Date of Award


Document Type


Degree Name

Master of Science


Department of Electrical and Computer Engineering

First Advisor

Maj. Jonathan Butts, PhD.


The U.S. Congress has mandated that all aircraft operating within the National Airspace System, military or civilian, be equipped with ADS-B transponders by the year 2020. The ADS-B aircraft tracking system, part of the Federal Aviation Administration's NextGen overhaul of the Air Transportation System, replaces Radar-based surveillance with a more accurate satellite-based surveillance system. However, the unencrypted nature of ADS-B communication poses an operational security risk to military and law enforcement aircraft conducting sensitive missions. The non-standard format of its message and the legacy communication channels used by its transponders make the ADS-B system unsuitable for traditional encryption mechanisms. FPE, a recent development in cryptography, provides the ability to encrypt arbitrarily formatted data without padding or truncation. Indeed, three new algorithms recommended by the NIST, may be suitable for encryption of ADS-B messages. This research assesses the security and hardware performance characteristics of the FF1, FF2, and FF3 algorithms, in terms of entropy of ciphertext, operational latency and resource utilization when implemented on a Field-Programmable Gate Array. While all of the algorithms inherit the security characteristics of the underlying AES block cipher, they exhibit differences in their performance profiles. Findings demonstrate that a Bump-in-the-Wire FPE cryptographic engine is a suitable solution for retrofitting encryption to ADS-B communication.

AFIT Designator


DTIC Accession Number