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Security and Communication Networks
Volume 2018, Article ID 1214681, 15 pages
https://doi.org/10.1155/2018/1214681
Research Article

A Wireless Covert Channel Based on Constellation Shaping Modulation

1The School of Automation, Nanjing University of Science and Technology, Nanjing 210094, China
2The School of Electrical and Computer Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China

Correspondence should be addressed to Guangjie Liu; nc.ude.tsujn@uileijg

Received 29 September 2017; Accepted 4 December 2017; Published 8 January 2018

Academic Editor: Rémi Cogranne

Copyright © 2018 Pengcheng Cao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Wireless covert channel is an emerging covert communication technique which conceals the very existence of secret information in wireless signal including GSM, CDMA, and LTE. The secret message bits are always modulated into artificial noise superposed with cover signal, which is then demodulated with the shared codebook at the receiver. In this paper, we first extend the traditional KS test and regularity test in covert timing channel detection into wireless covert channel, which can be used to reveal the very existence of secret data in wireless covert channel from the aspect of multiorder statistics. In order to improve the undetectability, a wireless covert channel for OFDM-based communication system based on constellation shaping modulation is proposed, which generates additional constellation points around the standard points in normal constellations. The carrier signal is then modulated with the dirty constellation and the secret message bits are represented by the selection mode of the additional constellation points; shaping modulation is employed to keep the distribution of constellation errors unchanged. Experimental results show that the proposed wireless covert channel scheme can resist various statistical detections. The communication reliability under typical interference is also proved.