# Defense and Security Mechanisms in the Internet of Things: A Review
## 6 Discussion
\begin{table}
\begin{tabular}{l l} \hline \hline
**Protocol Category** & **Papers** \\ \hline Authentication protocol & [110, 112, 114, 115, 117, 118, 120, 123] \\ Authentication and key agreement protocol & [15, 61, 121, 122, 124, 125, 126, 128, 131] \\ Key agreement protocol & [133, 134, 137] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of protocol categories. \begin{table}
\begin{tabular}{l l} \hline \hline
**IoT Solution** & **References** \\ \hline Medicine and healthcare & [61, 118, 124, 125, 131, 134] \\ Edge or cloud computing & [114, 133] \\ Crowdsourcing & [110] \\ Smart homes & [123] \\ Cross-domain & [15, 112, 115, 117, 120, 122, 126, 128, 137] \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of protocol approaches. Table 7 gives a random of the security features in the protocols we looked at. We have compiled a list of features and marked whether each protocol has that feature (shown as +). The - sign means the authors did not submit any information about that feature. The analysis showed that anonymity and secrecy are the most desirable security properties for security protocols in IoT environments. Both features in the IoT context are crucial in protecting privacy, data security, and user trust. Anonymity protects personal data and prevents the tracking of a user's identity. This is especially important for devices monitoring users' daily activities (for example, smartwatches and smart speakers). This helps maintain user anonymity and complicates the efforts of companies and third parties to build detailed behavioural profiles based on data collected from IoT devices. Furthermore, anonymity makes it more difficult for cybercriminals to target specific individuals, as linking device activity to a particular user becomes challenging. Confidentiality ensures that the data collected by IoT devices is safeguarded against unauthorised access, thereby minimising the risk of leaking sensitive information. Additionally, data transmission between IoT devices is secured against interception, which lowers the chances of MITM attacks. Moreover, ensuring data confidentiality increases users' trust in IoT devices and service providers, which is crucial for adopting the technology and increasing its popularity. All authors of the examined studies conducted performance evaluations of their regimens. They compared their proposals with similar communication, processing, and energy consumption options. According to their findings, the suggested techniques outperform similar solutions in every study. The authentication process is a vital part of communication in IoT environments. It involves verifying the identities of the parties engaged in the communication. During this process, we can use one or more factors; the more factors we incorporate, the more secure the authentication becomes. Relying solely on passwords can be a weak and vulnerable  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline
**Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** & **Protocol** \\ \hline
[110] & + & +  
security measure, as attackers can intercept, guess, or crack them. This is why biometrics is often considered a better option, as it helps prevent spoofing or impersonation attacks. The session keys (in securing communication) are essential for IoT security. Timestamped and protected with one-time session keys, messages guard against replay and man-in-the-middle attacks. This strategy enables the system to determine whether a legitimate network node produced the processed message and assesses if an attacker has intercepted and resent it. However, this improves the audience's understanding of this vital security mechanism because it highlights the complexity of maintaining secure communications. Although the technical aspects may seem daunting, grasping these concepts is necessary for effective security measures in the IoT landscape.