Communications Engineering

Device-compatible ultra-high-order quantum noise stream cipher based on delta-sigma modulator and optical chaos

Hanwen Luo, Ziheng Zhang, Longquan Dai, Linsheng Zhong, Qi Yang, Lei Deng, Deming Liu, Xiaoxiao Dai, Xiaojing Gao, Mengfan Cheng

Published Feb 7, 2024• 8 citations

Publisher

Abstract

Abstract Data security is a key feature of future communications networks. Physical layer introduces rich physical mechanisms to increase the complexity of deciphering and provides extensive protection, but faces challenges in compatibility with commercial systems. Quantum noise stream cipher (QNSC) has been proposed as a promising solution to overcome this problem by fusing the stream cryptography regime with the quantum noise masking physical mechanism. However, it has limitations in terms of digital to analog conversion and clock data synchronization of ultra-high-order ciphertext as well as flexible control of masking noise. Here we report a 147.9-Gbps device-compatible quadrature amplitude modulation (QAM) QNSC secure scheme over 75-km fiber. Thanks to delta-sigma modulator, the transmission of 220 × 220-order QAM-QNSC signal are established through the low-order digital signal. We develop a theoretical model for flexibly regulating the transmission rate and security performance. Broadband optical chaos introduces true randomness and acts on the masking noise.

DOI: 10.1038/s44172-024-00171-x

Related papers

Physical-Layer Secure Optical Transmission Based on Randomized Quantization Noise

Hanwen Luo, Ziheng Zhang, Longquan Dai +6 more

In this paper, we propose a novel physical layer security optical transmission scheme utilizing randomized quantization noise. The proposed approach encrypts low-order plaintext signals into ultra-high-order ciphertext using principles similar to quantum noise stream cipher (QNSC). While, the ultra-dense quadrature amplitude modulation (QAM) ciphertext waveforms are masked by intrinsic quantization noise. The combination of digital delta-sigma quantization and analog chaotic random scrambling not only produces randomized quantization noise, but also naturally supports one-time processing of masking ciphertext and generating keystream. Whereby, the in-band quantization noise (IBN) conceals nearby ciphertext levels bolstering security, and the out-of-band quantization noise (OOBN) is digitized to generate keystream using the Toeplitz hashing extractor. Experimental results show that 256-QAM plaintext signals were securely transmitted over standard single-mode fiber: 163-Gbps signals over 400 km, and 79.7-Gbps signals over 1800 km. To evaluate system performance, theoretical models for signal-to-noise ratio (SNR), bit error rate (BER), and number of masked signals (NMS) are derived as functions of the oversampling ratio (OSR). Our findings reveal a trade-off between transmission performance and security performance. Our results confirm that this scrambling effectively eliminates the correlation between the masking noise components. Toeplitz hashing extractor can effectively reduce the complexity of keystream generation and obtain a source-independent random keystream.

IEEE Transactions on Information Forensics and SecurityJan 1, 20253 citations

Experimental demonstration of 201.6-Gbit/s coherent probabilistic shaping QAM transmission with quantum noise stream cipher over a 1200-km standard single mode fiber

Jihui Sun, Lin Jiang, Anlin Yi +5 more

A probabilistic shaping (PS) quadrature amplitude modulation (QAM) based on Y-00 quantum noise stream cipher (QNSC) has been proposed. We experimentally demonstrated this scheme with data rate of 201.6Gbit/s over a 1200-km standard single mode fiber (SSMF) under a 20% SD-FEC threshold. Accounting for the 20% FEC and 6.25% pilot overhead, the achieved net data rate is ∼160Gbit/s. In the proposed scheme, a mathematical cipher (Y-00 protocol) is utilized to convert the original low-order modulation PS-16 (2 2 × 2 2 ) QAM into ultra-dense high-order modulation PS-65536 (2 8 × 2 8 ) QAM. Then, the physical randomness of quantum (shot) noise at photodetection and amplified spontaneous emission (ASE) noise from optical amplifiers are employed to mask the encrypted ultra-dense high-order signal for further improving the security. We further analyze the security performance by two metrics known in the reported QNSC systems, namely the number of masked signals (NMS) of noise and the detection failure probability (DFP). Experimental results show it is difficult or even impossible to extract transmission signals from quantum or ASE noise for an eavesdropper (Eve). We believe that the proposed PS-QAM/QNSC secure transmission scheme has the potential to be compatible with existing high-speed long-distance optical fiber communication systems.

Optics ExpressFeb 27, 202333 citations

DAC/ADC-free 4 × 12.9 Gbit/s 65,536-level quantum noise stream cipher secure optical WDM transmission based on delta-sigma modulation

Hanwen Luo, Linsheng Zhong, Xiaoxiao Dai +4 more

We propose and experimentally study a novel, to the best of our knowledge, quantum noise stream cipher (QNSC) secure transmission scheme based on the delta-sigma modulation (DSM) technique. The cooperation of the QNSC and DSM mechanisms makes it possible to transmit an ultrahigh-order encrypted signal in the non-return-to-zero (NRZ) on-off keying (OOK) format. The delivery of the NRZ OOK waveform over the fiber link allows us to send and receive signals using digital ports, instead of high-speed and high-resolution digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) in conventional QNSC systems. Meanwhile, clock synchronization can be achieved by using a simple clock data recovery algorithm. The extra clock signal transmission link in conventional QNSC systems is no longer needed. The proposed scheme is also compatible with wavelength division multiplexing (WDM) systems. In this work, 4 × 12.9 Gbit/s plaintext is encrypted to a 65,536-level QNSC signal and then transmitted over a 10-km standard single-mode fiber. The transmitter and receiver are established by commercial 100G QSFP28 optical modules with clock data recovery. This proposed scheme can be easily deployed in commercial systems due to its minimalist implementation architecture and relatively low hardware cost.

Optics LettersSep 12, 202210 citations

Security-enhanced ultra-high-order QAM quantum noise stream cipher assisted by intensity and phase chaotic encryption

Lin Jiang, Sijia Gu, Lianshan Yan +5 more

An ultra-high-order QAM quantum noise stream cipher (QNSC) scheme assisted by intensity and phase chaotic encryption is proposed. In this scheme, the legal transmitter (Alice) first encrypts the original low-order QAM signal into an ultra-high-order QAM signal according to the pre-shared seed key based on the Y-00 protocol, and then conceals the intensity and phase information of the ultra-high-order QAM signal through the intensity and phase chaos generated from a nonlinear delay chaotic source for enhancing the security. The intensity and phase chaotic carrier can be eliminated by the open-loop chaotic synchronization module at the legal receiver (Bob). The scheme was numerically verified in 112 Gbit/s (28 GBaud 16QAM plaintext) and 168 Gbit/s (28 GBaud 64QAM plaintext) 65536QAM/QNSC systems, which can achieve 600 km and 150 km transmission at 7% HD-FEC threshold, and 1000 km and 350 km transmission at 20% SD-FEC threshold, respectively. Meanwhile, the number of masked signals (NMS) and the detection failure probability (DFP) in the scheme are obviously higher than in the original QAM/QNSC system. We believe that the proposed scheme is a promising strategy for enhancing the security of QAM/QNSC transmission systems.

Optics ExpressMay 23, 20255 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

Intensity Modulated Quantum Noise Stream Cipher System Assisted by Optical Chaos

Gu Sijia, JIANG Lin, Yan Lianshan +4 more

【Objective】To further enhance the security of the Intensity Modulated (IM) / Quantum Noise Stream Cipher (QNSC) system, this paper proposes a security enhancement scheme for the IM/QNSC system assisted by chaotic encryption.【Methods】In this scheme, the legitimate transmitter encrypts the low-order 4-level Pulse Amplitude Modulation (PAM-4) signal into an ultra-high-order PAM-256 signal. Then it uses the intensity chaos generated by a nonlinear delayed chaos source to encrypt the ultra-high-order PAM signal, so as to enhance the security of the IM/QNSC system.【Results】This scheme was numerically verified in IM/QNSC dispersion-managed transmission systems with rates of 56 and 112 Gbit/s. The results show that under the 7% Hard Decision-Forward Error Correction (HD-FEC) threshold, the 56 and 112 Gbit/s encrypted systems achieve transmissions of 400 and 300 km. Under the 20% Soft Decision-Forward Error Correction (SD-FEC) threshold, they achieve transmissions of 700 and 600 km. The security analysis of the scheme shows that the Number of Masked Symbols (NMS) and Detection Failure Probability (DFP) of the scheme are higher than those of the original IM/QNSC system.【Conclusion】Chaotic encryption assistance amplifies the eavesdropping noise in the QNSC system. Compared with the original IM/QNSC system, it improves the system security.

Dec 1, 20250 citations