Abstract Entity authentication is crucial for ensuring secure quantum communication as it helps confirm the identity of participants before transmitting any confidential information. We propose a practical entity authentication protocol for quantum key distribution (QKD) network systems that utilizes authentication qubits. In this protocol, authentication qubits that are encoded with pre-shared information are generated and exchanged to verify the legitimacy of each entity. By using the authentication qubit, participants can identify each other with enhanced security level through the quantum channel. The proposed protocol can be easily integrated with existing QKD systems without the need for additional hardware. In this study, we demonstrated the efficacy of the proposed scheme using a 1xN QKD network system and verified its stable operation over a deployed fiber network. Additionally, a security analysis of the proposed entity authentication protocol and architecture is provided.
Abstract Entity authentication is crucial for ensuring secure quantum communication as it helps confirm the identity of participants before transmitting any confidential information. We propose a practical entity authentication protocol for quantum key distribution (QKD) network systems that utilizes authentication qubits. In this protocol, authentication qubits that are encoded with pre-shared information are generated and exchanged to verify the legitimacy of each entity. By using the authentication qubit, participants can identify each other with enhanced security level through the quantum channel. The proposed protocol can be easily integrated with existing QKD systems without the need for additional hardware. In this study, we demonstrated the efficacy of the proposed scheme using a 1xN QKD network system and verified its stable operation over a deployed fiber network. Additionally, a security analysis of the proposed entity authentication protocol and architecture is provided.
The paper addresses entity authentication in quantum key distribution (QKD) systems as a decisive condition of their practical security. It is shown that the information-theoretic security of quantum key agreement does not eliminate the need to authenticate the communicating parties: an unauthenticated classical channel leaves the system exposed to the man-in-the-middle attack, since the eavesdropper can run independent QKD instances with each party and reconcile two keys under full control. Existing authentication methods are analysed and classified by the underlying cryptographic primitive: symmetric schemes based on Wegman–Carter universal hashing, pre-shared and fixed keys, public-key infrastructure, two-way authentication, quantum entity/identity authentication, and zero-knowledge proofs. For each class the operating principle, advantages and limitations are determined, with emphasis on key management, scalability and trust distribution. It is established that symmetric and quantum-layer methods rely on pre-shared secrets with a quadratic growth of key material, public-key infrastructure introduces a single trust bottleneck and quantum-vulnerable primitives, while existing zero-knowledge authentication schemes are quantum and bound to the physical layer or solve network properties other than identity. A comparative analysis reveals an unresolved scientific gap: the absence of a scalable entity-authentication method that simultaneously provides non-disclosure of the secret, quantum resistance, sub-quadratic scalability and minimisation of trust assumptions. On this basis, a prospective research direction is substantiated – the construction of entity-authentication methods based on post-quantum zero-knowledge proofs operating over the classical control plane of scalable QKD networks. The requirements for such a method are formulated, and its compatibility with formal QKD security proofs is discussed.
Quantum Key Distribution (QKD) offers theoretically unbreakable key exchange, but is vulnerable to man-in-the-middle attacks if the identities of the communicating parties are not rigorously verified. This paper proposes a novel QKD protocol integrating classical authentication to provide a layered security approach. The core concept involves utilizing a QKD system alongside a robust classical authentication mechanism. This layered approach significantly reduces the risk of successful attacks by ensuring that both parties are who they claim to be before key exchange occurs. The protocol's security relies on the assumption that the classical authentication system is itself secure. We detail the protocol's components, focusing on the integration of Bennett-Brassard (BB84) or a similar QKD scheme with a practical authentication protocol, and analyze its security properties. The proposed system is designed to mitigate the threats posed by adversaries who can intercept and manipulate the quantum key exchange without compromising the authentication process. The potential for improved security and resilience is demonstrated, representing a significant advancement in the practical application of QKD.
With the increasing importance of securing quantum communication networks, practical and robust entity authentication is a critical requirement. Accordingly, we propose and experimentally validate a quantum entity authentication (QEA) protocol specifically designed for integration with BB84-type quantum key distribution (QKD) workflows and existing terminal architectures. We analyze the protocol's security against intercept-resend man-in-the-middle (MitM) impersonation, showing that an unauthenticated adversary induces a characteristic 25% correlation error and that the rejection probability approaches unity as the number of detected authentication events increases. For practical realization, the protocol is deployed using weak coherent pulses (WCPs) with decoy-state estimation to bound single-photon contributions and mitigate photon-number-splitting (PNS)-enabled leakage. The system is demonstrated over a field-deployed fiber link of approximately 20 km with ~8 dB optical loss using signal/decoy intensities of ~0.5/~0.15 and sending probabilities 0.88/0.10/0.02 (signal/decoy/vacuum). Across both verification directions, stable operation is observed with quantum bit error rate (QBER) typically fluctuating between 1% and 4% while the sifted key rate remains constant over time. These results provide an experimental basis for integrating physical-layer entity authentication into deployed quantum communication networks.
In this review, we survey the cryptographic task of authentication from the perspective of quantum communication. We review three main flavours of authentication that are often conflated in the literature: authentication of classical messages, authentication of quantum messages, and entity authentication, also covering recent hardware-assisted approaches. We compare representative protocols for each functionality in terms of their security assumptions, set-up requirements, composability, and scalability in large or dynamic networks, and use these criteria to identify and recommend suitable candidates. Finally, applications are surveyed: we provide a detailed case study of authentication and quantum key distribution (QKD), then extend the discussion to protocols beyond QKD, where the role of authentication is more complex. Our take-home message is that an authentication requirement is not an intrinsic limitation of quantum networks: as with all secure communication, each protocol relies on a particular authentication resource, and the security claim of that protocol is meaningful only once the authentication resource and its deployment assumptions are made explicit. At the same time, the existing classical and quantum literature already offers a range of quantum-secure authentication schemes, which can support different applications when carefully matched to the required functionality, assumptions, and security guarantees.
Abstract Quantum key distribution (QKD) can provide information theoretically secure key exchange even in the era of quantum computers. However, QKD requires the classical channel to be authenticated, the current method for which is pre-sharing symmetric keys. For a QKD network of n users, this method requires Cn2=n(n−1)/2 C n 2 = n ( n − 1 ) / 2 pairs of symmetric keys to realize pairwise interconnection. In contrast, with the help of a mature public key infrastructure (PKI) and post-quantum cryptography (PQC) with quantum-resistant security, each user only needs to apply for one digital certificate from a certificate authority (CA) to achieve efficient and secure authentication for QKD. We need to assume only the short-term security of the PQC algorithm to achieve long-term security of the distributed keys. Here, we experimentally verified the feasibility, efficiency, and stability of the PQC algorithm in QKD authentication, and demonstrated the advantages when new users join the QKD network. Using the PQC public-key infrastructure, the nodes need to mutually trust only the CA to authenticate each other. QKD combined with PQC authentication will greatly promote and extend the application prospects of quantum-safe communication.
This paper proposes a novel protocol for authenticated quantum key distribution (QKD) that addresses the inherent vulnerabilities of traditional, centralized key management systems. The core concept leverages the security of QKD to establish a shared secret key, then integrates this key with a classical authentication protocol to verify the identities of the communicating parties. The protocol, denoted as AQKD, aims to enhance overall communication security by combining the unique properties of quantum key distribution with robust classical authentication mechanisms. The design incorporates a multi-round key exchange utilizing Bennett-May-Crabtree (BMC) protocol and incorporates a challenge-response mechanism for authentication. The proposed protocol mitigates risks associated with compromised central servers and provides a more resilient security posture. The primary contribution lies in the synergistic integration of these two established cryptographic paradigms, resulting in a more secure and adaptable communication system. The protocol's security is analyzed, considering potential attacks and demonstrating its resilience. The simulation results highlight the effectiveness of AQKD in establishing secure communication channels, particularly against eavesdropping and identity forgery attempts.