Secure Image Transmission in Wireless OFDM Systems Using Secure Block Compression-Encryption and Symbol Scrambling

In this paper, a joint compression-encryption and symbol scrambling scheme is proposed for orthogonal frequency-division multiplexing (OFDM) systems for image date. First, in the compression-encryption phase, the original image data is fist divided into sub-blocks and then an secure image block compressive sensing (BCS) is applied to resulting image data, in which a chaotic sparse basis matrix and a chaotic measurement matrix based on the discrete cosine transform (DCT) are used. Secondly, the resulting secure CS data is transform into binary phase shift keying (BPSK) symbols and then a chaotic scrambling operation is applied to the obtained BPSK symbols. The simulation results show that the proposed secure BCS scheme can achieve better peak signal-to-nose ratio (PSNR) performance than that of the conventional chaotic measurement method. The simulation results also show that a good trade-off performance of signals between PSNR and computational complexity can be achieved when the proper sub block size of image is adopted. In addition, the performances of the BPSK OFDM signal, which is generated from the secure BCS of the image, are evaluated over AWGN and multipath fading channels. The simulation results show that the proposed scheme not only achieve effective secure block compressive sensing and achieve secure transmission in physical layer. The security of the transmitted image data is enhanced by the joint compression-encryption and symbol scrambling.