HySLA: Hybrid DPoS-DAG Model for Secure, Scalable, Low Latency Access Control in Internet of Vehicles

Secure and efficient access control is a foundational requirement in the Internet of Vehicles (IoV), particularly for dynamic, safety critical services such as emergency routing, cooperative driving, and smart toll management. This paper proposes a hybrid two layer framework that combines a localized Delegated Proof of Stake (DPoS) consensus mechanism with a global Directed Acyclic Graph (DAG) structure to achieve scalable, low latency, and tamper resistant access validation. To operationalize this architecture, we develop three core algorithms, (1) a delegate election and verification protocol based on vehicular reliability metrics, (2) a secure inter layer communication protocol utilizing digital signatures and timestamp verification, and (3) a DAG integration and parallel validation procedure for high throughput ledger consistency. Simulations conducted across diverse vehicular densities and network conditions show that the proposed model achieves an average decision latency of 28.1 ms, end-to-end response time of 221.3 ms, and over 90% detection accuracy against Sybil, replay, and collusion attacks, with cryptographic signing overhead averaging only 0.51 ms. Compared to conventional DPoS architectures and others, the proposed system exhibits improved delegate stability and adversarial resilience, making it well suited for latency sensitive and trust critical IoV environments. This framework offers a modular and extensible foundation for secure and adaptive vehicular access control under real world constraints.