# Reputation and Trust Approach for Security and Safety Assurance in Intersection Management System
## 2 Related Work
### Vanets
Movement of nodes with high velocity means that nodes are constantly connected and disconnected from the network, and the topology constantly changes. VANETs are highly scalable and have to seamlessly transmit data under high network load conditions; high throughput and low latency are vital in terms of safety. Such networks imply communication between nodes at large distances and the technical characteristics of communications should allow for the transmission of data under environmental interference. The requirements above and characteristics of VANETs form the security challenges that VANETs face to ensure the reliable and stable system operation. According to the authors of [19; 20; 21], the main challenges of VANETs are:  
* Dynamic topology of the system. As described above, the VANETs should support communication between nodes in the conditions of their high mobility. For this reason, traditional authentication methods cannot be applied. Even though scientific papers propose solutions to these challenges, several issues remain unsolved [22]. * Time limits. The system safety depends on the time of data delivery and decision making based on the received data. To ensure safe operation, it is necessary to adhere to strict limits on the time of delivery, processing, and sending data, since the high dynamics of the system leaves critically little time for data processing. * Network scale. Prospects for the development of VANETs imply a large number of nodes interacting with each other, and the number of nodes constantly changes. Safe and stable operation of the entire system requires a scalable network infrastructure that can operate in an ever-changing network topology. * Ability to counter malicious network attacks. As in any network, VANETs are prone to malicious attacks. Since the functioning of VANETs is directly related to the participation of people, the implementation of an attack on VANETs can lead to critical consequences. Necessary mechanisms to counter attacks should include authentication procedures, non-repudiation, access control, privacy protection, confidentiality, integrity, and accessibility assurance. Classification of attacks to which AVs in VANETs are exposed is given in [5]. * Fault-tolerance. ITS collects and processes data obtained from vehicle sensors and uses it to optimize traffic and broadcast emergency and informational messages. The transmission of incorrect data due to a malfunctioning vehicle sensor, for example data on the speed or current location, can lead to traffic accidents and endanger other road users. * Privacy. To ensure privacy, data transmitted in VANETs should be anonymous [23]. It introduces an additional challenge for schemes using public key infrastructure (PKI), since it implies the identification of the sender and receiver of data [24]. However, vehicles can transmit incorrect data both unintentionally, e.g. in the event of a sensor failure, and intentionally, when an attacker makes unauthorized changes to the software and hardware components of the vehicle. Such attacks are called illusion attacks [25]. The bogus data broadcasting implies that other participants change their route, velocity, and plan further actions based on the data received. This can be used by an attacker both to artificially reduce the traffic jams on his route and to deliberately generate a traffic accident. Traditional authentication procedures and data integrity assurance in wireless networks are not effective against such attacks [26]. As a way to counter attacks aimed at contextual data integrity, the mechanisms based on reputation and trust can be used when each network member has its level of reputation in the system, and based on this level, the rest of the participants decide whether to trust the data received from this member. Below, we examine existing solutions, based on trust and reputation mechanisms.