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   1 /* -*-c-*-
   2  *
   3  * $Id: cast128.h,v 1.2 2004/04/08 01:36:15 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 /*----- Notes on the CAST-128 block cipher --------------------------------*
  31  *
  32  * CAST, designed by Carlisle Adams and Stafford Tavares, is a method for
  33  * designing block ciphers, based around the concept of `bent functions'.  It
  34  * is described in the paper `Constructing Symmetric Ciphers using the CAST
  35  * Design Procedure' by Carlisle Adams.
  36  *
  37  * CAST-128, defined in RFC2144, is a particular instance of the CAST design
  38  * procedure, The cipher seems strong and fairly quick.  The design procedure
  39  * itself is patented, although the cipher CAST-128 is free to use.
  40  *
  41  * Although CAST ciphers are resistant to differential and linear
  42  * cryptanalysis, some instances have been broken by more advanced techniques
  43  * -- the CAST procedure does not guarantee a strong cipher.  However,
  44  * CAST-128 has so far resisted all attacks against it, and has now been
  45  * accepted by the Canadian government for protection of all `Designated'
  46  * material.
  47  */
  48
  49 #ifndef CATACOMB_CAST128_H
  50 #define CATACOMB_CAST128_H
  51
  52 #ifdef __cplusplus
  53   extern "C" {
  54 #endif
  55
  56 /*----- Header files ------------------------------------------------------*/
  57
  58 #include <mLib/bits.h>
  59
  60 /*----- Magic numbers -----------------------------------------------------*/
  61
  62 #define CAST128_BLKSZ 8
  63 #define CAST128_KEYSZ 16
  64 #define CAST128_CLASS (N, B, 64)
  65
  66 extern const octet cast128_keysz[];
  67
  68 /*----- Data structures ---------------------------------------------------*/
  69
  70 typedef struct cast128_ctx {
  71   unsigned r;
  72   uint32 km[16];
  73   octet kr[16];
  74 } cast128_ctx;
  75
  76 /*----- Functions provided ------------------------------------------------*/
  77
  78 /* --- @cast128_init@ --- *
  79  *
  80  * Arguments:   @cast128_ctx *k@ = pointer to key block to fill in
  81  *              @const void *buf@ = pointer to buffer of key material
  82  *              @size_t sz@ = size of key material
  83  *
  84  * Returns:     ---
  85  *
  86  * Use:         Initializes a CAST-128 key buffer.  CAST-128 accepts
  87  *              128-bit keys or shorter.
  88  */
  89
  90 extern void cast128_init(cast128_ctx */*k*/,
  91                          const void */*buf*/, size_t /*sz*/);
  92
  93 /* --- @cast128_eblk@, @cast128_dblk@ --- *
  94  *
  95  * Arguments:   @const cast128_ctx *k@ = pointer to key block
  96  *              @const uint32 s[2]@ = pointer to source block
  97  *              @uint32 d[2]@ = pointer to destination block
  98  *
  99  * Returns:     ---
 100  *
 101  * Use:         Low-level block encryption and decryption.
 102  */
 103
 104 extern void cast128_eblk(const cast128_ctx */*k*/,
 105                          const uint32 */*s*/, uint32 */*d*/);
 106
 107 extern void cast128_dblk(const cast128_ctx */*k*/,
 108                          const uint32 */*s*/, uint32 */*d*/);
 109
 110 /*----- That's all, folks -------------------------------------------------*/
 111
 112 #ifdef __cplusplus
 113   }
 114 #endif
 115
 116 #endif