This paper proposes a chaotic constellation transformation (CCT) technique for physical-layer security enhancement in orthogonal frequency-division multiple access based passive optical networks (OFDMA-PONs). The CCT is performed by using an advanced cat map whose control parameters are generated by a cross chaotic map. Moreover, a pilot-aided security key agreement scheme is proposed to ensure that the security keys are securely distributed between the transmitter and receiver. A 18.86 Gb/s encrypted 16-ary quadrature amplitude modulation based OFDM signal transmission over a 25 km standard single mode fiber is experimentally demonstrated. The experimental results show that the proposed CCT technique and the pilot-aided secure key agreement are promising for physical-layer security enhancement in future OFDMA-PONs.

The widespread adoption of consumer electronics (CE), particularly in smart home ecosystems, has led to the proliferation of intelligent devices such as smart cameras, video doorbells, and smart door locks. While these devices enhance convenience and automation, they generate massive amounts of visual data containing sensitive personal information, thereby increasing the risk of privacy leakage and challenging traditional encryption methods in consumer IoT networks. To address this issue, a cryptanalysis-driven image encryption scheme via a chaos-based 3D S-box and genetic code is proposed, specifically designed to safeguard visual privacy in consumer applications. First, a novel dynamical architecture, formally termed 3D Non-degenerate Hyperchaos (3D-NDHC), is constructed to serve as a robust entropy source. Explicitly defined as a globally bounded volume-expanding hyperchaotic system, 3D-NDHC distinguishes itself from traditional dissipative maps by exhibiting global robust hyperchaos and scalable complexity, where the Lyapunov exponents grow logarithmically with control parameters, ensuring high unpredictability. Next, a dynamically generated three-dimensional S-box driven by these chaotic sequences is introduced to perform efficient image permutation. Subsequently, a genetic code method enhanced by cryptanalysis is applied to confuse the permuted image matrix, specifically addressing the security vulnerabilities often inherent in lightweight encryption algorithms. Finally, under the control of pseudo-chaotic sequences, a lightweight wave diffusion process is employed to spread the pixel values and produce the final ciphertext image. In contrast to conventional algorithms that rely on standard encryption techniques, the proposed approach integrates a chaos-driven 3D S-box with a cryptanalysis-enhanced genetic code scheme. This combination introduces a high level of confusion and diffusion, significantly increasing the difficulty for attackers attempting to illegally decrypt sensitive images from smart devices. Experimental results and security analyses demonstrate that the scheme effectively resists various cryptographic attacks and outperforms several recently proposed image encryption algorithms, offering a robust solution for protecting digital image privacy in smart home environments.

We propose a novel security enhancement technique for physical layer secure orthogonal frequency division multiplexed-based passive optical network (OFDM-PON) using chaotic Hilbert motion. By using chaos to construct Hilbert motion, the traversal and the scrambling of two-dimensional (2D) symbol matrix are completed. To enhance the security of the key, we use the key space as an encryption object for the first time, and then we use it as a supporter for key generation and distribution. The Hash value generated by this encryption result is applied as a digital signature to verify the data integrity. An experiment that the signals of 35.29 Gb/s are successfully transmitted over 20 km standard single-mode fiber (SSMF) and a back-to-back (BTB) system. The experimental results show that this scheme provides an effective and widely applicable solution for realizing secure OFDM-PON with high security and low complexity.

In order to improve the signal transmission performance and physical layer security in orthogonal frequency division multiplexing-based passive optical network (OFDM-PON), we propose a constellation shaping chaotic encryption (CSCEn) scheme with controllable statistical distribution. In this scheme, a q uadrature amplitude modulation (QAM) symbol sequence is divided into several sub-sequences, and a further probabilistic shaping (PS) is performed by constellation region replacement in terms of the corresponding statistical information ( SI ). Then the sequence SI is encoded and encrypted into chaotic signal phases by employing our key distribution algorithm. At the receiver, the SI is extracted first to restore the original signal . To verify the effectiveness of this scheme, we successfully demonstrate an encrypted PS-16-QAM signal transmission over a 25-km standard single mode fiber (SSMF). The results show that the proposed scheme can flexibly improve bit error rate (BER) performance with low deployment complexity and provide sufficient security to resist attacks from illegal optical network units ( ONUs), thus it displays a promising application prospect for future secure PON.

We propose a novel security enhancement technique for a physical layer secure orthogonal frequency division multiplexed passive optical network (OFDM-PON) based on three-dimensional Brownian motion and chaos in cell (3DBCC). This method confuses an OFDM symbol via transforming it into a 3D symbol matrix and a 3D cell matrix with different size lengths. Different dividing-confusion rules then generate different complementary cumulative distribution functions (CCDFs) of peak-to-average power ratio (PAPR). And we can pre-estimate bit error rate (BER) performance by calculating the CCDF values. We also find that the processing time decreases with the matrix’s side length decreasing simultaneously. A new weighted comprehensive value (Q_w) is further used to evaluate the overall performance between the processing time and the BER. Finally, an experiment successfully demonstrates a physical layer secure OFDM signal transmission with 22.06-Gb/s data rate over a 25.4-km standard single mode fiber (SSMF). These results indicate that cell (5³) has the weighted optimum overall performance, which verifies that the proposed encryption technique is promising for building a physical layer security enhanced OFDM-PON system with a low processing time delay and a good BER for future access network systems.

We propose and experimentally demonstrate a multiuser orthogonal frequency-division multiple access passive optical network (OFDMA-PON) with source-free optical network units (ONUs), enabled by tunable optical frequency comb generation technology. By cascading a phase modulator (PM) and an intensity modulator and dynamically controlling the peak-to-peak voltage of a PM driven signal, a tunable optical frequency comb source can be generated. It is utilized to assist the configuration of a multiple source-free ONUs enhanced OFDMA-PON where simultaneous and interference-free multiuser upstream transmission over a single wavelength can be efficiently supported. The proposed multiuser OFDMA-PON is scalable and cost effective, and its feasibility is successfully verified by experiment.