code: def setup_signing(self, secret_key, sign_outgoing=True, allow_unsigned_callback=None, initial_timestamp=None, link_id=None):
          '''setup for MAVLink2 signing'''
          self.mav.signing.secret_key = secret_key
          self.mav.signing.sign_outgoing = sign_outgoing
          self.mav.signing.allow_unsigned_callback = allow_unsigned_callback
          if link_id is None:
              # auto-increment the link_id for each link
              global global_link_id
              link_id = global_link_id
              global_link_id = min(global_link_id + 1, 255)
          self.mav.signing.link_id = link_id
          if initial_timestamp is None:
              # timestamp is time since 1/1/2015
              epoch_offset = 1420070400
              now = max(time.time(), epoch_offset)
              initial_timestamp = now - epoch_offset
              initial_timestamp = int(initial_timestamp * 100 * 1000)
          # initial_timestamp is in 10usec units
          self.mav.signing.timestamp = initial_timestamf setup_signing(self, secret_key, sign_outgoing=True, allow_unsigned_callback=None, initial_timestamp=None, link_id=None):
          '''setup for MAVLink2 signing'''
          self.mav.signing.secret_key = secret_key
          self.mav.signing.sign_outgoing = sign_outgoing
          self.mav.signing.allow_unsigned_callback = allow_unsigned_callback
          if link_id is None:
              # auto-increment the link_id for each link
              global global_link_id
              link_id = global_link_id
              global_link_id = min(global_link_id + 1, 255)
          self.mav.signing.link_id = link_id
          if initial_timestamp is None:
              # timestamp is time since 1/1/2015
              epoch_offset = 1420070400
              now = max(time.time(), epoch_offset)
              initial_timestamp = now - epoch_offset
              initial_timestamp = int(initial_timestamp * 100 * 1000)
          # initial_timestamp is in 10usec units
          self.mav.signing.timestamp = initial_timestamp
docs: setup for MAVLink2 signing