X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/02d7884df1f33c9c7dc3a14c4b1a5f520ebe090a..c65df27983057ec76ed0e72bb370f9a5ae7dad28:/mpmont.c

diff --git a/mpmont.c b/mpmont.c
index bfede63..39f51ed 100644
--- a/mpmont.c
+++ b/mpmont.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mpmont.c,v 1.18 2004/04/03 03:32:05 mdw Exp $
+ * $Id: mpmont.c,v 1.19 2004/04/08 01:36:15 mdw Exp $
  *
  * Montgomery reduction
  *
@@ -27,79 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: mpmont.c,v $
- * Revision 1.18  2004/04/03 03:32:05  mdw
- * General robustification.
- *
- * Revision 1.17  2004/04/01 12:50:09  mdw
- * Add cyclic group abstraction, with test code.  Separate off exponentation
- * functions for better static linking.  Fix a buttload of bugs on the way.
- * Generally ensure that negative exponents do inversion correctly.  Add
- * table of standard prime-field subgroups.  (Binary field subgroups are
- * currently unimplemented but easy to add if anyone ever finds a good one.)
- *
- * Revision 1.16  2002/01/13 13:40:31  mdw
- * Avoid trashing arguments before we've used them.
- *
- * Revision 1.15  2001/06/16 13:00:20  mdw
- * Use the generic exponentiation functions.
- *
- * Revision 1.14  2001/02/22 09:04:26  mdw
- * Cosmetic fix.
- *
- * Revision 1.13  2001/02/03 12:00:29  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.
- *
- * Revision 1.12  2000/10/08 15:48:35  mdw
- * Rename Karatsuba constants now that we have @gfx_kmul@ too.
- *
- * Revision 1.11  2000/10/08 12:04:27  mdw
- * (mpmont_reduce, mpmont_mul): Cope with negative numbers.
- *
- * Revision 1.10  2000/07/29 17:05:43  mdw
- * (mpmont_expr): Use sliding window exponentiation, with a drop-through
- * for small exponents to use a simple left-to-right bitwise routine.  This
- * can reduce modexp times by up to a quarter.
- *
- * Revision 1.9  2000/06/17 11:45:09  mdw
- * Major memory management overhaul.  Added arena support.  Use the secure
- * arena for secret integers.  Replace and improve the MP management macros
- * (e.g., replace MP_MODIFY by MP_DEST).
- *
- * Revision 1.8  1999/12/22 15:55:00  mdw
- * Adjust Karatsuba parameters.
- *
- * Revision 1.7  1999/12/11 01:51:14  mdw
- * Use a Karatsuba-based reduction for large moduli.
- *
- * Revision 1.6  1999/12/10 23:18:39  mdw
- * Change interface for suggested destinations.
- *
- * Revision 1.5  1999/11/22 13:58:40  mdw
- * Add an option to disable Montgomery reduction, so that performance
- * comparisons can be done.
- *
- * Revision 1.4  1999/11/21 12:27:06  mdw
- * Remove a division from the Montgomery setup by calculating
- * %$R^2 \bmod m$% first and then %$R \bmod m$% by Montgomery reduction of
- * %$R^2$%.
- *
- * Revision 1.3  1999/11/21 11:35:10  mdw
- * Performance improvement: use @mp_sqr@ and @mpmont_reduce@ instead of
- * @mpmont_mul@ for squaring in exponentiation.
- *
- * Revision 1.2  1999/11/19 13:17:26  mdw
- * Add extra interface to exponentiation which returns a Montgomerized
- * result.
- *
- * Revision 1.1  1999/11/17 18:02:16  mdw
- * New multiprecision integer arithmetic suite.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include "mp.h"
@@ -161,8 +88,7 @@ void mpmont_create(mpmont *mm, mp *m)
   /* --- Find the magic value @mi@ --- */
 
   mp_build(&r, r2->v + n, r2->vl);
-  mm->mi = MP_NEW;
-  mp_gcd(0, 0, &mm->mi, &r, m);
+  mm->mi = mp_modinv(MP_NEW, m, &r);
   mm->mi = mp_sub(mm->mi, &r, mm->mi);
 
   /* --- Discover the values %$R \bmod m$% and %$R^2 \bmod m$% --- */