chiark - git - mdw - catacomb/blob - symm/cbc.h

   1 /* -*-c-*-
   2  *
   3  * Ciphertext block chaining for block ciphers
   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 #ifndef CATACOMB_CBC_H
  29 #define CATACOMB_CBC_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Header files ------------------------------------------------------*/
  36
  37 #include <stddef.h>
  38
  39 #include <mLib/bits.h>
  40
  41 #ifndef CATACOMB_GCIPHER_H
  42 #  include "gcipher.h"
  43 #endif
  44
  45 /*----- Macros ------------------------------------------------------------*/
  46
  47 /* --- @CBC_DECL@ --- *
  48  *
  49  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  50  *
  51  * Use:         Creates declarations for CBC stealing mode.
  52  */
  53
  54 #define CBC_DECL(PRE, pre)                                              \
  55                                                                         \
  56 /* --- Cipher block chaining context --- */                             \
  57                                                                         \
  58 typedef struct pre##_cbcctx {                                           \
  59   pre##_ctx ctx;                        /* Underlying cipher context */ \
  60   uint32 iv[PRE##_BLKSZ / 4];           /* Previous ciphertext or IV */ \
  61 } pre##_cbcctx;                                                         \
  62                                                                         \
  63 /* --- @pre_cbcgetiv@ --- *                                             \
  64  *                                                                      \
  65  * Arguments:   @const pre_cbcctx *ctx@ = pointer to CBC context block  \
  66  *              @void *iv@ = pointer to output data block               \
  67  *                                                                      \
  68  * Returns:     ---                                                     \
  69  *                                                                      \
  70  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  71  *              is transparent to the CBC encryption or decryption      \
  72  *              process.                                                \
  73  */                                                                     \
  74                                                                         \
  75 extern void pre##_cbcgetiv(const pre##_cbcctx */*ctx*/,                 \
  76                            void */*iv*/);                               \
  77                                                                         \
  78 /* --- @pre_cbcsetiv@ --- *                                             \
  79  *                                                                      \
  80  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
  81  *              @cnost void *iv@ = pointer to IV to set                 \
  82  *                                                                      \
  83  * Returns:     ---                                                     \
  84  *                                                                      \
  85  * Use:         Sets the IV to use for subsequent encryption.           \
  86  */                                                                     \
  87                                                                         \
  88 extern void pre##_cbcsetiv(pre##_cbcctx */*ctx*/,                       \
  89                            const void */*iv*/);                         \
  90                                                                         \
  91 /* --- @pre_cbcsetkey@ --- *                                            \
  92  *                                                                      \
  93  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
  94  *              @const pre_ctx *k@ = pointer to cipher context          \
  95  *                                                                      \
  96  * Returns:     ---                                                     \
  97  *                                                                      \
  98  * Use:         Sets the CBC context to use a different cipher key.     \
  99  */                                                                     \
 100                                                                         \
 101 extern void pre##_cbcsetkey(pre##_cbcctx */*ctx*/,                      \
 102                             const pre##_ctx */*k*/);                    \
 103                                                                         \
 104 /* --- @pre_cbcinit@ --- *                                              \
 105  *                                                                      \
 106  * Arguments:   @pre_cbcctx *ctx@ = pointer to cipher context           \
 107  *              @const void *key@ = pointer to the key buffer           \
 108  *              @size_t sz@ = size of the key                           \
 109  *              @const void *iv@ = pointer to initialization vector     \
 110  *                                                                      \
 111  * Returns:     ---                                                     \
 112  *                                                                      \
 113  * Use:         Initializes a CBC context ready for use.  The @iv@      \
 114  *              argument may be passed as a null pointer to set a zero  \
 115  *              IV.  Apart from that, this call is equivalent to calls  \
 116  *              to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@.      \
 117  */                                                                     \
 118                                                                         \
 119 extern void pre##_cbcinit(pre##_cbcctx */*ctx*/,                        \
 120                           const void */*key*/, size_t /*sz*/,           \
 121                           const void */*iv*/);                          \
 122                                                                         \
 123 /* --- @pre_cbcencrypt@ --- *                                           \
 124  *                                                                      \
 125  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
 126  *              @const void *src@ = pointer to source data              \
 127  *              @void *dest@ = pointer to destination data              \
 128  *              @size_t sz@ = size of block to be encrypted             \
 129  *                                                                      \
 130  * Returns:     ---                                                     \
 131  *                                                                      \
 132  * Use:         Encrypts a block with a block cipher in CBC mode, with  \
 133  *              ciphertext stealing and other clever tricks.            \
 134  *              Essentially, data can be encrypted in arbitrary sized   \
 135  *              chunks, although decryption must use the same chunks.   \
 136  */                                                                     \
 137                                                                         \
 138 extern void pre##_cbcencrypt(pre##_cbcctx */*ctx*/,                     \
 139                              const void */*src*/, void */*dest*/,       \
 140                              size_t /*sz*/);                            \
 141                                                                         \
 142 /* --- @pre_cbcdecrypt@ --- *                                           \
 143  *                                                                      \
 144  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
 145  *              @const void *src@ = pointer to source data              \
 146  *              @void *dest@ = pointer to destination data              \
 147  *              @size_t sz@ = size of block to be encrypted             \
 148  *                                                                      \
 149  * Returns:     ---                                                     \
 150  *                                                                      \
 151  * Use:         Decrypts a block with a block cipher in CBC mode, with  \
 152  *              ciphertext stealing and other clever tricks.            \
 153  *              Essentially, data can be encrypted in arbitrary sized   \
 154  *              chunks, although decryption must use the same chunks.   \
 155  */                                                                     \
 156                                                                         \
 157 extern void pre##_cbcdecrypt(pre##_cbcctx */*ctx*/,                     \
 158                              const void */*src*/, void */*dest*/,       \
 159                              size_t /*sz*/);                            \
 160                                                                         \
 161 /* --- Generic cipher interface --- */                                  \
 162                                                                         \
 163 extern const gccipher pre##_cbc;
 164
 165 /*----- That's all, folks -------------------------------------------------*/
 166
 167 #ifdef __cplusplus
 168   }
 169 #endif
 170
 171 #endif