Hide-and-Lie: enhancing application-level privacy in opportunistic networks

A delay-tolerant network is a mobile ad hoc network where the message dissemination is based on the store-carry-and-forward principle. This principle raises new aspects of the privacy problem. In particular, an attacker can build a user profile and trace the nodes based on this profile even if the message exchange protocol provides anonymity. In this paper, an attacker model is presented and some proposed attackers are implemented. We analyze the efficiency of both the attacks and the proposed defense mechanism, called Hide-and-Lie Strategy. We show that without any defense mechanism, the nodes are traceable, but with the Hide-and-Lie Strategy, the success probability of an attacker can be made equal to the success probability of the simple guessing. Furthermore, in some scenarios, the Hide-and-Lie Strategy increases the message delivery ratio. The number of downloaded messages and the maximal memory size required to apply the proposed privacy defense mechanism is also investigated.