Abstract:Vehicle Ad Hoc Networks(VANETs)are the applications of mobile networks in transportation.The privacy protection of vehicle identity is an important part of VANETs security.Aiming at the problem of vehicle privacy protection,this paper proposes a vehicle privacy anonymity protection scheme combining blockchain and group signatures(BGAS).In this solution,when vehicle needs to communicate with a digital certificate authority(CA),the vehicle first sign to the group before it can communicate with the CA and store the vehicle's public key in the blockchain.In this process,if the vehicle provides false identity information,the group manager will use the group private key to reveal the signer's identity and authorize the CA to revoke the vehicle public key.Before communication occurs between vehicle and vehicle,the vehicle generates a pseudonym and communicates with the pseudonym.During the communication process,the vehicle obtains the communication information and requests the CA to decrypt the pseudonym and confirm the vehicle identity.The receiver needs to use the sender's public key to perform a hash operation to obtain Merkel roots,and use the calculated root value to compare with the roots in the blockchain through anonymous authentication to confirm the legitimacy of the vehicle.