update docs, test invalid x509 version

2 files changed, 8 insertions, 1 deletions

diff --git a/src/cryptography/exceptions.py b/src/cryptography/exceptions.py
index b0e1a993..23edcd02 100644
--- a/src/cryptography/exceptions.py
+++ b/src/cryptography/exceptions.py
@@ -53,3 +53,7 @@ class InvalidKey(Exception):
 
 class InvalidToken(Exception):
     pass
+
+
+class InvalidX509Version(Exception):
+    pass
diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index 0c6395f4..9f6f71d0 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -16,6 +16,7 @@ from __future__ import absolute_import, division, print_function
 import datetime
 
 from cryptography import utils, x509
+from cryptography.exceptions import InvalidX509Version
 from cryptography.hazmat.primitives import hashes, interfaces
 
 
@@ -60,7 +61,9 @@ class _X509Certificate(object):
         elif version == 2:
             return x509.X509Version.v3
         else:
-            raise StandardError("TODO")
+            raise InvalidX509Version(
+                "{0} is not a valid X509 version", version
+            )
 
     @property
     def serial(self):