Background Signature for Sensor Networks

Sensor networks are characterized by lack of trusted infrastructure and severe hardware limitations in terms of computational power and memory size. Securing the exchanges between a set of distributed sensors is challenging. On one hand, ad hoc infrastructures imply a lack of a priori trust between entities that can dynamically appear and disappear. In this context, it is necessary to ensure non-repudiation of origin and integrity of alarm messages sent by sensors: asymmetric cryptography must be available. On the other hand, asymmetric cryptography is too costly and drastically increases the response time of sensors. For instance, due to the signature slowdown, sending a measure or an alarm can take several seconds. This paper presents a new approach that allows strong acceleration of signatures by pre-computing the major part of the signature process. This scheme is based on onetime signatures and pre-computation of RSA signatures. This paper studies the impact of this scheme on computation and response time when a sensor has to send a signed message. Memory and communication restrictions are taken into account to find an optimal structure of one-time key pairs.