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

   1 /* -*-c-*-
   2  *
   3  * $Id: counter.h,v 1.1 2000/06/17 10:51:42 mdw Exp $
   4  *
   5  * Block cipher counter mode (or long cycle mode)
   6  *
   7  * (c) 2000 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: counter.h,v $
  33  * Revision 1.1  2000/06/17 10:51:42  mdw
  34  * Counter mode ciphers and pseudo-random generator.
  35  *
  36  */
  37
  38 #ifndef CATACOMB_COUNTER_H
  39 #define CATACOMB_COUNTER_H
  40
  41 #ifdef __cplusplus
  42   extern "C" {
  43 #endif
  44
  45 /*----- Header files ------------------------------------------------------*/
  46
  47 #include <stddef.h>
  48
  49 #include <mLib/bits.h>
  50
  51 #ifndef CATACOMB_GCIPHER_H
  52 #  include "gcipher.h"
  53 #endif
  54
  55 #ifndef CATACOMB_GRAND_H
  56 #  include "grand.h"
  57 #endif
  58
  59 /*----- Macros ------------------------------------------------------------*/
  60
  61 /* --- @COUNTER_DECL@ --- *
  62  *
  63  * Arguments:   @PRE@, @pre@ = prefixes for block cipher definitions
  64  *
  65  * Use:         Makes declarations for counter mode.
  66  */
  67
  68 #define COUNTER_DECL(PRE, pre)                                          \
  69                                                                         \
  70 /* --- Counter mode context --- */                                      \
  71                                                                         \
  72 typedef struct pre##_counterctx {                                       \
  73   pre##_ctx ctx;                        /* Underlying cipher context */ \
  74   unsigned off;                         /* Current offset in buffer */  \
  75   octet buf[PRE##_BLKSZ];               /* Output buffer */             \
  76   uint32 n[PRE##_BLKSZ / 4];            /* Counter */                   \
  77 } pre##_counterctx;                                                     \
  78                                                                         \
  79 /* --- @pre_countergetiv@ --- *                                         \
  80  *                                                                      \
  81  * Arguments:   @const pre_counterctx *ctx@ = pointer to counter        \
  82  *                      context                                         \
  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##_countergetiv(const pre##_counterctx */*ctx*/,         \
  94                                void */*iv*/);                           \
  95                                                                         \
  96 /* --- @pre_countersetiv@ --- *                                         \
  97  *                                                                      \
  98  * Arguments:   @pre_counterctx *ctx@ = pointer to counter context      \
  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##_countersetiv(pre##_counterctx */*ctx*/,               \
 107                                const void */*iv*/);                     \
 108                                                                         \
 109 /* --- @pre_counterbdry@ --- *                                          \
 110  *                                                                      \
 111  * Arguments:   @pre_counterctx *ctx@ = pointer to counter context      \
 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##_counterbdry(pre##_counterctx */*ctx*/);               \
 120                                                                         \
 121 /* --- @pre_countersetkey@ --- *                                        \
 122  *                                                                      \
 123  * Arguments:   @pre_counterctx *ctx@ = pointer to counter context      \
 124  *              @const pre_ctx *k@ = pointer to cipher context          \
 125  *                                                                      \
 126  * Returns:     ---                                                     \
 127  *                                                                      \
 128  * Use:         Sets the counter context to use a different cipher key. \
 129  */                                                                     \
 130                                                                         \
 131 extern void pre##_countersetkey(pre##_counterctx */*ctx*/,              \
 132                                 const pre##_ctx */*k*/);                \
 133                                                                         \
 134 /* --- @pre_counterinit@ --- *                                          \
 135  *                                                                      \
 136  * Arguments:   @pre_counterctx *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 counter context ready for use.  You       \
 144  *              should ensure that the IV chosen is unique: reusing an  \
 145  *              IV will compromise the security of the entire           \
 146  *              plaintext.  This is equivalent to calls to @pre_init@,  \
 147  *              @pre_countersetkey@ and @pre_countersetiv@.             \
 148  */                                                                     \
 149                                                                         \
 150 extern void pre##_counterinit(pre##_counterctx */*ctx*/,                \
 151                               const void */*key*/, size_t /*sz*/,       \
 152                           const void */*iv*/);                          \
 153                                                                         \
 154 /* --- @pre_counterencrypt@ --- *                                       \
 155  *                                                                      \
 156  * Arguments:   @pre_counterctx *ctx@ = pointer to counter context      \
 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 or decrypts a block with a block cipher in     \
 164  *              counter mode: encryption and decryption are the same in \
 165  *              counter.  The destination may be null to just churn the \
 166  *              feedback round for a bit.  The source may be null to    \
 167  *              use the cipher as a random data generator.              \
 168  */                                                                     \
 169                                                                         \
 170 extern void pre##_counterencrypt(pre##_counterctx */*ctx*/,             \
 171                                  const void */*src*/, void */*dest*/,   \
 172                                  size_t /*sz*/);                        \
 173                                                                         \
 174 /* --- @pre_counterrand@ --- *                                          \
 175  *                                                                      \
 176  * Arguments:   @const void *k@ = pointer to key material               \
 177  *              @size_t sz@ = size of key material                      \
 178  *                                                                      \
 179  * Returns:     Pointer to generic random number generator interface.   \
 180  *                                                                      \
 181  * Use:         Creates a random number interface wrapper around an     \
 182  *              counter-mode block cipher.                              \
 183  */                                                                     \
 184                                                                         \
 185 extern grand *pre##_counterrand(const void */*k*/, size_t /*sz*/);      \
 186                                                                         \
 187 /* --- Generic cipher interface --- */                                  \
 188                                                                         \
 189 extern const gccipher pre##_counter;
 190
 191 /*----- That's all, folks -------------------------------------------------*/
 192
 193 #ifdef __cplusplus
 194   }
 195 #endif
 196
 197 #endif