Research On Efficient Group Signatures Schemes In VANET

The group signature has been widely applied to VANET. Owing to the high speed of the vehicles in VANET, it is very frequent for group members to join and revoke. So the group signature schemes on VANET should allow the group members to join and revoke effectively. In the existing schemes, the dynamic join for group members has been well solved. That, when a new member wants to join the group, the group manager just needs to generate a key pair for the new member, and correspondingly updates the group public key.But it is still a difficult problem to revoke group members. In most of revocable group signature schemes, the revocation of a member will affect the key pairs of unrevoked members. When the schemes are applied in the dynamic VANET, the calculation road and communication delay are huge. Aiming at this problem, this thesis proposes a group signature scheme based on the Chinese remainder theorem, which is an efficient revocable group signature in VANET. In this scheme, the revocation of a group member does not affect the key pairs of unrevoked members, only the corresponding public key need to be updated. Also, the scheme can achieve the efficient addition of the group members and greatly reduces the computation load. Furthermore, the proposed scheme is proved to be anti-collusion, and compared with two existing schemes, our scheme is proved to be more efficient.In VANET, in a road with heavy traffic flow, every vehicle has a large quantity of messages to verify. Therefore, efficient authentication receives extensive attention in VANET. Based on batch verification and Schnorr signature algorithm, this thesis proposes an efficient revocable batch verification group signature scheme in VANET, which improves the last scheme.Although the improved scheme has improved the efficiency of the original scheme, the number of the exponentiation operation in the second scheme is linear ratio of the number of messages in the batch verification. To solve this problem, this thesis proposes an efficient revocable batch verification group signature scheme based on DSA signature algorithm in VANET. The number of the exponentiation operation is a constant, which is independent of the number of messages in the batch verification. The proposed scheme considerably reduces the computation load. In the thesis, the two schemes have been proved to be safe and efficient in security and performance analysis.