Security as a CoAP resource: An optimized DTLS implementation for the IoT

The growing number of applications based on Internet of Things (IoT) technologies is pushing towards standardized protocol stacks for machine-to-machine (M2M) communication and the adoption of standard-based security solutions, such as the Datagram Transport Layer Security (DTLS). Despite the huge diffusion of DTLS, there is a lack of optimized implementations tailored to resource constrained devices. High energy consumption and long delays of current implementations limit their effective usage in real-life deployments. The aim of this paper is to explain how to integrate the DTLS protocol inside the Constrained Application Protocol (CoAP), exploiting Elliptic Curve Cryptography (ECC) optimizations and minimizing ROM occupancy. We have implemented our solution on an off-the-shelf mote platform and evaluated its performance. Results show that our ECC optimizations outperform priors scalar multiplication in state of the art for class 1 mote platforms, and improve network lifetime by a factor of up to 6.5 with respect to a standard-based not optimized implementation.