Vehicular ad hoc networks (VANETs) are essential to facilitate intelligent transportation systems, providing increased security, optimised traffic management and enhanced connectivity between vehicles and infrastructure. The challenge of ensuring secure communication is significant because of factors such as dynamic topology, high mobility and latency requirements. Therefore, authentication techniques play a crucial role in protecting networks by verifying the identity of entities and preventing malicious activities. This paper begins by reviewing VANETs and their security characteristics, privacy issues and basic security requirements. We examine different authentication schemes designed for VANETs and categorise them on the basis of their underlying cryptographic techniques, performance indicators and security objectives. The requirements include authentication, message confidentiality, message integrity and access control. In addition, this study evaluates different schemes using technological tools to measure critical performance characteristics, such as latency, scalability and resilience to attacks. This evaluation is conducted in conjunction with a formal verification, which allows developers to analyse the protocols thoroughly and address any design flaws. The strengths and weaknesses of existing authentication methodologies are evaluated by leveraging test scenarios, providing insights into the balance between security and efficiency. This work emphasises the use of comparative analysis to guide the development of robust and effective authentication systems in the future, thus facilitating the creation of secure VANET infrastructure.