Independent Time Synchronization for Resilient GNSS Receivers

Ignacio Fernandez-Hernandez, Todd Walter, Andrew Neish, C. O’Driscoll

Peer Reviewed

Abstract:	This paper analyses time synchronization schemes for GNSS receivers that require time-delayed authentication. We review the synchronization process as defined for the TESLA (Timed-Efficient Stream Loss-Tolerant Authentication) protocol current literature and propose how it can be adapted for one-way communication systems like GNSS. The receiver to be synchronized at a given synchronization event S needs not only an independent reference time t^s_ref, but also a bound B of the reference time uncertainty. With these two parameters, the loose time synchronization requirement of the protocol T_L and the signal-in-space time t^s_sig, the receiver can start up the protocol. We analyze different startup cases and derive preconditions based on t^s_ref, t^s_sig, T_L, and B, and propose secure startup procedures that prevent data forging and other anomalous situations. We then analyze the practical aspects of GNSS receiver synchronization for network applications and aviation, and finalize with some conclusions. The conclusions can be extrapolated to other data or signal authentication protocols based on the delayed disclosure of cryptographic information.
Published in:	Proceedings of the 2020 International Technical Meeting of The Institute of Navigation January 21 - 24, 2020 Hyatt Regency Mission Bay San Diego, California
Pages:	964 - 978
Cite this article:	Fernandez-Hernandez, Ignacio, Walter, Todd, Neish, Andrew, O’Driscoll, C., "Independent Time Synchronization for Resilient GNSS Receivers," Proceedings of the 2020 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2020, pp. 964-978. https://doi.org/10.33012/2020.17190
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