UnsupportedAlgorithm error messages for Ciphers
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index 588a427..714823e 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -288,11 +288,19 @@
try:
adapter = registry[type(cipher), type(mode)]
except KeyError:
- raise UnsupportedAlgorithm
+ raise UnsupportedAlgorithm(
+ "cipher {0} in {1} mode is not supported "
+ "by this backend".format(
+ cipher.name, mode.name if mode else mode)
+ )
evp_cipher = adapter(self._backend, cipher, mode)
if evp_cipher == self._backend.ffi.NULL:
- raise UnsupportedAlgorithm
+ raise UnsupportedAlgorithm(
+ "cipher {0} in {1} mode is not supported "
+ "by this backend".format(
+ cipher.name, mode.name if mode else mode)
+ )
if isinstance(mode, interfaces.ModeWithInitializationVector):
iv_nonce = mode.initialization_vector
diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst
index f4d0457..dfadd89 100644
--- a/docs/hazmat/primitives/symmetric-encryption.rst
+++ b/docs/hazmat/primitives/symmetric-encryption.rst
@@ -61,7 +61,7 @@
provider.
If the backend doesn't support the requested combination of ``cipher``
- and ``mode`` an :class:`cryptography.exceptions.UnsupportedAlgorithm`
+ and ``mode`` an :class:`~cryptography.exceptions.UnsupportedAlgorithm`
will be raised.
.. method:: decryptor()
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 962959b..543a05f 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -23,13 +23,14 @@
from cryptography.hazmat.primitives.ciphers.modes import CBC
+@utils.register_interface(interfaces.Mode)
class DummyMode(object):
- pass
+ name = "dummy-mode"
@utils.register_interface(interfaces.CipherAlgorithm)
class DummyCipher(object):
- pass
+ name = "dummy-cipher"
class TestOpenSSL(object):
@@ -62,15 +63,16 @@
assert b.ffi is backend.ffi
assert b.lib is backend.lib
- def test_nonexistent_cipher(self):
+ @pytest.mark.parametrize("mode", [DummyMode(), None])
+ def test_nonexistent_cipher(self, mode):
b = Backend()
b.register_cipher_adapter(
DummyCipher,
- DummyMode,
+ type(mode),
lambda backend, cipher, mode: backend.ffi.NULL
)
cipher = Cipher(
- DummyCipher(), DummyMode(), backend=b,
+ DummyCipher(), mode, backend=b,
)
with pytest.raises(UnsupportedAlgorithm):
cipher.encryptor()
diff --git a/tests/hazmat/primitives/test_block.py b/tests/hazmat/primitives/test_block.py
index 02de386..573f563 100644
--- a/tests/hazmat/primitives/test_block.py
+++ b/tests/hazmat/primitives/test_block.py
@@ -31,9 +31,14 @@
)
+@utils.register_interface(interfaces.Mode)
+class DummyMode(object):
+ name = "dummy-mode"
+
+
@utils.register_interface(interfaces.CipherAlgorithm)
class DummyCipher(object):
- pass
+ name = "dummy-cipher"
class TestCipher(object):
@@ -101,9 +106,10 @@
assert pt == b"a" * 80
decryptor.finalize()
- def test_nonexistent_cipher(self, backend):
+ @pytest.mark.parametrize("mode", [DummyMode(), None])
+ def test_nonexistent_cipher(self, backend, mode):
cipher = Cipher(
- DummyCipher(), object(), backend
+ DummyCipher(), mode, backend
)
with pytest.raises(UnsupportedAlgorithm):
cipher.encryptor()