## 3 Vcc-Ssf
### Security Layer
External vehicles attempt to access the information for services such as collision prevention or traffic lane maintenance as well as V2V communication. In both cases, the corresponding vehicle should also control the access of the traffic infrastructure and external vehicles. Only correctly authenticated vehicles can exchange information, but the other vehicles cannot access the information without permission. Access control from outside the vehicle is divided into access for subjects that complete authentication and access for subjects that cannot. Table 4 shows the access control from outside the vehicle. For example, only when authenticated subjects with roles A1, A2, or A3 and partially authenticated subjects (first aid, rescue, police, _etc._) try to access the information is the access to the vehicle location or traffic information permitted. Unauthenticated subjects take on role N1; for them, access to all information is restricted. For role A1, access to all information is permitted for vehicles that complete authentication. For role A2 in the VANET environment, a small logical cluster is generated and V2V communication between subjects inside the cluster is \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Classification** & \multicolumn{1}{c}{**Role**} & **Description** \\ \hline \multirow{6}{*}{Authentication completed} & A1: Full access permitted & Can access all information \\ \cline{2-3}  & A2: Only authenticated vehicles inside the cluster & \multirow{2}{*}{Information can be shared only within the cluster} \\  & can access the information (e.g., location, destination, and traffic information sharing) & \\ \cline{2-3}  & A3: Only the authenticated traffic infrastructure & \multirow{2}{*}{Information transmission to the traffic infrastructure} \\  & can access the information & \\ \hline Partial authentication completed & \multirow{2}{*}{P1: Information is shared with emergency vehicles} & First aid, rescue, police vehicles, _etc._ \\ \hline Authentication is not possible & \multirow{2}{*}{N1: Cannot access the information} & Vehicles without permission cannot access any information \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Access control from outside the vehicle. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Object** & \multicolumn{2}{c}{**Access**} \\ \hline Vehicle owner & P1 & Can access all information \\ Guest driver & P2 & Driving information, traffic information \\ Car mechanic & P3 & Information of Drive System, Braking System, Steering System, _etc._ \\ Others & P4 & No access \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Access control information for each object. possible. However, only location, destination, traffic, and entertainment information can be shared inside the cluster. The VN or DN of each vehicle cannot be accessed. For role A3, because of the characteristics of the VCC environment, communication with nearby RSUs is frequent. In this case, an RSU requests access or sends data to the vehicle for authentication or traffic information collection. The corresponding vehicle checks the RID of the requesting RSU, bestows A3 authority, and blocks access to the DN. It permits access to other information for traffic analysis. However, access is restricted for unauthenticated RSUs. **Privacy Protection:** Among the information transmitted in the VCC environment, privacy protection should be considered for the driver or user identification information, vehicle location information, video or voice recorded by the vehicle black box, payment information used in Payment Services, _etc._ This information is used for the convenience of the driver or the user, but when it is exposed to malicious attackers, this could cause the user financial damage or defamation. We address privacy protection in the following two ways:  
* **Privacy protection with a vehicle alias ID:** In the VCC environment, the vehicle authentication process uses the PVID.