## 1 Introduction
These suites, listed in Table 1, are compatible with MQTT brokers and are recommended by the Agency for Digital Italy (AGID) guide for security protocols and cipher suites. Our analysis focuses on these cipher suites to ensure a balance between security and performance in IoT communications. \begin{table}
\begin{tabular}{l l} \hline \hline
**TLS Version 1.2** & **TLS Version 1.3** \\ \hline ECDHE\_ECDSA\_AES128\_GCM\_SHA256 & TLS-AES-128-GCM-SHA256 \\ \hline ECDHE\_RSA\_AES128\_GCM\_SHA256 & TLS-AES-256-GCM-SHA384 \\ \hline ECDHE\_ECDSA\_AES256\_GCM\_SHA384 & TLS-CHACHA20-POLY1305-SHA256 \\ \hline ECDHE\_RSA\_AES256\_GCM\_SHA384 & - \\ \hline ECDHE\_ECDSA\_CHACHA20\_POLY1305 & - \\ \hline ECDHE\_RSA\_CHACHA20\_POLY1305 & - \\ \hline DHE\_RSA\_AES128\_GCM\_SHA256 & - \\ \hline DHE\_RSA\_AES256\_GCM\_SHA384 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: OpenSSL Cipher Suites for MQTT Testbeds. This work aims to perform these analyses in the onion router (TOR) environment. We want to verify how much the loss of network performance, typical of this technology, can affect the choice of use, given the undoubted advantage in terms of privacy and ease of access guaranteed by the TOR network despite the classic traffic-blocking mechanisms of the perimeter companies unless the perimeter firewall filters TOR traffic exactly. Our MQTT benchmarking architecture over the TOR network is depicted in Figure 1.  
This study aims to provide a comprehensive performance analysis of MQTT security protocols in the context of Dark Net and IoT applications. While we do not propose a new theoretical model, our approach aligns with numerous respected works in the field that focus on empirical analysis and practical insights. Our goal is to explore the potential of Dark Net technologies in specific IoT scenarios where anonymity and privacy are crucial, providing valuable data on the trade-offs between security, privacy, and performance. Our research approach differentiates itself from existing studies in several key aspects. Firstly, we innovatively combine MQTT with TOR network technology, offering enhanced anonymity and privacy crucial for sensitive IoT applications. Secondly, we provide a comprehensive performance analysis of this combined approach across different network types (IEEE 802.3 ab [1] IEEE 802.11n/ac [2] and 3 GPP-4G [3]), offering insights into its practicality in diverse real-world scenarios. Thirdly, we focus on the impact of various cipher suites and quality of service (QoS) levels in the context of Dark Net communications, an area that has received limited attention in existing MQTT security research. Lastly, our work emphasizes the optimization of small payload messages (up to 5 kbytes) for Dark Net transmissions, a specific consideration not typically addressed in conventional MQTT security studies. These distinctive features provide novel insights into securing IoT communications in highly privacy-sensitive environments, extending beyond the scope of traditional MQTT security protocols. Through our analysis, we offer practical insights into the trade-offs between privacy, performance, and complexity in IoT deployments. These contributions aim to advance the field of IoT security and privacy, particularly in scenarios requiring high levels of anonymity. While this study focuses primarily on the integration of MQTT with the TOR network, there are several areas that present opportunities for future research. A comparative analysis of MQTT with other IoT protocols in Dark Net environments, for instance, could provide valuable insights into the relative strengths and weaknesses of different approaches. Additionally, our current work introduces increased latency due to TOR routing, presenting a trade-off between enhanced privacy and system performance. Future studies could explore innovative methods to mitigate this latency while maintaining the privacy benefits. These aspects, while beyond the scope of the current paper, represent promising directions  
Figure 1: MQTTs Over TOR Network Encryption Flow Architecture.