Dynamic Code Update for the Efficient Usage of Security Components in WSNs

Wireless sensor networks (WSN) will have a major impact on our everyday's life. A requirement for large-scaled deployment are extremely low-cost sensors though running with minimal resources regarding computational power, energy consumption, and memory size. Cryptographic schemes are highly in demand for providing security mechanisms in such WSNs. Asymmetric cryptography allows for flexible key management schemes at the cost of high resource demands whereas symmetric cryptography provides resource efficient solutions. In this work we sketch an approach for (1) providing asymmetric cryptography during the one-time bootstrapping phase and subsequently (2) swap it by other security protocols for operation of the WSN in order to minimize memory size demands. Our mechanism is based on dynamic code update, e.g. provided by the FlexCup plug-in for TinyOS. Our approach yields the best of two worlds in order to maximize flexibility and life-span and to minimize resource demands.