Dynamic quantum secret sharing protocol based on GHZ state

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.