# IoT and Blockchain Integration: Applications, Opportunities, and Challenges
## 1 Introduction
### Motivation and Contribution  
According to IoT Analytics ([[https://bit.ly/3](https://bit.ly/3) XPS99p]([https://bit.ly/3](https://bit.ly/3) XPS99p) (accessed on 30 December 2022)), the number of IoT devices grew by 9% to reach 12.3 B globally in 2021. The COVID-19 pandemic catalyzed IoT adoption in the workplace, education, and public services. It also reported that the predicted number of connected IoT devices will reach 27B by 2025. By 2025, IoT will produce (estimated) 79.4 zettabytes (ZB) (~79 \(\times\) 10\({}^{12}\) GB) of data. By the same year, the economic impact of IoT will reach (estimated) 11 trillion dollars ([[https://bit.ly/3](https://bit.ly/3) iXjRCy]([https://bit.ly/3](https://bit.ly/3) iXjRCy) (accessed on 14 June 2022)). In the meantime, 58% of cyberattacks occurred over IoT devices. Those attacks mainly were DDoS attacks and pilifering of confidential data. More than 1.5 B security breaches occurred over IoT in 2021 alone. While 64% global organizations use one or more IoT solutions, 43% do not protect them adequately ([[https://bit.ly/3D4](https://bit.ly/3D4) vQoP]([https://bit.ly/3D4](https://bit.ly/3D4) vQoP) (accessed on 14 May 2022)). The extent of growth and adoption of IoT is astounding. According to Cybersecurity Ventures, global cybercime expected costs to grow by 15 percent per year over the next five years, reaching USD 10.5 trillion annually by 2025, up from $3 trillion in 2015 ([[https://bit.ly/3](https://bit.ly/3) iT3 PsPz]([https://bit.ly/3](https://bit.ly/3) iT3 PsPz) (accessed on 14 June 2022)). According to IBM data breach report 2021 ([[https://ibm.co/3](https://ibm.co/3) XMOrcv]([https://ibm.co/3](https://ibm.co/3) XMOrcv) (accessed on 15 June 2022)), the average total cost of a data breach increased by nearly 10% ($3.86 M in 2020, $4.24 M in 2021) year over year, the most significant single-year cost increase in the last seven years. However, due to a deficiency of security knowledge applicable during deploying the IoT, harvesting data from IoT, and consuming the IoT data or services, the fate of the life and properties are at higher stake than ever [9]. On the other hand, blockchain technology [10, 11, 12], yet another popular technology that operates on top of the Internet, has been adopted as a revolutionary technology for \"trustless\" transaction verification and process automation. Popular blockchain frameworks such as Bitcoin [13] and Ethereum [14] have been increasingly utilized for payment for online transactions and transferring money between user accounts without the need for participating banks or credit card companies. It also tracks food, prescription drugs, and airline engine parts. As per Gartner ([[https://bit.ly/3](https://bit.ly/3) HIZacF]([https://bit.ly/3](https://bit.ly/3) HIZacF) (accessed on 25 July 2022)), the value of blockchain would be 3.1 trillion in business by 2030. In light of evolving technologies such as IoT and blockchain, this paper draws together the notion of IoT ecosystems and their existing and potential integration with blockchain technologies. This paper will discuss the overall desired security assurances in explaining the security challenges of two emerging technologies. Specifically, this paper:  
1. precisely defines and exemplifies IoT, blockchain technology-related, and relevant security terminologies. 2. examines the importance of IoT and Blockchain security as evolving technologies. 3. explains the challenges of IoT and Blockchain integration. The rest of the paper is structured as follows: In Section 2, we discuss the general architecture of an IoT network. Section 3 discusses the major applications of IoT. Section 4 exemplifies the types and applications of blockchain networks. Section 5 outlines the research methodologies. Section 6 explains the security assurances applicable to the IoT. The same section discusses the security threats of IoT. In Section 7, we explore the integration of IoT and blockchain technology. Section 8 discusses the significant challenges of IoT and blockchain integration.