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

   1 /* -*-c-*-
   2  *
   3  * $Id: idea.h,v 1.2 1999/12/10 23:29:48 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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: idea.h,v $
  33  * Revision 1.2  1999/12/10 23:29:48  mdw
  34  * Change header file guard names.
  35  *
  36  * Revision 1.1  1999/09/03 08:41:12  mdw
  37  * Initial import.
  38  *
  39  */
  40
  41 /*----- Notes on the IDEA block cipher ------------------------------------*
  42  *
  43  * IDEA was invented by James Massey and Xuejia Lai.  The fundamental idea
  44  * underlying the cipher is combining incompatible group operations.  The
  45  * algorithm's main claim to fame is that it is the symmetric cipher in PGP
  46  * version 2.
  47  *
  48  * The IDEA algorithm is allegedly patented by Ascom Tech A.G., even in the
  49  * UK and Europe.  Ascom are willing to grant licences for use in software
  50  * which forbids commercial use, but this is not compatible with Free
  51  * Software Foundation ideology.  The author recommends against the use of
  52  * the IDEA cipher entirely.  Blowfish is conceptually simpler, appears more
  53  * concervative, offers a larger keyspace, runs faster, and is in the public
  54  * domain.
  55  */
  56
  57 #ifndef CATACOMB_IDEA_H
  58 #define CATACOMB_IDEA_H
  59
  60 #ifdef __cplusplus
  61   extern "C" {
  62 #endif
  63
  64 /*----- Header files ------------------------------------------------------*/
  65
  66 #include <stddef.h>
  67
  68 #include <mLib/bits.h>
  69
  70 /*----- Magical numbers ---------------------------------------------------*/
  71
  72 #define IDEA_BLKSZ 8
  73 #define IDEA_KEYSZ 16
  74 #define IDEA_CLASS (N, B, 64)
  75
  76 /*----- Data structures ---------------------------------------------------*/
  77
  78 typedef struct idea_ctx {
  79   uint16 e[52];
  80   uint16 d[52];
  81 } idea_ctx;
  82
  83 /*----- Functions provided ------------------------------------------------*/
  84
  85 /* --- @idea_init@ --- *
  86  *
  87  * Arguments:   @idea_ctx *k@ = pointer to key block
  88  *              @const void *buf@ = pointer to key buffer
  89  *              @size_t sz@ = size of key material
  90  *
  91  * Returns:     ---
  92  *
  93  * Use:         Initializes an IDEA key buffer.  The buffer must be exactly
  94  *              16 bytes in size, because IDEA is only defined with a key
  95  *              size of 128 bits.
  96  */
  97
  98 extern void idea_init(idea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  99
 100 /* --- @idea_eblk@, @idea_dblk@ --- *
 101  *
 102  * Arguments:   @const idea_ctx *k@ = pointer to a key block
 103  *              @const uint32 s[2]@ = pointer to source block
 104  *              @uint32 d[2]@ = pointer to destination block
 105  *
 106  * Returns:     ---
 107  *
 108  * Use:         Low-level block encryption and decryption.
 109  */
 110
 111 extern void idea_eblk(const idea_ctx */*k*/,
 112                       const uint32 */*s*/, uint32 */*d*/);
 113 extern void idea_dblk(const idea_ctx */*k*/,
 114                       const uint32 */*s*/, uint32 */*d*/);
 115
 116 /*----- That's all, folks -------------------------------------------------*/
 117
 118 #ifdef __cplusplus
 119   }
 120 #endif
 121
 122 #endif