# Reputation and Trust Approach for Security and Safety Assurance in Intersection Management System
## 2 Related Work
### Trust and Reputation Models and Approaches in VANETs  
In a dynamic VANETs environment, there is much uncertainty in deciding who to trust. Existing trust models in VANETs include entity-oriented trust models and data-oriented trust models. Entity-oriented trust models focus on the modeling of the trustworthiness of peers. Data-oriented trust models put more emphasis on evaluating the trustworthiness of data. The authors of [27] compared two types of protocols for secure routing in VANETs: topology-based protocols and position-based protocols. Topology based protocols are traditional ones for mobile ad-hoc networks (MANETs); they use a source to destination information which is stored in the routing table. The sub-categories of topology-based protocols are proactive, reactive, and hybrid protocols. The routing table in proactive protocols (Destination-Sequenced Distance Vector routing protocol, Optimised Link State Routing protocol, and Fisheye State Routing) updates frequently on dynamic topology, and they choose the shortest path algorithm for routing. Reactive protocols (Ad hocOn-demand Distance Vector routing protocol, Dynamic Source Routing Protocol, and Temporally Ordered Routing Algorithm) are used for large networks as they propose high mobility and dynamic nature. When the source communicates with the destination node, the route is discovered by the second one. Later, the destination node sends a reply message to the source. Hybrid protocol (Zone Routing Protocol) is a combination of the first two types and it is used according to the network scenario. The purpose of the hybrid routing protocol is to accelerate the packet delivery and reduce overload. Position-based routing employs the positional information of nodes. The source sends a packet according to the position of another node when each node may decide everyone's location using GPS. Examples of position-based protocols are DTN protocols, non-DTN protocols, and hybrid protocols. In [28], [PERSON] introduced a similarity-based trust and reputation framework for VANETs. The message has to be verified after receiving it. A similarity mining algorithm was used to compute the similarity between non-linear similar data. Recommendations of agents and direct experience of the result are integrated as reputation evaluation. As soon as the message content is checked, the values of trust and reputation are updated. Another algorithm used for trust management, presented in [29] and named BARS, is a blockchain-based anonymous reputation system. Vehicles use two blockchain mechanisms for the authentication based on proofs of presence and absence. Public keys are used as the pseudonyms to protect a vehicle privacy. The broadcasted messages are recorded in one blockchain to evaluate the reputation of vehicles. The results show that BARS effectively improves the trustworthiness of broadcasted messages and protects vehicle privacy efficiently. In [30], the authors proposed Lightweight Self-Organized Trust (LSOT) Model as an algorithm to protect VANETs communications. In the model, the nodes are self-organized; they aggregate trust certificate-based and recommendation-based performance. [PERSON] and [PERSON] [31] described an Attack-Resistant Trust model (ART) to evaluate the trustworthiness of both traffic data and vehicle nodes for VANETs as two separate metrics, namely data trust and node trust. Data trust is used to verify data, but the node trust indicates how trustworthy the nodes in VANETs are. To evaluate the efficiency of ART model, experiments were conducted. The results prove that the ART model copes with malicious attacks. The authors of [32] used three indicators for trust and proposed REK Trust Evaluation model based on parameters of reputation, experience, and knowledge. Reputation indicates how well the trustee has exchanged data with all of the entities until now. Experience indicates that how well the trustor has accomplished exchanging data with the trustee until now.