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

   1 /* -*-c-*-
   2  *
   3  * $Id: cbc.h,v 1.4 2004/04/08 01:36:15 mdw Exp $
   4  *
   5  * Ciphertext block chaining 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 #ifndef CATACOMB_CBC_H
  31 #define CATACOMB_CBC_H
  32
  33 #ifdef __cplusplus
  34   extern "C" {
  35 #endif
  36
  37 /*----- Header files ------------------------------------------------------*/
  38
  39 #include <stddef.h>
  40
  41 #include <mLib/bits.h>
  42
  43 #ifndef CATACOMB_GCIPHER_H
  44 #  include "gcipher.h"
  45 #endif
  46
  47 /*----- Macros ------------------------------------------------------------*/
  48
  49 /* --- @CBC_DECL@ --- *
  50  *
  51  * Arguments:   @PRE@, @pre@ = prefixes for the underlying block cipher
  52  *
  53  * Use:         Creates declarations for CBC stealing mode.
  54  */
  55
  56 #define CBC_DECL(PRE, pre)                                              \
  57                                                                         \
  58 /* --- Cipher block chaining context --- */                             \
  59                                                                         \
  60 typedef struct pre##_cbcctx {                                           \
  61   pre##_ctx ctx;                        /* Underlying cipher context */ \
  62   uint32 iv[PRE##_BLKSZ / 4];           /* Previous ciphertext or IV */ \
  63 } pre##_cbcctx;                                                         \
  64                                                                         \
  65 /* --- @pre_cbcgetiv@ --- *                                             \
  66  *                                                                      \
  67  * Arguments:   @const pre_cbcctx *ctx@ = pointer to CBC context block  \
  68  *              @void *iv@ = pointer to output data block               \
  69  *                                                                      \
  70  * Returns:     ---                                                     \
  71  *                                                                      \
  72  * Use:         Reads the currently set IV.  Reading and setting an IV  \
  73  *              is transparent to the CBC encryption or decryption      \
  74  *              process.                                                \
  75  */                                                                     \
  76                                                                         \
  77 extern void pre##_cbcgetiv(const pre##_cbcctx */*ctx*/,                 \
  78                            void */*iv*/);                               \
  79                                                                         \
  80 /* --- @pre_cbcsetiv@ --- *                                             \
  81  *                                                                      \
  82  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
  83  *              @cnost void *iv@ = pointer to IV to set                 \
  84  *                                                                      \
  85  * Returns:     ---                                                     \
  86  *                                                                      \
  87  * Use:         Sets the IV to use for subsequent encryption.           \
  88  */                                                                     \
  89                                                                         \
  90 extern void pre##_cbcsetiv(pre##_cbcctx */*ctx*/,                       \
  91                            const void */*iv*/);                         \
  92                                                                         \
  93 /* --- @pre_cbcsetkey@ --- *                                            \
  94  *                                                                      \
  95  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
  96  *              @const pre_ctx *k@ = pointer to cipher context          \
  97  *                                                                      \
  98  * Returns:     ---                                                     \
  99  *                                                                      \
 100  * Use:         Sets the CBC context to use a different cipher key.     \
 101  */                                                                     \
 102                                                                         \
 103 extern void pre##_cbcsetkey(pre##_cbcctx */*ctx*/,                      \
 104                             const pre##_ctx */*k*/);                    \
 105                                                                         \
 106 /* --- @pre_cbcinit@ --- *                                              \
 107  *                                                                      \
 108  * Arguments:   @pre_cbcctx *ctx@ = pointer to cipher context           \
 109  *              @const void *key@ = pointer to the key buffer           \
 110  *              @size_t sz@ = size of the key                           \
 111  *              @const void *iv@ = pointer to initialization vector     \
 112  *                                                                      \
 113  * Returns:     ---                                                     \
 114  *                                                                      \
 115  * Use:         Initializes a CBC context ready for use.  The @iv@      \
 116  *              argument may be passed as a null pointer to set a zero  \
 117  *              IV.  Apart from that, this call is equivalent to calls  \
 118  *              to @pre_init@, @pre_cbcsetkey@ and @pre_cbcsetiv@.      \
 119  */                                                                     \
 120                                                                         \
 121 extern void pre##_cbcinit(pre##_cbcctx */*ctx*/,                        \
 122                           const void */*key*/, size_t /*sz*/,           \
 123                           const void */*iv*/);                          \
 124                                                                         \
 125 /* --- @pre_cbcencrypt@ --- *                                           \
 126  *                                                                      \
 127  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
 128  *              @const void *src@ = pointer to source data              \
 129  *              @void *dest@ = pointer to destination data              \
 130  *              @size_t sz@ = size of block to be encrypted             \
 131  *                                                                      \
 132  * Returns:     ---                                                     \
 133  *                                                                      \
 134  * Use:         Encrypts a block with a block cipher in CBC mode, with  \
 135  *              ciphertext stealing and other clever tricks.            \
 136  *              Essentially, data can be encrypted in arbitrary sized   \
 137  *              chunks, although decryption must use the same chunks.   \
 138  */                                                                     \
 139                                                                         \
 140 extern void pre##_cbcencrypt(pre##_cbcctx */*ctx*/,                     \
 141                              const void */*src*/, void */*dest*/,       \
 142                              size_t /*sz*/);                            \
 143                                                                         \
 144 /* --- @pre_cbcdecrypt@ --- *                                           \
 145  *                                                                      \
 146  * Arguments:   @pre_cbcctx *ctx@ = pointer to CBC context block        \
 147  *              @const void *src@ = pointer to source data              \
 148  *              @void *dest@ = pointer to destination data              \
 149  *              @size_t sz@ = size of block to be encrypted             \
 150  *                                                                      \
 151  * Returns:     ---                                                     \
 152  *                                                                      \
 153  * Use:         Decrypts a block with a block cipher in CBC mode, with  \
 154  *              ciphertext stealing and other clever tricks.            \
 155  *              Essentially, data can be encrypted in arbitrary sized   \
 156  *              chunks, although decryption must use the same chunks.   \
 157  */                                                                     \
 158                                                                         \
 159 extern void pre##_cbcdecrypt(pre##_cbcctx */*ctx*/,                     \
 160                              const void */*src*/, void */*dest*/,       \
 161                              size_t /*sz*/);                            \
 162                                                                         \
 163 /* --- Generic cipher interface --- */                                  \
 164                                                                         \
 165 extern const gccipher pre##_cbc;
 166
 167 /*----- That's all, folks -------------------------------------------------*/
 168
 169 #ifdef __cplusplus
 170   }
 171 #endif
 172
 173 #endif