Privacy-Preserving Vehicular Announcements Aggregation Scheme Based on   Threshold Ring Signature
  As the most promising application in VANETs, the vehicular announcement allows vehicles to send announcement messages about road conditions to other vehicles far away. The security requirements of reliability and privacy in the vehicular announcement are not easily achieved simultaneously due to the notorious sybil attack. In this paper, we present a novel privacy-preserving vehicular announcements aggregation scheme. The proposed scheme provides threshold authentication and flexible anonymity using message aggregation and interactive threshold ring signature which allows nondeterministic different signers to generate signature commonly in the environment not fully trusted. Different from existing works in an attack-then-trace mode, our scheme defends against the sybil attack beforehand. To our best knowledge, it is the first privacy-preserving scheme preventing the malicious users from launching the sybil attack in advance. Through extensive evaluation, we show the availability and the efficiency of the proposed scheme. 
Yichen Jiang
cs.CR cs.NI