Time-Based Confidentiality Enhancement Scheme for Mobile Wireless Networks

A multi-hop wireless network with highly dynamic members and mobility is vulnerable to many attacks due to the open wireless media and the difficulty of establishing strict security mechanisms. In order to send messages confidentially, one approach is to send multiple shares of the original message simultaneously through different paths. This approach has limitations when spacial multi-paths can not be found in sparse networks or geographically constrained networks. To address this problem, we propose a novel approach that exploits mobility. In our scheme, the source sends shares at different times. Due to node mobility, these shares will be routed through different intermediate nodes. It is highly unlikely that a particular intermediate node (an eavesdropper) is able to be on many of these routes and to collect enough shares to reconstruct the original message. The scheme is particularly suitable for applications that can tolerate long message delays, as studied in Delay Tolerant Networks. The paper focuses on analyzing the feasibility of this scheme. We describe a general approach to calculate the probability of nodes other than source and destination intercepting enough shares, and use the isotropic random walk model to illustrate the calculation. The scheme is further evaluated using simulation. The results show that for random walk type of mobility, the probability is small. In all, this time-based message delivery scheme provides a valuable alternative for delay tolerant applications to enhance message confidentiality.