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

   1 /* -*-c-*-
   2  *
   3  * $Id: ofb.h,v 1.2 1999/12/10 23:16:40 mdw Exp $
   4  *
   5  * Output feedback for block ciphers
   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 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: ofb.h,v $
  33  * Revision 1.2  1999/12/10 23:16:40  mdw
  34  * Split mode macros into interface and implementation.
  35  *
  36  * Revision 1.1  1999/09/03 08:41:12  mdw
  37  * Initial import.
  38  *
  39  */
  40
  41 #ifndef CATACOMB_OFB_H
  42 #define CATACOMB_OFB_H
  43
  44 #ifdef __cplusplus
  45   extern "C" {
  46 #endif
  47
  48 /*----- Header files ------------------------------------------------------*/
  49
  50 #include <stddef.h>
  51
  52 #include <mLib/bits.h>
  53
  54 #ifndef CATACOMB_GCIPHER_H
  55 #  include "gcipher.h"
  56 #endif
  57
  58 #ifndef CATACOMB_GRAND_H
  59 #  include "grand.h"
  60 #endif
  61
  62 /*----- Macros ------------------------------------------------------------*/
  63
  64 /* --- @OFB_DECL@ --- *
  65  *
  66  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
  67  *
  68  * Use:         Makes declarations for output feedback mode.
  69  */
  70
  71 #define OFB_DECL(PRE, pre)                                              \
  72                                                                         \
  73 /* --- Output feedback context --- */                                   \
  74                                                                         \
  75 typedef struct pre##_ofbctx {                                           \
  76   pre##_ctx ctx;                        /* Underlying cipher context */ \
  77   int off;                              /* Current offset in buffer */  \
  78   octet iv[PRE##_BLKSZ];                /* Output buffer and IV */      \
  79 } pre##_ofbctx;                                                         \
  80                                                                         \
  81 /* --- @pre_ofbgetiv@ --- *                                             \
  82  *                                                                      \
  83  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  84  *              @void *iv#@ = pointer to output data block              \
  85  *                                                                      \
  86  * Returns:     ---                                                     \
  87  *                                                                      \
  88  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  89  *              is not transparent to the cipher.  It will add a `step' \
  90  *              which must be matched by a similar operation during     \
  91  *              decryption.                                             \
  92  */                                                                     \
  93                                                                         \
  94 extern void pre##_ofbgetiv(const pre##_ofbctx */*ctx*/,                 \
  95                            void */*iv*/);                               \
  96                                                                         \
  97 /* --- @pre_ofbsetiv@ --- *                                             \
  98  *                                                                      \
  99  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 100  *              @cnost void *iv@ = pointer to IV to set                 \
 101  *                                                                      \
 102  * Returns:     ---                                                     \
 103  *                                                                      \
 104  * Use:         Sets the IV to use for subsequent encryption.           \
 105  */                                                                     \
 106                                                                         \
 107 extern void pre##_ofbsetiv(pre##_ofbctx */*ctx*/,                       \
 108                            const void */*iv*/);                         \
 109                                                                         \
 110 /* --- @pre_ofbbdry@ --- *                                              \
 111  *                                                                      \
 112  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 113  *                                                                      \
 114  * Returns:     ---                                                     \
 115  *                                                                      \
 116  * Use:         Inserts a boundary during encryption.  Successful       \
 117  *              decryption must place a similar boundary.               \
 118  */                                                                     \
 119                                                                         \
 120 extern void pre##_ofbbdry(pre##_ofbctx */*ctx*/);                       \
 121                                                                         \
 122 /* --- @pre_ofbsetkey@ --- *                                            \
 123  *                                                                      \
 124  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 125  *              @const pre_ctx *k@ = pointer to cipher context          \
 126  *                                                                      \
 127  * Returns:     ---                                                     \
 128  *                                                                      \
 129  * Use:         Sets the OFB context to use a different cipher key.     \
 130  */                                                                     \
 131                                                                         \
 132 extern void pre##_ofbsetkey(pre##_ofbctx */*ctx*/,                      \
 133                             const pre##_ctx */*k*/);                    \
 134                                                                         \
 135 /* --- @pre_ofbinit@ --- *                                              \
 136  *                                                                      \
 137  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 138  *              @const void *key@ = pointer to the key buffer           \
 139  *              @size_t sz@ = size of the key                           \
 140  *              @const void *iv@ = pointer to initialization vector     \
 141  *                                                                      \
 142  * Returns:     ---                                                     \
 143  *                                                                      \
 144  * Use:         Initializes a OFB context ready for use.  You should    \
 145  *              ensure that the IV chosen is unique: reusing an IV will \
 146  *              compromise the security of the entire plaintext.  This  \
 147  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 148  *              and @pre_ofbsetiv@.                                     \
 149  */                                                                     \
 150                                                                         \
 151 extern void pre##_ofbinit(pre##_ofbctx */*ctx*/,                        \
 152                           const void */*key*/, size_t /*sz*/,           \
 153                           const void */*iv*/);                          \
 154                                                                         \
 155 /* --- @pre_ofbencrypt@ --- *                                           \
 156  *                                                                      \
 157  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 158  *              @const void *src@ = pointer to source data              \
 159  *              @void *dest@ = pointer to destination data              \
 160  *              @size_t sz@ = size of block to be encrypted             \
 161  *                                                                      \
 162  * Returns:     ---                                                     \
 163  *                                                                      \
 164  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 165  *              mode: encryption and decryption are the same in OFB.    \
 166  *              The destination may be null to just churn the feedback  \
 167  *              round for a bit.  The source may be null to use the     \
 168  *              cipher as a random data generator.                      \
 169  */                                                                     \
 170                                                                         \
 171 extern void pre##_ofbencrypt(pre##_ofbctx */*ctx*/,                     \
 172                              const void */*src*/, void */*dest*/,       \
 173                              size_t /*sz*/);                            \
 174                                                                         \
 175 /* --- @pre_ofbrand@ --- *                                              \
 176  *                                                                      \
 177  * Arguments:   @const void *k@ = pointer to key material               \
 178  *              @size_t sz@ = size of key material                      \
 179  *                                                                      \
 180  * Returns:     Pointer to generic random number generator interface.   \
 181  *                                                                      \
 182  * Use:         Creates a random number interface wrapper around an     \
 183  *              OFB-mode block cipher.                                  \
 184  */                                                                     \
 185                                                                         \
 186 extern grand *pre##_ofbrand(const void */*k*/, size_t /*sz*/);          \
 187                                                                         \
 188 /* --- Generic cipher interface --- */                                  \
 189                                                                         \
 190 extern const gccipher pre##_ofb;
 191
 192 /*----- That's all, folks -------------------------------------------------*/
 193
 194 #ifdef __cplusplus
 195   }
 196 #endif
 197
 198 #endif