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
diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index 917c184..af7fe43 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -76,6 +76,8 @@
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 70ef817..62a1c2c 100644
--- a/cryptography/primitives/block/modes.py
+++ b/cryptography/primitives/block/modes.py
@@ -31,10 +31,10 @@
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 6f74ccf..c1fc991 100644
--- a/cryptography/primitives/interfaces.py
+++ b/cryptography/primitives/interfaces.py
@@ -20,3 +20,7 @@
class ModeWithInitializationVector(six.with_metaclass(abc.ABCMeta)):
pass
+
+
+class ModeWithNonce(six.with_metaclass(abc.ABCMeta)):
+ pass
diff --git a/docs/primitives/symmetric-encryption.rst b/docs/primitives/symmetric-encryption.rst
index 7ec42a3..587c94b 100644
--- a/docs/primitives/symmetric-encryption.rst
+++ b/docs/primitives/symmetric-encryption.rst
@@ -68,18 +68,16 @@
reuse an ``initialization_vector`` with
a given ``key``.
-.. class:: cryptography.primitives.block.modes.OFB(initialization_vector)
+.. class:: cryptography.primitives.block.modes.OFB(nonce)
OFB (Output Feedback) is a mode of operation for block ciphers. It
transforms a block cipher into a stream cipher.
- :param bytes initialization_vector: Must be random bytes. They do not need
- to be kept secret (they can be included
- in a transmitted message). Must be the
- same number of bytes as the
- ``block_size`` of the cipher. Do not
- reuse an ``initialization_vector`` with
- a given ``key``.
+ :param bytes nonce: Must be random bytes. They do not need to be kept
+ secret (they can be included in a transmitted message).
+ Must be the same number of bytes as the ``block_size``
+ of the cipher. Reuse of a ``nonce`` with a given
+ ``key`` can allow recovery of the original plaintext.
Insecure Modes