Efficient and Secure Use of Cryptography for Watermarked Signal Authentication

This work discusses and applies techniques to efficiently and securely use cryptography for signal authentication in civil (open) satellite navigation signals such as Chips-Message Robust Authentication (“Chimera”). By efficient and secure, we mean maintaining a cryptographic security strength requirement with minimum data bandwidth and watermark signal degradation. We exploit many strategies, including using Timed-Efficient Stream Loss-tolerant Authentication (“TESLA”), sectioned parallelized cryptographic secret distribution, and only one constant, independent spreading code watermark degradation. Our design allows multi-cadence (i.e., slow and fast) distribution even with only a single watermark degradation. Our design maintains standard 128-bit security with a single minimum bandwidth channel while allowing for authentication of many GNSS services.