Anonymous roaming in universal mobile telecommunication system mobile networks

A secure roaming protocol for mobile networks is proposed. Roaming has been analysed in some schemes from the security point of view; however, there are vulnerabilities in most of them and so the claimed security level is not achieved. The scheme offered by Wan et al. recently is based on hierarchical identity-based encryption, in which the roaming user and the foreign network mutually authenticate each other without the help of the home network. Although the idea behind this proposal is interesting, it contradicts technical considerations such as routing and billing. The proposed protocol makes use of similar functions used in Wan et al.'s scheme but contributes a distinguished structure that overcomes the previous shortcomings and achieves a higher possible level of security in mobile roaming as well as enhancing the security of the key issuing procedure

Deposit-case attack against secure roaming

A secure roaming protocol involves three parties: a roaming user, a visiting foreign server and the user\u27s home server. The protocol allows the user and the foreign server to establish a session key and carry out mutual authentication with the help of the home server. In the mutual authentication, user authentication is generally done in two steps. First, the user claims that a particular server is his home server. Second, that particular server is called in by the foreign server for providing a \u27credential\u27 which testifies the user\u27s claim. We present a new attacking technique which allows a malicious server to modify the user\u27s claim in the first step without being detected and provide a fake credential to the foreign server in the second step in such a way that the foreign server believes that the malicious server is the user\u27s home server. We give some examples to explain why it is undesirable in practice if a roaming protocol is vulnerable to this attack. We also show that there are three roaming protocols proposed previously which are vulnerable to this attack