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# 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
from cryptography import utils
from cryptography.exceptions import AlreadyFinalized
from cryptography.hazmat.primitives import interfaces
class Cipher(object):
def __init__(self, algorithm, mode, backend=None):
if backend is None:
from cryptography.hazmat.bindings import (
_default_backend as backend,
)
if not isinstance(algorithm, interfaces.CipherAlgorithm):
raise TypeError("Expected interface of interfaces.CipherAlgorithm")
self.algorithm = algorithm
self.mode = mode
self._backend = backend
def encryptor(self):
return _CipherContext(self._backend.create_symmetric_encryption_ctx(
self.algorithm, self.mode
))
def decryptor(self):
return _CipherContext(self._backend.create_symmetric_decryption_ctx(
self.algorithm, self.mode
))
@utils.register_interface(interfaces.CipherContext)
class _CipherContext(object):
def __init__(self, ctx):
self._ctx = ctx
def update(self, data):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized")
return self._ctx.update(data)
def finalize(self):
if self._ctx is None:
raise AlreadyFinalized("Context was already finalized")
data = self._ctx.finalize()
self._ctx = None
return data
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