A randomized countermeasure against parasitic adversaries in wireless sensor networks

Due to their limited capabilities, wireless sensor nodes are subject to physical attacks that are hard to defend against. In this paper, we first identify a typical attacker, called parasitic adversary, who seeks to exploit sensor networks by obtaining measurements in an unauthorized way. As a countermeasure, we first employ a randomized key refreshing: with low communication cost, it aims at confining (but not eliminating) the effects of the adversary. Moreover, our low-complexity solution, GossiCrypt, leverages on the large scale of sensor networks to protect data confidentiality, efficiently and effectively. GossiCrypt applies symmetric key encryption to data at their source nodes; and it applies re-encryption at a randomly chosen subset of nodes en route to the sink. The combination of randomized key refreshing and GossiCrypt protects data confidentiality with a probability of almost 1; we show this analytically and with simulations. In addition, the energy consumption of GossiCrypt is lower than a public-key based solution by several orders of magnitude.