Preventing Unauthorized Messages and Achieving End-to-End Security in Delay Tolerant Heterogeneous Wireless Networks

Maintaining user connectivity over heterogeneous wireless networks will be a necessity with the wide spread of wireless networks and limited geographic coverage and capacity of each network. In [1], we propose a super node system architecture based on the concept of delay tolerant network (DTN) to overcome roaming user intermittent connections over interconnected heterogeneous wireless networks. Mobile ad hoc networks play a key role in the super node system as it can provide a coverage for areas that lack a network infrastructure to bridge gaps between wireless networks within the system. Long delays combined with the lack of continuous communications with a network server introduces new challenges in information security for mobile nodes in a DTN environment. One of the major open challenges is to prevent unauthorized traffic from entering the network. This paper addresses this problem within the super node system. Two schemes are proposed: one is based on asymmetric key cryptography by authenticating the message sender, and the other is based on the idea of separating message authorization checking at intermediate nodes from message sender authentication. Consequently, the second scheme uses symmetric key cryptography in order to reduce the computation overhead imposed on intermediate mobile nodes, where one-way key chains are used. A simulation study is conducted to demonstrate the effectiveness of each scheme and compare the performance with and without using an authorization scheme. Moreover, the problem of secure end-to-end message exchanges is introduced by mapping the problem from a challenged network domain (i.e., among roaming nodes) to a reliable network domain (i.e., among super nodes over the Internet backbone). The proposed symmetric key based scheme is extended to achieve end-to-end security.