Galileo Open Service Navigation Message Authentication: Preparation Phase and Drivers for Future Service Provision

Martin Götzelmann, Evelyn Köller, Ignacio Viciano Semper, Dirk Oskam, Elias Gkougkas, Javier Simon, Antoine de Latour

Abstract: While Galileo approaches Full Operational Capability and is close to completion of the deployed satellite constellation, a portfolio of new Galileo service features is under development and validation. The Galileo Open Service (OS) is planned to be enhanced with the provision of Navigation Message Authentication (NMA). OSNMA enables the Galileo OS user to verify by means of cryptography, if received navigation messages truly originate from the GNSS system. This evolution of the Open Service shall help the user to detect malicious data forging attacks or to prevent the user from self-spoofing. Galileo OSNMA is based on the TESLA (Time Efficient Stream Loss-tolerant Authentication) broadcast authentication protocol for data origin authentication [5], adapted and optimized for Galileo. The E1B I/NAV message will provide the OSNMA user with keys, Message Authentication Codes and digital signatures, which are processed by the receiver to verify the authenticity of the received navigation data. In November 2020, the Galileo satellites started broadcasting OSNMA test data for an internal preparation phase of four months duration. The objective of this test period was to determine and select the OSNMA test signal configuration for a subsequent ‘Public Observation phase’, a significant step towards a future Galileo OSNMA service provision. The OSNMA configuration shall both satisfy the security needs required by OSNMA users (e.g. Smart Tachograph) and maintain at the same time the highclass service performance in terms of service availability and PVT accuracy, which users of the standard Galileo Open Service are accustomed to. In view of the upcoming Public Observation phase, the paper presents the main outcomes of the preparation phase for a set of defined OSNMA performance parameters. Airbus is supporting the Galileo service provider, the European Union Agency for the Space Programme (EUSPA), both in Galileo service definition and in planning and execution of OSNMA test activities, which have been performed during this preparation phase. PVT availability, PVT accuracy and Time to First Fix of the OSNMA user are characterized in different user environment (rural and urban) and compared with the performance of the standard Open Service. Test campaigns have been set up for fixed, pedestrian and vehicle OSNMA users at and around Airbus premises in Munich. EUSPA has provided Airbus with OSNMA-enabled user terminals for testing. In addition, an Airbus proprietary OSNMA software package N#MAtch is used for processing of OSNMA data received from any standard GNSS receiver in order to evaluate the performance of different types of OSNMA users. The comprehensive Airbus toolset for OSNMA signal monitoring and validation provides continuous monitoring of the OSNMA data broadcast by the Galileo satellites, characterizes OSNMA data dissemination availability for the global Galileo service volume, and verifies and confirms the authenticity of the complete OSNMA data set broadcast by any Galileo satellite by performing all required cryptographic OSNMA receiver operations. In addition to the abovementioned user tests, key results on global OSNMA availability and dissemination coverage are presented and discussed in this paper. Finally, operational aspects relevant for the future service provision, such as TESLA chain and public key renewal and revocation processes, were tested in the end-to-end system and results are reported and discussed. The scope of this paper is to present the results of the OSNMA testing activities performed by Airbus in the implementation of a contract signed with the European Union Agency for the Space Programme and financed by the European Union under the Galileo Programme budget.
Published in: Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021)
September 20 - 24, 2021
Union Station Hotel
St. Louis, Missouri
Pages: 385 - 401
Cite this article: Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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