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   1 /* -*-c-*-
   2  *
   3  * $Id: dsarand.h,v 1.2 2000/06/17 10:54:14 mdw Exp $
   4  *
   5  * Random number generator for DSA
   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: dsarand.h,v $
  33  * Revision 1.2  2000/06/17 10:54:14  mdw
  34  * Typesetting fixes.
  35  *
  36  * Revision 1.1  1999/12/22 15:53:12  mdw
  37  * Random number generator for finding DSA parameters.
  38  *
  39  */
  40
  41 #ifndef CATACOMB_DSARAND_H
  42 #define CATACOMB_DSARAND_H
  43
  44 #ifdef __cplusplus
  45   extern "C" {
  46 #endif
  47
  48 /*----- Header files ------------------------------------------------------*/
  49
  50 #include <mLib/bits.h>
  51
  52 #ifndef CATACOMB_GRAND_H
  53 #  include "grand.h"
  54 #endif
  55
  56 #ifndef CATACOMB_SHA_H
  57 #  include "sha.h"
  58 #endif
  59
  60 /*----- Data structures ---------------------------------------------------*/
  61
  62 typedef struct dsarand {
  63   octet *p;                             /* Pointer to seed (modified) */
  64   size_t sz;                            /* Size of the seed buffer */
  65   unsigned passes;                      /* Number of passes to make */
  66 } dsarand;
  67
  68 /*----- Functions provided ------------------------------------------------*/
  69
  70 /* --- @dsarand_init@ --- *
  71  *
  72  * Arguments:   @dsarand *d@ = pointer to context
  73  *              @const void *p@ = pointer to seed buffer
  74  *              @size_t sz@ = size of the buffer
  75  *
  76  * Returns:     ---
  77  *
  78  * Use:         Initializes a DSA random number generator.
  79  */
  80
  81 extern void dsarand_init(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
  82
  83 /* --- @dsarand_reseed@ --- *
  84  *
  85  * Arguments:   @dsarand *d@ = pointer to context
  86  *              @const void *p@ = pointer to seed buffer
  87  *              @size_t sz@ = size of the buffer
  88  *
  89  * Returns:     ---
  90  *
  91  * Use:         Initializes a DSA random number generator.
  92  */
  93
  94 extern void dsarand_reseed(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
  95
  96 /* --- @dsarand_destroy@ --- *
  97  *
  98  * Arguments:   @dsarand *d@ = pointer to context
  99  *
 100  * Returns:     ---
 101  *
 102  * Use:         Disposes of a DSA random number generation context.
 103  */
 104
 105 extern void dsarand_destroy(dsarand */*d*/);
 106
 107 /* --- @dsarand_fill@ --- *
 108  *
 109  * Arguments:   @dsarand *d@ = pointer to context
 110  *              @void *p@ = pointer to output buffer
 111  *              @size_t sz@ = size of output buffer
 112  *
 113  * Returns:     ---
 114  *
 115  * Use:         Fills an output buffer with pseudorandom data.
 116  *
 117  *              Let %$p$% be the numerical value of the input buffer, and let
 118  *              %$b$% be the number of bytes required.  Let
 119  *              %$z = \lceil b / 20 \rceil$% be the number of SHA outputs
 120  *              required.  Then the output of pass %$n$% is
 121  *
 122  *                %$P_n = \sum_{0 \le i < z} 2^{160i} SHA(p + nz + i)$%
 123  *                                                      %${} \bmod 2^{8b}$%
 124  *
 125  *              and the actual result in the output buffer is the XOR of all
 126  *              of the output passes.
 127  *
 128  *              The DSA procedure for choosing @q@ involves two passes with
 129  *              %$z = 1$%; the procedure for choosing @p@ involves one pass
 130  *              with larger %$z$%.  This generalization of the DSA generation
 131  *              procedure is my own invention but it seems relatively sound.
 132  */
 133
 134 extern void dsarand_fill(dsarand */*d*/, void */*p*/, size_t /*sz*/);
 135
 136 /*----- Generic pseudorandom-number generator interface -------------------*/
 137
 138 /* --- Miscellaneous operations --- */
 139
 140 enum {
 141   DSARAND_PASSES = GRAND_SPECIFIC
 142 };
 143
 144 /* --- @dsarand_create@ --- *
 145  *
 146  * Arguments:   @const void *p@ = pointer to seed buffer
 147  *              @size_t sz@ = size of seed buffer
 148  *
 149  * Returns:     Pointer to a generic generator.
 150  *
 151  * Use:         Constructs a generic generator interface over a Catacomb
 152  *              entropy pool generator.
 153  */
 154
 155 extern grand *dsarand_create(const void */*p*/, size_t /*sz*/);
 156
 157 /*----- That's all, folks -------------------------------------------------*/
 158
 159 #ifdef __cplusplus
 160   }
 161 #endif
 162
 163 #endif