/* -*-c-*-
*
- * $Id: pfilt.c,v 1.2 2000/06/17 11:54:27 mdw Exp $
+ * $Id: pfilt.c,v 1.6 2004/04/08 01:36:15 mdw Exp $
*
* Finding and testing prime numbers
*
* (c) 1999 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* 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 --------------------------------------------------*
+/*----- Header files ------------------------------------------------------*/
+
+#include "mp.h"
+#include "mpint.h"
+#include "pfilt.h"
+#include "pgen.h"
+#include "primetab.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @smallenough@ --- *
*
- * $Log: pfilt.c,v $
- * Revision 1.2 2000/06/17 11:54:27 mdw
- * Use new MP memory management functions.
+ * Arguments: @mp *m@ = integer to test
*
- * Revision 1.1 1999/12/22 15:49:39 mdw
- * Renamed from `pgen'. Reworking for new prime-search system.
+ * Returns: One of the @PGEN@ result codes.
*
- * Revision 1.3 1999/12/10 23:28:35 mdw
- * Track suggested destination changes.
+ * Use: Assuming that @m@ has been tested by trial division on every
+ * prime in the small-primes array, this function will return
+ * @PGEN_DONE@ if the number is less than the square of the
+ * largest small prime.
+ */
+
+static int smallenough(mp *m)
+{
+ static mp *max = 0;
+ int rc = PGEN_TRY;
+
+ if (!max) {
+ max = mp_fromuint(MP_NEW, MAXPRIME);
+ max = mp_sqr(max, max);
+ max->a->n--; /* Permanent allocation */
+ }
+ if (MP_CMP(m, <=, MP_ONE))
+ rc = PGEN_FAIL;
+ else if (MP_CMP(m, <, max))
+ rc = PGEN_DONE;
+ return (rc);
+}
+
+/* --- @pfilt_smallfactor@ --- *
*
- * Revision 1.2 1999/11/20 22:23:05 mdw
- * Add multiply-and-add function for Diffie-Hellman safe prime generation.
+ * Arguments: @mp *m@ = integer to test
*
- * Revision 1.1 1999/11/19 13:17:57 mdw
- * Prime number generator and tester.
+ * Returns: One of the @PGEN@ result codes.
*
+ * Use: Tests a number by dividing by a number of small primes. This
+ * is a useful first step if you're testing random primes; for
+ * sequential searches, @pfilt_create@ works better.
*/
-/*----- Header files ------------------------------------------------------*/
+int pfilt_smallfactor(mp *m)
+{
+ int rc = PGEN_TRY;
+ int i;
+ size_t sz = MP_LEN(m);
+ mparena *a = m->a ? m->a : MPARENA_GLOBAL;
+ mpw *v = mpalloc(a, sz);
-#include "mp.h"
-#include "mpmont.h"
-#include "pfilt.h"
-#include "pgen.h"
-#include "primetab.h"
+ /* --- Fill in the residues --- */
-/*----- Main code ---------------------------------------------------------*/
+ for (i = 0; i < NPRIME; i++) {
+ if (!mpx_udivn(v, v + sz, m->v, m->vl, primetab[i])) {
+ if (MP_LEN(m) == 1 && m->v[0] == primetab[i])
+ rc = PGEN_DONE;
+ else
+ rc = PGEN_FAIL;
+ break;
+ }
+ }
+
+ /* --- Check for small primes --- */
+
+ if (rc == PGEN_TRY)
+ rc = smallenough(m);
+
+ /* --- Done --- */
+
+ mpfree(a, v);
+ return (rc);
+}
/* --- @pfilt_create@ --- *
*
{
int rc = PGEN_TRY;
int i;
- mp *r = MP_NEW;
- mpw qw;
- mp q;
+ size_t sz = MP_LEN(m);
+ mparena *a = m->a ? m->a : MPARENA_GLOBAL;
+ mpw *v = mpalloc(a, sz);
/* --- Take a copy of the number --- */
/* --- Fill in the residues --- */
- mp_build(&q, &qw, &qw + 1);
for (i = 0; i < NPRIME; i++) {
- qw = primetab[i];
- mp_div(0, &r, m, &q);
- p->r[i] = r->v[0];
+ p->r[i] = mpx_udivn(v, v + sz, m->v, m->vl, primetab[i]);
if (!p->r[i] && rc == PGEN_TRY) {
if (MP_LEN(m) == 1 && m->v[0] == primetab[i])
rc = PGEN_DONE;
}
}
+ /* --- Check for small primes --- */
+
+ if (rc == PGEN_TRY)
+ rc = smallenough(m);
+
/* --- Done --- */
- mp_drop(r);
+ mpfree(a, v);
return (rc);
}
}
}
- /* --- Small numbers must be prime --- */
+ /* --- Check for small primes --- */
- if (rc == PGEN_TRY && MP_LEN(p->m) == 1 &&
- p->m->v[0] < MAXPRIME * MAXPRIME)
- rc = PGEN_DONE;
+ if (rc == PGEN_TRY)
+ rc = smallenough(p->m);
/* --- Done --- */
}
/* --- Gallivant through the residue table --- */
-
+
for (i = 0; i < NPRIME; i++) {
p->r[i] = (q->r[i] * m + a) % primetab[i];
if (!p->r[i] && rc == PGEN_TRY) {
}
}
- /* --- Small numbers must be prime --- */
+ /* --- Check for small primes --- */
- if (rc == PGEN_TRY && MP_LEN(p->m) == 1 &&
- p->m->v[0] < MAXPRIME * MAXPRIME)
- rc = PGEN_DONE;
+ if (rc == PGEN_TRY)
+ rc = smallenough(p->m);
/* --- Finished --- */
}
}
- /* --- Small numbers must be prime --- */
+ /* --- Check for small primes --- */
- if (rc == PGEN_TRY && MP_LEN(p->m) == 1 &&
- p->m->v[0] < MAXPRIME * MAXPRIME)
- rc = PGEN_DONE;
+ if (rc == PGEN_TRY)
+ rc = smallenough(p->m);
/* --- Done --- */
projects / u / mdw / catacomb / blobdiff