.uk Git - u/mdw/catacomb/blob - symm/cast128.h

   1 /* -*-c-*-
   2  *
   3  * The CAST-128 block cipher
   4  *
   5  * (c) 2000 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   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.
  16  *
  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.
  21  *
  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
  28 /*----- Notes on the CAST-128 block cipher --------------------------------*
  29  *
  30  * CAST, designed by Carlisle Adams and Stafford Tavares, is a method for
  31  * designing block ciphers, based around the concept of `bent functions'.  It
  32  * is described in the paper `Constructing Symmetric Ciphers using the CAST
  33  * Design Procedure' by Carlisle Adams.
  34  *
  35  * CAST-128, defined in RFC2144, is a particular instance of the CAST design
  36  * procedure, The cipher seems strong and fairly quick.  The design procedure
  37  * itself is patented, although the cipher CAST-128 is free to use.
  38  *
  39  * Although CAST ciphers are resistant to differential and linear
  40  * cryptanalysis, some instances have been broken by more advanced techniques
  41  * -- the CAST procedure does not guarantee a strong cipher.  However,
  42  * CAST-128 has so far resisted all attacks against it, and has now been
  43  * accepted by the Canadian government for protection of all `Designated'
  44  * material.
  45  */
  46
  47 #ifndef CATACOMB_CAST128_H
  48 #define CATACOMB_CAST128_H
  49
  50 #ifdef __cplusplus
  51   extern "C" {
  52 #endif
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #include <mLib/bits.h>
  57
  58 /*----- Magic numbers -----------------------------------------------------*/
  59
  60 #define CAST128_BLKSZ 8
  61 #define CAST128_KEYSZ 16
  62 #define CAST128_CLASS (N, B, 64)
  63
  64 extern const octet cast128_keysz[];
  65
  66 /*----- Data structures ---------------------------------------------------*/
  67
  68 typedef struct cast128_ctx {
  69   unsigned r;
  70   uint32 km[16];
  71   octet kr[16];
  72 } cast128_ctx;
  73
  74 /*----- Functions provided ------------------------------------------------*/
  75
  76 /* --- @cast128_init@ --- *
  77  *
  78  * Arguments:   @cast128_ctx *k@ = pointer to key block to fill in
  79  *              @const void *buf@ = pointer to buffer of key material
  80  *              @size_t sz@ = size of key material
  81  *
  82  * Returns:     ---
  83  *
  84  * Use:         Initializes a CAST-128 key buffer.  CAST-128 accepts
  85  *              128-bit keys or shorter.
  86  */
  87
  88 extern void cast128_init(cast128_ctx */*k*/,
  89                          const void */*buf*/, size_t /*sz*/);
  90
  91 /* --- @cast128_eblk@, @cast128_dblk@ --- *
  92  *
  93  * Arguments:   @const cast128_ctx *k@ = pointer to key block
  94  *              @const uint32 s[2]@ = pointer to source block
  95  *              @uint32 d[2]@ = pointer to destination block
  96  *
  97  * Returns:     ---
  98  *
  99  * Use:         Low-level block encryption and decryption.
 100  */
 101
 102 extern void cast128_eblk(const cast128_ctx */*k*/,
 103                          const uint32 */*s*/, uint32 */*d*/);
 104
 105 extern void cast128_dblk(const cast128_ctx */*k*/,
 106                          const uint32 */*s*/, uint32 */*d*/);
 107
 108 /*----- That's all, folks -------------------------------------------------*/
 109
 110 #ifdef __cplusplus
 111   }
 112 #endif
 113
 114 #endif