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   1 /* -*-c-*-
   2  *
   3  * $Id: ofb.h,v 1.4 2001/06/17 00:10:51 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 1.4  2001/06/17 00:10:51  mdw
  34  * Typesetting fixes
  35  *
  36  * Revision 1.3  2000/06/17 11:48:24  mdw
  37  * Change buffer offset to be unsigned.
  38  *
  39  * Revision 1.2  1999/12/10 23:16:40  mdw
  40  * Split mode macros into interface and implementation.
  41  *
  42  * Revision 1.1  1999/09/03 08:41:12  mdw
  43  * Initial import.
  44  *
  45  */
  46
  47 #ifndef CATACOMB_OFB_H
  48 #define CATACOMB_OFB_H
  49
  50 #ifdef __cplusplus
  51   extern "C" {
  52 #endif
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #include <stddef.h>
  57
  58 #include <mLib/bits.h>
  59
  60 #ifndef CATACOMB_GCIPHER_H
  61 #  include "gcipher.h"
  62 #endif
  63
  64 #ifndef CATACOMB_GRAND_H
  65 #  include "grand.h"
  66 #endif
  67
  68 /*----- Macros ------------------------------------------------------------*/
  69
  70 /* --- @OFB_DECL@ --- *
  71  *
  72  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
  73  *
  74  * Use:         Makes declarations for output feedback mode.
  75  */
  76
  77 #define OFB_DECL(PRE, pre)                                              \
  78                                                                         \
  79 /* --- Output feedback context --- */                                   \
  80                                                                         \
  81 typedef struct pre##_ofbctx {                                           \
  82   pre##_ctx ctx;                        /* Underlying cipher context */ \
  83   unsigned off;                         /* Current offset in buffer */  \
  84   octet iv[PRE##_BLKSZ];                /* Output buffer and IV */      \
  85 } pre##_ofbctx;                                                         \
  86                                                                         \
  87 /* --- @pre_ofbgetiv@ --- *                                             \
  88  *                                                                      \
  89  * Arguments:   @const pre_ofbctx *ctx@ = pointer to OFB context block  \
  90  *              @void *iv@ = pointer to output data block               \
  91  *                                                                      \
  92  * Returns:     ---                                                     \
  93  *                                                                      \
  94  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  95  *              is not transparent to the cipher.  It will add a `step' \
  96  *              which must be matched by a similar operation during     \
  97  *              decryption.                                             \
  98  */                                                                     \
  99                                                                         \
 100 extern void pre##_ofbgetiv(const pre##_ofbctx */*ctx*/,                 \
 101                            void */*iv*/);                               \
 102                                                                         \
 103 /* --- @pre_ofbsetiv@ --- *                                             \
 104  *                                                                      \
 105  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 106  *              @cnost void *iv@ = pointer to IV to set                 \
 107  *                                                                      \
 108  * Returns:     ---                                                     \
 109  *                                                                      \
 110  * Use:         Sets the IV to use for subsequent encryption.           \
 111  */                                                                     \
 112                                                                         \
 113 extern void pre##_ofbsetiv(pre##_ofbctx */*ctx*/,                       \
 114                            const void */*iv*/);                         \
 115                                                                         \
 116 /* --- @pre_ofbbdry@ --- *                                              \
 117  *                                                                      \
 118  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 119  *                                                                      \
 120  * Returns:     ---                                                     \
 121  *                                                                      \
 122  * Use:         Inserts a boundary during encryption.  Successful       \
 123  *              decryption must place a similar boundary.               \
 124  */                                                                     \
 125                                                                         \
 126 extern void pre##_ofbbdry(pre##_ofbctx */*ctx*/);                       \
 127                                                                         \
 128 /* --- @pre_ofbsetkey@ --- *                                            \
 129  *                                                                      \
 130  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 131  *              @const pre_ctx *k@ = pointer to cipher context          \
 132  *                                                                      \
 133  * Returns:     ---                                                     \
 134  *                                                                      \
 135  * Use:         Sets the OFB context to use a different cipher key.     \
 136  */                                                                     \
 137                                                                         \
 138 extern void pre##_ofbsetkey(pre##_ofbctx */*ctx*/,                      \
 139                             const pre##_ctx */*k*/);                    \
 140                                                                         \
 141 /* --- @pre_ofbinit@ --- *                                              \
 142  *                                                                      \
 143  * Arguments:   @pre_ofbctx *ctx@ = pointer to cipher context           \
 144  *              @const void *key@ = pointer to the key buffer           \
 145  *              @size_t sz@ = size of the key                           \
 146  *              @const void *iv@ = pointer to initialization vector     \
 147  *                                                                      \
 148  * Returns:     ---                                                     \
 149  *                                                                      \
 150  * Use:         Initializes a OFB context ready for use.  You should    \
 151  *              ensure that the IV chosen is unique: reusing an IV will \
 152  *              compromise the security of the entire plaintext.  This  \
 153  *              is equivalent to calls to @pre_init@, @pre_ofbsetkey@   \
 154  *              and @pre_ofbsetiv@.                                     \
 155  */                                                                     \
 156                                                                         \
 157 extern void pre##_ofbinit(pre##_ofbctx */*ctx*/,                        \
 158                           const void */*key*/, size_t /*sz*/,           \
 159                           const void */*iv*/);                          \
 160                                                                         \
 161 /* --- @pre_ofbencrypt@ --- *                                           \
 162  *                                                                      \
 163  * Arguments:   @pre_ofbctx *ctx@ = pointer to OFB context block        \
 164  *              @const void *src@ = pointer to source data              \
 165  *              @void *dest@ = pointer to destination data              \
 166  *              @size_t sz@ = size of block to be encrypted             \
 167  *                                                                      \
 168  * Returns:     ---                                                     \
 169  *                                                                      \
 170  * Use:         Encrypts or decrypts a block with a block cipher in OFB \
 171  *              mode: encryption and decryption are the same in OFB.    \
 172  *              The destination may be null to just churn the feedback  \
 173  *              round for a bit.  The source may be null to use the     \
 174  *              cipher as a random data generator.                      \
 175  */                                                                     \
 176                                                                         \
 177 extern void pre##_ofbencrypt(pre##_ofbctx */*ctx*/,                     \
 178                              const void */*src*/, void */*dest*/,       \
 179                              size_t /*sz*/);                            \
 180                                                                         \
 181 /* --- @pre_ofbrand@ --- *                                              \
 182  *                                                                      \
 183  * Arguments:   @const void *k@ = pointer to key material               \
 184  *              @size_t sz@ = size of key material                      \
 185  *                                                                      \
 186  * Returns:     Pointer to generic random number generator interface.   \
 187  *                                                                      \
 188  * Use:         Creates a random number interface wrapper around an     \
 189  *              OFB-mode block cipher.                                  \
 190  */                                                                     \
 191                                                                         \
 192 extern grand *pre##_ofbrand(const void */*k*/, size_t /*sz*/);          \
 193                                                                         \
 194 /* --- Generic cipher interface --- */                                  \
 195                                                                         \
 196 extern const gccipher pre##_ofb;
 197
 198 /*----- That's all, folks -------------------------------------------------*/
 199
 200 #ifdef __cplusplus
 201   }
 202 #endif
 203
 204 #endif