Evaluating CoAP End to End Security for Constrained Wireless Sensor Networks

In the past few years, Internet Engineering Task Force (IETF) has standardized "lightweight" IPv4/IPv6 protocol variations for Wireless Sensor Network (WSN) on resource constrained devices. In the above approaches, security is considered a strong requirement, however, adapting IP oriented security protocols (like the IETF Data-gram Transport Layer Protocol DTLS) to actual WSN security enabled implementations requires tradeoffs between performance, energy consumption and security level. In this paper, the above tradeoffs are explored for the latest version of the widely accepted Contiki OS (version 3.x) when DTLS security is enabled for the IETF supported Constrained Application Protocol (CoAP). More specifically, the DTLS framework is integrated in the Contiki 3 CoAP stack for 2 different cipher suites and the performance in comparison with non secure CoAP applications is evaluated through simulation, in terms of speed, memory overhead and energy consumption for various WSN clientserver network environment. Finally, tradeoff and recommendation for balanced performance versus security are proposed.