1 files changed, 62 insertions, 0 deletions
diff --git a/pyecsca/ec/mult.py b/pyecsca/ec/mult.py
new file mode 100644
index 0000000..6a127d3
--- /dev/null
+++ b/pyecsca/ec/mult.py
@@ -0,0 +1,62 @@
+from copy import copy
+from typing import Mapping
+
+from .context import Context
+from .curve import EllipticCurve
+from .formula import Formula, AdditionFormula, DoublingFormula, ScalingFormula
+from .point import Point
+
+
+class ScalarMultiplier(object):
+    curve: EllipticCurve
+    formulas: Mapping[str, Formula]
+    context: Context
+
+    def __init__(self, curve: EllipticCurve, ctx: Context = None, **formulas: Formula):
+        for formula in formulas.values():
+            if formula is not None and formula.coordinate_model is not curve.coordinate_model:
+                raise ValueError
+        self.curve = curve
+        if ctx:
+            self.context = ctx
+        else:
+            self.context = Context()
+        self.formulas = dict(formulas)
+
+    def multiply(self, scalar: int, point: Point) -> Point:
+        raise NotImplementedError
+
+
+class LTRMultiplier(ScalarMultiplier):
+    always: bool
+
+    def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
+                 scl: ScalingFormula = None,
+                 ctx: Context = None, always: bool = False):
+        super().__init__(curve, ctx, add=add, dbl=dbl, scl=scl)
+        self.always = always
+
+    def multiply(self, scalar: int, point: Point) -> Point:
+        pass
+
+
+class RTLMultiplier(ScalarMultiplier):
+    always: bool
+
+    def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
+                 scl: ScalingFormula = None,
+                 ctx: Context = None, always: bool = False):
+        super().__init__(curve, ctx, add=add, dbl=dbl, scl=scl)
+        self.always = always
+
+    def multiply(self, scalar: int, point: Point) -> Point:
+        q = copy(point)
+        r = copy(self.curve.neutral)
+        while scalar > 0:
+            q = self.context.execute(self.formulas["dbl"], q, **self.curve.parameters)
+            if scalar & 1 != 0:
+                r = self.context.execute(self.formulas["add"], q, r, **self.curve.parameters)
+            elif self.always:
+                self.context.execute(self.formulas["add"], q, r, **self.curve.parameters)
+            scalar >>= 1
+        return r