Though DTNs(Delay Tolerant Networks) arise in many situations and may take many forms, our terminology in this paper is slanted towards the particular example of rural area DTNs. The use of this concrete example aids exposition and provides motivation, but does not reduce the applicability of our work to other types of DTNs.
Figure 1 illustrates a typical rural area DTN.
Figure 1: A Typical Rural Area DTN
- The approach is applicable to villages and rural areas with no Internet connectivity due to geographic or economic constraints.
- There is an Internet connection available in a nearby town and a transport medium from the rural area to the town in the form of a vehicle, such as a bus or a car.
- The terminal with Internet connectivity is called the gateway. A transport medium that carries data from the end users in a village to a gateway is called a mobile router.
- There is also a special static router called a kiosk, which serves as a computing facility for DTN users. The kiosk also provides a persistent data transfer facility, so users do not have to wait for a mobile router to show up.
- There are two types of end users, mobile users, who use their own personal devices to connect directly to routers (typically a kiosk), and kiosk users, who use a shared terminal at a kiosk.Our anonymous secure communication architecture mainly targets mobile users. However, if a kiosk is trusted, our architecture provides equivalent security and anonymity to kiosk users.
Achieving security and privacy in such disconnected networks is a demanding task, but it is necessary in hostile environments with malicious attackers or even just passive listeners. In rural area DTNs, security and privacy are necessary to effectively implement concepts like e-governance, citizen journalism, distance education and telemedicine. In a hostile environment, secure and anonymous DTN communication can provide an efficient way to let informers transfer information while hiding their identity from an enemy. Therefore, the utility of a DTN is greatly expanded when the DTN provides end-to-end security and privacy. The limitations of DTNs require the design of new security and privacy protocols for DTNs, which forms the basis for this work.