Secure event logging in sensor networks

Health care applications based on sensors are gaining popularity. In wireless body area networks (WBANs), sensing data are gathered from a set of nodes deployed on the patient's body and sent to a central server. In such environments, security and privacy must be top priorities. Moreover, since decision-making is performed on the basis of the collected data, it can be important to maintain the chronological order of events in a secure way. In view of this, this paper proposes a system for secure logging of events in sensor networks by gathering in a secure and reliable way all information at one central point. The system guarantees the chronological order of logged events sent by the different sensors. It also allows one to detect the modification, deletion, and addition of logged data. As a proof of concept, we have designed a prototype of the gateway sensor on an FPGA platform that is responsible for the secure logging and the secure transmission of this information. Our prototype is based on the low-cost Spartan-6 FPGA which is equipped with several hard IP-cores such as Ethernet and CompactFlash, which makes it suitable for event storage. As it turns out, the FPGA board (SP-605) is able to store 20,830 logged events, computes digests in 2.51 @ms and only uses 56% of the LUTs of the FPGA. Thus, the reconfigurable nature of FPGAs makes them suitable for use in extending the capabilities of commercial gateways, in order to provide secure logging in a WSN.