Strip down the HMAC interface to be HashContext.

1 files changed, 13 insertions, 21 deletions

diff --git a/cryptography/hazmat/primitives/hmac.py b/cryptography/hazmat/primitives/hmac.py
index 4da0cc3f..02770863 100644
--- a/cryptography/hazmat/primitives/hmac.py
+++ b/cryptography/hazmat/primitives/hmac.py
@@ -17,43 +17,35 @@ import binascii
 
 import six
 
+from cryptography.hazmat.primitives import interfaces
 
+
+@interfaces.register(interfaces.HashContext)
 class HMAC(object):
-    def __init__(self, key, msg=None, digestmod=None, ctx=None, backend=None):
+    def __init__(self, key, algorithm, ctx=None, backend=None):
         super(HMAC, self).__init__()
+        self.algorithm = algorithm
+
         if backend is None:
             from cryptography.hazmat.bindings import _default_backend
             backend = _default_backend
 
-        if digestmod is None:
-            raise TypeError("digestmod is a required argument")
-
         self._backend = backend
-        self.digestmod = digestmod
-        self.key = key
+        self._key = key
         if ctx is None:
-            self._ctx = self._backend.hmacs.create_ctx(key, self.digestmod)
+            self._ctx = self._backend.hmacs.create_ctx(key, self.algorithm)
         else:
             self._ctx = ctx
 
-        if msg is not None:
-            self.update(msg)
-
     def update(self, msg):
         if isinstance(msg, six.text_type):
             raise TypeError("Unicode-objects must be encoded before hashing")
         self._backend.hmacs.update_ctx(self._ctx, msg)
 
     def copy(self):
-        return self.__class__(self.key, digestmod=self.digestmod,
-                              backend=self._backend, ctx=self._copy_ctx())
-
-    def digest(self):
-        return self._backend.hmacs.finalize_ctx(self._copy_ctx(),
-                                                self.digestmod.digest_size)
-
-    def hexdigest(self):
-        return str(binascii.hexlify(self.digest()).decode("ascii"))
+        return self.__class__(self._key, self.algorithm, backend=self._backend,
+                              ctx=self._backend.hmacs.copy_ctx(self._ctx))
 
-    def _copy_ctx(self):
-        return self._backend.hmacs.copy_ctx(self._ctx)
+    def finalize(self):
+        return self._backend.hmacs.finalize_ctx(self._ctx,
+                                                self.algorithm.digest_size)