  With the rapid development of vehicular ad hoc Network (VANET), it is gaining
significant popularity and receiving increasing attentions from academics and
industry in security and efficiency. To address security and efficiency issues,
a self-authentication and deniable efficient group key agreement protocol is
proposed in this paper. This scheme establishes a group between road-side unit
(RSU) and vehicles by using self-authentication without certification
authority, and enhances certification efficiency by using group key (GK)
transmission method. At the same time, to avoid the attacker to attack the
legal vehicle by RSU, we adopt deniable group key agreement method to
negotiation session key (sk) and use it to transmit GK between RSU. In
addition, vehicles not only broadcast messages to other vehicles, but also
communicate with other members in the same group. So group communication is
necessary in VANET. Finally, the security and performance analysis shown that
our scheme is security, meanwhile the verification delay, transmission
overheard and message delay are more efficient than other related schemes in
authentication, transmission and communication.
