/* -*-c-*-
*
- * $Id: pgen.c,v 1.7 2001/02/03 16:05:32 mdw Exp $
+ * $Id: pgen.c,v 1.8 2002/01/13 13:42:53 mdw Exp $
*
* Prime generation glue
*
/*----- Revision history --------------------------------------------------*
*
* $Log: pgen.c,v $
+ * Revision 1.8 2002/01/13 13:42:53 mdw
+ * More efficient Rabin-Miller test: with random witnesses, skip redundant
+ * Montgomerization. (Being bijective, it can't affect the distribution.)
+ *
* Revision 1.7 2001/02/03 16:05:32 mdw
* Now @mp_drop@ checks its argument is non-NULL before attempting to free
* it. Note that the macro version @MP_DROP@ doesn't do this.
rabin_create(r, ev->m);
rc = PGEN_TRY;
break;
- case PGEN_TRY: {
- mp *a = mprand_range(MP_NEW, ev->m, ev->r, 0);
- rc = rabin_test(r, a);
- mp_drop(a);
- } break;
+ case PGEN_TRY:
+ if (!ev->tests)
+ rc = rabin_rtest(r, MP_TWO);
+ else {
+ mp *a = mprand_range(MP_NEW, ev->m, ev->r, 0);
+ rc = rabin_rtest(r, a);
+ mp_drop(a);
+ }
+ break;
case PGEN_DONE:
rabin_destroy(r);
rc = PGEN_DONE;
ev.m = MP_COPY(m);
else
ev.m = 0;
- ev.steps = steps;
- ev.tests = tests;
+ ev.steps = 0;
+ ev.tests = 0;
ev.r = fibrand_create(0);
/* --- Tell the event handler we're under way --- */
/* --- If decrementing counters is requested, do that --- */
if ((act & A_STEP) && steps) {
- ev.steps--;
- if (!ev.steps) {
+ ev.steps++;
+ if (ev.steps == steps) {
act |= A_EVENT | A_ENDSTEP | A_DONE;
rc = PGEN_ABORT;
}
- ev.tests = tests;
+ ev.tests = 0;
}
if ((act & A_TEST) && tests) {
- ev.tests--;
- if (!ev.tests) {
+ ev.tests++;
+ if (ev.tests == tests) {
act |= A_ENDTEST | A_ENDSTEP | A_DONE;
rc = PGEN_DONE;
}
/* -*-c-*-
*
- * $Id: rabin.c,v 1.6 2001/06/16 12:56:38 mdw Exp $
+ * $Id: rabin.c,v 1.7 2002/01/13 13:42:53 mdw Exp $
*
* Miller-Rabin primality test
*
/*----- Revision history --------------------------------------------------*
*
* $Log: rabin.c,v $
+ * Revision 1.7 2002/01/13 13:42:53 mdw
+ * More efficient Rabin-Miller test: with random witnesses, skip redundant
+ * Montgomerization. (Being bijective, it can't affect the distribution.)
+ *
* Revision 1.6 2001/06/16 12:56:38 mdw
* Fixes for interface change to @mpmont_expr@ and @mpmont_mexpr@.
*
mpmont_destroy(&r->mm);
}
-/* --- @rabin_test@ --- *
+/* --- @rabin_test@, @rabin_rtest@ --- *
*
* Arguments: @rabin *r@ = pointer to Rabin-Miller context
* @mp *g@ = base to test the number against
* if it succeeded.
*
* Use: Performs a single iteration of the Rabin-Miller primality
- * test.
+ * test. The @rtest@ variant assumes that %$g$% is either
+ * already in Montgomery representation, or you don't care.
*/
-int rabin_test(rabin *r, mp *g)
+int rabin_rtest(rabin *r, mp *g)
{
mp *y;
mp *dd, *spare = MP_NEW;
* @y@ here has an extra factor of %$R$%.
*/
- y = mpmont_mul(&r->mm, MP_NEW, g, r->mm.r2);
- y = mpmont_expr(&r->mm, y, y, r->r);
+ y = mpmont_expr(&r->mm, MP_NEW, g, r->r);
if (MP_EQ(y, r->mm.r) || MP_EQ(y, r->m1)) {
rc = PGEN_PASS;
goto done;
return (rc);
}
+int rabin_test(rabin *r, mp *g)
+{
+ int rc;
+ g = mpmont_mul(&r->mm, MP_NEW, g, r->mm.r2);
+ rc = rabin_rtest(r, g);
+ mp_drop(g);
+ return (rc);
+}
+
/* --- @rabin_iters@ --- *
*
* Arguments: @unsigned len@ = number of bits in value
/* -*-c-*-
*
- * $Id: rabin.h,v 1.5 2000/07/09 21:32:16 mdw Exp $
+ * $Id: rabin.h,v 1.6 2002/01/13 13:42:53 mdw Exp $
*
* Miller-Rabin primality test
*
/*----- Revision history --------------------------------------------------*
*
* $Log: rabin.h,v $
+ * Revision 1.6 2002/01/13 13:42:53 mdw
+ * More efficient Rabin-Miller test: with random witnesses, skip redundant
+ * Montgomerization. (Being bijective, it can't affect the distribution.)
+ *
* Revision 1.5 2000/07/09 21:32:16 mdw
* rabin_test: Correct error in comment.
*
extern void rabin_destroy(rabin */*r*/);
-/* --- @rabin_test@ --- *
+/* --- @rabin_test@, @rabin_rtest@ --- *
*
* Arguments: @rabin *r@ = pointer to Rabin-Miller context
* @mp *g@ = base to test the number against
* if it succeeded.
*
* Use: Performs a single iteration of the Rabin-Miller primality
- * test.
+ * test. The @rtest@ variant assumes that %$g$% is either
+ * already in Montgomery representation, or you don't care.
*/
+extern int rabin_rtest(rabin */*r*/, mp */*g*/);
extern int rabin_test(rabin */*r*/, mp */*g*/);
/* --- @rabin_iters@ --- *