Securing Satellite Key Distribution via Covert Channels: A Cooperative Jamming and Watermarking Approach

Authors: Simone Soderi, Enrico Casinni and Mauro Conti

As Non-Terrestrial Networks (NTNs) move toward integration with 6G infrastructures, Low Earth Orbit (LEO) satellite constellations become central to delivering ubiquitous global connectivity. Recent cyberattacks targeting space systems and the rapid expansion of LEO satellite technology have heightened the need to address emerging vulnerabilities and design robust countermeasures. To this end, we propose a novel data link–layer security scheme combining cooperative jamming with watermark-based covert signaling, specifically developed to facilitate secure key distribution in satellite communications. Our approach leverages a Low Probability of Intercept (LPI) covert channel to securely communicate frame indices designated for intentional obfuscation through friendly jamming. Concurrently, a spread-spectrum watermark embedded within the payload enables authorized receivers to efficiently recover jammed bits without the overhead of frequent cryptographic rekeying. The proposed solution integrates seamlessly into existing CCSDS-compliant satellite protocols, ensuring backward compatibility and minimal hardware disruption. Numerical simulations, including detailed Free Space Optical (FSO) link budget analyses, demonstrate robust secrecy performance, significantly mitigating risks of eavesdropping and man-in-the-middle attacks. Utilizing a shared spreading code, this watermarked cooperative-jamming approach provides a secure, agile, and resource-efficient method suitable for future satellite networks.