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

   1 /* -*-c-*-
   2  *
   3  * Implementation of the IDEA cipher
   4  *
   5  * (c) 1999 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 IDEA block cipher ------------------------------------*
  29  *
  30  * IDEA was invented by James Massey and Xuejia Lai.  The fundamental idea
  31  * underlying the cipher is combining incompatible group operations.  The
  32  * algorithm's main claim to fame is that it is the symmetric cipher in PGP
  33  * version 2.
  34  *
  35  * The IDEA algorithm is allegedly patented by Ascom Tech A.G., even in the
  36  * UK and Europe.  Ascom are willing to grant licences for use in software
  37  * which forbids commercial use, but this is not compatible with Free
  38  * Software Foundation ideology.  The author recommends against the use of
  39  * the IDEA cipher entirely.  Blowfish is conceptually simpler, appears more
  40  * concervative, offers a larger keyspace, runs faster, and is in the public
  41  * domain.
  42  */
  43
  44 #ifndef CATACOMB_IDEA_H
  45 #define CATACOMB_IDEA_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 /*----- Magical numbers ---------------------------------------------------*/
  58
  59 #define IDEA_BLKSZ 8
  60 #define IDEA_KEYSZ 16
  61 #define IDEA_CLASS (N, B, 64)
  62
  63 extern const octet idea_keysz[];
  64
  65 /*----- Data structures ---------------------------------------------------*/
  66
  67 typedef struct idea_ctx {
  68   uint16 e[52];
  69   uint16 d[52];
  70 } idea_ctx;
  71
  72 /*----- Functions provided ------------------------------------------------*/
  73
  74 /* --- @idea_init@ --- *
  75  *
  76  * Arguments:   @idea_ctx *k@ = pointer to key block
  77  *              @const void *buf@ = pointer to key buffer
  78  *              @size_t sz@ = size of key material
  79  *
  80  * Returns:     ---
  81  *
  82  * Use:         Initializes an IDEA key buffer.  The buffer must be exactly
  83  *              16 bytes in size, because IDEA is only defined with a key
  84  *              size of 128 bits.
  85  */
  86
  87 extern void idea_init(idea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  88
  89 /* --- @idea_eblk@, @idea_dblk@ --- *
  90  *
  91  * Arguments:   @const idea_ctx *k@ = pointer to a key block
  92  *              @const uint32 s[2]@ = pointer to source block
  93  *              @uint32 d[2]@ = pointer to destination block
  94  *
  95  * Returns:     ---
  96  *
  97  * Use:         Low-level block encryption and decryption.
  98  */
  99
 100 extern void idea_eblk(const idea_ctx */*k*/,
 101                       const uint32 */*s*/, uint32 */*d*/);
 102 extern void idea_dblk(const idea_ctx */*k*/,
 103                       const uint32 */*s*/, uint32 */*d*/);
 104
 105 /*----- That's all, folks -------------------------------------------------*/
 106
 107 #ifdef __cplusplus
 108   }
 109 #endif
 110
 111 #endif