Quantum key distribution is a revolutionary way of quantum cryptography which guarantees absolute security by using the fundamental principle of quantum mechanics. Quantum network consist of two or more nodes of $QKD$ connected via optical fiber or free space. Free space channel can connect two nodes at distances more than 1000Km s apart, whereas fiber links will be used to connect the end users in nearby vicinity. Here we present a study on potential quantum key distribution protocol which can be used in the future quantum network, leading to quantum internet on large scale.
Quantum key distribution is a revolutionary way of quantum cryptography which guarantees absolute security by using the fundamental principle of quantum mechanics. Quantum network consist of two or more nodes of QKD connected via optical fiber or free space. Free space channel can connect two nodes at distances more than 1000Km s apart, whereas fiber links will be used to connect the end users in nearby vicinity. Here we present a study on potential quantum key distribution protocol which can be used in the future quantum network, leading to quantum internet on large scale.
Quantum key distribution (QKD) constitutes a symmetric secret key negotiation protocol capable of maintaining information-theoretic security. Given the recent advances in QKD networks, they have evolved from academic research to some preliminary applications. A QKD network consists of two or more QKD nodes interconnected by optical fiber or free space links. The secret keys are negotiated between any pair of QKD nodes, and then they can be delivered to multiple users in various areas for ensuring long-term protection and forward secrecy. We commence by introducing the QKD basics, followed by reviewing the development of QKD networks and their implementation in practice. Subsequently, we describe the general QKD network architecture, its elements, as well as its interfaces and protocols. Next, we provide an in-depth overview of the associated physical layer and network layer solutions, followed by the standardization efforts as well as the application scenarios associated with QKD networks. Finally, we discuss the potential future research directions and provide design guidelines for QKD networks.
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.
Quantum key distribution (QKD), in which security is ensured by physical quantum laws, is shown as the most secure communication between two distant users [1]–[3]. Recent efforts in global research focus on providing the infrastructure that can support QKD and extending applications to large scale of users and distances. Three types of links are explored up to date: terrestrial free-space links (limited by visible distance), fiber-based links (repeater-free range limited to a few 100 km [1]) and finally satellite links, which allow to bridge intercontinental distances. For each of these scenarios, different types of hardware are involved and state encoding (polarization-, time- [1]–[2], spatial- and frequency-based [3]) is tailored to mitigate link impairments. Additionally, the effort towards higher QKD rates is given [1]–[3] that future global quantum communication networks support a wider range of use cases.
Quantum Key Distribution (QKD) is a mechanism for ensuring secure key exchange based on the fundamental principles of quantum mechanics. It has evolved significantly over the past four decades. QKD networks have evolved from experiments to large-scale deployments, enabling longer transmission distances and enhanced security performance. Existing information security relies on modern cryptographic primitives such as Elliptic Curve Diffie–Hellman (ECDH), RSA, and AES. Although AES-256 is considered quantum-resistant, ECDH and RSA cannot withstand attacks by a specific quantum computer. Specifically, with enough quantum bits, Shor’s and Grover’s algorithms can break RSA and ECDH through rapid integer factorization and quantum search capabilities, respectively. Consequently, QKD offers a promising method towards information-theoretic security, using trusted nodes, optical routers, and future quantum repeaters. However, completely replacing current infrastructure with QKD systems is both costly and impractical. Thus, existing QKD can be integrated into current infrastructure, including dark fiber and satellite systems. Previous surveys have primarily focused on isolated aspects such as fiber-based QKD, free-space QKD, or theoretical Internet architectures. There is a lack of a comprehensive survey that simultaneously presents fundamentals, QKD protocols and security, network implementations, and experimental advances. This makes it difficult for readers to grasp the full scope of the field. This survey focuses on QKD from the ground up, covering the essential foundations of QKD, exploring various QKD protocols, concerning different types of attacks, reviewing real-world QKD network deployments, and highlighting challenges and future directions.
In today's communication networks, the widespread use of optical fiber and passive optical elements allows to use quantum key distribution (QKD) in the current standard optical network infrastructure. In the past few years, quantum key distribution schemes have attracted much study. The security of modern cryptographic methods, like asymmetric cryptography, relies heavily on the problem of factoring large integers (Rivest et al., 1978), (Schneier, 1996). In the future, if quantum computers become reality, any information exchange using current classical cryptographic schemes will be immediately insecure (Shor, 1994), (Shor, 1997). Current classical cryptographic methods are not able to guarantee longterm security. Other cryptographic methods, with absolute security must be applied in the future.
Information security faces unprecedented challenges in the digital age, particularly in the face of cyber threats and the emergence of quantum computing. This research examines QKD as a solution for secure communications in urban fiber networks. The study analyzes QKD protocols, including BB84 and Twin-Field QKD, implementing a 46-node metropolitan quantum network and key distribution over distances greater than 1002 kilometers. Various transmission media, such as multicore optical fibers and free-space communication, were evaluated, demonstrating high-capacity quantum communication with advanced noise mitigation techniques. The results reveal significant advances in quantum communication security, highlighting the potential of QKD to provide theoretically secure key distribution based on quantum mechanical principles. The research addresses challenges such as transmission loss, environmental disturbances, and network scalability, laying the groundwork for future implementations in metropolitan networks. This work contributes significantly to the standardization of evaluation protocols and metrics, which is crucial for the global adoption of QKD in a world increasingly dependent on cybersecurity, especially in developing smart cities.