Format Preserving Encryption: Evaluating FFX for Use Within the NextGen Air Traffic Control System

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Master of Science


Department of Electrical and Computer Engineering


The national airspace system is reliant on legacy systems that artificially limit air traffic capacity. With the demand for air transportation increasing each year, the Federal Aviation Administration has introduced the Next Generation (NextGen) upgrade to modernize Air Traffic Control (ATC) capabilities. Automatic Dependent Surveillance Broadcast (ADS-B), a key component of the NextGen upgrade, enables an aircraft to generate and broadcast digital messages that contain the aircraft's global positioning system coordinates. The- incorporation of ADS-B surveillance is intended to provide enhanced surveillance accuracy, efficiency, and safety. The open design of the system, however introduces inherent security concerns related to the confidentiality and integrity of messages. These issues are particularly concerning for organizations such as military, law enforcement and political dignitaries which necessarily operate within the FAA's controlled airspace but possess the need for operational security and public anonymity. This research evaluates limitations of the legacy systems currently associated with the ATC and explores the feasibility of employing format preserving encryption, specifically the FFX algorithm, within the ADS-B environment. The algorithm's ability to encrypt and mask predictable ADS-B messages is measured using classical Shannon entropy. Experimental results demonstrate the utility of FFX encryption based upon its ability to confuse and diffuse ADSB message content. The findings of this research show that the FFX algorithm is an effective and feasible solution for enhancing ADS-B system security. In turn, the increased security enables ADS-B surveillance to be readily adopted for use in an operational military environment where the lack of pre-existing surveillance infrastructure prohibits effective traditional aircraft control (e.g., Afghanistan), ultimately reducing the risk of aircraft mishaps.

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