## 6 Architectures Comparison
### Security Comparison  
Each category within the STRIDE threat modeling framework encompasses a distinct set of components. Notably, a component that may constitute an entry point for an attack in one architectural design may not be considered critical in another. This variance stems from the inherent differences in the architectures themselves, as well as the specific context in which they are employed. It is possible to classify threats into four groups following the equation defined in (1) and Table 3. The greatest number of threats are classified as very low and medium, as reported in Figure 7, by following the attack vector approach. For very low threats, it is not needed to put in place any security mechanisms and we decided to accept them; for the medium-level threats, we applied mitigation to all threats, while more details are given in the next sections for the high-risk threats. Although most components \begin{table}
\begin{tabular}{l c c} \hline \hline
**Component** & [27] & [28] \\ \hline GPS & ✓ & ✓ \\ \hline Accelerometer and gyroscope & ✓ & ✓ \\ (6-axis sensor) & ✓ & ✓ \\ \hline Camera & ✓ & ✓ \\ \hline Sound & ✓ & ✓ \\ \hline Temperature & & ✓ \\ \hline Pulse & & ✓ \\ \hline OBD-II redundancy & ✓ & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Components detected in each architecture belonging to sensing layer. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Communication Protocols** & [27] & [28] \\ \hline Cellular & ✓ & \\ \hline
3G/4G & ✓ & \\ \hline Bluetooth & ✓ & \\ \hline BLE & ✓ & \\ \hline WiFi & ✓ & ✓ \\ \hline WiFi dongle & & ✓ \\ \hline TCP & & ✓ \\ \hline CAN bus & ✓ & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Components detected in each architecture belonging to communication layer. are shared from both architectures, such as GPS and ECU, some others are different. After the threats were created through the Ansys medi \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Threat** & **Very Low** & **Low** & **Medium** & **High** \\ \hline Information Disclosure & 31 (36.5\%) & 23 (27.1\%) & 37 (43.5\%) & 1 (1.2\%) \\ \hline Tampering & 28 (32.9\%) & 16 (18.8\%) & 32 (37.6\%) & 13 (15.3\%) \\ \hline DoS & 33 (38.4\%) & 18 (20.9\%) & 27 (31.4\%) & 15 (17.4\%) \\ \hline Repudiation & 6 (40\%) & 3 (20\%) & 4 (26.7\%) & 3 (20\%) \\ \hline Spoofing & 2 (13.3\%) & 3 (20\%) & 8 (53.3\%) & 3 (20\%) \\ \hline Elevation of Privilege & 6 (40\%) & 1 (6.7\%) & 4 (26.7\%) & 4 (26.7\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Security analysis of [PERSON] et al. [27] architecture. The ratio of the number of current risk levels of that category to the total number of threats related to that category is given in parentheses. Figure 7: Number of threats detected using TARA, classified by risk level. 2. **Low-Risk Threats:** This category represents a low level of threat to the component that it relates to. Through the application of TARA we concluded that 64 (19.9%) of all of the threats fitted into this level of risk. From the above analysis, it is clear that a low percentage of threats fall into this category, with the highest percentage of these being information disclosure threats (25%). Information disclosure of assets like temperature sensor, pulse sensor, and accelerometer data would not harm the user physically or cause failure of systems. The lowest percentage of low-risk threats is elevation of privilege threats, with only one threat (6.7%). There is no compromising event that an attacker can cause, only the control over the display can be obtained. The rest of the attacks contribute less than 20%. 3. **Medium-Risk Threats:** The threats presented here are the ones that are classified as medium risk, through the application of TARA. We concluded that 112 (34.9%) of all of the threats fitted into this level of risk. It is evident that information disclosure threats and spoofing contribute the most to the medium-risk threat category. When the information of some of the assets can be monitored by the attacker, harm could be done to the user.