GalSAS-SDR-SIM: An End-to-End Simulation Platform for Galileo Signal Authentication Service

2026-08-03

AI Summary

This work addresses the lack of realistic and controllable Galileo Signal Authentication Service (SAS) signals, which has hindered receiver development and reproducible research. To bridge this gap, we present the first open-source software-defined radio (SDR) simulation platform that faithfully replicates the end-to-end SAS workflow in accordance with official specifications. The platform concurrently models signal generation across E1, E5b, and E6 bands, integrates OSNMA message authentication, and emulates E6 spreading code encryption. It supports multi-frequency operation, cross-satellite OSNMA configurations, and adaptability to receivers with varying computational capabilities. Using this framework, we successfully demonstrate synchronized authentication of navigation messages and spreading codes and provide quantitative evaluations of authentication performance and computational overhead under diverse SAS configurations. This tool fills a critical void in SAS simulation infrastructure, offering essential support for future receiver development and authentication research.

Abstract

Galileo is developing a Signal Authentication Service (SAS) that integrates Open Service Navigation Message Authentication (OSNMA) on the E1 band with Spreading Code Authentication (SCA) on the E6 band to strengthen its resilience to spoofing attacks. As Galileo SAS is still under development, access to realistic and controllable SAS signals remains limited, hindering both the early development of compatible receivers and reproducible research on signal authentication. To bridge this gap, this paper presents GalSAS-SDR-SIM, an open-source software-defined radio (SDR) simulation platform that emulates the SAS workflow by coupling E6 code encryption with the OSNMA key-disclosure process. The platform allows flexible SAS configuration of code encryption parameters to accommodate receivers with different computational capabilities. It also supports the concurrent generation of Galileo E1, E5b, and E6 signals for user-defined locations and times, and OSNMA cross-satellite configurations. Experimental results demonstrate simultaneous verification of navigation messages and spreading codes. We further evaluate SAS authentication performance and computational resource costs under different SAS configurations. Implemented according to publicly available official specifications, GalSAS-SDR-SIM provides a practical tool for accelerating SAS-capable receiver development and supporting the research community in evaluating and improving Galileo signal-authentication techniques.

Problem

• Galileo Signal Authentication Service
• spoofing attacks
• OSNMA
• Spreading Code Authentication
• reproducible research

Innovation

• Signal Authentication Service (SAS)
• Software-Defined Radio (SDR)
• Spreading Code Authentication (SCA)
• OSNMA
• GNSS spoofing resilience