Cluster Shift Keying: Covert Transmission of Information via Cluster Synchronization in Chaotic Networks

A network of chaotic systems can be designed in such a way that the cluster patterns formed by synchronous nodes can be controlled through the coupling parameters. We present a novel approach to exploiting such a network for covert communication, where controlled clusters encode symbols spatio-temporally. The cluster synchronization network is divided into two subnetworks: transmitter and receiver. First, we specifically design the network with controlled parameters in the transmitter. Second, we ensure that the nodes of the links connecting the transmitter and receiver are not in the same clusters for all the control parameters. The former condition ensures that the control parameters changed at the transmitter change the whole clustering scheme. The second condition enforces that the transmitted signals are always continuous and chaotic. Hence, the transmitted signals are not modulated by the information directly but distributed over the links connecting the subnetworks. Without knowing the network topology, the information cannot be deciphered by eavesdropping on the channel links. The performance has been assessed by extensive simulations of bit error rates under noisy channel conditions.