Allow to compute non-affine factor set.

2 files changed, 15 insertions, 8 deletions

diff --git a/pyecsca/sca/re/zvp.py b/pyecsca/sca/re/zvp.py
index 0f04fe5..53a38a2 100644
--- a/pyecsca/sca/re/zvp.py
+++ b/pyecsca/sca/re/zvp.py
@@ -164,16 +164,20 @@ def is_homogeneous(polynomial: Poly, weighted_variables: List[Tuple[str, int]])
 
 
 @public
-def compute_factor_set(formula: Formula) -> Set[Poly]:
+def compute_factor_set(formula: Formula, affine: bool = True) -> Set[Poly]:
     """
     Compute a set of factors present in the :paramref:`~.compute_factor_set.formula`.
 
     :param formula: Formula to compute the factor set of.
+    :param affine: Whether to transform the polynomials into affine form.
     :return: The set of factors present in the formula.
     """
     unrolled = unroll_formula(formula)
     unrolled = filter_out_nonhomogenous_polynomials(formula, unrolled)
-    unrolled = map_to_affine(formula, unrolled)
+    if affine:
+        unrolled = map_to_affine(formula, unrolled)
+
+    curve_params = set(formula.coordinate_model.curve_model.parameter_names)
 
     factors = set()
     # Go over all the unrolled intermediates
@@ -184,9 +188,8 @@ def compute_factor_set(formula: Formula) -> Set[Poly]:
         for factor, power in factor_list:
             # Remove unnecessary variables from the Poly
             reduced = factor.exclude()
-            # If there are only one-letter variables remaining, those are only curve parameters
-            # so we do not care about the polynomial
-            if all(len(str(gen)) == 1 for gen in reduced.gens):  # type: ignore[attr-defined]
+            # If there are only curve parameters, we do not care about the polynomial
+            if set(reduced.gens).issubset(curve_params):  # type: ignore[attr-defined]
                 continue
             # Divide out the GCD of the coefficients from the poly
             _, reduced = reduced.primitive()
diff --git a/test/sca/test_zvp.py b/test/sca/test_zvp.py
index 32132fd..ceb8941 100644
--- a/test/sca/test_zvp.py
+++ b/test/sca/test_zvp.py
@@ -39,7 +39,7 @@ def test_map_to_affine(formula):
 
 
 def test_factor_set(formula):
-    factor_set = compute_factor_set(formula)
+    factor_set = compute_factor_set(formula, affine=True)
     assert factor_set is not None
     assert isinstance(factor_set, set)
     expr_set = set(map(lambda poly: poly.as_expr(), factor_set))
@@ -154,15 +154,19 @@ def test_zvp(secp128r1, formula):
     unrolled = unroll_formula(formula)
     unrolled = map_to_affine(formula, unrolled)
     # Try all intermediates, zvp_point should return empty set if ZVP points do not exist
+    # Try with a few scalars to actually test more resulting ZVP points
     for name, poly in unrolled:
-        points = zvp_points(poly, secp128r1.curve, 5, secp128r1.order)
+        for k in (2, 3, 5):
+            points = zvp_points(poly, secp128r1.curve, k, secp128r1.order)
+            if points:
+                break
         assert isinstance(points, set)
 
         # If points are produced, try them all.
         for point in points:
             inputs = [point.to_model(formula.coordinate_model, secp128r1.curve)]
             if formula.num_inputs > 1:
-                second_point = secp128r1.curve.affine_multiply(point, 5)
+                second_point = secp128r1.curve.affine_multiply(point, k)
                 inputs.append(
                     second_point.to_model(formula.coordinate_model, secp128r1.curve)
                 )