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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.
import pytest
from cryptography import utils
from cryptography.exceptions import UnsupportedAlgorithm
from cryptography.hazmat.backends.interfaces import (
CipherBackend, HashBackend, HMACBackend, PBKDF2HMACBackend, RSABackend
)
from cryptography.hazmat.backends.multibackend import MultiBackend
from cryptography.hazmat.primitives import hashes, hmac
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
@utils.register_interface(CipherBackend)
class DummyCipherBackend(object):
def __init__(self, supported_ciphers):
self._ciphers = supported_ciphers
def cipher_supported(self, algorithm, mode):
return (type(algorithm), type(mode)) in self._ciphers
def create_symmetric_encryption_ctx(self, algorithm, mode):
if not self.cipher_supported(algorithm, mode):
raise UnsupportedAlgorithm
def create_symmetric_decryption_ctx(self, algorithm, mode):
if not self.cipher_supported(algorithm, mode):
raise UnsupportedAlgorithm
@utils.register_interface(HashBackend)
class DummyHashBackend(object):
def __init__(self, supported_algorithms):
self._algorithms = supported_algorithms
def hash_supported(self, algorithm):
return type(algorithm) in self._algorithms
def create_hash_ctx(self, algorithm):
if not self.hash_supported(algorithm):
raise UnsupportedAlgorithm
@utils.register_interface(HMACBackend)
class DummyHMACBackend(object):
def __init__(self, supported_algorithms):
self._algorithms = supported_algorithms
def hmac_supported(self, algorithm):
return type(algorithm) in self._algorithms
def create_hmac_ctx(self, key, algorithm):
if not self.hmac_supported(algorithm):
raise UnsupportedAlgorithm
@utils.register_interface(PBKDF2HMACBackend)
class DummyPBKDF2HMACBackend(object):
def __init__(self, supported_algorithms):
self._algorithms = supported_algorithms
def pbkdf2_hmac_supported(self, algorithm):
return type(algorithm) in self._algorithms
def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
key_material):
if not self.pbkdf2_hmac_supported(algorithm):
raise UnsupportedAlgorithm
@utils.register_interface(RSABackend)
class DummyRSABackend(object):
def generate_rsa_private_key(self, public_exponent, private_key):
pass
class TestMultiBackend(object):
def test_ciphers(self):
backend = MultiBackend([
DummyHashBackend([]),
DummyCipherBackend([
(algorithms.AES, modes.CBC),
])
])
assert backend.cipher_supported(
algorithms.AES(b"\x00" * 16), modes.CBC(b"\x00" * 16)
)
cipher = Cipher(
algorithms.AES(b"\x00" * 16),
modes.CBC(b"\x00" * 16),
backend=backend
)
cipher.encryptor()
cipher.decryptor()
cipher = Cipher(
algorithms.Camellia(b"\x00" * 16),
modes.CBC(b"\x00" * 16),
backend=backend
)
with pytest.raises(UnsupportedAlgorithm):
cipher.encryptor()
with pytest.raises(UnsupportedAlgorithm):
cipher.decryptor()
def test_hashes(self):
backend = MultiBackend([
DummyHashBackend([hashes.MD5])
])
assert backend.hash_supported(hashes.MD5())
hashes.Hash(hashes.MD5(), backend=backend)
with pytest.raises(UnsupportedAlgorithm):
hashes.Hash(hashes.SHA1(), backend=backend)
def test_hmac(self):
backend = MultiBackend([
DummyHMACBackend([hashes.MD5])
])
assert backend.hmac_supported(hashes.MD5())
hmac.HMAC(b"", hashes.MD5(), backend=backend)
with pytest.raises(UnsupportedAlgorithm):
hmac.HMAC(b"", hashes.SHA1(), backend=backend)
def test_pbkdf2(self):
backend = MultiBackend([
DummyPBKDF2HMACBackend([hashes.MD5])
])
assert backend.pbkdf2_hmac_supported(hashes.MD5())
backend.derive_pbkdf2_hmac(hashes.MD5(), 10, b"", 10, b"")
with pytest.raises(UnsupportedAlgorithm):
backend.derive_pbkdf2_hmac(hashes.SHA1(), 10, b"", 10, b"")
def test_rsa(self):
backend = MultiBackend([
DummyRSABackend()
])
backend.generate_rsa_private_key(
key_size=1024, public_exponent=65537
)
backend = MultiBackend([])
with pytest.raises(UnsupportedAlgorithm):
backend.generate_rsa_private_key(key_size=1024, public_exponent=3)
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