Add cyclic group abstraction, with test code. Separate off exponentation

[u/mdw/catacomb] / ec.c

diff --git a/ec.c b/ec.c
index d4dfafb..13e9b84 100644 (file)
--- a/ec.c
+++ b/ec.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec.c,v 1.7 2004/03/27 17:54:11 mdw Exp $
+ * $Id: ec.c,v 1.8 2004/04/01 12:50:09 mdw Exp $
  *
  * Elliptic curve definitions
  *
@@ -30,6 +30,13 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: ec.c,v $
+ * Revision 1.8  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 1.7  2004/03/27 17:54:11  mdw
  * Standard curves and curve checking.
  *
@@ -63,10 +70,25 @@
 /*----- Header files ------------------------------------------------------*/
 
 #include "ec.h"
-#include "ec-exp.h"
 
 /*----- Trivial wrappers --------------------------------------------------*/
 
+/* --- @ec_samep@ --- *
+ *
+ * Arguments:  @ec_curve *c, *d@ = two elliptic curves
+ *
+ * Returns:    Nonzero if the curves are identical (not just isomorphic).
+ *
+ * Use:                Checks for sameness of curves.  This function does the full
+ *             check, not just the curve-type-specific check done by the
+ *             @sampep@ field operation.
+ */
+
+int ec_samep(ec_curve *c, ec_curve *d)
+{
+  return (field_samep(c->f, d->f) && c->ops == d->ops && EC_SAMEP(c, d));
+}
+
 /* --- @ec_create@ --- *
  *
  * Arguments:  @ec *p@ = pointer to an elliptic-curve point
@@ -135,6 +157,20 @@ int ec_eq(const ec *p, const ec *q) { return (EC_EQ(p, q)); }
 
 /*----- Standard curve operations -----------------------------------------*/
 
+/* --- @ec_stdsamep@ --- *
+ *
+ * Arguments:  @ec_curve *c, *d@ = two elliptic curves
+ *
+ * Returns:    Nonzero if the curves are identical (not just isomorphic).
+ *
+ * Use:                Simple sameness check on @a@ and @b@ curve members.
+ */
+
+int ec_stdsamep(ec_curve *c, ec_curve *d)
+{
+  return (MP_EQ(c->a, d->a) && MP_EQ(c->b, d->b));
+}
+
 /* --- @ec_idin@, @ec_idout@, @ec_idfix@ --- *
  *
  * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
@@ -432,48 +468,4 @@ ec *ec_rand(ec_curve *c, ec *d, grand *r)
   return (EC_OUT(c, d, d));    
 }
 
-/* --- @ec_imul@, @ec_mul@ --- *
- *
- * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
- *             @ec *d@ = pointer to the destination point
- *             @const ec *p@ = pointer to the generator point
- *             @mp *n@ = integer multiplier
- *
- * Returns:    The destination @d@.
- *
- * Use:                Multiplies a point by a scalar, returning %$n p$%.  The
- *             @imul@ variant uses internal representations for argument
- *             and result.
- */
-
-ec *ec_imul(ec_curve *c, ec *d, const ec *p, mp *n)
-{
-  ec t = EC_INIT;
-
-  EC_COPY(&t, p);
-  if (t.x && (n->f & MP_BURN))
-    t.x->f |= MP_BURN;
-  MP_SHRINK(n);
-  EC_SETINF(d);
-  if (MP_LEN(n) == 0)
-    ;
-  else {
-    if (n->f & MP_NEG)
-      EC_NEG(c, &t, &t);
-    if (MP_LEN(n) < EXP_THRESH)
-      EXP_SIMPLE(*d, t, n);
-    else
-      EXP_WINDOW(*d, t, n);
-  }
-  EC_DESTROY(&t);
-  return (d);
-}
-
-ec *ec_mul(ec_curve *c, ec *d, const ec *p, mp *n)
-{
-  EC_IN(c, d, p);
-  ec_imul(c, d, d, n);
-  return (EC_OUT(c, d, d));
-}
-
 /*----- That's all, folks -------------------------------------------------*/