Chi-MERA: Defending Orbit-Based Authentication of LEO Satellites with the Space Oddity of MLAT (Long Version)

2026-07-21

AI Summary

This work addresses the vulnerability of physical-layer authentication in low Earth orbit (LEO) satellite systems to coordinated multi-device spoofing attacks, which can induce false alarm rates as high as 40%. To counter this threat, the authors propose Chi-MERA, a novel scheme that integrates multilateration (MLAT) residual analysis with a resilient signature mechanism that eliminates the need for a single trusted reference receiver. By leveraging orbital dynamics to distinguish between genuine satellites and terrestrial spoofers, Chi-MERA significantly enhances authentication robustness. In a network of n receivers, the method tolerates up to n/2 compromised devices while achieving a false alarm rate below 2% and a miss rate of approximately 3%; under extreme conditions, the false alarm rate further drops below 1%.

Abstract

An active research area, physical layer security can be a last resort in insecure legacy systems, a resource-efficient alternative, or a complementary backup for cryptographic techniques. In this paper, we demonstrate that previously established authentication schemes for LEO satellites are vulnerable to attackers that control multiple devices. In extensive experiments, such attackers produce false positive rates (FPR) of up to 40%. Based on a root cause analysis, we develop a novel scheme, called Chi-MERA, that improves authentication performance and is robust against multi-device attackers. Our scheme uses two enhancements: (1) multilateration (MLAT) to clearly distinguish between attackers and legitimate satellites, and (2), a new resilient signature scheme without dependency on a single dedicated reference receiver. Our evaluation shows that exploiting MLAT characteristics such as residual analysis to classify vastly different signal source categories (orbit vs. non-orbit) is highly effective. In extensive simulations, we show that the new authentication achieves low FPR of $<$2% and false negative rates of $<$3% for accidentally rejecting valid signals. Furthermore, our scheme's defense scales linearly: $n$ receivers reliably withstand spoofing (FPR $< 1%$) from attackers with $\frac{n}{2}$ devices.

Problem

• LEO satellites
• physical layer security
• authentication
• multi-device attackers
• spoofing

Innovation

• Chi-MERA
• multilateration (MLAT)
• LEO satellite authentication
• physical layer security
• multi-device spoofing defense