Multiparty quantum determined key distribution protocol using GHZ states

A multiparty quantum determined key distribution protocol using GHZ(Greenberger-Horne-Zeilinger) states is presented in this paper. Three parties can build a key with the help of GHZ states. The key can be a determined string in our protocol while the key is a random string built in the process of key distribution in previous protocols. We prove that our protocol is guaranteed to be unconditionally secure by the laws of quantum mechanics.