Source code for btclib_ecc.curves.curve_group_f

# Copyright (c) The btclib developers
# Distributed under the MIT software license, see the accompanying
# LICENSE file or https://opensource.org/license/mit for the full text.

"""CurveGroup explorer functions, for low-cardinality didactic curves.

Enumerating the points of a group is feasible only when the group is
tiny, which is what makes these useful in teaching and useless -- and
never used -- in the rest of the library.
"""

from __future__ import annotations

from btclib_ecc.alias import INF, Point
from btclib_ecc.curves.curve_group import CurveGroup, _assert_valid_ec
from btclib_ecc.exceptions import BTClibEccValueError

__all__ = [
    "find_all_points",
    "find_subgroup_points",
]




def find_all_points(ec: CurveGroup) -> list[Point]:
    """Attempt to find all group points, if p is low.

    Very unsofisticated walk-through approach, for didactic sake only.
    """
    _assert_valid_ec(ec)
    if ec.p > 10000:
        err_msg = f"p is too big to count all group points: {ec.p}"
        raise BTClibEccValueError(err_msg)

    points: list[Point] = [INF]
    for x in range(ec.p):
        try:
            y = ec.y_var(x)
        except BTClibEccValueError:
            continue

        points.append((x, y))
        if y != 0:
            points.append((x, ec.p - y))

    return points





def find_subgroup_points(ec: CurveGroup, G: Point) -> list[Point]:
    """Attempt to count all G-generated subgroup points, if p is low.

    Very unsofisticated walk-through approach, for didactic sake only.
    """
    _assert_valid_ec(ec)
    if ec.p > 10000:
        err_msg = f"p is too big to count all subgroup points: {ec.p}"
        raise BTClibEccValueError(err_msg)

    points = [G]
    while points[-1] != INF:
        Q = ec.add_var(points[-1], G)
        points.append(Q)

    return points