IEEE Photonics Technology Letters

Adaptive Secure Communications With Key Updating Using 4-D Hyper-Chaos in Digital Mobile Fronthaul

Shuang Wei, Yuang Li, Mingrui Zhang, Yajie Li, Yongli Zhao, Jie Zhang

Published Apr 7, 2026• 1 citation

Abstract

In this letter, an integration scheme of adaptive secure communications and key updating based on incremental delta sigma modulation (DSM) and 4D chaotic system is proposed, improving the security and tidal effect robustness in digital mobile fronthaul. The session key derives from the in-band noise (IBN) of DSM. 4D chaotic system prevents the leakage of transmission bit and session key. By adjusting oversampling ratio, the proposed scheme achieves adaptive error-free performance in the experiment, reaching a maximum transmission bit rate of 12.799 Gbit/s and key updating rate of 2.133 Gbit/s. We analyze the IBN property in terms of time and frequency domains. Further, the session key of 10 Gbits is proven to pass the randomness test. The key space with 10135can resist brute force attacks for plaintext and session keys.

DOI: 10.1109/lpt.2026.3681645

Related papers

Enhancing secure transmission and key distribution for ultrahigh-order QAM via delta-sigma modulation and discrete memristive-enhanced chaos

Jianye Zhao, Bo Liu, Jianxin Ren +8 more

In this Letter, we propose a method for ultrahigh-order QAM secure transmission and key distribution based on delta-sigma modulation (DSM) and discrete memristive-enhanced chaos (DMEC). The disturbance vectors generated by the DMEC scramble the DSM signals in both frequency and time domains, resulting in highly secure DSM signals. Through the key modulation and power adjustment and then superimposing them on the encrypted signals, the method achieves simultaneous transmission of keys and signals without the need for additional spectral resources. This approach allows for secure communication with continuous key iteration and updates, offering an effective solution for implementing "one-time pad" encryption. In the experimental demonstration, we achieved a secure transmission and key distribution of a 16384QAM signal at a rate of 17.09 Gb/s over 25 km in an intensity-modulated direct detection (IMDD) system, based on DSM.

Optics LettersMay 10, 20245 citations

Probabilistic shaping probability distribution scrambling based on a chaotic system for integrating secure transmission and adaptive key updating

Shuang Wei, Sheng Liu, Dong Wang +7 more

A probabilistic shaping probability distribution scramble (PSPDS) scheme based on chaotic systems is proposed to fulfill both secure transmission and adaptive key updating. The chaotic Chen and logistic systems are adopted to generate a chaotic random sequence. The probabilistic shaping is achieved by constant composition distribution matching (CCDM) and probabilistic amplitude shaping architecture. The chaotic, random sequences are used to scramble the probability distribution of CCDM, improving security. The session key is embedded into a probability distribution. The legal receiver extracts the error-free session key when OSNR is higher than the requirement of the forward error correction threshold. We employ a coherent OFDM 16QAM transmission experiment on 120 km fiber, confirming our proposed scheme with a net rate of 9.95 Gbit/s. The results show that the PSPDS scheme has no encryption penalty compared with the baseline without encryption. The key updating rate has the ability to vary adaptively and reaches 224.2 Mbit/s by adjusting the block length of CCDM in our experiment. The key space reaches 10 136 . Even if an illegal party obtains a ciphertext signal, the plaintext and session key can hardly be inferred due to a probability distribution scramble.

Optics ExpressOct 25, 20243 citations

Chaotic 4D Modulation With Intrusion Detection for Secure Data Centers

Wenjun Zeng, Chongfu Zhang, Jiebing Xia +5 more

Digital chaotic physical layer encryption plays a crucial role in safeguarding data transmission security within data center interconnections (DCIs). However, existing encryption schemes remain vulnerable to active attacks, such as illegal optical access. To address these challenges, we propose a chaotic four-dimensional (4D) modulation scheme integrated with intrusion detection, which aims at enhancing the security of DCIs. The proposed scheme utilizes chaotic permutation and substitution encryption during the 4D modulation process, along with cross-polarization permutation to protect performance gains. Additionally, we propose a cost-effective and easily implementable intrusion detection method based on constellation same set ratio (CSSR). By dynamically adjusting the confidence region through CSSR analysis, the scheme enhances its robustness against noise interference. The proposed scheme is validated through 392 Gbit/s encrypted data transmission over an 80 km standard single-mode fiber, simulating attack scenarios including optical eavesdropping and illegal optical access. These results demonstrate that the proposed scheme achieves an information entropy of 3.999956, with a key space extending to 10360. The intrusion detection mechanism provides dynamic noise tolerance without requiring additional equipment, enabling the identification of illegal signals across various optical signal-to-noise ratios. This scheme provides a novel approach for resisting illegal optical access at the physical layer, with potential application in secure DCIs.

Journal of Lightwave TechnologyJun 13, 202529 citations

All-Digital Device-Compatible Real-Time Physical Layer Secure Transmission Based on Delta-Sigma Modulation

Linsheng Zhong, Ruiyan Zhao, Tian Qiu +16 more

A novel physical layer digital encryption optical transmission method based on delta-sigma modulation is proposed and implemented using field programmable gate arrays (FPGA) for real-time transceivers. This approach converts ultra-high-order ciphertext, encrypted by a first-layer pseudorandom matrix, into 2-level signals via delta-sigma modulator (DSM), enabling all-digital transceiver operation with commercial optical transmission network. By employing a dynamically perturbed parameter matrix, the quantization noise introduced by the DSM is randomized, achieving a secondary masking of the ultra-high-order ciphertext. This method shares conceptual security principles with quantum noise stream cipher (QNSC) but focuses on enhancing device compatibility for physical layer secure optical transmission systems and removes the necessity for additional clock links often required by QNSC and most digital domain secure transmission technologies. In the experiment, the proposed system demonstrated bidirectional quantization noise masking physical layer secure transmission on a coarse wavelength division multiplexing (CWDM) grid, achieving a plaintext capacity of 8 × 10 Gb/s. Subsequently, real-time long-haul transmission was achieved using commercial coherent optical terminal unit (OTU4E) modules. In a 1000 km link, a 96-grid system covering the entire C-band was employed, with 9 grids measured at equal intervals across the band. Each measured grid occupied 50 GHz frequency range and achieved a plaintext transmission rate of 24.88 Gbps. This demonstrates that a potential capacity-distance product of 2.4 Pb/s·km can be achieved.

Journal of Lightwave TechnologyOct 14, 20245 citations

Secure OFDM transmission scheme based on chaotic encryption and noise-masking key distribution

Yibin Wan, Jianxin Ren, Bo Liu +8 more

In this Letter, we propose a secure orthogonal frequency division multiplexing (OFDM) transmission scheme based on chaotic encryption and noise-masking key distribution. With the implementation of a three-dimensional digital chaotic system, the security performance is effectively enhanced by scrambling the phase, symbol, and subcarrier frequency of the OFDM signal. The proposed noise-masking key distribution can mask the key information of the chaotic system into noise and transmit it with the chaotic encrypted signal simultaneously. By this mechanism, the legal receiver can realize uninterrupted authentication and decryption even if the key is constantly updated. Transmission of a 62.2-Gb/s quadrature phase shift keying (QPSK) and 124.4-Gb/s 16 quadrature amplitude modulation (16QAM) OFDM signal over a 2-km 7-core fiber using the proposed scheme is experimentally demonstrated. The results show that the proposed scheme can realize security enhancement and cost-effective key distribution without significant bit error ratio (BER) performance degradation.

Optics LettersMay 3, 202224 citations

High security lossless key-accompanying transmission method based on noise-masked 3D index mapping over four-core fiber

Shuaidong Chen, Bo Liu, Jianxin Ren +9 more

A lossless key-accompanying transmission method based on noise-masked three-dimensional (3D) index mapping over four-core fiber is proposed. This scheme utilizes a four-dimensional (4D) chaotic model to mask the bits of the original data and orthogonal frequency division multiplexing (OFDM) symbols. Its initial value key is transformed into binary bits, and the error-free transmission of the key is ensured by periodic key repetition. And the masking of the key is achieved by introducing noise bits. In the process of constellation mapping, the 16 constellation points are divided into inner constellations and outer constellations. The traceless loading of the key is achieved by controlling the mapping rule using noisy key bits. A 115-kilometer four-core fiber transmission experiment of the noise-masked 3D index mapping method was successfully verified. The experimental results show that the difference between different cores of the four-core fiber is no more than 0.35 dB. There is almost no signal-noise ratio (SNR) penalty before and after signal encryption. The difference in sensitivity at the receiver is only 0.05 dB, which proves that this scheme can achieve lossless key transmission. As this scheme adopts the method of key repetition, it can ensure the correct demodulation of the key and the precise index of the constellation B. Compared with the traditional 16 quadrature amplitude modulation (QAM) signal, a sensitivity gain of 0.75 dB can be achieved. As for the illegal receiver, due to the lack of correct keys and encryption methods, the accuracy rate of key extraction is 0%, and the bit error rate (BER) remains at around 0.5. Even if the key index position is displaced by one bit, the BER will soar above 0.48. And through five repetitions, 100% correct recovery of the key at the legitimate receiver can be guaranteed. This scheme has excellent transmission effect and security, and can effectively guarantee the performance of the next-generation communication system.

Optics ExpressFeb 16, 20260 citations