OFDM-PON physical layer encryption scheme based on chaotic Joseph ring and fractal system

In this paper, we present a novel encryption algorithm that combines the chaotic Joseph ring and fractal system to enhance system security and resistance to chosen plain text attacks (CPAs) in orthogonal frequency division multiplexing passive optical networks (OFDM-PONs). As for this scheme, a modified chaotic Joseph ring is designed and utilized to resist CPAs, which greatly increases the randomness of the output data. The fractal function is also modified to generate a larger range and random dataset, which is used to scramble the quadrature amplitude modulation (QAM) symbols to further improve the confidentiality of the system. It is noted that, a four-dimensional conserved chaotic system is also introduced into this system to generate the initial parameters of the Joseph rings and fractal systems, thereby improving the sensitivity of the encryption scheme. With these processing techniques, multiple data encryption with a key space of similar to 10(358) can be created to prevent exhaustive trials. A simulated OFDM-PON system was built to confirm the feasibility of the proposed scheme. The results show that our scheme can provide excellent confidentiality of data transmission against CPAs and brute-force attack. Besides, the grayscale images are utilized to further verify that the scheme is equally resistant to statistical and cutting attacks.