Initial work on a prioritized multibackend for which implements CipherBackend
diff --git a/cryptography/hazmat/backends/__init__.py b/cryptography/hazmat/backends/__init__.py
index cb1fee9..b4ef210 100644
--- a/cryptography/hazmat/backends/__init__.py
+++ b/cryptography/hazmat/backends/__init__.py
@@ -12,16 +12,17 @@
# limitations under the License.
from cryptography.hazmat.backends import openssl
+from cryptography.hazmat.backends.multibackend import PrioritizedMultiBackend
from cryptography.hazmat.bindings.commoncrypto.binding import (
- Binding as CCBinding
+ Binding as CommonCryptoBinding
)
_ALL_BACKENDS = [openssl.backend]
-if CCBinding.is_available():
+if CommonCryptoBinding.is_available():
from cryptography.hazmat.backends import commoncrypto
_ALL_BACKENDS.append(commoncrypto.backend)
def default_backend():
- return openssl.backend
+ return PrioritizedMultiBackend(_ALL_BACKENDS)
diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
new file mode 100644
index 0000000..9b91ff4
--- /dev/null
+++ b/cryptography/hazmat/backends/multibackend.py
@@ -0,0 +1,45 @@
+# 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 UnsupportedAlgorithm
+from cryptography.hazmat.backends.interfaces import CipherBackend
+
+
+@utils.register_interface(CipherBackend)
+class PrioritizedMultiBackend(object):
+ name = "multibackend"
+
+ def __init__(self, backends):
+ self._backends = backends
+
+ def cipher_supported(self, algorithm, mode):
+ return any(b.cipher_supported(algorithm, mode) for b in self._backends)
+
+ def create_symmetric_encryption_ctx(self, algorithm, mode):
+ for b in self._backends:
+ try:
+ return b.create_symmetric_encryption_ctx(algorithm, mode)
+ except UnsupportedAlgorithm:
+ pass
+ raise UnsupportedAlgorithm
+
+ def create_symmetric_decryption_ctx(self, algorithm, mode):
+ for b in self._backends:
+ try:
+ return b.create_symmetric_decryption_ctx(algorithm, mode)
+ except UnsupportedAlgorithm:
+ pass
+ raise UnsupportedAlgorithm
diff --git a/tests/conftest.py b/tests/conftest.py
index ecad1b2..00c44ca 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -4,13 +4,16 @@
from cryptography.hazmat.backends.interfaces import (
HMACBackend, CipherBackend, HashBackend, PBKDF2HMACBackend
)
+from cryptography.hazmat.backends.multibackend import PrioritizedMultiBackend
from .utils import check_for_iface, check_backend_support, select_backends
def pytest_generate_tests(metafunc):
names = metafunc.config.getoption("--backend")
- selected_backends = select_backends(names, _ALL_BACKENDS)
+ selected_backends = select_backends(
+ names, _ALL_BACKENDS + [PrioritizedMultiBackend(_ALL_BACKENDS)]
+ )
if "backend" in metafunc.fixturenames:
metafunc.parametrize("backend", selected_backends)