X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/4edc47b89bc56cd4041fdb0f4e8e892acd589ed8..c65df27983057ec76ed0e72bb370f9a5ae7dad28:/ec-bin.c

diff --git a/ec-bin.c b/ec-bin.c
index db1bebf..30e19a9 100644
--- a/ec-bin.c
+++ b/ec-bin.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec-bin.c,v 1.7 2004/04/01 21:28:41 mdw Exp $
+ * $Id: ec-bin.c,v 1.9 2004/04/08 01:36:15 mdw Exp $
  *
  * Arithmetic for elliptic curves over binary fields
  *
@@ -27,40 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: ec-bin.c,v $
- * Revision 1.7  2004/04/01 21:28:41  mdw
- * Normal basis support (translates to poly basis internally).  Rewrite
- * EC and prime group table generators in awk, so that they can reuse data
- * for repeated constants.
- *
- * Revision 1.6  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 1.5  2004/03/27 17:54:11  mdw
- * Standard curves and curve checking.
- *
- * Revision 1.4  2004/03/23 15:19:32  mdw
- * Test elliptic curves more thoroughly.
- *
- * Revision 1.3  2004/03/22 02:19:09  mdw
- * Rationalise the sliding-window threshold.  Drop guarantee that right
- * arguments to EC @add@ are canonical, and fix up projective implementations
- * to cope.
- *
- * Revision 1.2  2004/03/21 22:52:06  mdw
- * Merge and close elliptic curve branch.
- *
- * Revision 1.1.2.1  2004/03/21 22:39:46  mdw
- * Elliptic curves on binary fields work.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
 #include <mLib/sub.h>
@@ -191,9 +157,6 @@ static ec *ecprojdbl(ec_curve *c, ec *d, const ec *a)
     d->z = dz;
     MP_DROP(u);
     MP_DROP(v);
-    assert(!(d->x->f & MP_DESTROYED));
-    assert(!(d->y->f & MP_DESTROYED));
-    assert(!(d->z->f & MP_DESTROYED));
   }
   return (d);
 }
@@ -375,7 +338,7 @@ static void ecdestroy(ec_curve *c)
  * Arguments:	@field *f@ = the underlying field for this elliptic curve
  *		@mp *a, *b@ = the coefficients for this curve
  *
- * Returns:	A pointer to the curve.
+ * Returns:	A pointer to the curve, or null.
  *
  * Use:		Creates a curve structure for an elliptic curve defined over
  *		a binary field.  The @binproj@ variant uses projective
@@ -401,7 +364,14 @@ ec_curve *ec_binproj(field *f, mp *a, mp *b)
   cc->c.a = F_IN(f, MP_NEW, a);
   cc->c.b = F_IN(f, MP_NEW, b);
   cc->bb = F_SQRT(f, MP_NEW, cc->c.b);
-  cc->bb = F_SQRT(f, cc->bb, cc->bb);
+  if (cc->bb)
+    cc->bb = F_SQRT(f, cc->bb, cc->bb);
+  if (!cc->bb) {
+    MP_DROP(cc->c.a);
+    MP_DROP(cc->c.b);
+    DESTROY(cc);
+    return (0);
+  }
   return (&cc->c);
 }