Merge branch 'master' into urandom-engine

* master: (169 commits)
  Make just one call to ffi.cdef for most of the definitions
  Use pytest.fixture for backends
  drop to >= 0.8 to make pypy happy
  change to anonymous enum
  require cffi >= 0.8.1
  remove extraneous spaces
  add hmac to commoncrypto binding
  bytes byte back
  add check to confirm we've loaded error strings
  Bind all the PEM errors
  Spelling!
  oops, bytes plz
  don't leak a context in the test
  add tests to the openssl backend to verify that we've registered
  Nonsense I think we need.
  This is a dep
  init the ssl library in the backend
  Actuall install a thing
  Try to run the spellchecker on travis
  Use a normal quote here, not sure where the smart quote came from
  ...

Conflicts:
	cryptography/hazmat/bindings/openssl/binding.py
	tests/hazmat/backends/test_openssl.py

1 files changed, 12 insertions, 0 deletions

diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index 361b723e..edb24cd9 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -67,6 +67,18 @@ Interfaces used by the symmetric cipher modes described in
         The name may be used by a backend to influence the operation of a
         cipher in conjunction with the algorithm's name.
 
+    .. method:: validate_for_algorithm(algorithm)
+
+        :param CipherAlgorithm algorithm:
+
+        Checks that the combination of this mode with the provided algorithm
+        meets any necessary invariants. This should raise an exception if they
+        are not met.
+
+        For example, the :class:`~cryptography.hazmat.primitives.modes.CBC`
+        mode uses this method to check that the provided initialization
+        vector's length matches the block size of the algorithm.
+
 
 .. class:: ModeWithInitializationVector