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   1 /* -*-c-*-
   2  *
   3  * $Id: tea.h,v 1.2 2000/07/29 09:56:47 mdw Exp $
   4  *
   5  * The Tiny Encryption Algorithm
   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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: tea.h,v $
  33  * Revision 1.2  2000/07/29 09:56:47  mdw
  34  * Allow the number of rounds to be configured.  This isn't exported
  35  * through the gcipher interface, but it may be useful anyway.
  36  *
  37  * Revision 1.1  2000/07/15 13:44:31  mdw
  38  * New ciphers.
  39  *
  40  */
  41
  42 /*----- Notes on the Tiny Encryption Algorithm ----------------------------*
  43  *
  44  * TEA is an amazingly simple 64-round Feistel network.  It's tiny, fairly
  45  * quick and surprisingly strong.  It was invented by David Wheeler and Roger
  46  * Needham.  It's unpatented.  The keyspace is has only 126 effective bits,
  47  * and there are related-key attacks.  If you want these fixed, use XTEA.
  48  *
  49  * This implementation uses big-endian byte order, following SCAN.
  50  */
  51
  52 #ifndef CATACOMB_TEA_H
  53 #define CATACOMB_TEA_H
  54
  55 #ifdef __cplusplus
  56   extern "C" {
  57 #endif
  58
  59 /*----- Header files ------------------------------------------------------*/
  60
  61 #include <stddef.h>
  62
  63 #include <mLib/bits.h>
  64
  65 /*----- Magical numbers ---------------------------------------------------*/
  66
  67 #define TEA_BLKSZ 8
  68 #define TEA_KEYSZ 16
  69 #define TEA_CLASS (N, B, 64)
  70
  71 extern const octet tea_keysz[];
  72
  73 /*----- Data structures ---------------------------------------------------*/
  74
  75 typedef struct tea_ctx {
  76   unsigned r;
  77   uint32 ka, kb, kc, kd;
  78 } tea_ctx;
  79
  80 /*----- Functions provided ------------------------------------------------*/
  81
  82 /* --- @tea_init@ --- *
  83  *
  84  * Arguments:   @tea_ctx *k@ = pointer to key block
  85  *              @const void *buf@ = pointer to key buffer
  86  *              @size_t sz@ = size of key material
  87  *
  88  * Returns:     ---
  89  *
  90  * Use:         Initializes a TEA key buffer.  The key buffer may be up to 16
  91  *              bytes long.
  92  */
  93
  94 extern void tea_init(tea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  95
  96 /* --- @tea_eblk@, @tea_dblk@ --- *
  97  *
  98  * Arguments:   @const tea_ctx *k@ = pointer to key block
  99  *              @const uint32 s[2]@ = pointer to source block
 100  *              @uint32 d[2]@ = pointer to teatination block
 101  *
 102  * Returns:     ---
 103  *
 104  * Use:         Low-level block encryption and decryption.
 105  */
 106
 107 extern void tea_eblk(const tea_ctx */*k*/,
 108                      const uint32 */*s*/, uint32 */*d*/);
 109 extern void tea_dblk(const tea_ctx */*k*/,
 110                      const uint32 */*s*/, uint32 */*d*/);
 111
 112 /*----- That's all, folks -------------------------------------------------*/
 113
 114 #ifdef __cplusplus
 115   }
 116 #endif
 117
 118 #endif