ZK-Trace: Certified Collusion Tracing with Zero-Knowledge Credentials for Federated GNSS Interference Monitoring

ZK-Trace combines Tardos fingerprints and zero-knowledge credentials to trace leaked classifier copies in federated GNSS monitoring without leaker cooperation.

ZK-Trace addresses leakage of a proprietary classifier distributed to partly trusted stations in federated GNSS interference monitoring, combining public identity marks, recipient-specific Tardos fingerprints, and zero-knowledge credential verification to support offline tracing. The paper provides false-accusation and tracing-score bounds with an interval-arithmetic checker allocating a common budget across accusation and tamper decisions. In a simulated GNSS federation it isolates all 160 single-owner copies and traces 712 of 720 two-owner mixtures with a 0.001 false-naming budget, while feature marks survive feature matching in 20/20 runs at 4.8 percentage-point accuracy cost but are erased by function-only distillation.