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

   1 /* -*-c-*-
   2  *
   3  * The Tiny Encryption Algorithm
   4  *
   5  * (c) 2000 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 Tiny Encryption Algorithm ----------------------------*
  29  *
  30  * TEA is an amazingly simple 64-round Feistel network.  It's tiny, fairly
  31  * quick and surprisingly strong.  It was invented by David Wheeler and Roger
  32  * Needham.  It's unpatented.  The keyspace is has only 126 effective bits,
  33  * and there are related-key attacks.  If you want these fixed, use XTEA.
  34  *
  35  * This implementation uses big-endian byte order, following SCAN.
  36  */
  37
  38 #ifndef CATACOMB_TEA_H
  39 #define CATACOMB_TEA_H
  40
  41 #ifdef __cplusplus
  42   extern "C" {
  43 #endif
  44
  45 /*----- Header files ------------------------------------------------------*/
  46
  47 #include <stddef.h>
  48
  49 #include <mLib/bits.h>
  50
  51 /*----- Magical numbers ---------------------------------------------------*/
  52
  53 #define TEA_BLKSZ 8
  54 #define TEA_KEYSZ 16
  55 #define TEA_CLASS (N, B, 64)
  56
  57 extern const octet tea_keysz[];
  58
  59 /*----- Data structures ---------------------------------------------------*/
  60
  61 typedef struct tea_ctx {
  62   unsigned r;
  63   uint32 ka, kb, kc, kd;
  64 } tea_ctx;
  65
  66 /*----- Functions provided ------------------------------------------------*/
  67
  68 /* --- @tea_init@ --- *
  69  *
  70  * Arguments:   @tea_ctx *k@ = pointer to key block
  71  *              @const void *buf@ = pointer to key buffer
  72  *              @size_t sz@ = size of key material
  73  *
  74  * Returns:     ---
  75  *
  76  * Use:         Initializes a TEA key buffer.  The key buffer may be up to 16
  77  *              bytes long.
  78  */
  79
  80 extern void tea_init(tea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  81
  82 /* --- @tea_eblk@, @tea_dblk@ --- *
  83  *
  84  * Arguments:   @const tea_ctx *k@ = pointer to key block
  85  *              @const uint32 s[2]@ = pointer to source block
  86  *              @uint32 d[2]@ = pointer to teatination block
  87  *
  88  * Returns:     ---
  89  *
  90  * Use:         Low-level block encryption and decryption.
  91  */
  92
  93 extern void tea_eblk(const tea_ctx */*k*/,
  94                      const uint32 */*s*/, uint32 */*d*/);
  95 extern void tea_dblk(const tea_ctx */*k*/,
  96                      const uint32 */*s*/, uint32 */*d*/);
  97
  98 /*----- That's all, folks -------------------------------------------------*/
  99
 100 #ifdef __cplusplus
 101   }
 102 #endif
 103
 104 #endif