Security is a critical design issue in Mobile IPv6 since adversaries can take advantage of its routing process and arbitrarily channelize the traffic to different destinations. The original security scheme, the return routability (RR) procedure, used in Mobile IPv6 route optimization does not protect against adversaries who are on the path between the home agent (HA) and the correspondent node (CN) [11]. In addition, the long latency associated with the return routability test can impact delay-sensitive applications. This paper presents a hash chain based security mechanism to improve the security and performance of the return routability procedure in Mobile IPv6. Our fast authentication mechanism utilizes the hash chain element as an extra certificate to the mobile node in authenticating binding updates while running the routing process. In addition, by removing the necessity of the home test procedure in the RR test our mechanism can reduce the binding update latency. We analyze the...