7 files changed, 77 insertions, 7 deletions

diff --git a/docs/conf.py b/docs/conf.py
index 3e081ad..42b9090 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -194,7 +194,4 @@ epub_exclude_files = ['search.html']
 
 # -- Extension configuration -------------------------------------------------
 
-# -- Options for todo extension ----------------------------------------------
-
-# If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = True
\ No newline at end of file
diff --git a/pyecsca/ec/curve.py b/pyecsca/ec/curve.py
index 20dd3e0..ea18233 100644
--- a/pyecsca/ec/curve.py
+++ b/pyecsca/ec/curve.py
@@ -15,6 +15,7 @@ class EllipticCurve(object):
 
     def __init__(self, model: CurveModel, coordinate_model: CoordinateModel,
                  parameters: Mapping[str, int], neutral: Point):
+        # TODO: Add base_point arg, order arg, cofactor arg.
         if coordinate_model not in model.coordinates.values():
             raise ValueError
         if set(model.parameter_names).symmetric_difference(parameters.keys()):
@@ -27,6 +28,7 @@ class EllipticCurve(object):
         self.neutral = neutral
 
     def is_on_curve(self, point: Point) -> bool:
+        #TODO
         pass
 
     def is_neutral(self, point: Point) -> bool:
diff --git a/pyecsca/ec/formula.py b/pyecsca/ec/formula.py
index e155282..fd58a31 100644
--- a/pyecsca/ec/formula.py
+++ b/pyecsca/ec/formula.py
@@ -14,6 +14,8 @@ class Formula(object):
     _inputs: int
     _outputs: int
 
+    # TODO: Separate into EFDFormula?
+
     def __init__(self, path: str, name: str, coordinate_model: Any):
         self.name = name
         self.coordinate_model = coordinate_model
diff --git a/pyecsca/ec/model.py b/pyecsca/ec/model.py
index 40c19e9..cc474f5 100644
--- a/pyecsca/ec/model.py
+++ b/pyecsca/ec/model.py
@@ -20,6 +20,9 @@ class CurveModel(object):
     to_weierstrass: List[Module]
     from_weierstrass: List[Module]
 
+    #TODO: move the base_formulas into methods, operatin on affine points?
+    #      Also to_weierstrass anf from_weierstrass.
+
 
 class EFDCurveModel(CurveModel):
     _efd_name: str
diff --git a/pyecsca/ec/mult.py b/pyecsca/ec/mult.py
index d7c5bc6..aba2739 100644
--- a/pyecsca/ec/mult.py
+++ b/pyecsca/ec/mult.py
@@ -77,6 +77,11 @@ class ScalarMultiplier(object):
 
 @public
 class LTRMultiplier(ScalarMultiplier):
+    """
+    Classic double and add scalar multiplication algorithm, that scans the scalar left-to-right (msb to lsb)
+
+    The `always` parameter determines whether the double and add always method is used.
+    """
     always: bool
 
     def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
@@ -101,6 +106,11 @@ class LTRMultiplier(ScalarMultiplier):
 
 @public
 class RTLMultiplier(ScalarMultiplier):
+    """
+    Classic double and add scalar multiplication algorithm, that scans the scalar right-to-left (lsb to msb)
+
+    The `always` parameter determines whether the double and add always method is used.
+    """
     always: bool
 
     def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
@@ -124,8 +134,37 @@ class RTLMultiplier(ScalarMultiplier):
         return r
 
 
+class CoronMultiplier(ScalarMultiplier):
+    """
+    Coron's double and add resistant against SPA, from:
+
+    Resistance against Differential Power Analysis for Elliptic Curve Cryptosystems
+
+    https://link.springer.com/content/pdf/10.1007/3-540-48059-5_25.pdf
+    """
+
+    def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
+                 scl: ScalingFormula = None, ctx: Context = None):
+        super().__init__(curve, ctx, add=add, dbl=dbl, scl=scl)
+
+    def multiply(self, scalar: int, point: Optional[Point] = None):
+        q = self._init_multiply(point)
+        p0 = copy(q)
+        for i in range(scalar.bit_length() - 2, -1, -1):
+            p0 = self._dbl(p0)
+            p1 = self._add(p0, q)
+            if scalar & (1 << i) != 0:
+                p0 = p1
+        if "scl" in self.formulas:
+            p0 = self._scl(p0)
+        return p0
+
+
 @public
 class LadderMultiplier(ScalarMultiplier):
+    """
+    Montgomery ladder multiplier, using a three input, two output ladder formula.
+    """
 
     def __init__(self, curve: EllipticCurve, ladd: LadderFormula, scl: ScalingFormula = None,
                  ctx: Context = None):
@@ -147,6 +186,9 @@ class LadderMultiplier(ScalarMultiplier):
 
 @public
 class SimpleLadderMultiplier(ScalarMultiplier):
+    """
+    Montgomery ladder multiplier, using addition and doubling formulas.
+    """
 
     def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
                  scl: ScalingFormula = None, ctx: Context = None):
@@ -170,6 +212,9 @@ class SimpleLadderMultiplier(ScalarMultiplier):
 
 @public
 class BinaryNAFMultiplier(ScalarMultiplier):
+    """
+    Binary NAF (Non Adjacent Form) multiplier, left-to-right.
+    """
     _point_neg: Point
 
     def __init__(self, curve: EllipticCurve, add: AdditionFormula, dbl: DoublingFormula,
@@ -197,6 +242,9 @@ class BinaryNAFMultiplier(ScalarMultiplier):
 
 @public
 class WindowNAFMultiplier(ScalarMultiplier):
+    """
+    Window NAF (Non Adjacent Form) multiplier, left-to-right.
+    """
     _points: MutableMapping[int, Point]
     _width: int
 
diff --git a/pyecsca/ec/point.py b/pyecsca/ec/point.py
index 265a0ea..05f2503 100644
--- a/pyecsca/ec/point.py
+++ b/pyecsca/ec/point.py
@@ -15,6 +15,7 @@ class Point(object):
         self.coords = coords
 
     def __eq__(self, other):
+        # TODO: Somehow compare projective points. Via a map to an affinepoint?
         if type(other) is not Point:
             return False
         return self.coordinate_model == other.coordinate_model and self.coords == other.coords
diff --git a/test/ec/test_mult.py b/test/ec/test_mult.py
index cda9f76..100e53d 100644
--- a/test/ec/test_mult.py
+++ b/test/ec/test_mult.py
@@ -3,7 +3,8 @@ from unittest import TestCase
 from pyecsca.ec.curve import EllipticCurve
 from pyecsca.ec.mod import Mod
 from pyecsca.ec.model import ShortWeierstrassModel, MontgomeryModel
-from pyecsca.ec.mult import LTRMultiplier, RTLMultiplier, LadderMultiplier, BinaryNAFMultiplier, WindowNAFMultiplier, SimpleLadderMultiplier
+from pyecsca.ec.mult import (LTRMultiplier, RTLMultiplier, LadderMultiplier, BinaryNAFMultiplier,
+                             WindowNAFMultiplier, SimpleLadderMultiplier, CoronMultiplier)
 from pyecsca.ec.point import Point
 
 
@@ -46,6 +47,14 @@ class ScalarMultiplierTests(TestCase):
         other = mult.multiply(2, other)
         self.assertEqual(res, other)
 
+    def test_coron(self):
+        mult = CoronMultiplier(self.secp128r1, self.coords.formulas["add-1998-cmo"],
+                               self.coords.formulas["dbl-1998-cmo"], self.coords.formulas["z"])
+        res = mult.multiply(10, self.base)
+        other = mult.multiply(5, self.base)
+        other = mult.multiply(2, other)
+        self.assertEqual(res, other)
+
     def test_ladder(self):
         mult = LadderMultiplier(self.curve25519, self.coords25519.formulas["ladd-1987-m"],
                                 self.coords25519.formulas["scale"])
@@ -56,7 +65,8 @@ class ScalarMultiplierTests(TestCase):
 
     def test_simple_ladder(self):
         mult = SimpleLadderMultiplier(self.secp128r1, self.coords.formulas["add-1998-cmo"],
-                             self.coords.formulas["dbl-1998-cmo"], self.coords.formulas["z"])
+                                      self.coords.formulas["dbl-1998-cmo"],
+                                      self.coords.formulas["z"])
         res = mult.multiply(10, self.base)
         other = mult.multiply(5, self.base)
         other = mult.multiply(2, other)
@@ -113,6 +123,13 @@ class ScalarMultiplierTests(TestCase):
         self.assertEqual(res_wnaf, res_ltr)
 
         ladder = SimpleLadderMultiplier(self.secp128r1, self.coords.formulas["add-1998-cmo"],
-                             self.coords.formulas["dbl-1998-cmo"], self.coords.formulas["z"])
+                                        self.coords.formulas["dbl-1998-cmo"],
+                                        self.coords.formulas["z"])
         res_ladder = ladder.multiply(10, self.base)
-        self.assertEqual(res_ladder, res_ltr)
\ No newline at end of file
+        self.assertEqual(res_ladder, res_ltr)
+
+        coron = CoronMultiplier(self.secp128r1, self.coords.formulas["add-1998-cmo"],
+                                        self.coords.formulas["dbl-1998-cmo"],
+                                        self.coords.formulas["z"])
+        res_coron = coron.multiply(10, self.base)
+        self.assertEqual(res_coron, res_ltr)