Mixed public and secret-key cryptography for wireless sensor networks

Wireless sensor networks normally employ symmetric cryptography in their security systems. The most important issue in this area is the establishment of symmetric keys. In fact, even if many symmetric key management schemes have been proposed, none of them is optimal in every situation (e.g., in case of mobile nodes or no deployment knowledge or large networks). Furthermore, due to computational constraints of wireless sensor nodes, public-key cryptography is seldom used in wireless sensor networks. This paper investigates existing key management schemes and proposes a new key establishment routine that exploits both the benefits of public and symmetric encryption. The proposed routine exploits a symmetric transitory secret to authenticate nodes in the network, while actual pairwise keys are established using asymmetric cryptography.