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EPJ Quantum Technology

Multi-party quantum key distribution protocol in quantum network

Chia‐Wei Tsai, Chun‐Hsiang Wang

Published Sep 27, 2024• 7 citations
Publisher

Abstract

This study proposes a measurement property of graph states and applies it to design a mediated multiparty quantum key distribution (M-MQKD) protocol for a repeater-based quantum network in a restricted quantum environment. The protocol enables remote classical users, who cannot directly transmit qubits, to securely distribute a secret key with the assistance of potentially dishonest quantum repeaters. Classical users only require two quantum capabilities, while quantum repeaters handle entanglement transmission through single-photon measurements. The one-way transmission approach eliminates the need for additional defenses against quantum Trojan horse attacks, reducing maintenance costs compared to round-trip or circular transmission methods. As a result, the M-MQKD protocol is lightweight and easy to implement. The study also evaluates the security of the protocol and demonstrates its practicality through quantum network simulations.

DOI
10.1140/epjqt/s40507-024-00275-5

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This study proposes a measurement property of graph states and applies it to design a mediated multiparty quantum key distribution (M-MQKD) protocol for a repeater-based quantum network in a restricted quantum environment. The protocol enables remote classical users, who cannot directly transmit qubits, to securely distribute a secret key with the assistance of potentially dishonest quantum repeaters. Classical users only require two quantum capabilities, while quantum repeaters handle entanglement transmission through single-photon measurements. The one-way transmission approach eliminates the need for additional defenses against quantum Trojan horse attacks, reducing maintenance costs compared to round-trip or circular transmission methods. As a result, the M-MQKD protocol is lightweight and easy to implement. The study also evaluates the security of the protocol and demonstrates its practicality through quantum network simulations.
The mediated semi-quantum key distribution (MSQKD) protocol is an important research issue that lets two classical participants share secret keys securely between each other with the help of a third party (TP). However, in the existing MSQKD protocols, there are two improvable issues, namely (1) the classical participants must be equipped with expensive detectors to avoid Trojan horse attacks and (2) the trustworthiness level of TP must be honest. To the best of our knowledge, none of the existing MSQKD protocols can resolve both these issues. Therefore, this study takes Bell states as the quantum resource to propose a MSQKD protocol, in which the classical participants do not need a Trojan horse detector and the TP is dishonest. Furthermore, the proposed protocol is shown to be secure against well-known attacks and the classical participants only need two quantum capabilities. Therefore, in comparison to the existing MSQKD protocols, the proposed protocol is better practical.
Classical users can share a secret key with a quantum user by using a semi-quantum key distribution (SQKD) protocol. Allowing two classical users to share a secret key is the objective of the mediated semi-quantum key distribution (MSQKD) protocol. However, the existing MSQKD protocols need a quantum user to assist two classical users in distributing the secret keys, and these protocols require that the classical users be equipped with a Trojan horse photon detector. This reduces the practicability of the MSQKD protocols. Therefore, in this study we propose a lightweight MSQKD, in which the two participants and third party are classical users. Due to the usage of the one-way transmission strategy, the proposed lightweight MSQKD protocol is free from quantum Trojan horse attack. The proposed MSQKD is more practical than the existing MSQKD protocols.
Abstract The multiparty‐mediated quantum secret sharing (MQSS) protocol proposed by Tsai et al. [Quantum Inf. Process., 2022, 21, 63] allows n restricted users with limited quantum capabilities to share secret information using a dishonest third party with full quantum capabilities. Although the MQSS protocol allows restricted users to achieve secret sharing with lightweight quantum capabilities, the qubit efficiency of this protocol can be further improved. Therefore, this study proposes a measurement property of the graph state to design an efficient mediated quantum secret‐sharing protocol in the same quantum environment as that of Tsai et al.’s protocol. The proposed MQSS protocol not only inherits the lightweight property of Tsai et al.’s protocol but also improves the qubit efficiency of Tsai et al.’s protocol by times. Security analysis is performed to show that the proposed MQSS protocol can avoid collective, collusion, and Trojan horse attacks. Furthermore, this study uses quantum network simulation software to implement Tsai et al.’s protocol and the proposed protocol to prove the feasibility of the proposed MQSS protocol and show that it is more efficient than Tsai et al.’s protocol.
This study proposes the first multiparty-to-multiparty mediated quantum secret sharing (M2M-MQSS) protocol within a restricted quantum environment. Unlike existing fully quantum secret sharing (QSS) protocols, this protocol allows protocol participants with limited quantum capabilities—including (1) measuring a single qubit in the Z-basis and (2) performing a single-qubit unitary operation, Hadamard operation—to participate, significantly reducing implementation costs. By employing one-way qubit transmission, the proposed MMQSS protocol not only simplifies the quantum communication process but also effectively defends against quantum Trojan horse attacks. The correctness and security analyses demonstrate that the proposed M2M-MQSS protocol is robust against various well-known attack strategies. Simulation experiments confirm the feasibility of the protocol for various numbers of participants. It maintains high levels of efficiency and security even as the number of participants increases. Moreover, compared with existing protocols, the proposed M2M-MQSS protocol lowers the barrier to practical quantum communication deployment by reducing the quantum resources required for protocol participants.
ABSTRACT This study proposes a new lightweight quantum key distribution (LQKD) protocol based on the four‐particle cluster state within a quantum‐restricted environment. The protocol enables a quantum‐capable user to simultaneously establish two separate secret keys with two “classical” users, who are limited to performing only the Hadamard operation and measurements in the basis. By adopting a one‐way qubit transmission approach, the proposed protocol addresses several limitations of existing semi‐quantum key distribution (SQKD) schemes that rely on two‐way or circular transmission methods: (1) it eliminates the need for classical participants to be equipped with costly quantum devices to defend against quantum Trojan horse attacks; (2) it reduces the qubit transmission distance; and (3) it achieves higher qubit efficiency. Consequently, the proposed LQKD protocol is both more lightweight and practical than existing SQKD protocols. Furthermore, the security analysis shows that, in the ideal case, the protocol achieves the same level of security as fully quantum protocols. Finally, the study proves the unconditional security of the protocol in the non‐ideal case, demonstrating a noise tolerance close to that of the BB84 protocol.
Mediated semi-quantum key distribution (M-SQKD) permits two limited "semi-quantum" or "classical" users to establish a secret key with the help of a third party (TP), in which TP has fully quantum power and may be untrusted. Several protocols have been studied recently for two-party scenarios, but no one has considered M-SQKD for multi-party scenarios. In this paper, we design a circular M-SQKD protocol based on Bell states, which offers an approach to realizing multiple "classical" users' key distribution. Then, we prove the protocol is unconditional security in the asymptotic scenario. The protocol's key rate and noise tolerance can be derived by utilizing the parameters observed in the channel. The results show that our protocol may hold similar security to a fully quantum one. We also compare the proposed protocol with similar protocols in terms of noise tolerance, qubit efficiency, communication cost, and scalability. Finally, the security proof method of this paper may contribute to studying the security of other circular semi-quantum cryptography protocols.