The Internet of Things (IoT) is an emerging network paradigm that aims to obtain the interactions among pervasive things through heterogeneous networks. Security is an important task in the IoT. Luo et al. (Secur Commun Netw 7(10): 1560–1569, 2014 ) proposed a certificateless online/offline signcryption (COOSC) scheme for the IoT (hereafter called LTX). Unfortunately, Shi et al. showed that LTX is not secure. An adversary can easily obtain the private key of a user by a ciphertext. Recently, Li et al. proposed a new COOSC scheme (hereafter called LZZ). However, both LTX and LZZ need a point multiplication operation in the online phase, which is not suitable for resource-constrained devices. To overcome this weakness, we propose a new COOSC scheme and prove its security in the random oracle model. In addition, we analyze the performance of our scheme and show its application in the IoT.

Wireless sensor network (WSN) plays an important role in military sensing and tracking, target tracking, and environment monitoring. To query of the network to get useful information from anywhere and anytime, we need to integrate the WSN into the Internet as part of the Internet of Things (IoT). In this case, it is an important task to design an access control scheme that can authorize, authenticate and revoke a user to access the WSN. In this paper, we propose a heterogeneous signcryption scheme to control the access behavior of the users. We give the formal security proof of our scheme in the random oracle model. An important characteristic of our scheme is to allow a user in a certificateless cryptography (CLC) environment to send a message to a sensor node in an identity-based cryptography (IBC) environment. We give an access control scheme for the WSN in the context of the IoT using the proposed signcryption scheme. As compared with existing two access control schemes using signcryption, the computational cost of sensors in our scheme is reduced by about 22% and 53%, respectively and the energy consumption of sensors in our scheme is reduced by about 33% and 54%, respectively.