add X509Certificate version attribute
diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index 77aa001..d964f25 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -703,6 +703,12 @@
 
     .. versionadded:: 0.7
 
+    .. attribute:: version
+
+        :type: X509Version
+
+        The certificate version as an enumeration.
+
     .. method:: fingerprint(algorithm)
 
         :param algorithm: A
diff --git a/src/cryptography/hazmat/primitives/interfaces.py b/src/cryptography/hazmat/primitives/interfaces.py
index 561be97..18a6260 100644
--- a/src/cryptography/hazmat/primitives/interfaces.py
+++ b/src/cryptography/hazmat/primitives/interfaces.py
@@ -504,6 +504,12 @@
         Returns certificate serial number
         """
 
+    @abc.abstractproperty
+    def version(self):
+        """
+        Returns the certificate version
+        """
+
     @abc.abstractmethod
     def public_key(self):
         """