Fine-grained identification with real-time fairness in mobile social networks

Mutual user identification is a necessary step for trust establishment among users in an unattended mobile social network (MSN). Directly exposing identity information to others unknown may cause total unfairness in identity loss when the other party of the identification process misbehaves. Using an on-line trusted third party (TTP) for user identification will cause communication and security problems, while a traditional off-line TTP solution will generate delay in fairness enforcement. In this paper, we propose a novel fine-grained identification protocol, which provides confidentiality, unlinkability, and real-time fairness without the involvement of TTP. In the protocol, identification is carried out by an iterative identification information exchange process, where two participating users have to disclose part of their identification information to each other in each iteration. The process terminates whenever one of them fails to do so. In this way, if a user loses part of its identification information to another user, then it must have obtained an approximately equal amount of identification information of that user. Therefore, misbehavior is discouraged, and fairness is improved. Through analysis we demonstrate that fairness can be well guaranteed as long as users strictly follow the protocol rules. Extensive simulation results further confirm that the proposed protocol can significantly reduce fairness loss in MSN environment.