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

   1 /* -*-c-*-
   2  *
   3  * The Data Encryption Standard
   4  *
   5  * (c) 1999 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 Data Encryption Standard -----------------------------*
  29  *
  30  * Almost twenty years after it was first accepted, DES is still the standard
  31  * block cipher.  It's showing its age in its small key size and poor
  32  * optimiziation for software implementations, but it's not really been badly
  33  * dented by the intensive analysis thrown at it.
  34  *
  35  * This interface is here for compatibility with existing protocols, and
  36  * because it's a trivial veneer over the base DES code which is used by the
  37  * @des3@ interface which implements proper strong triple-DES.
  38  */
  39
  40 #ifndef CATACOMB_DES_H
  41 #define CATACOMB_DES_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 DES_BLKSZ 8
  56 #define DES_KEYSZ 7
  57 #define DES_CLASS (N, B, 64)
  58
  59 extern const octet des_keysz[];
  60
  61 /*----- Data structures ---------------------------------------------------*/
  62
  63 typedef struct des_ctx {
  64   uint32 k[32];
  65 } des_ctx;
  66
  67 /*----- Functions provided ------------------------------------------------*/
  68
  69 /* --- @des_expand@ --- *
  70  *
  71  * Arguments:   @const octet *k@ = pointer to key material
  72  *              @size_t n@ = number of octets of key material (7 or 8)
  73  *              @uint32 *xx, *yy@ = where to put the results
  74  *
  75  * Returns:     ---
  76  *
  77  * Use:         Extracts 64 bits of key material from the given buffer,
  78  *              possibly expanding it from 56 to 64 bits on the way.
  79  *              Parity is set correctly if the key is expanded.
  80  */
  81
  82 extern void des_expand(const octet */*k*/, size_t /*n*/,
  83                        uint32 */*xx*/, uint32 */*yy*/);
  84
  85 /* --- @des_init@ --- *
  86  *
  87  * Arguments:   @des_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 a DES key buffer.  The key buffer may be either 7
  94  *              or 8 bytes long.  If it's 8 bytes, the key is assumed to be
  95  *              padded with parity bits in the low order bit of each octet.
  96  *              These are stripped out without checking prior to the actual
  97  *              key scheduling.
  98  */
  99
 100 extern void des_init(des_ctx */*k*/, const void */*buf*/, size_t /*sz*/);
 101
 102 /* --- @des_eblk@, @des_dblk@ --- *
 103  *
 104  * Arguments:   @const des_ctx *k@ = pointer to key block
 105  *              @const uint32 s[2]@ = pointer to source block
 106  *              @uint32 d[2]@ = pointer to destination block
 107  *
 108  * Returns:     ---
 109  *
 110  * Use:         Low-level block encryption and decryption.
 111  */
 112
 113 extern void des_eblk(const des_ctx */*k*/,
 114                      const uint32 */*s*/, uint32 */*d*/);
 115 extern void des_dblk(const des_ctx */*k*/,
 116                      const uint32 */*s*/, uint32 */*d*/);
 117
 118 /*----- That's all, folks -------------------------------------------------*/
 119
 120 #ifdef __cplusplus
 121   }
 122 #endif
 123
 124 #endif