Projective coordinates for prime curves

[u/mdw/catacomb] / ec.h

diff --git a/ec.h b/ec.h
index 72ee7a9..476d898 100644 (file)
--- a/ec.h
+++ b/ec.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: ec.h,v 1.4.4.1 2003/06/10 13:43:53 mdw Exp $
+ * $Id: ec.h,v 1.4.4.2 2004/03/20 00:13:31 mdw Exp $
  *
  * Elliptic curve definitions
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: ec.h,v $
+ * Revision 1.4.4.2  2004/03/20 00:13:31  mdw
+ * Projective coordinates for prime curves
+ *
  * Revision 1.4.4.1  2003/06/10 13:43:53  mdw
  * Simple (non-projective) curves over prime fields now seem to work.
  *
@@ -83,27 +86,37 @@ typedef struct ec_mulfactor {
   mp *exp;                             /* The exponent */
 } ec_mulfactor;
 
-/* --- Elliptic curve operations --- */
+/* --- 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@.
+ */
 
 typedef struct ec_ops {
   void (*destroy)(ec_curve */*c*/);
   ec *(*in)(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
   ec *(*out)(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
+  ec *(*fix)(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
   ec *(*find)(ec_curve */*c*/, ec */*d*/, mp */*x*/);
   ec *(*neg)(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
   ec *(*add)(ec_curve */*c*/, ec */*d*/, const ec */*p*/, const ec */*q*/);
   ec *(*sub)(ec_curve */*c*/, ec */*d*/, const ec */*p*/, const ec */*q*/);
   ec *(*dbl)(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
+  int (*check)(ec_curve */*c*/, const ec */*p*/);
 } ec_ops;
 
 #define EC_IN(c, d, p)         (c)->ops->in((c), (d), (p))
 #define EC_OUT(c, d, p)                (c)->ops->out((c), (d), (p))
+#define EC_FIX(c, d, p)                (c)->ops->fix((c), (d), (p))
 
 #define EC_FIND(c, d, x)       (c)->ops->find((c), (d), (x))
 #define EC_NEG(c, d, x)                (c)->ops->neg((c), (d), (x))
 #define EC_ADD(c, d, p, q)     (c)->ops->add((c), (d), (p), (q))
 #define EC_SUB(c, d, p, q)     (c)->ops->sub((c), (d), (p), (q))
 #define EC_DBL(c, d, p)                (c)->ops->dbl((c), (d), (p))
+#define EC_CHECK(c, p)         (c)->ops->check((c), (p))
 
 /*----- Simple memory management things -----------------------------------*/
 
@@ -210,32 +223,6 @@ extern ec *ec_copy(ec */*d*/, const ec */*p*/);
 
 /*----- Interesting arithmetic --------------------------------------------*/
 
-/* --- @ec_in@ --- *
- *
- * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
- *             @ec *d@ = pointer to the destination point
- *             @const ec *p@ = pointer to the source point
- *
- * Returns:    The destination point.
- *
- * Use:                Converts a point to internal representation.
- */
-
-extern ec *ec_in(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
-
-/* --- @ec_out@ --- *
- *
- * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
- *             @ec *d@ = pointer to the destination point
- *             @const ec *p@ = pointer to the source point
- *
- * Returns:    The destination point.
- *
- * Use:                Converts a point to external representation.
- */
-
-extern ec *ec_out(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
-
 /* --- @ec_find@ --- *
  *
  * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
@@ -306,6 +293,18 @@ extern ec *ec_sub(ec_curve */*c*/, ec */*d*/,
 
 extern ec *ec_dbl(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 
+/* --- @ec_check@ --- *
+ *
+ * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
+ *             @const ec *p@ = pointer to the point
+ *
+ * Returns:    Zero if OK, nonzero if this is an invalid point.
+ *
+ * Use:                Checks that a point is actually on an elliptic curve.
+ */
+
+extern int ec_check(ec_curve */*c*/, const ec */*p*/);
+
 /* --- @ec_mul@, @ec_imul@ --- *
  *
  * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
@@ -343,7 +342,7 @@ extern ec *ec_immul(ec_curve */*c*/, ec */*d*/,
 
 /*----- Standard curve operations -----------------------------------------*/
 
-/* --- @ec_idin@, @ec_idout@ --- *
+/* --- @ec_idin@, @ec_idout@, @ec_idfix@ --- *
  *
  * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
  *             @ec *d@ = pointer to the destination
@@ -358,8 +357,9 @@ extern ec *ec_immul(ec_curve */*c*/, ec */*d*/,
 
 extern ec *ec_idin(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 extern ec *ec_idout(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
+extern ec *ec_idfix(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 
-/* --- @ec_projin@, @ec_projout@ --- *
+/* --- @ec_projin@, @ec_projout@, @ec_projfix@ --- *
  *
  * Arguments:  @ec_curve *c@ = pointer to an elliptic curve
  *             @ec *d@ = pointer to the destination
@@ -373,6 +373,7 @@ extern ec *ec_idout(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 
 extern ec *ec_projin(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 extern ec *ec_projout(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
+extern ec *ec_projfix(ec_curve */*c*/, ec */*d*/, const ec */*p*/);
 
 /* --- @ec_stdsub@ --- *
  *