# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import, division, print_function
import abc
import six
class CipherBackend(six.with_metaclass(abc.ABCMeta)):
@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.
"""
class HashBackend(six.with_metaclass(abc.ABCMeta)):
@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.
"""
class HMACBackend(six.with_metaclass(abc.ABCMeta)):
@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 HashContext for calculating a message authentication code.
"""
class PBKDF2HMACBackend(six.with_metaclass(abc.ABCMeta)):
@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.
"""
