X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/c3caa2face1cda7002eb58245ad75865bf437455..bc985cefafea2e1b02095a2ff2a9982c4c647d17:/ec.h

diff --git a/ec.h b/ec.h
index 07f1468..d398f4a 100644
--- a/ec.h
+++ b/ec.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec.h,v 1.5 2004/03/21 22:52:06 mdw Exp $
+ * $Id: ec.h,v 1.7 2004/03/23 15:19:32 mdw Exp $
  *
  * Elliptic curve definitions
  *
@@ -30,6 +30,14 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: ec.h,v $
+ * Revision 1.7  2004/03/23 15:19:32  mdw
+ * Test elliptic curves more thoroughly.
+ *
+ * Revision 1.6  2004/03/22 02:19:10  mdw
+ * Rationalise the sliding-window threshold.  Drop guarantee that right
+ * arguments to EC @add@ are canonical, and fix up projective implementations
+ * to cope.
+ *
  * Revision 1.5  2004/03/21 22:52:06  mdw
  * Merge and close elliptic curve branch.
  *
@@ -95,9 +103,12 @@ typedef struct ec_mulfactor {
 /* --- Elliptic curve operations --- *
  *
  * All operations (apart from @destroy@ and @in@) are guaranteed to be
- * performed on internal representations of points.  Moreover, the second
- * argument to @add@ and @mul@ is guaranteed to be the output of @in@ or
- * @fix@.
+ * performed on internal representations of points.
+ *
+ * (Historical note.  We used to guarantee that the second to @add@ and @mul@
+ * was the output of @in@ or @fix@, but this canonification turned out to
+ * make the precomputation in @ec_exp@ too slow.  Projective implementations
+ * must therefore cope with a pair of arbitrary points.)
  */
 
 typedef struct ec_ops {
@@ -227,6 +238,22 @@ extern ec *ec_setinf(ec */*p*/);
 
 extern ec *ec_copy(ec */*d*/, const ec */*p*/);
 
+/* --- @ec_eq@ --- *
+ *
+ * Arguments:	@const ec *p, *q@ = two points
+ *
+ * Returns:	Nonzero if the points are equal.  Compares external-format
+ *		points.
+ */
+
+#define EC_EQ(p, q)							\
+    ((EC_ATINF(p) && EC_ATINF(q)) ||					\
+     (!EC_ATINF(p) && !EC_ATINF(q) &&					\
+      MP_EQ((p)->x, (q)->x) &&						\
+      MP_EQ((p)->y, (q)->y)))
+
+extern int ec_eq(const ec *p, const ec *q);
+
 /*----- Interesting arithmetic --------------------------------------------*/
 
 /* --- @ec_find@ --- *
@@ -245,6 +272,19 @@ extern ec *ec_copy(ec */*d*/, const ec */*p*/);
 
 extern ec *ec_find(ec_curve */*c*/, ec */*d*/, mp */*x*/);
 
+/* --- @ec_rand@ --- *
+ *
+ * Arguments:	@ec_curve *c@ = pointer to an elliptic curve
+ *		@ec *d@ = pointer to the destination point
+ *		@grand *r@ = random number source
+ *
+ * Returns:	The destination @d@.
+ *
+ * Use:		Finds a random point on the given curve.
+ */
+
+extern ec *ec_rand(ec_curve */*c*/, ec */*d*/, grand */*r*/);
+
 /* --- @ec_neg@ --- *
  *
  * Arguments:	@ec_curve *c@ = pointer to an elliptic curve