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

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