From c9611069bd232ea482da173bd46b6b18fa393f3c 2014-07-11 19:30:50
From: Paul Ivanov <pi@berkeley.edu>
Date: 2014-07-11 19:30:50
Subject: [PATCH] support Python older than 2.7.7

---

diff --git a/IPython/kernel/zmq/session.py b/IPython/kernel/zmq/session.py
index 091e25c..a3d16e6 100644
--- a/IPython/kernel/zmq/session.py
+++ b/IPython/kernel/zmq/session.py
@@ -27,6 +27,13 @@ except:
     cPickle = None
     import pickle
 
+try:
+    from hmac import compare_digest
+except ImportError:
+    # Python < 2.7.7
+    def compare_digest(a,b):
+        return a == b
+
 import zmq
 from zmq.utils import jsonapi
 from zmq.eventloop.ioloop import IOLoop
@@ -818,7 +825,7 @@ class Session(Configurable):
                 raise ValueError("Duplicate Signature: %r" % signature)
             self._add_digest(signature)
             check = self.sign(msg_list[1:5])
-            if not hmac.compare_digest(signature, check):
+            if not compare_digest(signature, check):
                 raise ValueError("Invalid Signature: %r" % signature)
         if not len(msg_list) >= minlen:
             raise TypeError("malformed message, must have at least %i elements"%minlen)