# Internet of Things and Blockchain Integration: Security, Privacy, Technical, and Design Challenges
## 3 RQ 1 and RQ 2--Current Challenges and Recommendations to Enhance BIoT Integration  
This section answers the first and second research questions (i.e., RQ1: What are the challenges that face BIoT integration? RQ2: What recommendations have been provided in literature to overcome these challenges?). We looked through the pertinent literature to get the answers to the research questions. The search strategy used all well-known databases, including IEEE, MDPI, and Elsevier. This paper only contains academic papers that were authored in English. The full text, abstract, and title of the chosen papers were then examined. The study was excluded if it did not demonstrate any focus on IoT and BC. Table 5 displays the search terms, databases, exclusion criteria, and publications that were ultimately chosen.  
Although BC technology can be one of the most appealing options to deal with the security and privacy difficulties in IoT, many researchers and academics have suggested numerous research papers that promoted the notion of BIoT integration. Most IoT security and privacy frameworks are centralized and, therefore, not well suited for IoT due to the difficulty of scale, traffic, and single point of failure [83]. Moreover, the danger of device spoofing, erroneous authentication, and decreased data exchange reliability are still facing BIoT [21; 84]. In this section, a comprehensive taxonomy of the current BIoT challenges, as well as recommendations to mitigate the effects of these challenges, are discussed. It is worth noting that the majority of the research focused on Bitcoin's application in the IoT context; therefore, these challenges are concentrated on Bitcoin. Despite the ongoing debate about Bitcoin's applicability in an IoT setting, this study only reports on an assessment of the existing literature in the field's top academic databases.  
Seven challenge themes were synthesized from the literature: security, privacy, technical consideration, scalability, computational processing, regulations and guidelines, and BIoT  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Search Terms** & **Database** & **Inclusion Criteria** & **Selected Articles** \\ \hline \multirow{6}{*}{(Internet of things OR IoT) AND (Blockchain OR Bitcoin OR & \begin{tabular}{c} \\ \end{tabular} \\  & \begin{tabular}{c} Only papers written in English. \\ Result: 517 papers. \\ \end{tabular} \\  & \begin{tabular}{c} IEEE Xplore, Elsevier \\ ScienceDirect, MDPI Online, \\ Google Scholar, Wiley Online \\ \end{tabular} \\  & \begin{tabular}{c} Papers excluded on the basis of \\ the abstract (if not focused on \\ IoT and BC). Result: 273 papers. \\ \end{tabular} \\  & \
\begin{tabular}{c} Papers excluded on the basis of \\ \(49\),\(51\),\(53\),\(55\)–\(58\),\(61\)–\(64\),\(66\)–\(71\),\(73\)–\(80\),\(82\)–\(151\) \\ \end{tabular} \\  &
\begin{tabular}{c} Library, and Emerald Insight \\ \end{tabdesign. Under each of these categories, several challenges are discussed. The taxonomy of current BIoT challenges is shown in Figure 2. According to the current research, these BIoT integration issues are mostly based on the Bitcoin BC disadvantages. Moreover, a lack of BC capabilities is the primary cause of regulations and standards, as well as BIoT design difficulties. On the other hand, both IoT and BC concerns affect privacy, security, computational processing, technical considerations, and scalability. These problems will have an influence on the performance of BIoT integration in any of these scenarios. Accordingly, it is essential to investigate the overall impact of all of these difficulties on BIoT integration.