Commutative cipher based en-route filtering in wireless sensor networks

Wireless sensor networks offer unprecedented capabilities to monitor the physical world by reporting the occurrence of interesting events. Unfortunately, such networks are vulnerable to event fabrication attacks, in which the compromised nodes inject bogus reports into the network, fabricating non-existent events "appearing" at arbitrary locations. Most existing security solutions to these attacks need to share symmetric keys among sensor nodes. In this paper, we propose a commutative cipher based en-route filtering scheme (CCEF) that drops fabricated reports en-route without symmetric key sharing. In CCEF, the source node establishes a secret association with the base station on a per-session basis, while the intermediate forwarding nodes are equipped with a witness key. Through the usage of a commutative cipher, a forwarding node can use the witness key to verify the authenticity of the reports without knowing the original session key. As a result, CCEF can achieve stronger security protection than the existing symmetric key sharing approach.