Add Sliding window multiplier.

1 files changed, 42 insertions, 0 deletions

diff --git a/pyecsca/codegen/templates/mult_sliding_w.c b/pyecsca/codegen/templates/mult_sliding_w.c
new file mode 100644
index 0000000..87135cc
--- /dev/null
+++ b/pyecsca/codegen/templates/mult_sliding_w.c
@@ -0,0 +1,42 @@
+#include "mult.h"
+#include "point.h"
+
+static void scalar_mult_inner(bn_t *scalar, point_t *point, curve_t *curve, point_t *out) {
+	point_t *q = point_copy(curve->neutral);
+    point_t *points[{{ 2 ** (scalarmult.width - 1) }}];
+
+    point_t *current = point_copy(point);
+    point_t *dbl = point_new();
+    point_dbl(current, curve, dbl);
+    for (long i = 0; i < {{ 2 ** (scalarmult.width - 1) }}; i++) {
+        points[i] = point_copy(current);
+        point_add(current, dbl, curve, current);
+    }
+    point_free(current);
+    point_free(dbl);
+
+    {% if scalarmult.recoding_direction == ProcessingDirection.LTR %}
+	    wsliding_t *ws = bn_wsliding_ltr(scalar, {{ scalarmult.width }});
+	{% elif scalarmult.recoding_direction == ProcessingDirection.RTL %}
+	    wsliding_t *ws = bn_wsliding_rtl(scalar, {{ scalarmult.width }});
+	{% endif %}
+
+	for (long i = 0; i < ws->length; i++) {
+		point_dbl(q, curve, q);
+		uint8_t val = ws->data[i];
+		if (val) {
+			point_accumulate(q, points[(val - 1) / 2], curve, q);
+        }
+	}
+	free(ws->data);
+	free(ws);
+
+    {%- if "scl" in scalarmult.formulas %}
+    	point_scl(q, curve, q);
+    {%- endif %}
+    point_set(q, out);
+    for (long i = 0; i < {{ 2 ** (scalarmult.width - 1) }}; i++) {
+        point_free(points[i]);
+    }
+	point_free(q);
+}
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