Identification Friend or Foe transponder

The Identification Friend or Foe transponder, or IFF transponder, was an identity built into the core construction of every ship in the galaxy by at least the time of the Galactic Empire. It broadcast the identity of the ship to any other ship that came near enough. Altering this identity was considered theoretically impossible and it was also highly illegal to even attempt doing so. Despite this, the Millennium Falcon, as operated by Han Solo and Chewbacca, successfully defeated this system. It ran under a number of aliases, including the Jin-Den Smoke, the Broken Bell, the Foul Matter and the Lost and Found. This last alias was successfully used shortly following the Battle of Yavin when the ship was stopped by the Imperial-class Star Destroyer Vehement. Transponder codes could be altered with the use of codebreakers.