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  "   ˆl–Ãa¾”ªeJu@·pÜlJbÑ¿ÁƒqçÁÀ¿ ê    # This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import absolute_import, division, print_function

import abc

import six

from cryptography import utils


@six.add_metaclass(abc.ABCMeta)
class DSAParameters(object):
    @abc.abstractmethod
    def generate_private_key(self):
        """
        Generates and returns a DSAPrivateKey.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAParametersWithNumbers(DSAParameters):
    @abc.abstractmethod
    def parameter_numbers(self):
        """
        Returns a DSAParameterNumbers.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPrivateKey(object):
    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the prime modulus.
        """

    @abc.abstractmethod
    def public_key(self):
        """
        The DSAPublicKey associated with this private key.
        """

    @abc.abstractmethod
    def parameters(self):
        """
        The DSAParameters object associated with this private key.
        """

    @abc.abstractmethod
    def signer(self, signature_algorithm):
        """
        Returns an AsymmetricSignatureContext used for signing data.
        """

    @abc.abstractmethod
    def sign(self, data, algorithm):
        """
        Signs the data
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPrivateKeyWithSerialization(DSAPrivateKey):
    @abc.abstractmethod
    def private_numbers(self):
        """
        Returns a DSAPrivateNumbers.
        """

    @abc.abstractmethod
    def private_bytes(self, encoding, format, encryption_algorithm):
        """
        Returns the key serialized as bytes.
        """


@six.add_metaclass(abc.ABCMeta)
class DSAPublicKey(object):
    @abc.abstractproperty
    def key_size(self):
        """
        The bit length of the prime modulus.
        """

    @abc.abstractmethod
    def parameters(self):
        """
        The DSAParameters object associated with this public key.
        """

    @abc.abstractmethod
    def verifier(self, signature, signature_algorithm):
        """
        Returns an AsymmetricVerificationContext used for signing data.
        """

    @abc.abstractmethod
    def public_numbers(self):
        """
        Returns a DSAPublicNumbers.
        """

    @abc.abstractmethod
    def public_bytes(self, encoding, format):
        """
        Returns the key serialized as bytes.
        """

    @abc.abstractmethod
    def verify(self, signature, data, algorithm):
        """
        Verifies the signature of the data.
        """


DSAPublicKeyWithSerialization = DSAPublicKey


def generate_parameters(key_size, backend):
    return backend.generate_dsa_parameters(key_size)


def generate_private_key(key_size, backend):
    return backend.generate_dsa_private_key_and_parameters(key_size)


def _check_dsa_parameters(parameters):
    if utils.bit_length(parameters.p) not in [1024, 2048, 3072]:
        raise ValueError("p must be exactly 1024, 2048, or 3072 bits long")
    if utils.bit_length(parameters.q) not in [160, 256]:
        raise ValueError("q must be exactly 160 or 256 bits long")

    if not (1 < parameters.g < parameters.p):
        raise ValueError("g, p don't satisfy 1 < g < p.")


def _check_dsa_private_numbers(numbers):
    parameters = numbers.public_numbers.parameter_numbers
    _check_dsa_parameters(parameters)
    if numbers.x <= 0 or numbers.x >= parameters.q:
        raise ValueError("x must be > 0 and < q.")

    if numbers.public_numbers.y != pow(parameters.g, numbers.x, parameters.p):
        raise ValueError("y must be equal to (g ** x % p).")


class DSAParameterNumbers(object):
    def __init__(self, p, q, g):
        if (
            not isinstance(p, six.integer_types) or
            not isinstance(q, six.integer_types) or
            not isinstance(g, six.integer_types)
        ):
            raise TypeError(