Hardware-software implementation of public-key cryptography for wireless sensor networks

Security in wireless sensor networks is currently provided through symmetric key cryptography. Although the low computational complexity involved in private key algorithms is advantageous, session keys must be embedded in the sensor nodes before the nodes can be deployed. Protocols are also necessary to ensure synchronization of keys between the devices on a network. These protocols require significant communication and storage overhead. The limitation of such a cryptosystem is that it is not possible to guarantee the confidentiality of the session keys. It is commonly perceived that public key algorithms are slow, consume a lot of power and require a significant amount of architectural overhead. In this paper we show that it is possible to implement public key algorithms on resource constrained sensor node platforms. Using a hardware/software codesign approach, we have successfully mapped a public key cryptosystem based on Rabin's scheme onto the motes developed by Tyndall National Institute. Our implementation focuses on efficient architectures that execute the public key algorithms using minimal resources.