Detecting Byzantine Attacks Without Clean Reference

TL;DR

This paper proposes a physical-layer method to detect Byzantine attacks in relay networks without needing a clean reference, by leveraging channel observations and a non-manipulability condition.

Contribution

It introduces a novel detection technique that does not require pre-shared secrets and works under certain channel conditions to identify malicious relay behavior.

Findings

All attacks in the identified family can be detected with high probability given enough observations.

Detection is possible without pre-shared secrets or secret transmissions.

The detection effectiveness depends on the network satisfying a non-manipulability condition.

Abstract

We consider an amplify-and-forward relay network composed of a source, two relays, and a destination. In this network, the two relays are untrusted in the sense that they may perform Byzantine attacks by forwarding altered symbols to the destination. Note that every symbol received by the destination may be altered, and hence no clean reference observation is available to the destination. For this network, we identify a large family of Byzantine attacks that can be detected in the physical layer. We further investigate how the channel conditions impact the detection against this family of attacks. In particular, we prove that all Byzantine attacks in this family can be detected with asymptotically small miss detection and false alarm probabilities by using a sufficiently large number of channel observations \emph{if and only if} the network satisfies a non-manipulability condition. No pre-shared secret or secret transmission is needed for the detection of these attacks, demonstrating the value of this physical-layer security technique for counteracting Byzantine attacks.