Decentralized, tamper-proof blockchain is regarded as a solution to a challenging authentication issue in the Internet of Vehicles (IoVs). However, the consensus time and communication overhead of blockchain increase significantly as the number of vehicles connected to the blockchain. To address this issue, vehicular fog computing has been introduced to improve efficiency. However, existing studies ignore several key factors such as the number of vehicles in the fog computing system, which can impact the consensus communication overhead. Meanwhile, there is no comprehensive study on the stability of vehicular fog composition. The vehicle movement will lead to dynamic changes in fog. If the composition of vehicular fog is unstable, the blockchain formed by this fog computing system will be unstable, which can affect the consensus efficiency. With the above considerations, we propose an efficient and stable identity authentication (ESIA) empowered by hierarchical blockchain and fog computing. By grouping vehicles efficiently, ESIA has low communication complexity and achieves high stability. Moreover, to enhance the consensus security of the hierarchical blockchain, the consensus process is from the bottom layer to the up layer (bottom-up), which we call B2UHChain. Through theoretical analysis and simulation verification, our scheme achieves the design goals of high efficiency and stability while significantly improving the IoV scalability to the power of 1.5 (^1.5) under similar security to a single-layer blockchain. In addition, ESIA has less communication and computation overhead, lower latency, and higher throughput than other baseline authentication schemes.

翻译：去中心化、防篡改的区块链被视为解决车联网（IoVs）中具有挑战性的身份认证问题的方案之一。然而，随着接入区块链的车辆数量增加，区块链的共识时间和通信开销显著增长。为解决此问题，引入了车载雾计算以提高效率。但现有研究忽略了几个关键因素，例如雾计算系统中的车辆数量，该因素会影响共识通信开销。同时，目前缺乏对车载雾组成稳定性的全面研究。车辆移动将导致雾的动态变化。若车载雾的组成不稳定，由此雾计算系统形成的区块链将不稳定，进而影响共识效率。基于上述考虑，我们提出一种由分层区块链和雾计算赋能的高效稳定身份认证（ESIA）方案。通过高效分组车辆，ESIA具有低通信复杂度并实现了高稳定性。此外，为增强分层区块链的共识安全性，其共识过程采用从底层到顶层的自底向上（B2UHChain）方式。通过理论分析和仿真验证，我们的方案实现了高效性和稳定性的设计目标，同时在单层区块链相似的安全性下，将车联网的可扩展性显著提升至1.5次方（^1.5）。与其他基线认证方案相比，ESIA具有更低的通信和计算开销、更低的延迟以及更高的吞吐量。