Objectives: In Vehicular Ad Hoc Networks (VANETs), ensuring secure data communication is essential to uphold the integrity and reliability of vital vehicular applications. This study presents an innovative authentication scheme based on block chain technology, specifically designed to enhance data exchange security within VANETs. With a successful deployment and integration into our transportation systems, VANETs promise safer roads, reduced traffic congestion, and more efficient traffic management. These networks offer immediate communication of vital information to drivers, such as traffic conditions, accidents, and roadwork, helping to reduce accidents and save lives. VANET can enable intelligent traffic management, making real-time adjustments to traffic signals and routes based on data from the network. This can lead to reduced travel times and improved fuel efficiency, resulting in cost savings and reduced emissions. Methods: The scheme utilizes the SHAH (Secure Hash Algorithm with HMAC) Algorithm as a foundational component to safeguard data authenticity and confidentiality. Our proposed block chain-based authentication approach capitalizes on the decentralized nature of block chain technology, establishing a robust and tamper-resistant ledger for authentication purposes. This helps to secure data transmission. Findings: A comprehensive analysis of the proposed scheme showcases its efficacy in ensuring secure data communication within VANETs. These findings underscore the significant value of our proposed approach, contributing to a safer and more dependable environment for vehicular communication, thereby enhancing the overall reliability of VANET applications. Novelty: As a concluding note, this research not only introduces a unique block chain-based authentication scheme tailored specifically for VANETs but also underscores the indispensable role played by the SHAH Algorithm in achieving data security. The outcomes presented in this study inspire further exploration at the intersection of block chain and VANET technologies, ultimately advancing the https://www.indjst.org/ 4291