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

   1 /* -*-c-*-
   2  *
   3  * $Id: idea.h,v 1.4 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Implementation of the IDEA cipher
   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 /*----- Notes on the IDEA block cipher ------------------------------------*
  31  *
  32  * IDEA was invented by James Massey and Xuejia Lai.  The fundamental idea
  33  * underlying the cipher is combining incompatible group operations.  The
  34  * algorithm's main claim to fame is that it is the symmetric cipher in PGP
  35  * version 2.
  36  *
  37  * The IDEA algorithm is allegedly patented by Ascom Tech A.G., even in the
  38  * UK and Europe.  Ascom are willing to grant licences for use in software
  39  * which forbids commercial use, but this is not compatible with Free
  40  * Software Foundation ideology.  The author recommends against the use of
  41  * the IDEA cipher entirely.  Blowfish is conceptually simpler, appears more
  42  * concervative, offers a larger keyspace, runs faster, and is in the public
  43  * domain.
  44  */
  45
  46 #ifndef CATACOMB_IDEA_H
  47 #define CATACOMB_IDEA_H
  48
  49 #ifdef __cplusplus
  50   extern "C" {
  51 #endif
  52
  53 /*----- Header files ------------------------------------------------------*/
  54
  55 #include <stddef.h>
  56
  57 #include <mLib/bits.h>
  58
  59 /*----- Magical numbers ---------------------------------------------------*/
  60
  61 #define IDEA_BLKSZ 8
  62 #define IDEA_KEYSZ 16
  63 #define IDEA_CLASS (N, B, 64)
  64
  65 extern const octet idea_keysz[];
  66
  67 /*----- Data structures ---------------------------------------------------*/
  68
  69 typedef struct idea_ctx {
  70   uint16 e[52];
  71   uint16 d[52];
  72 } idea_ctx;
  73
  74 /*----- Functions provided ------------------------------------------------*/
  75
  76 /* --- @idea_init@ --- *
  77  *
  78  * Arguments:   @idea_ctx *k@ = pointer to key block
  79  *              @const void *buf@ = pointer to key buffer
  80  *              @size_t sz@ = size of key material
  81  *
  82  * Returns:     ---
  83  *
  84  * Use:         Initializes an IDEA key buffer.  The buffer must be exactly
  85  *              16 bytes in size, because IDEA is only defined with a key
  86  *              size of 128 bits.
  87  */
  88
  89 extern void idea_init(idea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  90
  91 /* --- @idea_eblk@, @idea_dblk@ --- *
  92  *
  93  * Arguments:   @const idea_ctx *k@ = pointer to a 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 idea_eblk(const idea_ctx */*k*/,
 103                       const uint32 */*s*/, uint32 */*d*/);
 104 extern void idea_dblk(const idea_ctx */*k*/,
 105                       const uint32 */*s*/, uint32 */*d*/);
 106
 107 /*----- That's all, folks -------------------------------------------------*/
 108
 109 #ifdef __cplusplus
 110   }
 111 #endif
 112
 113 #endif