/* -*-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
*
* 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>
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);
}
* 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
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);
}