X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a..HEAD:/math/ec-raw.h

diff --git a/math/ec-raw.h b/math/ec-raw.h
index 4792bd70..df8d1ab4 100644
--- a/math/ec-raw.h
+++ b/math/ec-raw.h
@@ -44,6 +44,71 @@
 
 /*----- Data formatting ---------------------------------------------------*/
 
+/* EC2OSP/OS2ECP bit mask. */
+#define EC_YBIT 1u			/* The compressed @y@-coordinate */
+#define EC_XONLY 1u			/* The @y@-coordinate is absent */
+#define EC_CMPR 2u			/* Compressed @y@-coordinate */
+#define EC_LSB 2u			/* Use `lsb' compression */
+#define EC_EXPLY 4u			/* Explicit @y@-coordinate */
+#define EC_SORT 8u			/* Use `sort' rather than `lsb' */
+
+/* --- @ec_ec2osp@ --- *
+ *
+ * Arguments:	@ec_curve *c@ = elliptic curve
+ *		@unsigned f@ = format flags for output
+ *		@buf *b@ = pointer to a buffer
+ *		@const ec *p@ = an elliptic curve point
+ *
+ * Returns:	Zero on success, nonzero on failure.
+ *
+ * Use:		Puts an elliptic curve point to the given buffer using the
+ *		standard uncompressed format described in P1363 and SEC1.
+ *		This requires at most @1 + 2 * c->f->noctets@ space in the
+ *		buffer.
+ *
+ *		Point compression features are determined by @f@ as follows.
+ *		If @EC_CMPR@ is set then point compression is performed and a
+ *		compressed form of the %$y$%-coordinate is contained in the
+ *		first output byte; if @EC_SORT@ is set then P1363a `SORT'
+ *		compression is used, otherwise LSB compression.  If
+ *		@EC_EXPLY@ is set, then an explicit %$y$%-coordinate is
+ *		output in full.  Otherwise the %$y$%-coordinate is
+ *		suppressed.
+ *
+ *		Returns failure (@-1@) if the flags are invalid, or if there
+ *		isn't enough space in the output buffer.
+ */
+
+extern int ec_ec2osp(ec_curve */*c*/, unsigned /*f*/,
+		     buf */*b*/, const ec */*p*/);
+
+/* --- @ec_os2ecp@ --- *
+ *
+ * Arguments:	@ec_curve *c = elliptic curve
+ *		@unsigned f@ = format flags for input
+ *		@buf *b@ = pointer to a buffer
+ *		@ec *d@ = an elliptic curve point
+ *
+ * Returns:	Zero on success, nonzero on failure.
+ *
+ * Use:		Reads an elliptic curve point from the given buffer using the
+ *		standard uncompressed format described in P1363 and SEC1.
+ *
+ *		Point compression features are determined by @f@ as follows.
+ *		If @EC_LSB@ is set, then accept an LSB-compressed %$y$%-
+ *		coordinate; if @EC_SORT@ is set, then accept a SORT-
+ *		compressed %$y$%-coordinate; if @EC_EXPLY@ is set, then
+ *		accept an explicit %$y$%-coordinate; if @EC_XONLY@ is set
+ *		then accept a bare %$x$%-coordinate (a correct
+ *		%$y$%-coordinate is chosen arbitrarily).  Hybrid forms are
+ *		acceptable, and the input is checked to verify that the
+ *		redundant representations are consistent.  If no flags are
+ *		set in @f@, then no input (other than the point at infinity)
+ *		will be acceptable.
+ */
+
+extern int ec_os2ecp(ec_curve */*c*/, unsigned /*f*/, buf */*b*/, ec */*d*/);
+
 /* --- @ec_putraw@ --- *
  *
  * Arguments:	@ec_curve *c@ = elliptic curve