--- /dev/null
+/* -*-apcalc-*-
+ *
+ * $Id: ecp.cal,v 1.1 2000/10/08 16:01:37 mdw Exp $
+ *
+ * Testbed for elliptic curve arithmetic over prime fields
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * 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 --------------------------------------------------*
+ *
+ * $Log: ecp.cal,v $
+ * Revision 1.1 2000/10/08 16:01:37 mdw
+ * Prototypes of various bits of code.
+ *
+ */
+
+/*----- Object types ------------------------------------------------------*/
+
+obj ecp_curve { a, b, p };
+obj ecp_pt { x, y, e };
+
+/*----- Main code ---------------------------------------------------------*/
+
+define ecp_curve(a, b, p)
+{
+ local obj ecp_curve e;
+ e.a = a;
+ e.b = b;
+ e.p = p;
+ return (e);
+}
+
+define ecp_pt(x, y, e)
+{
+ local obj ecp_pt p;
+ p.x = x % e.p;
+ p.y = y % e.p;
+ p.e = e;
+ return (p);
+}
+
+define ecp_pt_print(a)
+{
+ print "(" : a.x : ", " : a.y : ")" :;
+}
+
+define ecp_pt_add(a, b)
+{
+ local e, alpha;
+ local obj ecp_pt d;
+
+ if (a == 0)
+ d = b;
+ else if (b == 0)
+ d = a;
+ else if (!istype(a, b))
+ quit "bad type arguments to ecp_pt_add";
+ else if (a.e != b.e)
+ quit "points from different curves in ecp_pt_add";
+ else {
+ e = a.e;
+ if (a.x == b.x) {
+ if (a.y != b.y) {
+ return (0);
+ }
+ alpha = (3 * a.x^2 + e.a) * minv(2 * a.y, e.p) % e.p;
+ } else
+ alpha = (b.y - a.y) * minv(b.x - a.x, e.p) % e.p;
+
+ d.x = (alpha^2 - a.x - b.x) % e.p;
+ d.y = (-a.y + alpha * (a.x - d.x)) % e.p;
+ d.e = e;
+ }
+
+ return (d);
+}
+
+define ecp_pt_neg(a)
+{
+ local obj ecp_pt d;
+ d.x = a.x;
+ d.y = -a.y;
+ d.e = a.e;
+ return (d);
+}
+
+define ecp_pt_mul(a, b)
+{
+ local p, n;
+ local d;
+
+ if (istype(a, 1)) {
+ n = a;
+ p = b;
+ } else if (istype(b, 1)) {
+ n = b;
+ p = a;
+ } else
+ return (newerror("bad arguments to ecp_pt_mul"));
+
+ d = 0;
+ while (n) {
+ if (n & 1)
+ d += p;
+ n >>= 1;
+ p += p;
+ }
+ return (d);
+}
+
+/*----- That's all, folks -------------------------------------------------*/
+