This article proposes a redundancy-free multiple phase-offset based key distribution (MPO-KD) scheme for solving the physical-layer session key agreement in optical data center interconnections (DCIs). High-dimensional chaotic encryption is a promising technology expected to provide better security for massive-scale data transmission in DCIs. Considering the huge key space introduced by hyper-chaos, the proposed scheme converts digital keys into the phase of quadrature amplitude modulation (QAM) symbols by actively introducing controllable offsets. The solution of offset factor space is modeled as a multi-objective optimization problem for improving the key distribution performance. The Pareto optimal set is obtained using the non-dominated sorting moth-flame optimization (NS-MFO) algorithm. The two-channel 140 Gb/s 16-QAM, 176 Gb/s 32-QAM and 210 Gb/s 64-QAM orthogonal frequency division multiplexing (OFDM) signal transmissions are successfully demonstrated. The results indicate that this scheme achieves error-free key distribution without degrading system performance, which supports an expandable large key space and has good compatibility with various encryption algorithms.
This article proposes a redundancy-free multiple phase-offset based key distribution (MPO-KD) scheme for solving the physical-layer session key agreement in optical data center interconnections (DCIs). High-dimensional chaotic encryption is a promising technology expected to provide better security for massive-scale data transmission in DCIs. Considering the huge key space introduced by hyper-chaos, the proposed scheme converts digital keys into the phase of quadrature amplitude modulation (QAM) symbols by actively introducing controllable offsets. The solution of offset factor space is modeled as a multi-objective optimization problem for improving the key distribution performance. The Pareto optimal set is obtained using the non-dominated sorting moth-flame optimization (NS-MFO) algorithm. The two-channel 140 Gb/s 16-QAM, 176 Gb/s 32-QAM and 210 Gb/s 64-QAM orthogonal frequency division multiplexing (OFDM) signal transmissions are successfully demonstrated. The results indicate that this scheme achieves error-free key distribution without degrading system performance, which supports an expandable large key space and has good compatibility with various encryption algorithms.
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.
With the development of the internet, the security of the optical data center interconnections (DCIs) has become a highly concerned topic. However, current security schemes face limitations such as the absence of viable key distribution mechanisms and the sensitivity to channel condition fluctuations. To address the above challenges, we propose a novel physical layer encryption scheme for WDM-based DCIs that combines encryption with channel conditions. Considering the need for dynamic key updates in DCIs, we first propose embedding plaintext-related keys (PRKs) into wavelength-related pilot (WP) positions for distribution. Leveraging their controllable size to combat impairments under varying channel conditions enables dynamic error propagation. Additionally, the proposed recombination mechanism supplements DNA encryption, allowing data transmission across different channels during inter-strand base exchange. The two channel 111.12 Gb/s discrete multi-tone (DMT) signal transmissions are successfully demonstrated. These results indicate that this scheme can transmit data on different paths. The key space can reach 10360and the complexity is about O(n). Furthermore, the key can be transmitted without redundancy and strongly relies on channel conditions to control security. Moreover, this scheme can alleviate the damage caused by high peak to average power ratio (PAPR), with an increase of approximately 0.5dBm at the forward error correction (FEC) limit.
The network traffic of data centers (DCs) has increased unprecedentedly with the rapid development of digital economy. However, the data transmission faces security threats in the distributed optical interconnection and intensive interaction of DC networks. In this paper, we propose a chaotic phase noise-like encryption algorithm using geometric shaping (GS) for coherent DC interconnections (DCIs). A GS constellation is used to improve transmission performance, and it is combined with coherent equalization algorithms to improve security performance. Then, a chaotic encryption is designed based on phase noise-like transformation (PNLT). The data are effectively scrambled, and the confusion level of phase can be increased. Finally, 216 Gb/s 8-quadrature amplitude modulation (8-QAM) encrypted data are successfully verified on a 240 km transmission link of DCIs. The results show that this scheme can achieve a bit error rate (BER) performance gain of 1.1 dB and provide a highly compatible solution for realizing security enhanced DCIs.
A Quantum Key Distribution (QKD) based Physical Layer Security (PLS) scheme (QKD-PLS) for optical fiber links is proposed and evaluated. In detail, a novel amplitude and phase scrambling technique for exploiting and seamlessly integrating high key rate QKD for the encryption of the modulation parameters of conventional complex modulation schemes like M-ary Quadrature Amplitude Modulation (M-QAM) and Orthogonal Frequency Division Multiplexing (OFDM) is described. The technique masks the information at the bit level and blocks unauthorized access to the higher layer encrypted bitstream. Scrambling is applied to both the preamble (pilot) and payload segments of the transmission frame, to prevent the eavesdroppers from performing vital receiver functions such as frame synchronization and channel estimation. Additionally, a practical Key Management System (KMS) which takes care of all synchronization processes is developed and introduced. Experimental transmission scenario in fiber links is also presented and depicts the efficacy of the QKD-PLS. Moreover, another advantage of QKD exploitation to the proposed solution comes from the application of kbps-rate QKD keys which feed pseudo-random number generators, to modify the broadband modulation symbols in one-time pad, therefore significantly improving data protection.
This study investigates a multi-stage digital phase-encryption scheme designed for secure coherent optical communication. While the proposed method is implemented in DSP and can be modeled as a software-level stream cipher, it is explicitly co-designed with and tightly coupled to the physical-layer modulation structure. Unlike conventional XOR-based bitwise schemes, the encryption is applied to the symbol phase domain. It is integrated into the transmitter's modulation process, enabling symbol-level security evaluated in conjunction with transmission physics. By applying K-level phase-shift secret keys toM-ary quadrature amplitude modulation (QAM) signals, this method increases the number of secret-key bits per symbol without altering the signal constellation in its baseline configuration. This approach enhances encryption strength while maintaining signal integrity and reducing quantization overhead in phase-only operation. Experimental evaluations on nonlinear optical transmission channels confirm that baseline digital phase encryption preserves Q-factor stability under self-phase modulation, cross-phase modulation, and four-wave mixing. The proposed scheme ensures error-free transmission at forward error correction thresholds, effectively preventing eavesdroppers from reconstructing symbols under worst-case observation conditions. Additionally, simulations analyzing generalized mutual information and quantization errors demonstrate that the encryption scheme can minimize signal-to-noise ratio penalties, even when employing high-order QAM formats with limited digital-to-analog and analog-to-digital conversion resolutions. As an optional extension, we also analyze pseudo-quantum-noise-based IQ spreading and explicitly quantify the associated trade-off between additional noise masking and increased sensitivity to quantization. These findings position multi-stage digital phase encryption as a practical and power-efficient modulation-layer encryption technique whose behavior is systematically characterized under realistic nonlinear channel and hardware constraints, rather than as an entirely new cryptographic primitive.
In this paper, a scheme to realize encryption and digital identity authentication at the same time is proposed for enhancing the physical-layer security of point-to-point optical links (PPOL). Exploiting identity code encrypted by the key as authentication information effectively resists passive eavesdropping attacks in fingerprint authentication. The proposed scheme theoretically realizes secure key generation and distribution (SKGD) by phase noise estimation of the optical channel and the generation of identity codes with good randomness and unpredictability by the four-dimensional (4D) hyper-chaotic system. The local laser, erbium doped fiber amplifier (EDFA), and public channel provide the entropy source of uniqueness and randomness to extract symmetric key sequences for legitimate partners. The simulation conducted in a quadrature phase shift keying (QPSK) PPOL system over 100km standard single mode fiber verify successfully that 0.95Gbit/s error-free SKGD. The unpredictability and high sensitivity to the initial value and control parameters of the 4D hyper-chaotic system provide a huge space of ~10 125 for identity codes, which is sufficient to resist exhaustive attack. With the proposed scheme, the security level of key and identity can be increased markedly.