Examining the DoS resistance of HIP

We examine DoS resistance of the Host Identity Protocol (HIP) and discuss a technique to deny legitimate services. To demonstrate the experiment, we implement a formal model of HIP based on Timed Petri Nets and use a simulation approach provided in CPN Tools to achieve a formal analysis. By integrating adjustable puzzle difficulty, HIP can mitigate the effect of DoS attacks. However, the inability to protect against coordinated adversaries on a hash-based puzzle causes the responder to be susceptible to DoS attacks at the identity verification phase. As a result, we propose an enhanced approach by employing a time-lock puzzle instead of a hash-based scheme. Once the time-lock puzzle is adopted, the effect of coordinated attacks will be removed and the throughput from legitimate users will return to the desirable level.