5G-HCLS: An Authentication Protocol to Protect Bootstrapping Messages in 5G Network

The unprotected broadcast bootstrapping messages make it feasible to carry out the fake base station (FBS) attack. By setting up a FBS with higher signal strength, attackers can launch series of attacks in 5G cellular network. Although the latest 5G specifications have adopted multiple countermeasures to enhance the security of critical procedures and functions, it still fails to focus on the root cause of FBS attack. Specifically, the lack of authentication mechanism for initial messages results in user's improper decision on target base station. To address this issue, we propose 5G-HCLS, a hierarchical authentication protocol based on certificateless signature (CLS) for 5G network. The protocol provides authentication for bootstrapping messages, and successfully solves the key escrow problem without the usage of certificate. We also optimize the protocol's overhead and provide a novel mechanism to defend relay attack. To evaluate the performance of our protocol, we implement it on a common-used testbed, and the experimental results demonstrate that our protocol achieves minimal average communication overhead and acceptable computation overhead with higher security level.