Authenticating aviation augmentation system broadcasts

This paper studies the feasibility and means by which authentication can be overlaid upon the existing SBAS and GBAS designs. It considers how to achieve the authentication that is compatible with the current augmentation system and its users. It also considers how to perform the security necessary to support authentication within the current NAS framework. One important issue is secure key distribution and the paper presents some options designed to be reasonable for aviation infrastructure and operations. One means is a key distribution protocol that utilizes the operation of the aircraft and air traffic to aid in key verification. This provides to distribute keys and provide some ability to validate them without significant additions to the NAS. Another issue is bandwidth. The paper presents ways of modifying protocols such as TESLA to reduce bandwidth use while maintaining an acceptable level of security. The paper uses the current L1 SBAS and GBAS as case studies. The paper presents reasonable method to provide authentication on the current SBAS using about ten percent of bandwidth. The method is compatible to current SBAS user equipment in that they will not be adversely affected. GBAS can employ similar means. As it has greater data bandwidth, a more critical issue for GBAS is key distribution to the ground stations.