Merge pull request #950 from Ayrx/cmac-multibackend

CMAC multibackend

1 files changed, 18 insertions, 2 deletions

diff --git a/cryptography/hazmat/backends/multibackend.py b/cryptography/hazmat/backends/multibackend.py
index 86cded85..981a60bd 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 +157,18 @@ 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):
+        return any(
+            b.cmac_algorithm_supported(algorithm)
+            for b in self._filtered_backends(CMACBackend)
+        )
+
+    def create_cmac_ctx(self, algorithm):
+        for b in self._filtered_backends(CMACBackend):
+            try:
+                return b.create_cmac_ctx(algorithm)
+            except UnsupportedAlgorithm:
+                pass
+        raise UnsupportedAlgorithm("This backend does not support CMAC",
+                                   _Reasons.UNSUPPORTED_CIPHER)