# File lib/openid/consumer/idres.rb, line 242
      def create_check_auth_request
        signed_list = @message.get_arg(OPENID_NS, 'signed', NO_DEFAULT).split(',')

        # check that we got all the signed arguments
        signed_list.each {|k|
          @message.get_aliased_arg(k, NO_DEFAULT)
        }

        ca_message = @message.copy
        ca_message.set_arg(OPENID_NS, 'mode', 'check_authentication')

        return ca_message
      end