Securing Smart Cities through Blockchain Technology: Architecture, Requirements, and Challenges In recent years, unprecedented work has been done in the area of smart cities. The purpose of developing smart cities is to enhance quality of life factors for people dwelling within them. To achieve that purpose, technologies such as IoT and cloud computing have been utilized. Blockchain technology is also among the promising technologies that can offer countless valuable services to its end users. It is a immutable programmable digital register for the purpose of recording virtual assets having some value and was primarily developed for digital currencies like Bitcoin. To fully utilize the services of blockchain technology within smart cities, characteristics of blockchain technology, and its key requirements and research challenges need to be identified. Hence, in this article, an attempt has been made to identify the characteristics of blockchain technology. Furthermore, indispensable requirements for incorporating blockchain technology within smart cities are enumerated. A conceptual architecture for securing smart city using blockchain technology is proposed and explained using a possible use case study. An overview of a realworld threeblockchain based smart city case study is also presented. Finally, several imperative research challenges are identified and discussed.

Blockchain for Managing Heterogeneous Internet of Things: A Perspective Architecture IoT has the potential to transform the way we think about information and communication technology. IoT has been studied extensively across many disciplines such as the networking, communication, security, business, and management communities. However, many unsolved challenges, especially in managing heterogeneous IoTs, remain to be discussed. Recent studies propose using blockchain, an emerging technology that enables decentralized coordination, to address inherent challenges in IoT. This article presents a preliminary study on an architecture that implements blockchain in managing heterogeneous IoT systems. We start by pointing out the limitations of prior IoT systems and the difficulties of integrating IoT and blockchain. Then we outline an architecture to manage a largescale heterogeneous IoT system. Our main goal is to stimulate further effort and crossdisciplinary collaboration by providing guidance and reference for future studies.