Traditional privacy-preserving authentication schemes often rely heavily on centralized trusted authorities, which can hinder efficient auditing. To address these limitations, we propose a decentralized authentication scheme specifically designed for vehicular ad hoc networks (VANETs). Our approach leverages lightweight cryptographic primitives to accommodate the resource constraints for vehicular environments, ensuring minimal computational and communication overhead without compromising performance. The proposed scheme supports anonymous message authentication, enables identity traceability under authorized legal requests, and is resilient against forgery and replay attacks. We conduct a thorough security analysis, demonstrating that our scheme satisfies key security requirements, including anonymity, conditional traceability, and non-repudiation. Additionally, we perform a comprehensive performance evaluation and compare our solution with existing methods. The results show that our scheme is both efficient and practical, making it well-suited for deployment in VANETs.