Entity Authentication and Key Distribution

Simon Blake-Wilson⋆⋆, Alfred Menezes

Simon Blake-Wilson⋆⋆, Alfred Menezes

Yanfei Guo, Zhenfeng Zhang

Hojoong Park, Byung Kwon Park, Min Ki Woo +5 more

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.

Yevgen V. Kotukh, Maksym Korobchynskyi, Valerii Kozlovskyi +3 more

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.

Kaoru Kurosawa

An entity-authentication scheme is a two-party protocol by which a party in a distributed system confirms the identity of a communication partner. Bellare and Rogaway (1993) formulated this problem using a complexity theoretic framework. In this paper, we study entity-authentication in an information theoretic framework, where adversaries are infinitely powerful. We first modify the framework given by Bellare and Rogaway to an unconditionally secure setting. Communication between players is entirely controlled by an infinitely powerful adversary A. The adversary can deliver messages out of order and to unintended recipients, and can concoct messages of the adversary's own choosing. What is more, the adversary can control who is attempting to authenticate whom. We then present a lower bound on the cheating probability and a lower bound on the size of keys for unilateral entity authentication protocols. That is, in each session, P/sub i/ authenticates P/sub j/ but P/sub j/ does not authenticate P/sub i/. Finally, we show an entity authentication scheme which is proven to be secure and that meets all the equalities of our bounds.