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   1 /* -*-c-*-
   2  *
   3  * $Id: xtea.h,v 1.4 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * The Extended 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 /*----- Notes on the Tiny Encryption Algorithm ----------------------------*
  31  *
  32  * XTEA is an amazingly simple 64-round Feistel network.  It's tiny, fairly
  33  * quick and surprisingly strong.  It was invented by David Wheeler and Roger
  34  * Needham.  It's unpatented.  XTEA is a new version of TEA, by the same
  35  * designers, which fixes some weaknesses in TEA's key schedule.
  36  *
  37  * This implementation uses big-endian byte order, following SCAN.
  38  */
  39
  40 #ifndef CATACOMB_XTEA_H
  41 #define CATACOMB_XTEA_H
  42
  43 #ifdef __cplusplus
  44   extern "C" {
  45 #endif
  46
  47 /*----- Header files ------------------------------------------------------*/
  48
  49 #include <stddef.h>
  50
  51 #include <mLib/bits.h>
  52
  53 /*----- Magical numbers ---------------------------------------------------*/
  54
  55 #define XTEA_BLKSZ 8
  56 #define XTEA_KEYSZ 16
  57 #define XTEA_CLASS (N, B, 64)
  58
  59 extern const octet xtea_keysz[];
  60
  61 /*----- Data structures ---------------------------------------------------*/
  62
  63 typedef struct xtea_ctx {
  64   unsigned r;
  65   uint32 k[4];
  66 } xtea_ctx;
  67
  68 /*----- Functions provided ------------------------------------------------*/
  69
  70 /* --- @xtea_init@ --- *
  71  *
  72  * Arguments:   @xtea_ctx *k@ = pointer to key block
  73  *              @const void *buf@ = pointer to key buffer
  74  *              @size_t sz@ = size of key material
  75  *
  76  * Returns:     ---
  77  *
  78  * Use:         Initializes an XTEA key buffer.  The key buffer may be up to
  79  *              16 bytes long.
  80  */
  81
  82 extern void xtea_init(xtea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  83
  84 /* --- @xtea_eblk@, @xtea_dblk@ --- *
  85  *
  86  * Arguments:   @const xtea_ctx *k@ = pointer to key block
  87  *              @const uint32 s[2]@ = pointer to source block
  88  *              @uint32 d[2]@ = pointer to xteatination block
  89  *
  90  * Returns:     ---
  91  *
  92  * Use:         Low-level block encryption and decryption.
  93  */
  94
  95 extern void xtea_eblk(const xtea_ctx */*k*/,
  96                       const uint32 */*s*/, uint32 */*d*/);
  97 extern void xtea_dblk(const xtea_ctx */*k*/,
  98                       const uint32 */*s*/, uint32 */*d*/);
  99
 100 /*----- That's all, folks -------------------------------------------------*/
 101
 102 #ifdef __cplusplus
 103   }
 104 #endif
 105
 106 #endif