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

   1 /* -*-c-*-
   2  *
   3  * $Id: cast128.h,v 1.1 2000/06/17 10:49:14 mdw Exp $
   4  *
   5  * The CAST-128 block cipher
   6  *
   7  * (c) 2000 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: cast128.h,v $
  33  * Revision 1.1  2000/06/17 10:49:14  mdw
  34  * New cipher.
  35  *
  36  */
  37
  38 /*----- Notes on the CAST-128 block cipher --------------------------------*
  39  *
  40  * CAST, designed by Carlisle Adams and Stafford Tavares, is a method for
  41  * designing block ciphers, based around the concept of `bent functions'.  It
  42  * is described in the paper `Constructing Symmetric Ciphers using the CAST
  43  * Design Procedure' by Carlisle Adams.
  44  *
  45  * CAST-128, defined in RFC2144, is a particular instance of the CAST design
  46  * procedure, The cipher seems strong and fairly quick.  The design procedure
  47  * itself is patented, although the cipher CAST-128 is free to use.
  48  *
  49  * Although CAST ciphers are resistant to differential and linear
  50  * cryptanalysis, some instances have been broken by more advanced techniques
  51  * -- the CAST procedure does not guarantee a strong cipher.  However,
  52  * CAST-128 has so far resisted all attacks against it, and has now been
  53  * accepted by the Canadian government for protection of all `Designated'
  54  * material.
  55  */
  56
  57 #ifndef CATACOMB_CAST128_H
  58 #define CATACOMB_CAST128_H
  59
  60 #ifdef __cplusplus
  61   extern "C" {
  62 #endif
  63
  64 /*----- Header files ------------------------------------------------------*/
  65
  66 #include <mLib/bits.h>
  67
  68 /*----- Magic numbers -----------------------------------------------------*/
  69
  70 #define CAST128_BLKSZ 8
  71 #define CAST128_KEYSZ 16
  72 #define CAST128_CLASS (N, B, 64)
  73
  74 extern const octet cast128_keysz[];
  75
  76 /*----- Data structures ---------------------------------------------------*/
  77
  78 typedef struct cast128_ctx {
  79   unsigned r;
  80   uint32 km[16];
  81   octet kr[16];
  82 } cast128_ctx;
  83
  84 /*----- Functions provided ------------------------------------------------*/
  85
  86 /* --- @cast128_init@ --- *
  87  *
  88  * Arguments:   @cast128_ctx *k@ = pointer to key block to fill in
  89  *              @const void *buf@ = pointer to buffer of key material
  90  *              @size_t sz@ = size of key material
  91  *
  92  * Returns:     ---
  93  *
  94  * Use:         Initializes a CAST-128 key buffer.  CAST-128 accepts
  95  *              128-bit keys or shorter.
  96  */
  97
  98 extern void cast128_init(cast128_ctx */*k*/,
  99                          const void */*buf*/, size_t /*sz*/);
 100
 101 /* --- @cast128_eblk@, @cast128_dblk@ --- *
 102  *
 103  * Arguments:   @const cast128_ctx *k@ = pointer to key block
 104  *              @const uint32 s[2]@ = pointer to source block
 105  *              @uint32 d[2]@ = pointer to destination block
 106  *
 107  * Returns:     ---
 108  *
 109  * Use:         Low-level block encryption and decryption.
 110  */
 111
 112 extern void cast128_eblk(const cast128_ctx */*k*/,
 113                          const uint32 */*s*/, uint32 */*d*/);
 114
 115 extern void cast128_dblk(const cast128_ctx */*k*/,
 116                          const uint32 */*s*/, uint32 */*d*/);
 117
 118 /*----- That's all, folks -------------------------------------------------*/
 119
 120 #ifdef __cplusplus
 121   }
 122 #endif
 123
 124 #endif