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   1 /* -*-c-*-
   2  *
   3  * $Id: xtea.h,v 1.3 2000/07/29 09:56:47 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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: xtea.h,v $
  33  * Revision 1.3  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 1.2  2000/07/15 13:47:14  mdw
  38  * Whoops.  Fix the purpose comment.
  39  *
  40  * Revision 1.1  2000/07/15 13:44:31  mdw
  41  * New ciphers.
  42  *
  43  */
  44
  45 /*----- Notes on the Tiny Encryption Algorithm ----------------------------*
  46  *
  47  * XTEA is an amazingly simple 64-round Feistel network.  It's tiny, fairly
  48  * quick and surprisingly strong.  It was invented by David Wheeler and Roger
  49  * Needham.  It's unpatented.  XTEA is a new version of TEA, by the same
  50  * designers, which fixes some weaknesses in TEA's key schedule.
  51  *
  52  * This implementation uses big-endian byte order, following SCAN.
  53  */
  54
  55 #ifndef CATACOMB_XTEA_H
  56 #define CATACOMB_XTEA_H
  57
  58 #ifdef __cplusplus
  59   extern "C" {
  60 #endif
  61
  62 /*----- Header files ------------------------------------------------------*/
  63
  64 #include <stddef.h>
  65
  66 #include <mLib/bits.h>
  67
  68 /*----- Magical numbers ---------------------------------------------------*/
  69
  70 #define XTEA_BLKSZ 8
  71 #define XTEA_KEYSZ 16
  72 #define XTEA_CLASS (N, B, 64)
  73
  74 extern const octet xtea_keysz[];
  75
  76 /*----- Data structures ---------------------------------------------------*/
  77
  78 typedef struct xtea_ctx {
  79   unsigned r;
  80   uint32 k[4];
  81 } xtea_ctx;
  82
  83 /*----- Functions provided ------------------------------------------------*/
  84
  85 /* --- @xtea_init@ --- *
  86  *
  87  * Arguments:   @xtea_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 XTEA key buffer.  The key buffer may be up to
  94  *              16 bytes long.
  95  */
  96
  97 extern void xtea_init(xtea_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
  98
  99 /* --- @xtea_eblk@, @xtea_dblk@ --- *
 100  *
 101  * Arguments:   @const xtea_ctx *k@ = pointer to key block
 102  *              @const uint32 s[2]@ = pointer to source block
 103  *              @uint32 d[2]@ = pointer to xteatination block
 104  *
 105  * Returns:     ---
 106  *
 107  * Use:         Low-level block encryption and decryption.
 108  */
 109
 110 extern void xtea_eblk(const xtea_ctx */*k*/,
 111                       const uint32 */*s*/, uint32 */*d*/);
 112 extern void xtea_dblk(const xtea_ctx */*k*/,
 113                       const uint32 */*s*/, uint32 */*d*/);
 114
 115 /*----- That's all, folks -------------------------------------------------*/
 116
 117 #ifdef __cplusplus
 118   }
 119 #endif
 120
 121 #endif