mdw@git.distorted.org.uk Git - catacomb/blob - math/strongprime.h

   1 /* -*-c-*-
   2  *
   3  * Generate `strong' prime numbers
   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_STRONGPRIME_H
  29 #define CATACOMB_STRONGPRIME_H
  30
  31 #ifdef __cplusplus
  32   extern "C" {
  33 #endif
  34
  35 /*----- Header files ------------------------------------------------------*/
  36
  37 #ifndef CATACOMB_GRAND_H
  38 #  include "grand.h"
  39 #endif
  40
  41 #ifndef CATACOMB_PGEN_H
  42 #  include "pgen.h"
  43 #endif
  44
  45 /*----- Functions provided ------------------------------------------------*/
  46
  47 /* --- @strongprime_setup@ --- *
  48  *
  49  * Arguments:   @const char *name@ = pointer to name root
  50  *              @mp *d@ = destination for search start point
  51  *              @pfilt *f@ = where to store filter jump context
  52  *              @unsigned nbits@ = number of bits wanted
  53  *              @grand *r@ = random number source
  54  *              @unsigned n@ = number of attempts to make
  55  *              @pgen_proc *event@ = event handler function
  56  *              @void *ectx@ = argument for the event handler
  57  *
  58  * Returns:     A starting point for a `strong' prime search, or zero.
  59  *
  60  * Use:         Sets up for a strong prime search, so that primes with
  61  *              particular properties can be found.  It's probably important
  62  *              to note that the number left in the filter context @f@ is
  63  *              congruent to 2 (mod 4); that the jump value is twice the
  64  *              product of two large primes; and that the starting point is
  65  *              at least %$3 \cdot 2^{N-2}$%.  (Hence, if you multiply two
  66  *              such numbers, the product is at least
  67  *
  68  *                      %$9 \cdot 2^{2N-4} > 2^{2N-1}$%
  69  *
  70  *              i.e., it will be (at least) a %$2 N$%-bit value.
  71  */
  72
  73 extern mp *strongprime_setup(const char */*name*/, mp */*d*/, pfilt */*f*/,
  74                              unsigned /*nbits*/, grand */*r*/,
  75                              unsigned /*n*/, pgen_proc */*event*/,
  76                              void */*ectx*/);
  77
  78 /* --- @strongprime@ --- *
  79  *
  80  * Arguments:   @const char *name@ = pointer to name root
  81  *              @mp *d@ = destination integer
  82  *              @unsigned nbits@ = number of bits wanted
  83  *              @grand *r@ = random number source
  84  *              @unsigned n@ = number of attempts to make
  85  *              @pgen_proc *event@ = event handler function
  86  *              @void *ectx@ = argument for the event handler
  87  *
  88  * Returns:     A `strong' prime, or zero.
  89  *
  90  * Use:         Finds `strong' primes.  A strong prime %$p$% is such that
  91  *
  92  *                * %$p - 1$% has a large prime factor %$r$%,
  93  *                * %$p + 1$% has a large prime factor %$s$%, and
  94  *                * %$r - 1$% has a large prime factor %$t$%.
  95  */
  96
  97 extern mp *strongprime(const char */*name*/, mp */*d*/, unsigned /*nbits*/,
  98                        grand */*r*/, unsigned /*n*/,
  99                        pgen_proc */*event*/, void */*ectx*/);
 100
 101 /*----- That's all, folks -------------------------------------------------*/
 102
 103 #ifdef __cplusplus
 104   }
 105 #endif
 106
 107 #endif