CWoT-Share: Context-Based Web of Things Resource Sharing in Blockchain Environment

Web of Things(WoT)resources are not only numerous,but also have a wide range of applications and deployments.The centralized WoT resource sharing mechanism lacks flexibility and scalability,and hence cannot satisfy requirement of distributed resource sharing in large-scale environment.In response to this problem,a trusted and secure mechanism for WoT resources sharing based on context and blockchain(CWoT-Share)was proposed.Firstly,the mechanism can respond quickly to the changes of the application environment by dynamically determining resource access control rules according to the context.Then,the flexible resource charging strategies,which reduced the fees paid by the users who shared more resources and increased the fees paid by users who frequently used resources maliciously,were used to fulfill efficient sharing of WoT resources.Meanwhile,the charging strategies also achieve load balancing by dynamic selection of WoT resources.Finally,the open source blockchain platform Ethereum was used for the simulation and the simulation results show that CWoT-Share can flexibly adapt to the application environment and dynamically adjust strategies of resource access control and resource charging.

SeaHttp:A Resource-Oriented Protocol to Extend REST Style for Web of Things

Web of Things （WoT） makes it possible to connect tremendous embedded devices to web in Representational State Transfer （REST） style. Some lightweight RESTful protocols have been proposed for the WoT to replace the HTTP protocol running on embedded devices. However, they keep the principal characteristic of the REST style. In particular, they support one-to-one requests in the client-server mode by four standard RESTful methods （GET, PUT, POST, and DELETE）. This characteristic is however inconsistent with the practical networks of embedded devices, which typically perform a group operation. In order to meet the requirement of group communication in the WoT, we propose a resource-oriented protocol called SeaHttp to extend the REST style by introducing two new methods, namely BRANCH and COMBINE respectively. SeaHttp supports parallel processing of group requests by means of splitting and merging them. In addition SeaHttp adds spatiotemporal attributes to the standard URI for naming a dynamic request group of physical resource. Experimental results show that SeaHttp can reduce average energy consumption of group communication in the WoT by 18.5%, compared with the Constrained Application Protocol （CoAP）.

Secure smart contract-based digital twins for the Internet of Things

The proliferation of Internet of Things(IoT)devices that operate unattended providing a multitude of important and often sensitive services highlights the need for seamless interoperability and increased security.We argue that digital twins of IoT devices,with the right design,can enhance the security,reliability,auditability,and interoperability of IoT systems.The salient features of digital twins have made them key elements for the IoT and Industry 4.0.In this paper,we leverage advances in W3C’s Web of Things(WoT)standards and distributed ledger technologies(DLTs)to present a novel design of the smart contract-based digital twins with enhanced security,transparency,interoperability,and reliability.We provide two different variations of that general design using two different blockchains(one public and one private,permissioned blockchain),and we present design trade-offs.Furthermore,we introduce an architecture for accessing and controlling IoT devices securely and reliably,providing full auditability,while at the same time using the proposed digital twins as an indirection mechanism(proxy).The proposed architecture leverages the blockchain to offer notable properties,namely,decentralization,immutability,auditability,non-repudiation,availability,and reliability.Moreover,it introduces mass actuation,easier management of IoT devices,and enhanced security to the IoT gateways,enables new business models,and makes consumer devices(vendor-)agnostic.