| 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 |