Added CMACBackend to multibackend

2 files changed, 12 insertions, 3 deletions

diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
index 86cded85..b9388346 100644
--- a/cryptography/hazmat/backends/multibackend.py
+++ b/cryptography/hazmat/backends/multibackend.py
@@ -16,11 +16,12 @@ from __future__ import absolute_import, division, print_function
 from cryptography import utils
 from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
 from cryptography.hazmat.backends.interfaces import (
-    CipherBackend, DSABackend, HMACBackend, HashBackend, PBKDF2HMACBackend,
-    RSABackend
+    CMACBackend, CipherBackend, DSABackend, HMACBackend, HashBackend,
+    PBKDF2HMACBackend, RSABackend
 )
 
 
+@utils.register_interface(CMACBackend)
 @utils.register_interface(CipherBackend)
 @utils.register_interface(HashBackend)
 @utils.register_interface(HMACBackend)
@@ -156,3 +157,11 @@ class MultiBackend(object):
             return b.generate_dsa_private_key(parameters)
         raise UnsupportedAlgorithm("DSA is not supported by the backend",
                                    _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)
+
+    def cmac_algorithm_supported(self, algorithm):
+        for b in self._filtered_backends(CMACBackend):
+            return b.cmac_algorithm_supported(algorithm)
+
+    def create_cmac_ctx(self, algorithm):
+        for b in self._filtered_backends(CMACBackend):
+            return b.create_cmac_ctx(algorithm)
diff --git a/docs/hazmat/primitives/mac/cmac.rst b/docs/hazmat/primitives/mac/cmac.rst
index 8b88a3ce..69706bb7 100644
--- a/docs/hazmat/primitives/mac/cmac.rst
+++ b/docs/hazmat/primitives/mac/cmac.rst
@@ -22,7 +22,7 @@ A subset of CMAC with the AES-128 algorithm is described in :rfc:`4493`.
     CMAC objects take a
     :class:`~cryptography.hazmat.primitives.interfaces.BlockCipherAlgorithm` provider.
 
-    .. code-block:: pycon
+    .. doctest::
 
         >>> from cryptography.hazmat.backends import default_backend
         >>> from cryptography.hazmat.primitives import cmac