EAP-ZKP: A Zero-Knowledge Proof based Authentication Protocol to Prevent DDoS Attacks at the Edge in Beyond 5G

5G has Introduced the primary and secondary authentication procedures to authenticate the user equipment requesting access to mobile network operators (MNOs) and service providers (SPs) data networks, respectively. However, the possibility of running distributed denial of service (DDoS) attacks on the MNO 5G core network (CN) and the SPs data networks still remains. In this paper, we introduce a zero- knowledge proof (ZKP) authentication algorithm called Partial- ID ZKP that authenticates users without revealing their service credentials. We show that Partial-ID ZKP has completeness and soundness properties. Based on Partial-ID ZKP, we then propose an extensible authentication protocol called EAP-ZKP that can be used in primary and secondary authentications to mitigate DDoS attacks at the CN edge. Finally, as a proof of concept, we implement EAP-ZKP in the 5G authentication procedure. Using the 5G simulators free5GC and gnbsim, we show that EAP-ZKP significantly reduces the authentication time for fake authentication attempts during DDoS attacks. Results also demonstrate that EAP-ZKP is able to recognize DDoS attack authentication attempts in about 10 msec. Interestingly, for the legitimate authentication attempts, the average authentication time slightly increases from 3.05 sec in current 5G authentication protocols to 3.06 sec in EAP-ZKP. This indicates that EAP-ZKP is promising for Beyond 5G.