This research introduces a novel physical-layer encryption technique for metropolitan-optimized optical transport networks (M-OTNs) that integrates real-time optical signal time-domain scrambling/descrambling with decoy-state quantum key distribution (DS-QKD). The method processes real-time optical data from the optical service unit (OSU) using a series of tunable Fabry–Perot cavities (FPCs), synchronized and updated with a running key. Experimental validation demonstrates secure communication within the optical network’s physical layer during standard OTU2 data transmission (10.709 Gbps), achieving an online transmission distance exceeding 100 km over typical single-mode fiber with a power loss of approximately 1.77 dB. The results indicate that this integrated approach significantly enhances the security of the optical physical layer in M-OTNs.
This research introduces a novel physical-layer encryption technique for metropolitan-optimized optical transport networks (M-OTNs) that integrates real-time optical signal time-domain scrambling/descrambling with decoy-state quantum key distribution (DS-QKD). The method processes real-time optical data from the optical service unit (OSU) using a series of tunable Fabry–Perot cavities (FPCs), synchronized and updated with a running key. Experimental validation demonstrates secure communication within the optical network’s physical layer during standard OTU2 data transmission (10.709 Gbps), achieving an online transmission distance exceeding 100 km over typical single-mode fiber with a power loss of approximately 1.77 dB. The results indicate that this integrated approach significantly enhances the security of the optical physical layer in M-OTNs.
The Optical Transport Network (OTN) is a protocol for sending network messaging over optical fiber networks. Intelligent optical networks provide an ideal solution for high-bandwidth services. Currently, data encryption schemes for OTN typically rely on mathematical problems such as elliptic curve cryptography or discrete logarithms, which are vulnerable to attacks by quantum computers. This paper investigates a quantum-secure OTN Framework that integrates Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC) technologies, enabling OTN leased lines to resist quantum attacks. This framework can provide users with highly secure quantum-encrypted OTN leased lines services.
This paper reports a practical quantum-safe metro network, integrating optically-switched QKD systems with high speed reconfigurability to protect classical network traffic. Quantum signals are routed by millisecond optical switches and secure keys are shared between any two endpoints or network nodes via low-latency reconfigurable connections. Efficient quantum encryption topologies between different end-users are also presented. We show experimentally the feasibility of a rapidly reconfigured QKD transmission system between multiple users in the proposed network. Classical data and control signals coexist with the quantum signals in the same fibre. Proof-of-concept experiments are conducted over effective transmission distances of 30 km, 31.7 km, 33.1 km, and 44.6 km. Software controlled QKD transmission is established between four different transmitters (Alice) and one receiver (Bob) with a switching time of a few milliseconds. The quantum bit error rates for the four paths are proportional to the channel losses with values between 2.6% and 4.1%. Optimization of the reconciliation and clock distribution architecture is predicted to result in a maximum key generation delay of 20 s, far shorter than previously demonstrated.
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.
Data security plays an increasingly important role in modern telecommunications. The advent of quantum computational processors presents a significant threat to today's widely employed public key encryption algorithms, necessitating the adoption of new approaches to data encryption. Whilst quantum key distribution guarantees unconditional security for cryptographic key exchange in optical communication networks, the data rate is slow (Mbit/s), especially when compared to conventional optical communication. Here we present a highly secure encryption approach in which the encryption key, generated by quantum key distribution at a rate of up to 2.9 Mbit/s, was used to seed physical layer encryption performed using time domain spectral phase encoding (TDSPE). This allowed us to demonstrate encrypted 40 Gbit/s quadrature phase shift keyed data communications over 52.3 km of installed optical fiber, which cannot be eavesdropped using brute force computational attacks. Any attempt to eavesdrop the encrypted signal in the physical layer is highly time-sensitive – the phase states must be measured and decrypted prior to optical signal attenuation, which means that the attack procedure typically needs to be completed within a few milliseconds. This work represents the first example of quantum-enhanced physical layer encryption at realistic optical data rates that is fully secure from brute force computational attacks and the first demonstration of TDSPE using continuous-wave laser source and quadrature phase shift key modulation.
Protecting the security of optical network is a major worldwide challenge. The conventional schemes for securing communications are based on cryptography at the MAC layer and its higher layers, which are facing a great threat with the development of quantum computers. Optical encryption is a promising way for building security on the physical layer of optical communications. In this work, we propose a novel optical encryption scheme for wavelength division multiplexing (WDM) fiber-optic communication systems, by utilizing the private chaotic phase scrambling. Secure transmission of 50 Gbps signal over 50-km standard single-mode fiber is experimentally and numerically demonstrated. The results show that the WDM signal is efficiently encrypted into a noise-like signal, due to the spectral broadening effect of chaotic phase scrambling. Since the processes of encryption and decryption are totally implemented in the optical domain, the proposed scheme can encrypt the entire network traffic with low latency and high speed. Moreover, the proposed encryption scheme is compatible with the existing WDM optical networks, and only one pair of encryption and decryption devices is sufficient to encrypt all WDM channels, thus the scheme can be easily implemented at low hardware cost.
The quantum key distribution (QKD) method allows for the safe creation of encryption keys between trusted entities for secure communication. The suggested system is designed to enable secure communication between multiple parties (a single sender, Alice, and multiple receivers, Bobs) connected via a public channel susceptible to interception. It enables Alice to privately share encryption keys with each Bob over dedicated quantum channels, which can then be used to decrypt messages sent over the public network. The procedure involves Alice generating optical signals with randomly assigned properties such as intensity, phase, polarization, and frequencies. Alice randomly sends either signal states carrying information or decoy states with different frequencies to the receivers (Bobs) over the quantum channels. She also sends a synchronization signal for timing alignment with the quantum signals over the optical links. At the receiving end, the synchronization pulse timestamps the incoming quantum signals. Each Bob then randomly alters the frequencies of the received quantum signals and randomly measures their phase or polarization. The key is created from the frequency, phase, or polarization information of the quantum signals, resulting in longer keys. Key management agents manage the securely QKD-generated keys to encrypt information before sending it to the intended receivers. Essentially, this framework establishes authenticated, private communication by using QKD over dedicated ultra-secure quantum links to distribute decryption keys, ensuring that only intended users can access the content. The approach is designed to ensure end-to-end secure communication across the network.