Detection of channel degradation attack by Intermediary Node in Linear Networks

Abstract

We consider the problem of two sources wanting to share information through a potentially untrustworthy intermediary node. We assume that the two sources transmit random symbols simultaneously and that the intermediary node relays the information in the amplify-and-forward manner. We show that under a certain sufficient condition on the channel, it is possible to asymptotically detect whether or not the intermediary node is degrading the channel by sending out manipulated symbols. This can be done solely by each source examining its received distribution conditioned on what it transmitted; thus allowing for a minimally invasive approach to determining if the intermediary node is acting maliciously. More specifically, we model the potential malicious action of the intermediate node by an "attack" channel. An estimate of the attack channel is obtained from the received conditional distribution empirically observed by a source node. We show that the estimated attack channel converges in probability to the true attack channel if the intermediate node is not acting maliciously. Otherwise there is a separation between the estimated and true attacking channels with high probability. This result provides us a clear-cut criterion to determine whether the intermediate node is malicious or not.

Detecting Arbitrary Attacks Using Continuous Secured Side Information in Wireless Networks

“…Remark 1: Theorem 1 gives the detectability of continuous attacks over continuous channels. It extends the the detectability of discrete attacks given by [16] into continuous form. This extension is not trivial based on twofold work of this paper.…”

“…Firstly, we prove the convergence of F n Y n | X n (t | x ) (24) is established for arbitrary sufficient large n rather than fixed n , where the involved variables X, U , and V do not follow markov constraint. For completing such proof work, it is not available to straightforwardly use the methods of [16], which processes the discrete variables following markov constraint and having fixed dimensions of their alphabets. Secondly, the checking problem for non-manipulability of continuous channel is to check number of solutions to an integral equation.…”

“…Secondly, the checking problem for non-manipulability of continuous channel is to check number of solutions to an integral equation. The method of [16] for checking non-manipulability of discrete channel is to check number of solutions to an matrix equation. The checking method given by [16] cannot be used for integral equation.…”

“…It is difficult to extend this scheme to non-Gaussian channels and to the destination with restricted power. In our previous work [16]- [18], focusing on two-way relay system, we show that for discrete memoryless channels (DMCs), it is possible to detect arbitrary Byzantine attacks dispensing any AMD code or cryptographic keys. The basic idea is that each node utilizes its own transmitted symbols as secured SI for statistically checking against the other node's symbols forwarded by the relay.…”

Detecting Byzantine Attacks Without Clean Reference

“…However, it is difficult to extend this scheme to non-Gaussian channels. In our previous work [13]- [15], we show that for TWR networks with discrete memoryless channels (DMCs), it is possible to detect potential Byzantine attacks without any AMD code or cryptographic keys. The basic idea is that each node utilizes its own transmitted symbols as a clean reference for statistically checking against the other node's symbols forwarded by the relay.…”