Add Sliding window multiplier.

4 files changed, 77 insertions, 5 deletions

diff --git a/pyecsca/codegen/bn/bn.c b/pyecsca/codegen/bn/bn.c
index 77df5ab..e0c4bcb 100644
--- a/pyecsca/codegen/bn/bn.c
+++ b/pyecsca/codegen/bn/bn.c
@@ -543,7 +543,6 @@ wsliding_t *bn_wsliding_rtl(const bn_t *bn, int w) {
 		goto exit_mask;
 	}
 
-    int u = 0;
     int i = 0;
 	while (!bn_is_0(&k) && !(bn_get_sign(&k) == BN_NEG)) {
         if (!bn_get_bit(&k, 0)) {
diff --git a/pyecsca/codegen/common.py b/pyecsca/codegen/common.py
index 56ca261..2f3dfbd 100644
--- a/pyecsca/codegen/common.py
+++ b/pyecsca/codegen/common.py
@@ -7,9 +7,17 @@ from pyecsca.ec.configuration import EnumDefine, Configuration
 from pyecsca.ec.coordinates import CoordinateModel
 from pyecsca.ec.model import (CurveModel, ShortWeierstrassModel, MontgomeryModel, EdwardsModel,
                               TwistedEdwardsModel)
-from pyecsca.ec.mult import (LTRMultiplier, RTLMultiplier, CoronMultiplier,
-                             LadderMultiplier, SimpleLadderMultiplier, DifferentialLadderMultiplier,
-                             WindowNAFMultiplier, BinaryNAFMultiplier)
+from pyecsca.ec.mult import (
+    LTRMultiplier,
+    RTLMultiplier,
+    CoronMultiplier,
+    LadderMultiplier,
+    SimpleLadderMultiplier,
+    DifferentialLadderMultiplier,
+    WindowNAFMultiplier,
+    BinaryNAFMultiplier,
+    SlidingWindowMultiplier,
+)
 
 
 @public
@@ -65,6 +73,10 @@ MULTIPLIERS = [
     {
         "name": ("wnaf", "WindowNAFMultiplier"),
         "class": WindowNAFMultiplier
+    },
+    {
+        "name": ("sliding", "SlidingWindowMultiplier"),
+        "class": SlidingWindowMultiplier
     }
 ]
 
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);
+}
\ No newline at end of file
diff --git a/test/test_impl.py b/test/test_impl.py
index 1082a28..147792e 100644
--- a/test/test_impl.py
+++ b/test/test_impl.py
@@ -11,6 +11,7 @@ from pyecsca.ec.mult import (
     CoronMultiplier,
     BinaryNAFMultiplier,
     WindowNAFMultiplier,
+    SlidingWindowMultiplier,
     AccumulationOrder,
     ProcessingDirection,
     ScalarMultiplier,
@@ -129,6 +130,24 @@ def additional(request):
             ),
             id="WNAF2",
         ),
+        pytest.param(
+            (
+                SlidingWindowMultiplier,
+                "sliding",
+                ["add-1998-cmo", "dbl-1998-cmo"],
+                {"width": 3},
+            ),
+            id="SLI1",
+        ),
+        pytest.param(
+            (
+                SlidingWindowMultiplier,
+                "sliding",
+                ["add-1998-cmo", "dbl-1998-cmo"],
+                {"width": 3, "recoding_direction": ProcessingDirection.RTL},
+            ),
+            id="SLI2",
+        ),
     ],
 )
 def target(request, additional, secp128r1) -> ImplTarget:
@@ -254,4 +273,4 @@ def test_ecdsa(target, mult, secp128r1):
 
         expected = ecdsa.sign_data(message).to_DER()
         assert target.ecdsa_verify(message, expected)
-    target.disconnect()
\ No newline at end of file
+    target.disconnect()