Implementation Considerations for ACAS and Simulation Results

TL;DR

This paper discusses the design and simulation testing of ACAS, a signal authentication system for Galileo's E6-C signal, demonstrating its ability to detect and mitigate spoofing attacks effectively.

Contribution

It introduces new detection concepts and mitigation levels for ACAS, validated through simulations against advanced spoofing threats.

Findings

ACAS can detect advanced spoofing attacks

Mitigation levels improve threat defense

Simulation results confirm effectiveness

Abstract

The Assisted Commercial Authentication Service (ACAS) is a semi-assisted signal authentication concept currently being defined for Galileo, based on the E6-C encrypted signal. Leveraging the assumption that the true E6-C encrypted signal always arrives before any inauthentic signal, we define user concepts for signal detection, including vestigial signal search. We define three mitigation levels, each level defending against an increasing set of threats, incorporating the described concepts and additional checks. The concepts are analyzed and implemented in a simulation environment, and tested in both nominal conditions and under advanced spoofing attacks. The results suggest that even advanced attacks can be detected and mitigated by ACAS receivers.