Design a Wireless Covert Channel Based on Dither Analog Chaotic Code

Abstract

To conceal the very existence of communication, the noise-based wireless covert channel modulates secret messages into artificial noise, which is added to the normal wireless signal. Although the state-of-the-art work based on constellation modulation has made the composite and legitimate signal undistinguishable, there exists an imperfection on reliability due to the dense distribution of covert constellation points. In this study, the authors design a wireless covert channel based on dither analog chaotic code to improve the reliability without damaging the undetectability. The dither analog chaotic code (DACC) plays the role as the error correcting code. In the modulation, the analog variables converted from secret messages are encode into joint codewords by chaotic mapping and dither derivation of DACC. The joint codewords are mapped to artificial noise later. Simulation results show that the proposed scheme can achieve better reliability than the state-of-the-art scheme while maintaining the similar performance on undetectability.