## 2 Related Works
However, they did not ensure privacy preservation, as an intruder could easily tie the reputation score of each vehicle to reveal the confidentiality of its location. The privacy-preserving trust management (PPTM) scheme presented in [29] addresses this drawback. The proposed scheme preserves the privacy of vehicles in emergency signaling by utilizing reputation certificates. For this purpose, the reputation certificate is periodically issued by the trust center and signed with the secret key of the electronic digital signature of the legal vehicle. The development of solutions of counterattacks on integrity threats in VANET is also an urgent task. As a rule, digital signatures are used to solve this problem. Thus, counteraction to masquerading attacks, in which the intruder uses the ID and password of a legitimate user, is considered in [30]. Message tampering attacks are used by the intruder to force the owners to change the traffic route. These attacks and countermeasures against them are discussed in [31; 32]. Among cyberattacks on IoV, attacks on authentication occupy a special place. Therefore, the issues of OBU and RSU authentication are given great attention. Let us consider the main methods of authentication, the use of which in VANET can reduce the effectiveness of such attacks. It is known that authentication protocols can be conducted using symmetric or asymmetric encryption systems [33]. Interest in the use of symmetric ciphers in authentication protocols is justified by the fact that the procedure of the prover's authentication (OBU or RSU) is required to have minimal time costs. It is this parameter that plays an essential role in ensuring traffic safety in conditions of high traffic flow intensity. In [34; 35], it is proposed to use the lightweight symmetric cryptography algorithm TESLA. Since this protocol uses a keyed hash function, the authentication process does not require significant computational resources. In [36], a lightweight and efficient authentication scheme (LESPP) was developed for authentication in VANET. The symmetric encryption of the message authentication code (MAC) is proposed for recognizing OBUs and RSUs. In [37], the work of a decentralized and scalable privacy-preserving authentication scheme (DSPA) is described. The operation of this scheme is based on symmetric hash-based message authentication code (HMAC) authentication. In [38], it is proposed to use an LIAP (Lightweight IdentityAuthentication Protocol) for transport authentication. In this protocol, the secret key is generated based on the concatenation of the vehicle account identifier and the owner's password. Despite the relatively low computational and time costs, these authentication methods have the disadvantage that each vehicle must have its own secret key. The main disadvantage of authentication protocols using symmetric encryption systems is the problem of delivering secret keys to OBUs and RSUs and preventing unauthorized access to them by intruders. In addition to symmetric ciphers, asymmetric encryption methods are also used in VANET authentication methods. Most of these methods use public key encryption systems (PKI) [39; 40]. The main disadvantage of these methods is the significant time cost of authenticating an OBU or RSU. This has a negative impact on traffic safety in conditions of high traffic flow intensity. Authentication methods based on an identity-based batch authentication scheme [41; 42] allow for reducing the time cost of authentication in VANET compared to PKI. The works [43; 44; 45] consider the use of digital signatures for authentication in VANET. In [44; 45], the authors propose using a group signature. The advantage of this solution is that any group of vehicle owners, using their secret keys, can quite easily generate a collective public key. Let us consider the authentication methods that are currently used in the systems of \"friend-or-foe\" identification.