propagate signature_scheme config to parallel connection files

IPython/parallel/apps/ipcontrollerapp.py

@@ -251,7 +251,7 b' class IPControllerApp(BaseParallelApplication):'
             ecfg = json.loads(f.read())
         
         # json gives unicode, Session.key wants bytes
-        c.Session.key = ecfg['exec_key'].encode('ascii')
+        c.Session.key = ecfg['key'].encode('ascii')
         
         xport,ip = ecfg['interface'].split('://')
         
@@ -269,7 +269,7 b' class IPControllerApp(BaseParallelApplication):'
         with open(fname) as f:
             ccfg = json.loads(f.read())
         
-        for key in ('exec_key', 'registration', 'pack', 'unpack'):
+        for key in ('key', 'registration', 'pack', 'unpack', 'signature_scheme'):
             assert ccfg[key] == ecfg[key], "mismatch between engine and client info: %r" % key
         
         xport,addr = ccfg['interface'].split('://')
@@ -338,10 +338,11 b' class IPControllerApp(BaseParallelApplication):'
             # save to new json config files
             f = self.factory
             base = {
-                'exec_key'  : f.session.key.decode('ascii'),
+                'key'  : f.session.key.decode('ascii'),
                 'location'  : self.location,
                 'pack'      : f.session.packer,
                 'unpack'    : f.session.unpacker,
+                'signature_scheme' : f.session.signature_scheme,
             }
             
             cdict = {'ssh' : self.ssh_server}

IPython/parallel/apps/ipengineapp.py

@@ -227,9 +227,10 b' class IPEngineApp(BaseParallelApplication):'
         ip = disambiguate_ip_address(ip, location)
         d['interface'] = '%s://%s' % (proto, ip)
         
-        # DO NOT allow override of basic URLs, serialization, or exec_key
+        # DO NOT allow override of basic URLs, serialization, or key
         # JSON file takes top priority there
-        config.Session.key = cast_bytes(d['exec_key'])
+        config.Session.key = cast_bytes(d['key'])
+        config.Session.signature_scheme = d['signature_scheme']
         
         config.EngineFactory.url = d['interface'] + ':%i' % d['registration']
         

IPython/parallel/client/client.py

@@ -462,7 +462,8 b' class Client(HasTraits):'
         # configure and construct the session
         extra_args['packer'] = cfg['pack']
         extra_args['unpacker'] = cfg['unpack']
-        extra_args['key'] = cast_bytes(cfg['exec_key'])
+        extra_args['key'] = cast_bytes(cfg['key'])
+        extra_args['signature_scheme'] = cfg['signature_scheme']
         
         self.session = Session(**extra_args)