def getSignedNS(self, ns_uri):
        """Get signed arguments from the response message.  Return a
        dict of all arguments in the specified namespace.  If any of
        the arguments are not signed, return None.
        """
        msg_args = self.message.getArgs(ns_uri)

        for key in msg_args.iterkeys():
            if not self.isSigned(ns_uri, key):
                logging.info("SuccessResponse.getSignedNS: (%s, %s) not signed."
                            % (ns_uri, key))
                return None

        return msg_args