Find `safe' primes (i.e., %$p = 2q + 1$%).

[u/mdw/catacomb] / pgen.h

/* -*-c-*-
 *
 * $Id: pgen.h,v 1.4 1999/12/22 16:01:11 mdw Exp $
 *
 * Prime generation glue
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: pgen.h,v $
 * Revision 1.4  1999/12/22 16:01:11  mdw
 * Same file, completely different code.  Main interface for new prime-
 * search system.
 *
 */

#ifndef CATACOMB_PGEN_H
#define CATACOMB_PGEN_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#ifndef CATACOMB_GRAND_H
#  include "grand.h"
#endif

#ifndef CATACOMB_MP_H
#  include "mp.h"
#endif

#ifndef CATACOMB_PFILT_H
#  include "pfilt.h"
#endif

#ifndef CATACOMB_RABIN_H
#  include "rabin.h"
#endif

/*----- Event handling ----------------------------------------------------*
 *
 * Different programs and architectures will want to show progress of prime
 * searches and similar processes in different ways.  Of course, for simple
 * searches, it's possible to use the @pfilt@ and @rabin@ functions and
 * maintain control over the general control flow throughout the search.
 *
 * For more complex cases, this sort of control is undesirable.  It's
 * possible to specify an event handler which is informed in abstract about
 * the search.  The event handler can also request the search be aborted.
 */

/* --- Event code constants --- *
 *
 * You're allowed to rely on the values of @PGEN_DONE@ and @PGEN_ABORT@.
 */

enum {
  PGEN_BEGIN = 1,			/* Search for value begins */
  PGEN_TRY,				/* A new candidate has appeared */
  PGEN_FAIL,				/* The candidate failed the test */
  PGEN_PASS,				/* The candidate passed a test */
  PGEN_DONE = 0,			/* A good value has been found */
  PGEN_ABORT = -1			/* The search has been aborted */
};

/* --- Event information --- *
 *
 * Note that the pseudorandom number generator supplied is not
 * cryptographically strong.
 */

typedef struct pgen_event {
  const char *name;			/* Which quantity is being found */
  mp *m;				/* Current value under test */
  unsigned steps;			/* Number of candidates left */
  unsigned tests;			/* Tests left before passing */
  grand *r;				/* Source of random numbers */
} pgen_event;

/*----- Prime search parameters -------------------------------------------*
 *
 * The prime search is parameterized in a large number of ways, although this
 * isn't so much of a surprise given the different sorts of properties
 * required from prime numbers in cryptographic applications.
 *
 * There are two main things which need to be configured: stepping, and
 * testing.  (Filtering is done as part of stepping.)
 *
 * The functions here provide a toolkit for constructing stepping and testing
 * routines.  In a lot of cases, the functions can be used directly; in
 * others, simple bits of glue need be written.
 *
 * Two types of functions are defined: steppers and testers, but their
 * interfaces are substantially similar.  Each is given a request code, a
 * context block and an event block.  It is meant to update its context and
 * the event block and return an event code.
 *
 * A call with a request of @PGEN_BEGIN@ asks the stepper or tester to
 * initialize itself using the information in its event block and context.  A
 * return of @PGEN_FAIL@ reports an immediate failure; @PGEN_ABORT@ reports a
 * fatal problem; @PGEN_DONE@ reports immediate success.  @PGEN_TRY@ reports
 * successful initialization and requests test iterations.
 *
 * A call to a stepper with a request of @PGEN_TRY@ asks it to step to the
 * next possible candidate, replacing the value @m@ in the event block with
 * the new candidate.  A call to a tester with a request of @PGEN_TRY@
 * runs one pass of the test.  It should return @PGEN_FAIL@ to report a
 * failure, @PGEN_PASS@ to report a success and request another iteration,
 * @PGEN_DONE@ to report final acceptance and @PGEN_ABORT@ to terminate the
 * search unsuccessfully.  Note that even if the search is aborted, a
 * shutdown request is still made.
 *
 * A call with a request of @PGEN_DONE@ closes down the stepper or tester.
 * After a successful initialization (i.e., a return of something other than
 * @PGEN_ABORT@), a shutdown call is guaranteed.  The return code is ignored.
 */

typedef int pgen_proc(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/*----- Simple handler functions ------------------------------------------*/

/* --- @pgen_filter@ --- *
 *
 * A prime generation context contains the information required for the
 * simple prime filter and tester presented here.
 */

typedef struct pgen_filterctx {
  unsigned step;			/* Step size (set by client) */
  pfilt f;				/* The rapid prime filter */
} pgen_filterctx;

extern int pgen_filter(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/* --- @pgen_jump@ --- *
 *
 * Similar to the standard @pgen_filter@, but jumps in large steps rather
 * than small ones.
 */

typedef struct pgen_jumpctx {
  const pfilt *j;
  pfilt f;
} pgen_jumpctx;

extern int pgen_jump(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/* --- @pgen_test@ --- *
 *
 * Runs the Rabin-Miller primality test.  The context block is simply a
 * @rabin@ context.
 */

extern int pgen_test(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/*----- Safe prime functions ----------------------------------------------*/

/* --- @pgen_safestep@ --- *
 *
 * Steps two numbers, %$q$% and %$p = 2q + 1$%, such that neither has any
 * small factors.  %$p$% is put in the event block.
 */

typedef struct pgen_safestepctx {
  pfilt q, p;
} pgen_safestepctx;

extern int pgen_safestep(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/* --- @pgen_safetest@ --- *
 *
 * Applies Rabin-Miller tests to %$p$% and %$(p - 1)/2$%.
 */

typedef struct pgen_safetestctx {
  pgen_safestepctx c;
  rabin q, p;
} pgen_safetestctx;

extern int pgen_safetest(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/*----- Standard event handlers -------------------------------------------*/

/* --- @pgen_evspin@ --- *
 *
 * Displays a spinning baton to show progress.
 */

extern int pgen_evspin(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/* --- @pgen_ev@ --- *
 *
 * Traditional event handler, shows dots for each test.
 */

extern int pgen_ev(int /*rq*/, pgen_event */*ev*/, void */*p*/);

/*----- The main driver ---------------------------------------------------*/

/* --- @pgen@ --- *
 *
 * Arguments:	@const char *name@ = name of the value being searched for
 *		@mp *d@ = destination for resulting integer
 *		@mp *m@ = start value to pass to stepper
 *		@pgen_proc *event@ = event handler function
 *		@void *ectx@ = context argument for event andler
 *		@unsigned steps@ = number of steps to take in search
 *		@pgen_proc *step@ = stepper function to use
 *		@void *sctx@ = context argument for stepper
 *		@unsigned tests@ = number of tests to make
 *		@pgen_proc *test@ = tester function to use
 *		@void *tctx@ = context argument for tester
 *
 * Returns:	If successful, @PGEN_DONE@; otherwise @PGEN_ABORT@.
 *
 * Use:		A generalized prime-number search skeleton.  Yes, that's a
 *		scary number of arguments.
 */

extern mp *pgen(const char */*name*/, mp */*d*/, mp */*m*/,
		pgen_proc */*event*/, void */*ectx*/,
		unsigned /*steps*/, pgen_proc */*step*/, void */*sctx*/,
		unsigned /*tests*/, pgen_proc */*test*/, void */*tctx*/);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif