## 6 Conclusions  
This study aimed to propose a traceable security system. We involved smart contracts and blockchain technologies in this scheme. Every record from the accessing party to the blockchain center is sent and chained. We used the characteristics of the blockchain center to solve the trust problem between the security company and the client. We also proposed a fair and clear arbitration mechanism for the clarification of responsibilities, which was not available in the security industry in the past. The proposed method achieves the following goals. Firstly, the characteristic data through the blockchain can be publicly verified and the information will not be modified. Secondly, we used BAN logic to prove mutual authentication. Thirdly, the official agency is able to query the information with the signature from the accessing party and validate the legality of the event record. Fourthly, the proposed method achieves traceability, integrity, and non-repudiation. The method can also resist man-in-the-middle attacks, replay attacks, and forgery attacks. In this study, we also considered the threat models during the communication phase. Every message from the IoT main controller in the client's house will not be able to send a false alarm to the security control center. It also allows the control center to stay connected with the IoT main controller at any time. In future works, the proposed method of a blockchain center can be expanded to become a blockchain alliance with multiple security companies able to connect to blockchain alliance services with traceability and authentication. The authors' contributions are summarized below. [PERSON] and [PERSON] made substantial contributions to conception and design. [PERSON] and [PERSON] were involved in drafting the manuscript. [PERSON] and [PERSON] acquired data and analyses and conducted the interpretation of the data. The critically important intellectual content of this manuscript was revised by [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Authors** & **Year** & **Objective** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** \\ \hline
**[PERSON] et al. [19]** & 2020 & Blockchain-based access control system & Y & Y & Y & N & N & N & N & N & N \\ \hline
**[PERSON] et al. [20]** & 2018 &
\begin{tabular}{c} Blockchain-based access control to access \\ control for industry 4.0 \\ \end{tabular} & Y & Y & N & N & Y & Y & Y & N & N \\ \hline
**[PERSON] et al. [22]** & 2020 &
\begin{tabular}{c} Smart campus with the Internet of \\ Things and blockchain \\ \end{tabular} & Y & Y & N & N & N & Y & N & N & N \\ \hline
**[PERSON] et al. [23]** & 2019 &
\begin{tabular}{c} Accessing private smart home with smart \\ devices through an IFTTT Gateway \\ \end{tabular} & N & N & Y & Y & Y & N & N & Y & N \\ \hline
**[PERSON] et al. [24]** & 2020 &
\begin{tabular}{c} Remote anonymous authentication for \\ smart home \\ \end{tabular} & N & N & Y & Y & N & Y & N & Y & N \\ \hline
**Ours** & 2021 &
\begin{tabular}{c} Proposed a traceable and authenticated \\ security company record on the blockchain \\ \end{tabular} & Y & Y & Y & Y & Y & Y & Y & Y & Y \\ \hline \hline \end{tabular}  
Notes: 1: Focus on a blockchain, 2: Smart contract, 3. Protocol, 4: Proof of mutual authentication, 5: Traceability, 6: Integrity, 7: Non-repudiation, 8: Threat models, 9: Control center, Y: Yes, N: No.  
\end{table} 
Table 6: Comparison of related works and the proposed study. **Funding:** The APC was funded by Chaoyang University of Technology. **Institutional Review Board Statement:** This study is based entirely on theoretical basic research. It does not involve humans. **Informed Consent Statement:** This study is based entirely on theoretical basic research. It does not involve humans. **Data Availability Statement:** The data used to support the findings of this study are available from the corresponding author upon request.