diff options
Diffstat (limited to 'pyecsca/ec/transformations.py')
| -rw-r--r-- | pyecsca/ec/transformations.py | 55 |
1 files changed, 41 insertions, 14 deletions
diff --git a/pyecsca/ec/transformations.py b/pyecsca/ec/transformations.py index 986064b..0987235 100644 --- a/pyecsca/ec/transformations.py +++ b/pyecsca/ec/transformations.py @@ -22,8 +22,12 @@ def __M_map(params, param_names, map_parameters, map_point, model): else: neutral = map_point(param_one, param_other, params.curve.neutral, aff) curve = EllipticCurve(model, aff, params.curve.prime, neutral, parameters) - return DomainParameters(curve, map_point(param_one, param_other, params.generator, aff), params.order, - params.cofactor) + return DomainParameters( + curve, + map_point(param_one, param_other, params.generator, aff), + params.order, + params.cofactor, + ) @public @@ -35,7 +39,8 @@ def M2SW(params: DomainParameters) -> DomainParameters: :return: The converted domain parameters. """ if not isinstance(params.curve.model, MontgomeryModel) or not isinstance( - params.curve.coordinate_model, AffineCoordinateModel): + params.curve.coordinate_model, AffineCoordinateModel + ): raise ValueError def map_parameters(A, B): @@ -48,7 +53,9 @@ def M2SW(params: DomainParameters) -> DomainParameters: v = pt.y / B return Point(aff, x=u, y=v) - return __M_map(params, ("a", "b"), map_parameters, map_point, ShortWeierstrassModel()) + return __M_map( + params, ("a", "b"), map_parameters, map_point, ShortWeierstrassModel() + ) @public @@ -60,7 +67,8 @@ def M2TE(params: DomainParameters) -> DomainParameters: :return: The converted domain parameters. """ if not isinstance(params.curve.model, MontgomeryModel) or not isinstance( - params.curve.coordinate_model, AffineCoordinateModel): + params.curve.coordinate_model, AffineCoordinateModel + ): raise ValueError def map_parameters(A, B): @@ -85,7 +93,8 @@ def TE2M(params: DomainParameters) -> DomainParameters: :return: The converted domain parameters. """ if not isinstance(params.curve.model, TwistedEdwardsModel) or not isinstance( - params.curve.coordinate_model, AffineCoordinateModel): + params.curve.coordinate_model, AffineCoordinateModel + ): raise ValueError def map_parameters(a, d): @@ -110,16 +119,25 @@ def SW2M(params: DomainParameters) -> DomainParameters: :return: The converted domain parameters. """ if not isinstance(params.curve.model, ShortWeierstrassModel) or not isinstance( - params.curve.coordinate_model, AffineCoordinateModel): + params.curve.coordinate_model, AffineCoordinateModel + ): raise ValueError ax = symbols("α") field = FF(params.curve.prime) - rhs = Poly(ax ** 3 + field(int(params.curve.parameters["a"])) * ax + field(int(params.curve.parameters["b"])), ax, domain=field) + rhs = Poly( + ax ** 3 + + field(int(params.curve.parameters["a"])) * ax + + field(int(params.curve.parameters["b"])), + ax, + domain=field, + ) roots = rhs.ground_roots() if not roots: - raise ValueError("Curve cannot be transformed to Montgomery model (x^3 + ax + b has no root).") + raise ValueError( + "Curve cannot be transformed to Montgomery model (x^3 + ax + b has no root)." + ) alpha = Mod(int(next(iter(roots.keys()))), params.curve.prime) - beta = (3 * alpha**2 + params.curve.parameters["a"]).sqrt() + beta = (3 * alpha ** 2 + params.curve.parameters["a"]).sqrt() def map_parameters(a, b): A = (3 * alpha) / beta @@ -143,16 +161,25 @@ def SW2TE(params: DomainParameters) -> DomainParameters: :return: The converted domain parameters. """ if not isinstance(params.curve.model, ShortWeierstrassModel) or not isinstance( - params.curve.coordinate_model, AffineCoordinateModel): + params.curve.coordinate_model, AffineCoordinateModel + ): raise ValueError ax = symbols("α") field = FF(params.curve.prime) - rhs = Poly(ax ** 3 + field(int(params.curve.parameters["a"])) * ax + field(int(params.curve.parameters["b"])), ax, domain=field) + rhs = Poly( + ax ** 3 + + field(int(params.curve.parameters["a"])) * ax + + field(int(params.curve.parameters["b"])), + ax, + domain=field, + ) roots = rhs.ground_roots() if not roots: - raise ValueError("Curve cannot be transformed to Montgomery model (x^3 + ax + b has no root).") + raise ValueError( + "Curve cannot be transformed to Montgomery model (x^3 + ax + b has no root)." + ) alpha = Mod(int(next(iter(roots.keys()))), params.curve.prime) - beta = (3 * alpha**2 + params.curve.parameters["a"]).sqrt() + beta = (3 * alpha ** 2 + params.curve.parameters["a"]).sqrt() def map_parameters(a, b): a = 3 * alpha + 2 * beta |