The present invention provides a method involving a mobile node, a home agent, and an authentication server in a wireless communication system. The method includes generating, at the authentication server, a first security key that indicates a secure association between the home agent and the mobile node based on a second security key that indicates a secure association between the mobile node and the authentication server. The method also includes generating, at the authentication server, at least one first index associated with the first security key. The first index is also generated by the mobile node. The method also includes storing, at the authentication server, the first index and the first security key.