It has been a concern of business aviation officials that mode-S transponder transmissions can be tracked online and traced to the originator. Since most networking with ICAO addresses is now processed via the internet, reservations have been expressed throughout the aviation community and a working group was set up as part of the ADS-B Equip 2020 panel to investigate and discuss privacy concerns, and to put forward proposals for tight security for transmissions.
A white paper was delivered surrounding measures for proposed security for mode-S transponders this week and includes proposed development of the ability to change codes on a regular basis. This would involve the introduction of a privacy office to handle such changes. In the long-term, the FAA should explore encryption possibilities within the transponder itself.