# Aspects of Cyber Security in Autonomous and Connected Vehicles
## 6 Defenses or Countermeasures for Autonomous and Connected Vehicles
### Defenses for V2X  
#### 6.1.1 Symmetric and Asymmetric Encryption  
Cryptography is used to transfer data into encrypted data for communication. This process is conducted with the help of keys and there are two types of cryptography techniques symmetric encryption and asymmetric encryption. In symmetric encryption, a single key is used for both encryption and decryption of the data as shown in Figure 6a. These are mostly used in point-to-point communication and used in situations where data is stored on the main server. This method is popular because easy to implement and secure [22]. There are different ways to approach this encryption, the two-factor lightweight privacy-preserving (2 FLIP) algorithm works in two ways [76; 77], pseudonymous authentication with conditional privacy (PACP) generates keys to authenticate the data [78], the elliptic-curve digital signature (ECDSA) algorithm works in three ways: key and signa  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Autonomous and** & & & \\
**Connected Vehicle** & & & \\
**Classification** & & & \\ \hline \hline \multirow{6}{*}{Safety systems} & \multirow{6}{*}{ASS} & \multirow{6}{*}{KSV} & \multirow{6}{*}{KSV} & \multirow{6}{*}{KSV} \\ \cline{4-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \hline \hline \end{tabular}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{Safety systems}} & \multirow{2}{*}{ASS} & \multirow{2}{*}{KSV} \\ \cline{4-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \hline \hline \multirow{6}{*}{Connectivity} & \multirow{6}{*}{Smart features} & \multirow{2}{*}{Key less entry system} & \multirow{2}{*}{Password attack [67], keyless entry attacks [16], key fob attacks [16]} \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \hline \hline \multirow{6}{*}{Diagnostics} & \multirow{6}{*}{OBD port} & \multirow{6}{*}{CAN bus} & Frame sniffing attack [68], frame falsifying attack [11] \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \cline{3-4} \cline{6-5}  & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Possible attacks on the autonomous and connected vehicle.  
ture generation and signature verification [79], secure and authenticated key-management protocol (SAKMP) [80].  
In asymmetric encryption, two keys are used one is for encryption and another for the decryption of data as shown in Figure 6b. The asymmetric method is slower than the symmetric method because two keys are involved and more mathematical calculations are involved in this process. Different ways to achieve this are the pseudonym-based authentication method [81], privacy-preserving group communication scheme (PPGCV) [82], temporary anonymous certified keys (TACKs) [83], temporary authentication and revocation indicator (TARI) [84], and group signature and identity-based signature (GSIS) [85].