Covert, Low-Delay, Coded Message Passing in Mobile (IoT) Networks

TL;DR

This paper presents a covert message passing protocol in IoT networks using random walks and coding, balancing covertness and delay in the presence of a warden observing the network.

Contribution

It introduces a novel gossip-like protocol for covert communication in mobile IoT networks with analysis of covertness and delay trade-offs.

Findings

Higher message splitting improves covertness probability.

Adding redundancy reduces message passing delay.

Trade-off exists between covertness and delay depending on parameters.

Abstract

We introduce a gossip-like protocol for covert message passing between Alice and Bob as they move in an area watched over by a warden Willie. The area hosts a multitude of Internet of (Battlefield) Things (Io\b{eta}T) objects. Alice and Bob perform random walks on a random regular graph. The Io\b{eta}T objects reside on the vertices of this graph, and some can serve as relays between Alice and Bob. The protocol starts with Alice splitting her message into small chunks, which she can covertly deposit to the relays she encounters. The protocol ends with Bob collecting the chunks. Alice may encode her data before the dissemination. Willie can either perform random walks as Alice and Bob do or conduct uniform surveillance of the area. In either case, he can only observe one relay at a time. We evaluate the system performance by the covertness probability and the message passing delay. In our protocol, Alice splits her message to increase the covertness probability and adds (coded) redundancy to reduce the transmission delay. The performance metrics depend on the graph, communications delay, and code parameters. We show that, in most scenarios, it is impossible to find the design parameters that simultaneously maximize the covertness probability and minimize the message delay.