change OFB iv to nonce to reflect dstufft nomenclature pitch

* Namely, we should try to call things IV if reuse leaks a small amount
  of data and nonce if reuse can result in a complete break. This can
  be somewhat ambiguous, but we'll track in #58

3 files changed, 9 insertions, 3 deletions

diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index 917c1846..af7fe438 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -76,6 +76,8 @@ class API(object):
         assert evp_cipher != self._ffi.NULL
         if isinstance(mode, interfaces.ModeWithInitializationVector):
             iv_nonce = mode.initialization_vector
+        elif isinstance(mode, interfaces.ModeWithNonce):
+            iv_nonce = mode.nonce
         else:
             iv_nonce = self._ffi.NULL
 
diff --git a/cryptography/primitives/block/modes.py b/cryptography/primitives/block/modes.py
index 70ef8178..62a1c2c9 100644
--- a/cryptography/primitives/block/modes.py
+++ b/cryptography/primitives/block/modes.py
@@ -31,10 +31,10 @@ class ECB(object):
 class OFB(object):
     name = "OFB"
 
-    def __init__(self, initialization_vector):
+    def __init__(self, nonce):
         super(OFB, self).__init__()
-        self.initialization_vector = initialization_vector
+        self.nonce = nonce
 
 
 interfaces.ModeWithInitializationVector.register(CBC)
-interfaces.ModeWithInitializationVector.register(OFB)
+interfaces.ModeWithNonce.register(OFB)
diff --git a/cryptography/primitives/interfaces.py b/cryptography/primitives/interfaces.py
index 6f74ccf7..c1fc9910 100644
--- a/cryptography/primitives/interfaces.py
+++ b/cryptography/primitives/interfaces.py
@@ -20,3 +20,7 @@ import six
 
 class ModeWithInitializationVector(six.with_metaclass(abc.ABCMeta)):
     pass
+
+
+class ModeWithNonce(six.with_metaclass(abc.ABCMeta)):
+    pass