Add MACContext and make HMAC and CMAC to use it.

5 files changed, 41 insertions, 3 deletions

diff --git a/cryptography/hazmat/backends/interfaces.py b/cryptography/hazmat/backends/interfaces.py
index 69d776ff..ecb5bf48 100644
--- a/cryptography/hazmat/backends/interfaces.py
+++ b/cryptography/hazmat/backends/interfaces.py
@@ -66,7 +66,7 @@ class HMACBackend(object):
     @abc.abstractmethod
     def create_hmac_ctx(self, key, algorithm):
         """
-        Create a HashContext for calculating a message authentication code.
+        Create a MACContext for calculating a message authentication code.
         """
 
 
@@ -81,7 +81,7 @@ class CMACBackend(object):
     @abc.abstractmethod
     def create_cmac_ctx(self, algorithm):
         """
-        Create a CMACContext for calculating a message authentication code.
+        Create a MACContext for calculating a message authentication code.
         """
 
 
diff --git a/cryptography/hazmat/backends/openssl/cmac.py b/cryptography/hazmat/backends/openssl/cmac.py
index 7acf4391..f1d068eb 100644
--- a/cryptography/hazmat/backends/openssl/cmac.py
+++ b/cryptography/hazmat/backends/openssl/cmac.py
@@ -20,6 +20,7 @@ from cryptography.hazmat.primitives import interfaces
 from cryptography.hazmat.primitives.ciphers.modes import CBC
 
 
+@utils.register_interface(interfaces.MACContext)
 @utils.register_interface(interfaces.CMACContext)
 class _CMACContext(object):
     def __init__(self, backend, algorithm, ctx=None):
diff --git a/cryptography/hazmat/primitives/cmac.py b/cryptography/hazmat/primitives/cmac.py
index fa463ae0..968fa463 100644
--- a/cryptography/hazmat/primitives/cmac.py
+++ b/cryptography/hazmat/primitives/cmac.py
@@ -21,6 +21,7 @@ from cryptography.hazmat.backends.interfaces import CMACBackend
 from cryptography.hazmat.primitives import constant_time, interfaces
 
 
+@utils.register_interface(interfaces.MACContext)
 @utils.register_interface(interfaces.CMACContext)
 class CMAC(object):
     def __init__(self, algorithm, backend, ctx=None):
diff --git a/cryptography/hazmat/primitives/hmac.py b/cryptography/hazmat/primitives/hmac.py
index 026ad3b3..23292432 100644
--- a/cryptography/hazmat/primitives/hmac.py
+++ b/cryptography/hazmat/primitives/hmac.py
@@ -21,6 +21,7 @@ from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import constant_time, interfaces
 
 
+@utils.register_interface(interfaces.MACContext)
 @utils.register_interface(interfaces.HashContext)
 class HMAC(object):
     def __init__(self, key, algorithm, backend, ctx=None):
diff --git a/cryptography/hazmat/primitives/interfaces.py b/cryptography/hazmat/primitives/interfaces.py
index 6ae0a4c5..dacabb2e 100644
--- a/cryptography/hazmat/primitives/interfaces.py
+++ b/cryptography/hazmat/primitives/interfaces.py
@@ -393,11 +393,12 @@ class KeyDerivationFunction(object):
 @six.add_metaclass(abc.ABCMeta)
 class CMACContext(object):
     @abc.abstractmethod
-    def update(self, data):
+    def update(self):
         """
         Processes the provided bytes.
         """
 
+    @abc.abstractmethod
     def finalize(self):
         """
         Returns the message authentication code as bytes.
@@ -486,3 +487,37 @@ class EllipticCurvePublicKeyWithNumbers(EllipticCurvePublicKey):
         """
         Returns an EllipticCurvePublicNumbers.
         """
+
+
+@six.add_metaclass(abc.ABCMeta)
+class MACContext(object):
+    @abc.abstractproperty
+    def algorithm(self):
+        """
+        The algorithm that will be used by this context.
+        """
+
+    @abc.abstractmethod
+    def update(self, data):
+        """
+        Processes the provided bytes.
+        """
+
+    @abc.abstractmethod
+    def finalize(self):
+        """
+        Returns the message authentication code as bytes.
+        """
+
+    @abc.abstractmethod
+    def copy(self):
+        """
+        Return a MACContext that is a copy of the current context.
+        """
+
+    @abc.abstractmethod
+    def verify(self):
+        """
+        Checks if the generated message authentication code matches the
+        signature.
+        """