# A V2V Identity Authentication and Key Agreement Scheme Based on Identity-Based Cryptograph
## 2 C-V2X Security Risk and Security Technology Overview
### C-V2X Security Technology  
With the gradual maturity and commercial application of C-V2X technology, its security technology has attracted more and more attention. Scholars have carried out a series of research on the C-V2X security technology, increased C-V2X security technology and standards research, formulated a perfect security scheme, and promoted the healthy development of the automobile industry and transportation industry.  
The existing C-V2X security technology involves security isolation, access control, identity authentication, data encryption, data signature, data backup, and other technologies. However, overall, the C-V2X security system is still in its infancy. Scholars pay more attention to the traditional network security issues, and C-V2X personalized security technology, such as equipment efficient authentication, privacy protection, and data security-sharing technology is weak. The C-V2X security technology needs to be improved urgently.  
National researchers are highly concerned about the C-V2X security technology, and there is not a unified C-V2X security standard and security scheme. Identity authentication can be used to distinguish legal equipment from malicious equipment. The C-V2X system can set different access levels for different equipment through authorization management, protect the data in the C-V2X system through data encryption, set data priority to ensure the system availability, and set an integrity check to ensure the information is not modified or deleted by malicious users [3]. The PKI (public key infrastructure) mechanism based on a public key certificate is used to ensure the security authentication and secure communication between the equipment and digital signature; encryption and other technologies are used to achieve the communication security between the equipment. The security functions, such as certificate issuance, certificate revocation, equipment information security collection, data management and exception analysis, can be achieved through the security management system. The blockchain technology is used to achieve the communication security and establish trusted relationships between the C-V2X equipment through distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithm. When vehicles communicate directly through the PC5 interface, a trust relationship must be established between vehicles [4]. The general method is to authenticate the identity of the equipment based on the PKI mechanism, but in this way, the equipment needs to obtain in advance the equipment certificate from the certification authority in a secure way and requires a complex certificate verification process. Different security domains can be segmented according to geographical regions, and each domain has different security levels [5]. Data access control and encrypted data retrieval can be carried out based on roles and attributes, and vehicle data can be encrypted and protected through an access control policy and policy execution engine [6]. Privacy protection mainly includes user identity privacy protection and location privacy protection. Identity privacy is protected by group signature technology, and location privacy is protected by pseudonym change strategy and location-based service [7]. Equipment authentication and key agreement can be achieved based on the elliptic curves cryptography (ECC) algorithm to protect equipment communication security and data security [8].