Title: Message Authentication, Channel Coding & Anti-Spoong
Author(s): James T. Curran, Cillian O’Driscoll
Published in: Proceedings of the 29th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2016)
September 12 - 16, 2016
Oregon Convention Center
Portland, Oregon
Pages: 2948 - 2959
Cite this article: Curran, James T., O’Driscoll, Cillian, "Message Authentication, Channel Coding & Anti-Spoong," Proceedings of the 29th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2016), Portland, Oregon, September 2016, pp. 2948-2959.
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Abstract: In this paper the potential implementation of navigation message authentication schemes in modernized GNSS Signals is examined. Specifically, the effectiveness of adding high-entropy cryptographic data to the navigation message in providing anti-replay capability to the signal is studied. Particular attention is paid to the use of forward error correction in encoding the navigation message. It is shown that if the target receiver employs soft-decision decoding, then the forward error correction scheme can be exploited to render the authentication scheme largely ineffective against a loosely synchronized spoofing attack. This would allow an adversary to generate replicas of the signal both advanced and delayed relative to the genuine signal. Two case-studies considering current GNSS signals are examined, adopting their respective coding schemes and message-layouts. Details of two attacks are presented, illustrating the methods in which the error correction and interleaving schemes can be exploited and demonstrating the extent to which they can compromise the receiver. Details of the vulnerability are then leveraged to suggest possible countermeasures.