Testing Galileo SAS with Encrypted Signal-in-Space

Rafael Terris-Gallego, José A. López-Salcedo, Gonzalo Seco-Granados, Aleix Galan-Figueras, Ignacio Fernandez-Hernandez

Abstract:	Galileo Signal Authentication Service (SAS) provides civil signal authentication by applying spreading code encryption on E6-C and TESLA keys disclosed via OSNMA on E1-B, thus avoiding any long-term secret storage in receivers. After years of development, Galileo has recently conducted encrypted E6-C signal-in-space trials, enabling end-toend SAS testing. This paper reports the first results with encrypted signal-in-space using an SDR-based test-bed that implements the receiver-side SAS workflow: retrieval and parsing of Re-Encrypted Code Sequences (RECS), snapshot recording of E6-C and E1-B, and post-disclosure decryption and correlation. Campaign results confirm successful E6-C detections and validate key configuration parameters in the current specification, including RECS length and period, and the Key Delay Index (KDI). Acquisition is assisted by E1-B, consistent with the nominal SAS operating mode. These results represent a step toward operational SAS, validating the end-to-end transmission and reception chain.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	10 - 21
Cite this article:	Terris-Gallego, Rafael, López-Salcedo, José A., Seco-Granados, Gonzalo, Galan-Figueras, Aleix, Fernandez-Hernandez, Ignacio, "Testing Galileo SAS with Encrypted Signal-in-Space," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 10-21. https://doi.org/10.33012/2025.20223
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