The Automatic Dependent Surveillance-Broadcast is due in 2020 but currently does not provide for the protection of flight plans and positions and other state data.

Potentially blockchain has the ability to maintain aircraft privacy and anonymity while providing secure communication with Air Traffic Services. It is being proposed using smart contract support and cryptographic security of blockchain to ensure private communication between aircraft and authorized participants.
https://cointelegraph.com/news/nasa-publishes-p...dium=email