Abstract
CoAP is an application layer protocol designed for resource-constrained devices in Internet-of-Things (IoT). Object Security of CoAP (OSCoAP) is an IETF draft for addressing security issues with CoAP messages that can arise with the use of intermediate proxies. These proxies are employed for better performance, scalability and offloading expensive operations. OSCoAP adopts the counter with cipher block chaining message authentication code (CCM) mode of authenticated encryption with associated data (AEAD) that simultaneously ensures confidentiality, integrity, and authentication of the messages. The current implementation of CCM for OSCoAP is carried out in software. In this paper, we propose a cross-layer approach towards exploiting the CCM for OSCoAP using mac-layer security suite in IoT devices. The motivation is based on the fact that most of these devices are equipped with 802.15.4 radio chips. The IEEE 802.15.4 standard mandates the availability of some security features for mac-layer encryption in these radio chips including the CCM. We propose an algorithm that takes advantage of these on-board features by efficiently implementing the CCM operations for OSCoAP. The results show that our implementation of CCM is memory efficient, save up to 10 times more energy, improves battery life by 30% and is 37% faster than state of the art software implementation of CCM for OSCoAP. (C) 018 Elsevier B.V. All rights reserved.