Emit an encrypted signature / key identifying this system. PLEASE
                NOTE: This protocol has been kept simple, so
                transmitting the key requires an encrypted channel for
                true safety.

                key                       : key (char)

def auth_key_send(self, key, force_mavlink1=False):
                '''
                Emit an encrypted signature / key identifying this system. PLEASE
                NOTE: This protocol has been kept simple, so
                transmitting the key requires an encrypted channel for
                true safety.

                key                       : key (char)

                '''
                return self.send(self.auth_key_encode(key), force_mavlink1=force_mavlink1)