## 2 Security Issues Facing AVs and Solutions
### Sensors  
The type and functionality of a sensor determines the extent to which it could contribute to scoping out secure threats, as well as the extent to which it could inform potential implications should it be compromised [5]. Table 1 summarizes the applications, security issues, and the corresponding solutions for common sensors mounted on AVs.  
For partially autonomous vehicles, sensors only assist the driver to obtain some information and the vehicle is still monitored and controlled by the driver. Even for Google's driverless car that operates autonomously at most times, the driver will take over of control immediately if the automation system cannot process dangerous situations. Therefore, the impact of attacks on these sensors may be mitigated by the driver's surveillance or management. Even so, autonomous vehicles significantly depend on these various types of sensors to perceive the surroundings and the status of the vehicles to assist driving or automatically drive by itself. For example, Paper [9] utilized multiple sensors such as radar, LIDAR, and cameras to perform autonomous lane changing. Paper [10] reviews vision-based autonomous driving systems. Paper [11] proposes an effective empirical formula solution to assist autonomous driving in a GPS-denied environment. Paper [12] provide a survey on intelligent tires for tire-road interaction recognition. Paper [13] proposed a localization system for autonomous driving using gyroscopes and accelerometers. In the future, fully autonomous vehicle will completely operate without driver involvement. Thus, attacks on these sensors will cause serious issues, and calls for more attention.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type** & **Application** & **Security Issues** & **Solutions** & **References** \\ \hline Camera & Interpets objects/signs. An array of cameras to provide 300 views, while & Extra light from other sources may decrease the sensitivity of the sensors; intense light (e.g., laser, IR LEDs) can directly blind/blaze the sensors. & (1) & Camera filter to prevent blinding. \\ Camera & Interpets objects/signs. An array of cameras to provide 300 views, while & Extra light from other sources may decrease the sensitivity of the sensors; intense light (e.g., laser, IR LEDs) can directly blind/blaze the sensors. & (2) & Installation of multi-cameras to improve the detection. \\ Camera & Interpets objects/signs. An array of cameras can extract extra depth information. & Extra light from other sources may decrease the sensitivity of the sensors; intense light (e.g., laser, IR LEDs) can directly blind/blaze the sensors. & (3) & Fuse with other sensors to improve the accuracy of detection. \\ \hline Lidar, radar, and ultrasonic & Lidar provides a “3D” map of the surrounding environment and depth perception. Radar detects obstacles and measures distances in bad weather conditions/low light situations. Ultrasonic assists short-range detection. & (1) & Tunable wavelength emission and random probing to disturb the attacker. (2) & Tunable wavelength emission and random probing to disturb the attacker. (3,2,18, 19, 20) & Tunable wavelength emission and random probing to disturb the attacker. (3,20,18, 19, 21) & Tunable wavelength emission and random probing to disturb the attacker. (3,20,18, 19, 20) & (4,5,9,18, 22, 23) \\ Lidar, radar, and ultrasonic & Lidar, radar, and ultrasonic & Specifying jamming, saturation, cancellation attacks, and replay attacks. & (1) & Tunable wavelength emission and random probing to disturb the attacker. (3,20,18, 19, 20) & (4,5,9,18, 21, 22, 23) \\  & Weather conditions/low light situations. Ultrasonic assists short-range detection. & & (2) & Data fusion from other sources, such as V2V communication, to correct the measurement errors. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Security issues and solutions of sensors mounted on AVs.  
Figure 2: Security issues facing an AV.