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Modern Physics Letters B

Continuous-variable multiparty quantum key agreement based on third party

Yi‐Hua Zhou, Jing Zhang, Wei‐Min Shi, Yu‐Guang Yang, Mao-Feng Wang

Published Feb 3, 2020• 10 citations
Publisher

Abstract

General quantum key agreement (QKA) protocols require each participant to make the same contribution to the generation of a shared key, but this situation cannot meet the needs of government or military which require a third party only to control key agreement process. This paper proposed a continuous-variable quantum key agreement (CVQKA) protocol with multi-party Greenberg–Horne–Zeilinger (GHZ) entangled states generated by a third party. The third party prepares quantum states by sending multi-photon beam with higher emission frequency and stronger signal. Taking continuous variable as carrier, the information carried by each carrier increases, which improves the security key rate. In this paper, the third party controls but does not contribute to the final key. After receiving the states, each participant encodes his or her own key, adds a decoy state and sends it to the next participant, until receiving the quantum state that was encoded by all the participants. Then, participants can measure and calculate to get the final shared key. It shows that our protocol is easy to implement and has high efficiency. Security analysis shows that our protocol can resist collusion attacks, beam splitter attack, etc.

DOI
10.1142/s0217984920500839

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This paper introduces the design process of a multiparty quantum key agreement protocol based on the Greenberger-Horne-Zeilinger state in detail. Building on the traditional circle-type quantum key agreement protocol, we introduce a star structure, which significantly improves the speed and efficiency of key agreement. To facilitate the reader’s understanding, we provide an example of a four participants quantum key agreement protocol. In the process of quantum state transmission, we perform operations using the Pauli matrix and the Hadamard matrix to ensure that the quantum state remains in one of the four basis states. This significantly enhances the security of the protocol. After rigorous security analysis, we find that the protocol can effectively resist intercept-resend attack, entangle-measure attack, collective attack, and dishonest participant attack. Under a collective attack, if the first particle is subjected to bit-flipping noise, then p<0.2430p<0.2430p<0.2430 only guarantees r>0.2r>0.2r>0.2 when a=1a=1a=1 . Additionally, we conduct a fairness analysis and evaluate the practical performance of the proposed protocol. In an ideal depolarization noise-free environment, the protocol can achieve a positive key rate only when the global detection efficiency exceeds 0.9636. Finally, we conduct a comprehensive comparative analysis of the protocols. The results show that our proposed protocol is superior to other existing schemes in terms of efficiency and running time.
In this paper, we propose a two-party and a three-party controlled quantum key agreement (QKA) protocols with three-qubit GHZ states and Bell measurements. Compared with previous protocols, the significant change of our schemes is that a supervisor is introduced for controlling the agreement process to improve the controllability. Moreover, our protocols ensure each communication participant contribute equally to the agreement keys, and all participants can negotiate the shared keys without exchanging classical bits between them. The performance analysis shows that our protocols can be immune to outsider and participant attack.
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