N
  :   ˆl–Ãa¾”ªeJu@·pÜlJbÑ¿Á„ëÿa–Ü4ý('TËmJq@³q±\iå1hßÄ ('    # 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


@six.add_metaclass(abc.ABCMeta)
class CipherBackend(object):
    @abc.abstractmethod
    def cipher_supported(self, cipher, mode):
        """
        Return True if the given cipher and mode are supported.
        """

    @abc.abstractmethod
    def create_symmetric_encryption_ctx(self, cipher, mode):
        """
        Get a CipherContext that can be used for encryption.
        """

    @abc.abstractmethod
    def create_symmetric_decryption_ctx(self, cipher, mode):
        """
        Get a CipherContext that can be used for decryption.
        """


@six.add_metaclass(abc.ABCMeta)
class HashBackend(object):
    @abc.abstractmethod
    def hash_supported(self, algorithm):
        """
        Return True if the hash algorithm is supported by this backend.
        """

    @abc.abstractmethod
    def create_hash_ctx(self, algorithm):
        """
        Create a HashContext for calculating a message digest.
        """


@six.add_metaclass(abc.ABCMeta)
class HMACBackend(object):
    @abc.abstractmethod
    def hmac_supported(self, algorithm):
        """
        Return True if the hash algorithm is supported for HMAC by this
        backend.
        """

    @abc.abstractmethod
    def create_hmac_ctx(self, key, algorithm):
        """
        Create a MACContext for calculating a message authentication code.
        """


@six.add_metaclass(abc.ABCMeta)
class CMACBackend(object):
    @abc.abstractmethod
    def cmac_algorithm_supported(self, algorithm):
        """
        Returns True if the block cipher is supported for CMAC by this backend
        """

    @abc.abstractmethod
    def create_cmac_ctx(self, algorithm):
        """
        Create a MACContext for calculating a message authentication code.
        """


@six.add_metaclass(abc.ABCMeta)
class PBKDF2HMACBackend(object):
    @abc.abstractmethod
    def pbkdf2_hmac_supported(self, algorithm):
        """
        Return True if the hash algorithm is supported for PBKDF2 by this
        backend.
        """

    @abc.abstractmethod
    def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
                           key_material):
        """
        Return length bytes derived from provided PBKDF2 parameters.
        """


@six.add_metaclass(abc.ABCMeta)
class RSABackend(object):
    @abc.abstractmethod
    def generate_rsa_private_key(self, public_exponent, key_size):
        """
        Generate an RSAPrivateKey instance with public_exponent and a modulus
        of key_size bits.
        """

    @abc.abstractmethod
    def rsa_padding_supported(self, padding):
        """
        Returns True if the backend supports the given padding options.
        """

    @abc.abstractmethod
    def generate_rsa_parameters_supported(self, public_exponent, key_size):
        """
        Returns True if the backend supports the given parameters for key
        generation.
        """

    @abc.abstractmethod
    def load_rsa_private_numbers(self, numbers):
        """
        Returns an RSAPrivateKey provider.
        """

    @abc.abstractmethod
    def load_rsa_public_numbers(self, numbers):
        """
        Returns an RSAPublicKey provider.
        """


@six.add_metaclass(abc.ABCMeta)
class DSABackend(object):
    @abc.abstractmethod
    def generate_dsa_parameters(self, key_size):
        """
        Generate a DSAParameters instance with a modulus of key_size bits.
        """

    @abc.abstractmethod
    def generate_dsa_private_key(self, parameters):
        """
        Generate a DSAPrivateKey instance with parameters as a DSAParameters
        object.
        """

    @abc.abstractmethod
    def generate_dsa_private_key_and_parameters(self, key_size):
        """
        Generate a DSAPrivateKey inst