Enhanced security in lossless audio encryption using zigzag scrambling, DNA coding, SHA-256, and hopfield networks: a practical vlc system implementation

This paper presents a novel lossless audio encryption algorithm based on a modified zigzag scrambling technique, SHA-256, DNA coding, cipher block chaining (CBC) mode, and the delayed Hopfield neural network (HNN). The algorithm mainly includes the scrambling and diffusion stages. In the scrambling stage, the audio signal is converted into a square matrix on which the modified zigzag scrambling technique is applied. Then follows the confusion stage in which bit-level permutation, DNA coding, and CBC mode are applied successively. Besides, the delayed HNN serving in the encryption process is controlled by the plain audio signal through the hash function SHA-256 to resist differential attack. The proposed algorithm has been assessed on ten audio signals using more than fourteen performance measures. Compare to the state-of-the-art, the obtained results show better performances. Indeed, higher resistance to differential attack is obtained; this is seen through higher values of number of sample change rate (NSCR) and unified average changing intensity (UACI). Also, more disorder is detected in the encrypted audio signal through higher values of the information entropy. Furthermore, the proposed algorithm possesses a larger key space arising from the high number of parameters of the delayed HNN, which results in a higher resistance to brute force attacks. A real-life implementation of the proposed encryption technique is achieved with a visible light communication (VLC) system; this highlights its feasibility and effectiveness in securing optical wireless communication systems.