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

   1 /* -*-c-*-
   2  *
   3  * $Id: idea.h,v 1.3 2000/06/17 11:24:08 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 1.3  2000/06/17 11:24:08  mdw
  34  * New key size interface.
  35  *
  36  * Revision 1.2  1999/12/10 23:29:48  mdw
  37  * Change header file guard names.
  38  *
  39  * Revision 1.1  1999/09/03 08:41:12  mdw
  40  * Initial import.
  41  *
  42  */
  43
  44 /*----- Notes on the IDEA block cipher ------------------------------------*
  45  *
  46  * IDEA was invented by James Massey and Xuejia Lai.  The fundamental idea
  47  * underlying the cipher is combining incompatible group operations.  The
  48  * algorithm's main claim to fame is that it is the symmetric cipher in PGP
  49  * version 2.
  50  *
  51  * The IDEA algorithm is allegedly patented by Ascom Tech A.G., even in the
  52  * UK and Europe.  Ascom are willing to grant licences for use in software
  53  * which forbids commercial use, but this is not compatible with Free
  54  * Software Foundation ideology.  The author recommends against the use of
  55  * the IDEA cipher entirely.  Blowfish is conceptually simpler, appears more
  56  * concervative, offers a larger keyspace, runs faster, and is in the public
  57  * domain.
  58  */
  59
  60 #ifndef CATACOMB_IDEA_H
  61 #define CATACOMB_IDEA_H
  62
  63 #ifdef __cplusplus
  64   extern "C" {
  65 #endif
  66
  67 /*----- Header files ------------------------------------------------------*/
  68
  69 #include <stddef.h>
  70
  71 #include <mLib/bits.h>
  72
  73 /*----- Magical numbers ---------------------------------------------------*/
  74
  75 #define IDEA_BLKSZ 8
  76 #define IDEA_KEYSZ 16
  77 #define IDEA_CLASS (N, B, 64)
  78
  79 extern const octet idea_keysz[];
  80
  81 /*----- Data structures ---------------------------------------------------*/
  82
  83 typedef struct idea_ctx {
  84   uint16 e[52];
  85   uint16 d[52];
  86 } idea_ctx;
  87
  88 /*----- Functions provided ------------------------------------------------*/
  89
  90 /* --- @idea_init@ --- *
  91  *
  92  * Arguments:   @idea_ctx *k@ = pointer to key block
  93  *              @const void *buf@ = pointer to key buffer
  94  *              @size_t sz@ = size of key material
  95  *
  96  * Returns:     ---
  97  *
  98  * Use:         Initializes an IDEA key buffer.  The buffer must be exactly
  99  *              16 bytes in size, because IDEA is only defined with a key
 100  *              size of 128 bits.
 101  */
 102
 103 extern void idea_init(idea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
 104
 105 /* --- @idea_eblk@, @idea_dblk@ --- *
 106  *
 107  * Arguments:   @const idea_ctx *k@ = pointer to a key block
 108  *              @const uint32 s[2]@ = pointer to source block
 109  *              @uint32 d[2]@ = pointer to destination block
 110  *
 111  * Returns:     ---
 112  *
 113  * Use:         Low-level block encryption and decryption.
 114  */
 115
 116 extern void idea_eblk(const idea_ctx */*k*/,
 117                       const uint32 */*s*/, uint32 */*d*/);
 118 extern void idea_dblk(const idea_ctx */*k*/,
 119                       const uint32 */*s*/, uint32 */*d*/);
 120
 121 /*----- That's all, folks -------------------------------------------------*/
 122
 123 #ifdef __cplusplus
 124   }
 125 #endif
 126
 127 #endif