FGI-OSNMA: An Open Source Implementation of Galileo’s Open Service Navigation Message Authentication

Abstract

The European Global Navigation Satellite System (GNSS) Galileo is launching the Open Service Navigation Message Authentication (OSNMA) to enable navigation message authentication for all users, and therefore increasing the resiliency against spoofing. The Finnish Geospatial Research Institute (FGI) has developed an open source implementation of Galileo’s OSNMA, henceforth known as FGI-OSNMA. FGI-OSNMA is a Python library functioning as a OSNMA computation engine with special emphasis put into its modularity, usability in real time, and integrability as a library in third party applications. In particular, the library is being integrated to the software receiver FGI-GSRx and the GNSS situational awareness service GNSS-Finland. In addition to this, our software package contains useful tools, such as scripts to compute and visualize key performance indicators (KPIs) related to authentication, and a filter to remove unauthenticated messages from RINEX navigation and observables files. This paper presents an overview of the features of FGI-OSNMA, followed by description of the architecture and the rationale behind the design. Finally, the paper concludes by demonstrating practical examples and real-world applications of the library.