Abstract: The authenticity of data packets in internet of vehicles communications is directly related to the security of internet of vehicles communications. The new vehicle broadcast authentication protocol Gatekeeper has the advantages of source identity authentication and protection against DoS attacks, and will be one of the mainstream vehicle networking communication protocols in the future. However, it currently lacks a guarantee mechanism for data authenticity, causing in-vehicle communications to destroy the integrity, robustness, and security of communications due to the lack of data authenticity. Therefore, by establishing multiple feedback mechanisms in the communication of the original protocol, adding authentication methods for data authenticity, and extending it into the Gatekeeper+ protocol, we made up for the shortcomings in the data authenticity guarantee mechanism. It also used sequential logic CTL to establish logical expressions of data authenticity, and used model detection technology to verify that the Gatekeeper+ protocol met the authenticity nature of data transmission. It further verified the security and integrity of the expanded Gatekeeper+ protocol to ensure the safety and reliability of the protocol in vehicle communication services.