Eavesdropping on quantum secret sharing protocols based on ring topology (pp0587-0600)
          Dong Jiang, Yongkai Yang, Qisheng Guang, Chaohui Gao, and Lijun Chen
          doi: https://doi.org/10.26421/QIC19.7-8-4
Abstracts: Quantum secret sharing (QSS) is the process of splitting a secret message into multiple parts such that no subset of parts is sufficient to reconstruct the secret message, but the entire set is. Ever since the first protocol was proposed, QSS has attracted intensive study, and many protocols have been proposed and implemented over recent years. However, we discover that several ring-topology based QSS protocols cannot resist Trojan-horse attacks. In this paper, we first give a modified Trojan-horse attack strategy and show that the eavesdropper can obtain any player's private data and the dealer's secret message without leaving any trace. Then we show that existing defense strategies cannot resist our attack. To defeat such attacks, we design a defense strategy based on quantum memory and evaluate its performance. The evaluation results indicate that the eavesdropper's attack significantly increases the quantum bit error rate and can thus be detected.
Key words:  Quantum secret sharing; Ring topology; Trojan-horse attack