pyecsca.ec.params module

Provides functions for obtaining domain parameters from the std-curves repository [STD].

It also provides a domain parameter class and a class for a whole category of domain parameters.

class DomainParameters(curve, generator, order, cofactor, name=None, category=None)[source]

Bases: object

Domain parameters which specify a subgroup on an elliptic curve.

>>> secp256r1 = get_params("secg", "secp256r1", "projective")
>>> str(secp256r1)
'DomainParameters(secg/secp256r1)'
>>> secp256r1.order
115792089210356248762697446949407573529996955224135760342422259061068512044369
>>> secp256r1.cofactor
1
>>> secp256r1.generator
Point([X=48439561293906451759052585252797914202762949526041747995844080717082404635286, Y=36134250956749795798585127919587881956611106672985015071877198253568414405109, Z=1] in shortw/projective)
>>> secp256r1.curve.prime
115792089210356248762697446949407573530086143415290314195533631308867097853951
>>> secp256r1.curve.parameters  
{'a': 115792089210356248762697446949407573530086143415290314195533631308867097853948,
 'b': 41058363725152142129326129780047268409114441015993725554835256314039467401291}
curve: EllipticCurve[source]
generator: Point[source]
order: int[source]
cofactor: int[source]
name: Optional[str][source]
category: Optional[str][source]
to_coords(coordinate_model)[source]

Convert the domain parameters into a different coordinate model, only possible if they are currently affine.

Parameters:

coordinate_model (CoordinateModel) – The target coordinate model.

Return type:

DomainParameters

Returns:

The transformed domain parameters

to_affine()[source]

Convert the domain parameters into the affine coordinate model, if possible.

Return type:

DomainParameters

Returns:

The transformed domain parameters

property full_order: int[source]
class DomainParameterCategory(name, description, curves)[source]

Bases: object

A category of domain parameters.

name: str[source]
description: str[source]
curves: List[DomainParameters][source]
load_category(file, coords, infty=True)[source]

Load a category of domain parameters containing several curves from a JSON file.

Parameters:

  • file (Union[str, Path, BinaryIO, IO[bytes]]) – The file to load from.

  • coords (Union[str, Callable[[str], str]]) – The name of the coordinate system to use. Can be a callable that takes as argument the name of the curve and produces the coordinate system to use for that curve.

  • infty (Union[bool, Callable[[str], bool]]) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system. Can be a callable that takes as argument the name of the curve and returns the infinity option to use for that curve.

Return type:

DomainParameterCategory

Returns:

The category.

load_params(file, coords, infty=True)[source]

Load a curve from a JSON file.

Parameters:

  • file (Union[str, Path, BinaryIO]) – The file to load from.

  • coords (str) – The name of the coordinate system to use.

  • infty (bool) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system.

Return type:

DomainParameters

Returns:

The curve.

load_params_ecgen(file, coords, infty=True)[source]

Load a curve from a file that is output of ecgen.

Parameters:

  • file (Union[str, Path, BinaryIO]) – The file to load from.

  • coords (str) – The name of the coordinate system to use.

  • infty (bool) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system.

Return type:

DomainParameters

Returns:

The curve.

load_params_ectester(file, coords, infty=True)[source]

Load a curve from a file that uses the format of ECTester.

Parameters:

  • file (Union[str, Path, BinaryIO]) – The file to load from.

  • coords (str) – The name of the coordinate system to use.

  • infty (bool) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system.

Return type:

DomainParameters

Returns:

The curve.

get_category(category, coords, infty=True)[source]

Retrieve a category from the std-curves database at https://github.com/J08nY/std-curves.

Parameters:

  • category (str) – The category to retrieve.

  • coords (Union[str, Callable[[str], str]]) – The name of the coordinate system to use. Can be a callable that takes as argument the name of the curve and produces the coordinate system to use for that curve.

  • infty (Union[bool, Callable[[str], bool]]) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system. Can be a callable that takes as argument the name of the curve and returns the infinity option to use for that curve.

Return type:

DomainParameterCategory

Returns:

The category.

get_params(category, name, coords, infty=True)[source]

Retrieve a curve from a set of stored parameters.

Uses the std-curves database at https://github.com/J08nY/std-curves.

Parameters:

  • category (str) – The category of the curve.

  • name (str) – The name of the curve.

  • coords (str) – The name of the coordinate system to use.

  • infty (bool) – Whether to use the special InfinityPoint (True) or try to use the point at infinity of the coordinate system.

Return type:

DomainParameters

Returns:

The curve.