We provide a practical implementation of a free space optical quantum key distribution (FSO-QKD) system within a vehicle-to-infrastructure (V2I) application developed under the Innovate UK AirQKD project. The FSO-QKD system provides the quantum secure encryption keys that serve as the foundation for secure communications throughout the V2I application to address known concerns over V2I security. This document includes summaries of the quantum key generation process and the deployed V2I technology. Subsequently, a high-level view of the system design, the practical experiment, and its execution are presented. Multiple AirQKD project partners developed technologies ranging from semiconductors and hardware to security protocols and software, to enable the QKD-secured V2I system. The developed technology includes a novel zero-trust security protocol used to protect the V2I communications, ensuring that spoofed V2I messages from a compromised device are not accepted by the system.
We provide a practical implementation of a free space optical quantum key distribution (FSO-QKD) system within a vehicle-to-infrastructure (V2I) application developed under the Innovate UK AirQKD project. The FSO-QKD system provides the quantum secure encryption keys that serve as the foundation for secure communications throughout the V2I application to address known concerns over V2I security. This document includes summaries of the quantum key generation process and the deployed V2I technology. Subsequently, a high-level view of the system design, the practical experiment, and its execution are presented. Multiple AirQKD project partners developed technologies ranging from semiconductors and hardware to security protocols and software, to enable the QKD-secured V2I system. The developed technology includes a novel zero-trust security protocol used to protect the V2I communications, ensuring that spoofed V2I messages from a compromised device are not accepted by the system.
Next generation communications will require the exploration of alternatives to existing technologies to enable end-to-end connections for secure data exchange. 5G presents advanced connectivity opportunities even for remote rural areas. However, existing 5G platforms will benefit from complementary methods to enhance network capabilities and fulfill trust requirements. Due to high throughput data links, high-beam directivity, and energy efficiency, free-space optics (FSO) is an alternative solution with the potential to deliver high-performance and efficient security. FSO systems can be improved by adding quantum-key-distribution security to overcome advances in quantum computation. However, practical FSO quantum key distribution (FSO-QKD) requires simultaneous engineering of many elements. To oversee this requirement, the Innovate-UK project addresses the possibility of metropolitan-scale “last-mile” quantum secure connectivity through the use of free-space QKD links to support real-life use cases. In this article, we outline the design, development, and deployment of these elements within the AirQKD project.
As the demand for better security and higher capacity grows, quantum key distribution (QKD) using free-space optics (FSO) presents an innovative solution for 5G networks and beyond. The Innovate-UK AirQKD project explores how FSO–QKD could enable quantum-secure connections at a metropolitan scale, focusing on the critical “last-mile” of connectivity. However, implementing FSO–QKD in the real world brings several engineering challenges, spanning software, hardware, system integration, and security. This paper dives into the complexities of system architecture and integration, QKD transmission over FSO, and the post-processing of keys. We showcase a cohesive system design that blends the quantum and classical domains, incorporating cutting-edge FSO–QKD hardware and software. The system’s functionality is demonstrated for key processes such as transmission, post-processing, network control, and key management. As a case study, we tested an FSO–QKD link over 135 m at BT’s Adastral Park in Suffolk, UK. The setup achieved a photon count rate of up to 585 kcps through a channel with 15.9 dB of loss and 12 kHz of background noise, resulting in a security key rate (SKR) of up to 84.3 kbps using two detectors. We also conducted simulations to estimate the SKR and compared them with the experimental results. Both approaches confirm the system’s ability to generate keys and successfully transmit orthogonal polarization states, highlighting its potential for practical application.
With ever increasing requirements for security and capacity, Quantum Key Distribution (QKD) over Free-space Optics (FSO) offers an alternative solution for 5G and beyond. The Innovate-UK AirQKD project addresses the possibility of metropolitan-scale ‘last-mile’ quantum secure connectivity through FSO-QKD. However, the practical implementation of FSO-QKD faces a multitude of engineering problems across software, hardware, and security. In this paper we examine the challenges of system architecture, integration, QKD transmission via FSO, and the post-processing of keys. We illustrate the design of an integrated system architecture with quantum and classical domains combining advanced FSO-QKD hardware and software, demonstrating its functionality for transmission, post-processing, network control and key management. Moreover, we show the results of an FSO-QKD link over 135 m at BT's Adastral Park in Suffolk, UK, and demonstrate a photon count rate up to 585 kcps over the channel loss of 15.9 dB, with 12 kHz background noise. The post-processing results show the potential key generation capability of the system and verify the feasibility of the successful transmission of orthogonal polarization states.
Due to the recent rapid growth of computing technologies, today's encrypted information based on classical computational complexities will soon no longer remain secure. Quantum cryptography, or quantum key distribution (QKD), relying on the physical laws of quantum mechanics, stands out as a more powerful cryptographic solution that enables the secret key to be shared securely over publicly unsecured communication channels in the presence of eavesdroppers. QKD can be possibly implemented over both optical fiber and free-space optical (FSO) links. Compared to optical fiber, FSO has the immediate advantage of flexibility and cost-effectiveness in terms of infrastructure deployment. More interestingly, recent advancements in satellite communications using FSO links promise the future of a global QKD network for highly secure applications. This paper reviews the development of QKD over FSO for both terrestrial and satellite channels, which highlights the most up-to-date QKD protocols. Owing to how the information is encoded, different QKD protocols are classified into technology-focused categories, where their properties are reviewed and compared. The feasibility of current QKD protocols is then investigated with respect to its specific application scenarios for terrestrial and satellite FSO links, equipped with results from both theoretical and experimental studies. Based on the latest free-space QKD achievements, novel perspectives for future developments and challenges to enhance the secrecy performance and reduce implementation cost are then summarized and comprehensively discussed. The potential combination of QKD and physical layer cryptography for the newly emerging wireless mobile communications networks involved with unmanned aerial vehicles (UAV) is also introduced.
Abstract The evolution of Connected and Autonomous Vehicles (CAVs) promises improvements in our travel experience and the potential to enhance road safety and reduce environmental impact. This will be utilising highly diverse traffic environments that enable several advanced mobility applications. A secure, efficient, reliable, and resilient communications infrastructure is required to support developments in these CAV systems. Next generation of telecommunication networks will seamlessly integrate terrestrial, satellite, and airborne networks into a single wireless system satisfying the requirements of trustworthy future transport systems. Given the increasing importance of CAVs, coupled with their attractiveness as a cyber‐attack for threat agents (e.g., disruption of transportation systems by nation states), security is paramount. Future communications systems offer an opportunity to integrate Quantum Key Distribution (QKD) into vehicular environments, protecting against advances in quantum computation that render many of the classical algorithms that underpin Public Key Infrastructure obsolete. This paper proposes a method for the integration of QKD in V2I networks to enable secure data communication. Quantum Key Distribution is used in the end‐to‐end path of vehicle‐to‐infrastructure (V2I) networks. Furthermore, an overarching Software‐Defined Network, with integrated QKD, is introduced. We have investigated the security performance of QKD in a V2I network over an urban environment.
Quantum Key Distribution (QKD) offers a revolutionary method for achieving information-theoretic security in communication systems by leveraging quantum mechanical principles. With foundational protocols like BB84 and newer innovations such as phase-matching and device-independent QKD, the field has rapidly progressed from theoretical constructs to real-world prototypes. Recent advancements in integrated photonics, high-speed key generation, and satellite-based systems suggest a transformative potential for global cybersecurity infrastructure. However, significant challenges remain in extending secure communication distances, ensuring practical implementation security, reducing cost and size of components, and integrating QKD into existing network architectures. This paper reviews the state-of-the-art in QKD, discusses emerging trends such as chip-based and layered QKD systems, evaluates satellite and free-space deployments, and examines the practical limitations and solutions for long-distance and high-rate secure communications. It concludes by highlighting future directions including standardization, hybrid classical-quantum infrastructures, and software-defined QKD networks.