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This work proposes a new dynamic quantum secret sharing (DQSS) protocol using the measurement property of Greenberger---Horne---Zeilinger state and the controlled-NOT gate. In the proposed DQSS protocol, an agent can obtain a shadow of the secret key by simply performing a measurement on single photons. In comparison with the existing DQSS protocols, it provides better qubit efficiency and has an easy way to add a new agent. The proposed protocol is also free from the eavesdropping attack, the collusion attack, and can have an honesty check on a revoked agent.

This study points out a man-in-the-middle (MIM) attack on many of quantum secure communication with authentication protocols. The MIM attack is due to a design carelessness on performing public discussions on a nonauthenticated classical channel. A possible solution is proposed to solve the problem.

Hsu et al. (Quantum Inf Process 12:331---344,2013) proposed a dynamic quantum secret sharing (DQSS) protocol using the entanglement swapping of Bell states for an agent to easily join (or leave) the system. In 2013, Wang and Li (Quantum Inf Process 12(5):1991---1997, 2013) proposed a collusion attack on Hsu et al.'s DQSS protocol. Nevertheless, this study points out a new security issue on Hsu et al.'s DQSS protocol regarding to the honesty of a revoked agent. Without considering this issue, the DQSS protocol could be failed to provide secret sharing function.