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

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * The Data Encryption Standard
   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 /*----- Notes on the Data Encryption Standard -----------------------------*
  31  *
  32  * Almost twenty years after it was first accepted, DES is still the standard
  33  * block cipher.  It's showing its age in its small key size and poor
  34  * optimiziation for software implementations, but it's not really been badly
  35  * dented by the intensive analysis thrown at it.
  36  *
  37  * This interface is here for compatibility with existing protocols, and
  38  * because it's a trivial veneer over the base DES code which is used by the
  39  * @des3@ interface which implements proper strong triple-DES.
  40  */
  41
  42 #ifndef CATACOMB_DES_H
  43 #define CATACOMB_DES_H
  44
  45 #ifdef __cplusplus
  46   extern "C" {
  47 #endif
  48
  49 /*----- Header files ------------------------------------------------------*/
  50
  51 #include <stddef.h>
  52
  53 #include <mLib/bits.h>
  54
  55 /*----- Magical numbers ---------------------------------------------------*/
  56
  57 #define DES_BLKSZ 8
  58 #define DES_KEYSZ 7
  59 #define DES_CLASS (N, B, 64)
  60
  61 extern const octet des_keysz[];
  62
  63 /*----- Data structures ---------------------------------------------------*/
  64
  65 typedef struct des_ctx {
  66   uint32 k[32];
  67 } des_ctx;
  68
  69 /*----- Functions provided ------------------------------------------------*/
  70
  71 /* --- @des_expand@ --- *
  72  *
  73  * Arguments:   @const octet *k@ = pointer to key material
  74  *              @size_t n@ = number of octets of key material (7 or 8)
  75  *              @uint32 *xx, *yy@ = where to put the results
  76  *
  77  * Returns:     ---
  78  *
  79  * Use:         Extracts 64 bits of key material from the given buffer,
  80  *              possibly expanding it from 56 to 64 bits on the way.
  81  *              Parity is set correctly if the key is expanded.
  82  */
  83
  84 extern void des_expand(const octet */*k*/, size_t /*n*/,
  85                        uint32 */*xx*/, uint32 */*yy*/);
  86
  87 /* --- @des_init@ --- *
  88  *
  89  * Arguments:   @des_ctx *k@ = pointer to key block
  90  *              @const void *buf@ = pointer to key buffer
  91  *              @size_t sz@ = size of key material
  92  *
  93  * Returns:     ---
  94  *
  95  * Use:         Initializes a DES key buffer.  The key buffer may be either 7
  96  *              or 8 bytes long.  If it's 8 bytes, the key is assumed to be
  97  *              padded with parity bits in the low order bit of each octet.
  98  *              These are stripped out without checking prior to the actual
  99  *              key scheduling.
 100  */
 101
 102 extern void des_init(des_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
 103
 104 /* --- @des_eblk@, @des_dblk@ --- *
 105  *
 106  * Arguments:   @const des_ctx *k@ = pointer to key block
 107  *              @const uint32 s[2]@ = pointer to source block
 108  *              @uint32 d[2]@ = pointer to destination block
 109  *
 110  * Returns:     ---
 111  *
 112  * Use:         Low-level block encryption and decryption.
 113  */
 114
 115 extern void des_eblk(const des_ctx */*k*/,
 116                      const uint32 */*s*/, uint32 */*d*/);
 117 extern void des_dblk(const des_ctx */*k*/,
 118                      const uint32 */*s*/, uint32 */*d*/);
 119
 120 /*----- That's all, folks -------------------------------------------------*/
 121
 122 #ifdef __cplusplus
 123   }
 124 #endif
 125
 126 #endif