Merge pull request #919 from Ayrx/cmac-interfaces

CMAC interfaces + documentation

2 files changed, 35 insertions, 0 deletions

diff --git a/cryptography/hazmat/backends/interfaces.py b/cryptography/hazmat/backends/interfaces.py
index e4c1df34..4137b534 100644
--- a/cryptography/hazmat/backends/interfaces.py
+++ b/cryptography/hazmat/backends/interfaces.py
@@ -142,3 +142,18 @@ class OpenSSLSerializationBackend(object):
         Load a private key from PEM encoded data, using password if the data
         is encrypted.
         """
+
+
+@six.add_metaclass(abc.ABCMeta)
+class CMACBackend(object):
+    @abc.abstractmethod
+    def cmac_supported(self):
+        """
+        Returns True if the backend supports CMAC
+        """
+
+    @abc.abstractmethod
+    def create_cmac_ctx(self, algorithm):
+        """
+        Create a CMACContext for calculating a message authentication code.
+        """
diff --git a/cryptography/hazmat/primitives/interfaces.py b/cryptography/hazmat/primitives/interfaces.py
index 4d92ef27..810a67a4 100644
--- a/cryptography/hazmat/primitives/interfaces.py
+++ b/cryptography/hazmat/primitives/interfaces.py
@@ -469,3 +469,23 @@ class KeyDerivationFunction(object):
         Checks whether the key generated by the key material matches the
         expected derived key. Raises an exception if they do not match.
         """
+
+
+@six.add_metaclass(abc.ABCMeta)
+class CMACContext(object):
+    @abc.abstractmethod
+    def update(self, data):
+        """
+        Processes the provided bytes.
+        """
+
+    def finalize(self):
+        """
+        Returns the message authentication code as bytes.
+        """
+
+    @abc.abstractmethod
+    def copy(self):
+        """
+        Return a CMACContext that is a copy of the current context.
+        """