They propose a scalable privacy-enhanced traffic monitoring (SPETM) framework. In this framework, the traffic monitoring center can collect authenticated individual vehicle driving status and the road usage information, with the help of the distributed roadside units (RSUs) who can simultaneously obtain local view of the traffic in their respective domains. Neither external attackers, malicious vehicles nor compromised RSUs can know the identity of the reporting vehicles, which guarantees enhanced privacy for vehicles. However, misbehaving vehicles abusing the privacy mechanisms can be jointly traced by the semi-trusted vehicle management authorities, which provides desirable liability in privacy-preserving vehicular reports. The researchers instantiate a concrete SPETM scheme with well-established cryptographic technologies. Thorough analyses show that their scheme is secure and practical for deployment.
Please, read the full paper at: https://link.springer.com/article/10.1007%2Fs00500-015-1737-y