Abstract: An authentication protocol for TETRA with authentication algorithm running in HLR instead of VLR is presented in this paper. The proposed protocol can effectively avoid the generation of an open attack for known text once the communication security between VLR and HLR can not be guaranteed.It is good for roaming between networks, meets the requirements for the independence of the authentication algorithm. The proposed protocol can improve the security of actual digital trunked system.

Key words: authentication, digital trunked system, challengeresponse protocol