Merge pull request #53 from reaperhulk/ecb-support-im-sorry

ECB Support

3 files changed, 40 insertions, 4 deletions

diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index 54a74d03..917c1846 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -13,6 +13,8 @@
 
 from __future__ import absolute_import, division, print_function
 
+from cryptography.primitives import interfaces
+
 import cffi
 
 
@@ -72,11 +74,14 @@ class API(object):
         )
         evp_cipher = self._lib.EVP_get_cipherbyname(ciphername.encode("ascii"))
         assert evp_cipher != self._ffi.NULL
-        # TODO: only use the key and initialization_vector as needed. Sometimes
-        # this needs to be a DecryptInit, when?
+        if isinstance(mode, interfaces.ModeWithInitializationVector):
+            iv_nonce = mode.initialization_vector
+        else:
+            iv_nonce = self._ffi.NULL
+
+        # TODO: Sometimes this needs to be a DecryptInit, when?
         res = self._lib.EVP_EncryptInit_ex(
-            ctx, evp_cipher, self._ffi.NULL, cipher.key,
-            mode.initialization_vector
+            ctx, evp_cipher, self._ffi.NULL, cipher.key, iv_nonce
         )
         assert res != 0
 
diff --git a/cryptography/primitives/block/modes.py b/cryptography/primitives/block/modes.py
index de31f086..c722e739 100644
--- a/cryptography/primitives/block/modes.py
+++ b/cryptography/primitives/block/modes.py
@@ -13,6 +13,8 @@
 
 from __future__ import absolute_import, division, print_function
 
+from cryptography.primitives import interfaces
+
 
 class CBC(object):
     name = "CBC"
@@ -20,3 +22,10 @@ class CBC(object):
     def __init__(self, initialization_vector):
         super(CBC, self).__init__()
         self.initialization_vector = initialization_vector
+
+
+class ECB(object):
+    name = "ECB"
+
+
+interfaces.ModeWithInitializationVector.register(CBC)
diff --git a/cryptography/primitives/interfaces.py b/cryptography/primitives/interfaces.py
new file mode 100644
index 00000000..6f74ccf7
--- /dev/null
+++ b/cryptography/primitives/interfaces.py
@@ -0,0 +1,22 @@
+# 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 ModeWithInitializationVector(six.with_metaclass(abc.ABCMeta)):
+    pass