Add ZVP point computation.

2 files changed, 19 insertions, 2 deletions

diff --git a/pyecsca/ec/configuration.py b/pyecsca/ec/configuration.py
index 03dc86b..6ed2190 100644
--- a/pyecsca/ec/configuration.py
+++ b/pyecsca/ec/configuration.py
@@ -1,5 +1,6 @@
 """Provides a way to work with and enumerate implementation configurations."""
 import warnings
+from abc import ABC
 from dataclasses import dataclass
 from enum import Enum
 from itertools import product
@@ -146,7 +147,7 @@ def all_configurations(**kwargs) -> Generator[Configuration, Configuration, None
         for subclass in subs:
             if subclass.__subclasses__():
                 result.update(leaf_subclasses(subclass))
-            else:
+            elif not issubclass(subclass, ABC):
                 result.add(subclass)
         return result
 
@@ -240,6 +241,7 @@ def all_configurations(**kwargs) -> Generator[Configuration, Configuration, None
                 continue
             coords_formulas = coords.formulas.values()
             mult_classes = leaf_subclasses(ScalarMultiplier)
+
             if "scalarmult" in kwargs:
                 if isinstance(kwargs["scalarmult"], ScalarMultiplier):
                     mults = [kwargs["scalarmult"]]
diff --git a/pyecsca/ec/curve.py b/pyecsca/ec/curve.py
index fb567e8..8cc7dba 100644
--- a/pyecsca/ec/curve.py
+++ b/pyecsca/ec/curve.py
@@ -2,7 +2,7 @@
 from ast import Module
 from astunparse import unparse
 from copy import copy
-from typing import MutableMapping, Union, List, Optional, Dict
+from typing import MutableMapping, Union, List, Optional, Dict, Set
 
 from public import public
 from sympy import FF, sympify
@@ -303,6 +303,21 @@ class EllipticCurve:
                 f"Wrong encoding type: {hex(encoded[0])}, should be one of 0x04, 0x06, 0x02, 0x03 or 0x00"
             )
 
+    def affine_lift_x(self, x: Mod) -> Set[Point]:
+        """
+        Lift an x-coordinate to the curve.
+
+        :param x: The x-coordinate.
+        :return: Lifted (affine) points, if any.
+        """
+        loc = {**self.parameters, "x": x}
+        ysquared = eval(compile(self.model.ysquared, "", mode="eval"), loc)
+        if not ysquared.is_residue():
+            return set()
+        y = ysquared.sqrt()
+        return {Point(AffineCoordinateModel(self.model), x=x, y=y),
+                Point(AffineCoordinateModel(self.model), x=x, y=-y)}
+
     def affine_random(self) -> Point:
         """Generate a random affine point on the curve."""
         while True: