Concurrently Deniable Group Key Agreement and Its Application to Privacy-Preserving VANETs

Abstract

VANETs need secure communication. Authentication in VANETs resists the attack on the receipt of false information. Authenticated group key agreement (GKA) is used to establish a confidential and authenticated communication channel for the multiple vehicles. However, authentication incurs privacy leakage, that is, by using digital signature. Therefore, the deniability is deserved for GKA (which is termed as DGKA) due to the privacy protection. In the DGKA protocol, each participant interacts with intended partners to establish a common group session key. After this agreement session, each participant can not only be regarded as the intended sender but also deny that it has ever participated in this session. Therefore, under this established key, vehicles send confidential messages with authentication property and the deniability protects the vehicles privacy. We present a novel transformation from an unauthenticated group key agreement to a deniable (authenticated) group key agreement without increasing communication round. Our full deniability is achieved even in the concurrent setting which suits the Internet environment. In addition, we design an authenticated and privacy-preserving communication protocol for VANETs by using the proposed deniable group key agreement.