ABSTRACT
Blockchain is a technology that initially served as Bitcoin infrastructure technology architecture, and it is characterized by its solid decentralized model that shares the truth fullness of its core. Over the years, the Bitcoin value has grown from a few dollars to more than ten thousand in a volatile scheme and continued to earn acceptance in various well-known organizations. Hence, the scientific community considered its pillar of success, a.k.a. the blockchain, and utilizes it in different applications. Likewise, Internet of things or IoT in short, referring to the billions of sensors interacting and turning the physical world phenomenon into consumable digital data, continues to grow exponentially and conquering all sectors. However, security concerns have become on the rise; thus, it is extremely important to have control over these machines that starts to discreetly inhabit our environment. Hence, blockchain could possibly be an instrument to protect IoT systems from unwanted threats. This chapter provides an overview of IoT, Smart cities, Complex events, and Blockchain technologies and explains how the latter plays an essential role in securing its applications against malicious users. It also discusses different approaches to integrate Blockchain in IoT applications, and the challenges it poses.
