Simple (non-projective) curves over prime fields now seem to work.

[u/mdw/catacomb] / calc / ecp.cal

diff --git a/calc/ecp.cal b/calc/ecp.cal
index 04971aa..82600f5 100644 (file)
--- a/calc/ecp.cal
+++ b/calc/ecp.cal
@@ -1,6 +1,6 @@
 /* -*-apcalc-*-
  *
- * $Id: ecp.cal,v 1.1 2000/10/08 16:01:37 mdw Exp $
+ * $Id: ecp.cal,v 1.1.4.1 2003/06/10 13:43:53 mdw Exp $
  *
  * Testbed for elliptic curve arithmetic over prime fields
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: ecp.cal,v $
+ * Revision 1.1.4.1  2003/06/10 13:43:53  mdw
+ * Simple (non-projective) curves over prime fields now seem to work.
+ *
  * Revision 1.1  2000/10/08 16:01:37  mdw
  * Prototypes of various bits of code.
  *
@@ -96,6 +99,18 @@ define ecp_pt_add(a, b)
   return (d);
 }
 
+define ecp_pt_dbl(a)
+{
+  local e, alpha;
+  local obj ecp_pt d;
+  e = a.e;
+  alpha = (3 * a.x^2 + e.a) * minv(2 * a.y, e.p) % e.p;
+  d.x = (alpha^2 - 2 * a.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;
@@ -105,6 +120,15 @@ define ecp_pt_neg(a)
   return (d);
 }
 
+define ecp_pt_check(a)
+{
+  local e;
+
+  e = a.e;
+  if (a.y^2 % e.p != (a.x^3 + e.a * a.x + e.b) % e.p)
+    quit "bad curve point";
+}
+
 define ecp_pt_mul(a, b)
 {
   local p, n;
@@ -124,10 +148,18 @@ define ecp_pt_mul(a, b)
     if (n & 1)
       d += p;
     n >>= 1;
-    p += p;
+    p = ecp_pt_dbl(p);
   }
   return (d);
 }
 
+/*----- FIPS186-2 standard curves -----------------------------------------*/
+
+p192 = ecp_curve(-3, 0x64210519e59c80e70fa7e9ab72243049feb8deecc146b9b1,
+                6277101735386680763835789423207666416083908700390324961279);
+p192_r = 6277101735386680763835789423176059013767194773182842284081;
+p192_g = ecp_pt(0x188da80eb03090f67cbf20eb43a18800f4ff0afd82ff1012,
+               0x07192b95ffc8da78631011ed6b24cdd573f977a11e794811, p192);
+
 /*----- That's all, folks -------------------------------------------------*/