chiark - git - mdw - catacomb/blob - cfb.h

   1 /* -*-c-*-
   2  *
   3  * $Id: cfb.h,v 1.3 2000/06/17 10:50:55 mdw Exp $
   4  *
   5  * Ciphertext 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: cfb.h,v $
  33  * Revision 1.3  2000/06/17 10:50:55  mdw
  34  * Change buffer offset to be unsigned.
  35  *
  36  * Revision 1.2  1999/12/10 23:16:39  mdw
  37  * Split mode macros into interface and implementation.
  38  *
  39  * Revision 1.1  1999/09/03 08:41:11  mdw
  40  * Initial import.
  41  *
  42  */
  43
  44 #ifndef CATACOMB_CFB_H
  45 #define CATACOMB_CFB_H
  46
  47 #ifdef __cplusplus
  48   extern "C" {
  49 #endif
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 #include <stddef.h>
  54
  55 #include <mLib/bits.h>
  56
  57 #ifndef CATACOMB_GCIPHER_H
  58 #  include "gcipher.h"
  59 #endif
  60
  61 /*----- Data structures ---------------------------------------------------*/
  62
  63 /* --- @CFB_DECL@ --- *
  64  *
  65  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  66  *
  67  * Use:         Creates declarations for CFB mode.
  68  */
  69
  70 #define CFB_DECL(PRE, pre)                                              \
  71                                                                         \
  72 /* --- Ciphertext feedback context --- */                               \
  73                                                                         \
  74 typedef struct pre##_cfbctx {                                           \
  75   pre##_ctx ctx;                        /* Underlying cipher context */ \
  76   unsigned off;                         /* Offset into @iv@ buffer */   \
  77   octet iv[PRE##_BLKSZ];                /* Previous ciphertext or IV */ \
  78 } pre##_cfbctx;                                                         \
  79                                                                         \
  80 /* --- @pre_cfbgetiv@ --- *                                             \
  81  *                                                                      \
  82  * Arguments:   @const pre_cfbctx *ctx@ = pointer to CFB context block  \
  83  *              @void *iv#@ = pointer to output data block              \
  84  *                                                                      \
  85  * Returns:     ---                                                     \
  86  *                                                                      \
  87  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  88  *              is not transparent to the cipher.  It will add a `step' \
  89  *              which must be matched by a similar operation during     \
  90  *              decryption.                                             \
  91  */                                                                     \
  92                                                                         \
  93 extern void pre##_cfbgetiv(const pre##_cfbctx */*ctx*/,                 \
  94                            void */*iv*/);                               \
  95                                                                         \
  96 /* --- @pre_cfbsetiv@ --- *                                             \
  97  *                                                                      \
  98  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
  99  *              @cnost void *iv@ = pointer to IV to set                 \
 100  *                                                                      \
 101  * Returns:     ---                                                     \
 102  *                                                                      \
 103  * Use:         Sets the IV to use for subsequent encryption.           \
 104  */                                                                     \
 105                                                                         \
 106 extern void pre##_cfbsetiv(pre##_cfbctx */*ctx*/,                       \
 107                            const void */*iv*/);                         \
 108                                                                         \
 109 /* --- @pre_cfbbdry@ --- *                                              \
 110  *                                                                      \
 111  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 112  *                                                                      \
 113  * Returns:     ---                                                     \
 114  *                                                                      \
 115  * Use:         Inserts a boundary during encryption.  Successful       \
 116  *              decryption must place a similar boundary.               \
 117  */                                                                     \
 118                                                                         \
 119 extern void pre##_cfbbdry(pre##_cfbctx */*ctx*/);                       \
 120                                                                         \
 121 /* --- @pre_cfbsetkey@ --- *                                            \
 122  *                                                                      \
 123  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 124  *              @const pre_ctx *k@ = pointer to cipher context          \
 125  *                                                                      \
 126  * Returns:     ---                                                     \
 127  *                                                                      \
 128  * Use:         Sets the CFB context to use a different cipher key.     \
 129  */                                                                     \
 130                                                                         \
 131 extern void pre##_cfbsetkey(pre##_cfbctx */*ctx*/,                      \
 132                             const pre##_ctx */*k*/);                    \
 133                                                                         \
 134 /* --- @pre_cfbinit@ --- *                                              \
 135  *                                                                      \
 136  * Arguments:   @pre_cfbctx *ctx@ = pointer to cipher context           \
 137  *              @const void *key@ = pointer to the key buffer           \
 138  *              @size_t sz@ = size of the key                           \
 139  *              @const void *iv@ = pointer to initialization vector     \
 140  *                                                                      \
 141  * Returns:     ---                                                     \
 142  *                                                                      \
 143  * Use:         Initializes a CFB context ready for use.  You should    \
 144  *              ensure that the IV chosen is unique: reusing an IV will \
 145  *              compromise the security of at least the first block     \
 146  *              encrypted.  This is equivalent to calls to @pre_init@,  \
 147  *              @pre_cfbsetkey@ and @pre_cfbsetiv@.                     \
 148  */                                                                     \
 149                                                                         \
 150 extern void pre##_cfbinit(pre##_cfbctx */*ctx*/,                        \
 151                           const void */*key*/, size_t /*sz*/,           \
 152                           const void */*iv*/);                          \
 153                                                                         \
 154 /* --- @pre_cfbencrypt@ --- *                                           \
 155  *                                                                      \
 156  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 157  *              @const void *src@ = pointer to source data              \
 158  *              @void *dest@ = pointer to destination data              \
 159  *              @size_t sz@ = size of block to be encrypted             \
 160  *                                                                      \
 161  * Returns:     ---                                                     \
 162  *                                                                      \
 163  * Use:         Encrypts a block with a block cipher in CFB mode.  The  \
 164  *              input block may be arbitrary in size.  CFB mode is not  \
 165  *              sensitive to block boundaries.                          \
 166  */                                                                     \
 167                                                                         \
 168 extern void pre##_cfbencrypt(pre##_cfbctx */*ctx*/,                     \
 169                              const void */*src*/, void */*dest*/,       \
 170                              size_t /*sz*/);                            \
 171                                                                         \
 172 /* --- @pre_cfbencrypt@ --- *                                           \
 173  *                                                                      \
 174  * Arguments:   @pre_cfbctx *ctx@ = pointer to CFB context block        \
 175  *              @const void *src@ = pointer to source data              \
 176  *              @void *dest@ = pointer to destination data              \
 177  *              @size_t sz@ = size of block to be encrypted             \
 178  *                                                                      \
 179  * Returns:     ---                                                     \
 180  *                                                                      \
 181  * Use:         Decrypts a block with a block cipher in CFB mode.  The  \
 182  *              input block may be arbitrary in size.  CFB mode is not  \
 183  *              sensitive to block boundaries.                          \
 184  */                                                                     \
 185                                                                         \
 186 extern void pre##_cfbdecrypt(pre##_cfbctx */*ctx*/,                     \
 187                              const void */*src*/, void */*dest*/,       \
 188                              size_t /*sz*/);                            \
 189                                                                         \
 190 /* --- Generic cipher interface --- */                                  \
 191                                                                         \
 192 extern const gccipher pre##_cfb;
 193
 194 /*----- That's all, folks -------------------------------------------------*/
 195
 196 #ifdef __cplusplus
 197   }
 198 #endif
 199
 200 #endif