A mutual trust scheme for vehicular Ad-Hoc networks under sparse RSUs environment

In this paper, based on the concept of chameleon hash function, we propose a secure mutual trust scheme for vehicular ad-hoc networks (VANETs). In the proposed scheme, the trusted authorizer (TA), holding two common secrets, will issue an identity to every entity that may be road side unit (RSU) or vehicle. An identity contains a public ID and a private key. The public ID is used to present an entity, and the private key is used to make mutual trust keys with other entity's public ID. A public ID can be verified to be a legal one, and the mutual trust key will be the evidence that a node owns the related public ID. At the starting time of a time slot or after finding malicious entities, TA will broadcast a new group key to all valid RSUs that will response the group key request from vehicles. Using the new group key, vehicles can change new parameters, public ID and private key to do mutual trust with other vehicles. The security analysis shows that the proposed scheme can revoke the right of malicious RSUs or vehicles, work well under malicious attacking and satisfy the requirement of a secure VANETs. As the result of functionality and performance comparison, the proposed mutual trust scheme is superior to the related works.