param_sweep.py

"""
This module provides a function to iterate over multiple inputs to the
Lattice Estimator, and graph the resulting bits of security of the associated
lattice instances.

Note: running the parameter sweep can take minutes to hours, depending on the
number of parameter combinations (the larger the ranges and the smaller the
increment intervals, the more parameter combinations will be computed). For
faster and rougher results, use the `LWE.estimate.rough` function.
"""

import pickle
import time
import math
import os
import itertools as it
from multiprocessing import Pool
from functools import partial
from dataclasses import dataclass, astuple
from typing import Iterable, Union, Optional, Callable

import numpy as np
from matplotlib import pyplot as plt

from estimator import ND, LWE
from estimator.io import Logging


class ParameterSweep:
    """
    A class that provides utilities for performing and graphing the results
    from performing parameter sweeps using the lattice estimator.
    """

    @staticmethod
    def parameter_sweep(
        n: Union[int, Iterable],
        q: Union[int, Iterable],
        e: Union[float, Iterable],
        s: Union[float, Iterable],
        m: Optional[Union[int, Iterable]] = None,
        Xe: Callable = ND.DiscreteGaussian,
        e_log: bool = True,
        Xs: Callable = ND.DiscreteGaussian,
        s_log: bool = True,
        tag: str = None,
        f: Callable = LWE.estimate,
        num_proc: int = 8,
        log_level: int = 0,
    ) -> dict:
        """
        Performs a sweep over the parameters specified.

        :param n: the dimension of the LWE sample vector (Z/qZ)^n.
        :param q: the modulus of the space Z/qZ of integers for the LWE samples.
        :param e: the input to the distribution function for the error term.
        :param s: the input to the distribution function for the secret term.
        :param m: the number of LWE samples allowed to an attacker.
        :param Xe: the distribution function for the error term.
        :param e_log: whether to plot the error on a logarithmic scale.
        :param Xs: the distribution function for the secret term.
        :param s_log: whether to plot the secret on a logarithmic scale.
        :param tag: a name for the patameter set
        :param f: the estimation function. Use `LWE.estimate.rough` for speed.
        :param num_proc: the number of parallel processes for computation.
        :param log_level: the logging level.
        :returns: a dictionary mapping from a set of parameters, to the
            estimated security level for those parameters. The ordering of
            the parameters in the dict key is: (n, q, e, s, m).

        EXAMPLE ::

            >>> from estimator import LWE, ND
            >>> from param_sweep import ParameterSweep as PS
            >>> n_list = [600, 900]
            >>> e_list = [7, 9]
            >>> results = PS.parameter_sweep(\
                    n=n_list,\
                    q=2**32,\
                    e=e_list,\
                    s=2,\
                    s_log=False,\
                    Xs=ND.UniformMod,\
                    f=LWE.estimate.rough,\
                    tag='test',\
                    log_level=2,\
                    num_proc=1,\
                )
            usvp                 :: rop: ≈2^45.6, red: ≈2^45.6, δ: 1.007290, β: 156, d: 1120, tag: usvp
            dual_hybrid          :: rop: ≈2^45.7, red: ≈2^45.6, guess: ≈2^41.9, β: 156, p: 2, ζ: 0, t: 20, β': 156, ...
            usvp                 :: rop: ≈2^51.7, red: ≈2^51.7, δ: 1.006767, β: 177, d: 1124, tag: usvp
            dual_hybrid          :: rop: ≈2^51.4, red: ≈2^51.4, guess: ≈2^46.6, β: 176, p: 2, ζ: 0, t: 30, β': 176, ...
            usvp                 :: rop: ≈2^82.9, red: ≈2^82.9, δ: 1.005021, β: 284, d: 1661, tag: usvp
            dual_hybrid          :: rop: ≈2^80.5, red: ≈2^80.3, guess: ≈2^77.1, β: 275, p: 2, ζ: 0, t: 60, β': 275, ...
            usvp                 :: rop: ≈2^92.6, red: ≈2^92.6, δ: 1.004667, β: 317, d: 1650, tag: usvp
            dual_hybrid          :: rop: ≈2^89.4, red: ≈2^89.1, guess: ≈2^87.3, β: 305, p: 2, ζ: 0, t: 70, β': 305, ...
            >>> results[(600, 4294967296, 9.0, 2.0, 600, 'test')]
            51.4434...
            >>> results[(600, 4294967296, 7.0, 2.0, 600, 'test')]
            45.552
            >>> results[(900, 4294967296, 7.0, 2.0, 900, 'test')]
            80.450...
            >>> results[(900, 4294967296, 9.0, 2.0, 900, 'test')]
            89.442...
        """
        n, q, m, e, s = [
            param if hasattr(param, "__iter__") else [param] for param in (n, q, m, e, s)
        ]

        @dataclass
        class Params:
            n: int
            q: int
            e: float
            s: float
            m: int

            def __post_init__(self):
                if self.m is None:
                    self.m = self.n
                # Check types are same as annotations
                for name, field_type in self.__annotations__.items():
                    obj = self.__dict__[name]
                    if not isinstance(obj, field_type):
                        # Attempt conversion to correct type
                        setattr(self, name, field_type(obj))

        tasks = [astuple(Params(*params)) for params in it.product(n, q, e, s, m)]

        fn = partial(
            ParameterSweep.security_level,
            Xe=Xe,
            e_log=e_log,
            Xs=Xs,
            s_log=s_log,
            tag=tag,
            f=f,
            log_level=log_level,
        )

        if num_proc <= 1:
            return {(*task, tag): fn(task) for task in tasks}

        # Parallel process the calculations
        with Pool(processes=min(num_proc, len(tasks))) as pool:
            return {(*task, tag): value for task, value in zip(tasks, pool.map(fn, tasks))}

    @staticmethod
    def security_level(
        input_params: tuple[int, float],
        Xe: Callable = ND.DiscreteGaussian,
        e_log: bool = True,
        Xs: Callable = ND.DiscreteGaussian,
        s_log: bool = True,
        tag: str = None,
        f: Callable = LWE.estimate,
        log_level: int = 0,
    ) -> float:
        """
        Calls the lattice-estimator for a given set of input
        parameters, and appends the output to the `result_dict` dict.

        :param input_params: a tuple of params to estimate security for.
            Parameter ordering is: (n: int, q: int, e: float, s: float, m: int).
        :param result_dict: the dictionary to append the output to. The key is
            the tuple of parameters from input_params.
        :param Xe: the distribution function for the error term.
        :param e_log: whether to plot the error on a logarithmic scale.
        :param Xs: the distribution function for the secret term.
        :param s_log: whether to plot the secret on a logarithmic scale.
        :param tag: a name for the patameter set
        :param f: the estimation function. Use `LWE.estimate.rough` for speed.
        :param log_level: the logging level.
        """
        n_ = int(input_params[0])
        q_ = int(input_params[1])
        e_ = 2 ** input_params[2] if e_log else input_params[2]
        s_ = 2 ** input_params[3] if s_log else input_params[3]
        # If m = infinity, pass infinity to the estimator (since infinity can't be cast to an int).
        m_ = float("inf") if input_params[4] == float("inf") else int(input_params[4])

        lwe_params = LWE.Parameters(
            n=n_,
            q=q_,
            Xe=Xe(e_),
            Xs=Xs(s_),
            m=m_,
            tag=tag,
        )
        estimator_result = f(lwe_params)
        security = min([math.log(res.get("rop", 0), 2) for res in estimator_result.values()])
        if not security:
            raise ValueError("ROP for a estimator result was 0, estimator failed")
        Logging.log("sweep", log_level, f"Parameters = {lwe_params}; security = {security}")
        return security

    @staticmethod
    def graph_parameter_sweep(
        n: Union[int, Iterable],
        q: Union[int, Iterable],
        e: Union[float, Iterable],
        s: Union[float, Iterable],
        m: Optional[Union[int, Iterable]] = None,
        Xe: Callable = ND.DiscreteGaussian,
        e_log: bool = True,
        Xs: Callable = ND.DiscreteGaussian,
        s_log: bool = True,
        tag: str = None,
        f: Callable = LWE.estimate,
        num_proc: int = 8,
        log_level: int = 0,
        make_pickle: bool = False,
        load_pickle: bool = False,
        security_cutoff: int = None,
        directory: str = None,
        file_name: str = None,
        extension: str = ".png",
    ) -> None:
        """
        Gets the results of a parameter sweep, and creates graph visualizations
        of the data. The type of graph depends on the number of variables.

        :param n: the dimension of the LWE sample vector (Z/qZ)^n.
        :param q: the modulus of the space Z/qZ of integers for the LWE samples.
        :param e: the input to the distribution function for the error term.
        :param s: the input to the distribution function for the secret term.
        :param m: the number of LWE samples allowed to an attacker.
        :param Xe: the distribution function for the error term.
        :param e_log: whether to plot the error on a logarithmic scale.
        :param Xs: the distribution function for the secret term.
        :param s_log: whether to plot the secret on a logarithmic scale.
        :param tag: a name for the patameter set
        :param f: the estimation function. Use `LWE.estimate.rough` for speed.
        :param num_proc: the number of parallel processes for computation.
        :param log_level: the logging level.
        :param make_pickle: whether to make a pickle file of the results dict.
        :param load_pickle: whether to load a pickle file of the results dict.
        :param security_cutoff: makes a separate graph with a security cutoff.
        :param directory: the directory to load files from and/or save files to.
        :param file_name: the file name to load files from and/or save files to.
        :param extension: the extension of the graph(s). Ex: .png, .pdf, .svg.

        EXAMPLE ::

            >>> from estimator import LWE, nd
            >>> from param_sweep import ParameterSweep as PS
            >>> import uuid
            >>> from pathlib import Path
            >>> e_range = range(7, 10, 2)
            >>> s_range = range(2, 5, 2)
            >>> file_name = 'test_file_' + str(uuid.uuid4())
            >>> _ = PS.graph_parameter_sweep(\
                    n=700,\
                    q=2**32,\
                    e=e_range,\
                    s=s_range,\
                    f=LWE.estimate.rough,\
                    tag='test',\
                    directory='/tmp',\
                    make_pickle=True,\
                    security_cutoff=128,\
                    file_name=file_name,\
                    num_proc=1,\
                )
            usvp                 :: rop: ≈2^69.2, red: ≈2^69.2, δ: 1.005647, β: 237, d: 1396, tag: usvp
            dual_hybrid          :: rop: ≈2^70.7, red: ≈2^70.7, guess: ≈2^63.6, β: 242, p: 3, ζ: 0, t: 0, β': 242, ...
            usvp                 :: rop: ≈2^78.8, red: ≈2^78.8, δ: 1.005191, β: 270, d: 1396, tag: usvp
            dual_hybrid          :: rop: ≈2^80.6, red: ≈2^80.6, guess: ≈2^74.0, β: 276, p: 3, ζ: 0, t: 0, β': 276, ...
            usvp                 :: rop: ≈2^78.8, red: ≈2^78.8, δ: 1.005191, β: 270, d: 1391, tag: usvp
            dual_hybrid          :: rop: ≈2^80.6, red: ≈2^80.6, guess: ≈2^70.0, β: 276, p: 3, ζ: 0, t: 0, β': 276, ...
            usvp                 :: rop: ≈2^90.5, red: ≈2^90.5, δ: 1.004738, β: 310, d: 1394, tag: usvp
            dual_hybrid          :: rop: ≈2^92.6, red: ≈2^92.6, guess: ≈2^82.3, β: 317, p: 3, ζ: 0, t: 0, β': 317, ...

            >>> Path(f'/tmp/{file_name}.pickle').exists()
            True
            >>> Path(f'/tmp/{file_name}_gradient.png').exists()
            True
            >>> Path(f'/tmp/{file_name}_cutoff.png').exists()
            True
            >>> results = pickle.load(open(f'/tmp/{file_name}.pickle', 'rb'))
            >>> results[(700, 4294967296, 9.0, 2.0, 700, 'test')]
            78.83999999999999
            >>> results[(700, 4294967296, 9.0, 4.0, 700, 'test')]
            90.52000000000001
            >>> results[(700, 4294967296, 7.0, 4.0, 700, 'test')]
            78.83999999999999
            >>> results[(700, 4294967296, 7.0, 2.0, 700, 'test')]
            69.204
        """
        if directory is None:
            directory = os.path.dirname(os.path.realpath(__file__))
        if file_name is None:
            file_name = time.strftime("%d-%m-%Y_%H-%M-%S")
        file_name = os.path.join(directory, file_name)
        assert num_proc >= 1, "need at least one process to execute"

        pickle_filename = f"{file_name}.pickle"
        if load_pickle is True:
            with open(pickle_filename, "rb") as f:
                result_dict = pickle.load(f)
        else:
            result_dict = ParameterSweep.parameter_sweep(
                n, q, e, s, m, Xe, e_log, Xs, s_log, tag, f, num_proc, log_level
            )
            if make_pickle is True:
                # Pickle the intermediate computation results
                with open(pickle_filename, "wb") as f:
                    pickle.dump(result_dict, f)
                Logging.log(
                    "sweep",
                    log_level,
                    "Pickled the intermediate computations to: %s",
                    pickle_filename,
                )

        Xe_string = "log_2(Xe)" if e_log else "Xe"
        Xs_string = "log_2(Xs)" if s_log else "Xs"
        params = {
            "n": (n, 0),
            "q": (q, 1),
            Xe_string: (e, 2),
            Xs_string: (s, 3),
            "m": (m, 4),
        }

        ParameterSweep.graph_results(
            result_dict,
            params,
            file_name,
            security_cutoff,
            log_level,
            extension,
        )

    @staticmethod
    def graph_results(
        result_dict: dict,
        params: dict[str, (list[Union[int, float]], int)],
        file_name: str,
        security_cutoff: int = None,
        log_level: int = 0,
        extension: str = ".png",
    ):
        """
        Graph the security estimate results in `result_dict`, using the
        parameters in `params` for labeling the plot axes and titles.
        - For 1 variable: creates a line plot.
        - For 2 variables: creates a heatmap plot, and an optional cutoff plot.

        :param result_dict: a mapping from a set of parameters, to security.
            Parameter ordering: (n: int, q: int, e: float, s: float, m: int).
        :param params: a mapping from the string representation of a parameter,
            to a tuple of the parameter and its associated order in the
            `result_dict` key. Example: {'n': (600, 0), 'q'': (4294967296, 1)}
        :param file_name: the file name to write the output graphs to.
        :param security_cutoff: makes a separate graph with a security cutoff.
        :param log_level: the logging level
        :param extension: the extension of the graph(s). Ex: .png, .pdf, .svg.
        """

        # Convert parameter iterators to lists.
        # Also keep track of the axis and fixed variables, for labeling.
        axis_vars = {}
        fixed_vars = {}
        for p, sec in params.items():
            try:
                # The variable is an axis variable
                params[p] = (list(sec[0]), sec[1])
                axis_vars[p] = len(sec[0])
            except TypeError:
                # The variable is a fixed variable
                params[p] = ([sec[0]], sec[1])
                fixed_vars[p] = sec[0]

        if len(axis_vars) == 0:
            raise ValueError(
                "Cannot plot when there are no variables. Call the lattice estimator directly for security."
            )
        elif len(axis_vars) == 1:
            variable_param = list(axis_vars.keys())[0]  # a string like 'Xe'
            x = sorted(params[variable_param][0])
            y = sorted(result_dict.items(), key=lambda x: x[params[variable_param][1]])
            y = list(zip(*y))[1]
            fig, ax = plt.subplots(figsize=(20, 20), dpi=80)

            ax.plot(x, y)
            ax.set_xlabel(f"Parameter: {variable_param}")
            ax.set_ylabel("Security")

            plot_filename = f"{file_name}_plot{extension}"
            plt.title(f"Security with parameters {fixed_vars}")
            fig.savefig(plot_filename)
            Logging.log("sweep", log_level, "Saved the line plot graph to: %s", plot_filename)
        elif len(axis_vars) == 2:
            axis_vars = sorted(axis_vars.items(), key=lambda x: params[x[0]][1])
            x_param = axis_vars[0][0]
            x = sorted(params[x_param][0])
            y_param = axis_vars[1][0]
            y = sorted(params[y_param][0])

            values = [v for _, v in sorted(result_dict.items(), key=lambda x: x[0])]
            mat = np.flip(np.array(values).reshape((len(set(x)), len(set(y)))), axis=1).transpose()

            fig, ax = plt.subplots(figsize=(20, 20), dpi=80)

            ax.imshow(mat)
            ax.set_xticks(np.arange(0, len(set(x)), 1))
            ax.set_yticks(np.arange(0, len(set(y)), 1))
            ax.set_xticklabels(sorted(set(x)))
            ax.set_yticklabels(sorted(set(y), reverse=True))

            plt.title(f"Security with fixed parameters {fixed_vars}")

            for (j, i), label in np.ndenumerate(mat):
                ax.text(
                    i,
                    j,
                    round(label, 1),
                    ha="center",
                    va="center",
                    color="white",
                )

            ax.set_xlabel(f"Parameter: {x_param}")
            ax.set_ylabel(f"Parameter: {y_param}")

            gradient_filename = f"{file_name}_gradient{extension}"
            fig.savefig(gradient_filename)
            Logging.log("sweep", log_level, "Saved the gradient graph to: %s", gradient_filename)

            if security_cutoff:
                fig2, ax2 = plt.subplots(figsize=(20, 20), dpi=80)
                binary_mat = mat >= security_cutoff
                ax2.imshow(binary_mat)
                ax2.set_xticks(np.arange(0, len(set(x)), 1))
                ax2.set_yticks(np.arange(0, len(set(y)), 1))
                ax2.set_xticklabels(sorted(set(x)))
                ax2.set_yticklabels(sorted(set(y), reverse=True))

                for (j, i), label in np.ndenumerate(mat):
                    ax2.text(
                        i,
                        j,
                        round(label, 1),
                        ha="center",
                        va="center",
                        color="white" if label < security_cutoff else "black",
                    )

                    ax.text(
                        i,
                        j,
                        round(label, 1),
                        ha="center",
                        va="center",
                        color="white",
                    )
                plt.title(
                    f"Security with fixed parameters {fixed_vars} and cutoff at {security_cutoff}"
                )

                ax2.set_xlabel(f"Parameter: {x_param}")
                ax2.set_ylabel(f"Parameter: {y_param}")

                cutoff_filename = f"{file_name}_cutoff{extension}"
                fig2.savefig(cutoff_filename)
                Logging.log("sweep", log_level, "Saved the cutoff graph to: %s", cutoff_filename)
        else:
            raise ValueError(
                "Cannot plot more than two variables. Try freezing one or more of them."
            )