LPDB: Lightweight Policy-Driven Blockchain With Batch Verification for Rail Transit Systems

Rail transit is a commonly used mode of transportation for daily commuting, but traditional Rail Transit Systems (RTS) typically face significant challenges such as high mobility and low latency. Furthermore, the RTS generates a substantial volume of real-time interactive data, posing difficulties in ensuring user privacy while maintaining practicality. To address these concerns, blockchain as a promising technology, has been leveraged to safeguard data transmission and access. However, public blockchains such as Bitcoin and Ethereum may not be suitable for real-time interactive RTS scenarios due to their lack of flexibility and control. To overcome this, the notion of the Policy-Driven Blockchain (PDB) was introduced, which is a private blockchain with flexible policy control and management mechanisms. PDB can be quickly customized and deployed according to specific business requirements and rules, making it a valuable feature for RTS scenarios. However, their scheme relies on bilinear pairings, which incurs high computational overhead and does not support batch validation. In this article, we propose a Lightweight Policy-Driven Blockchain (LPDB) scheme to overcome these challenges, the core of which is the design of a Pairing-free Policy-Driven Signature (PFPDS) scheme better tailored to meet the specific requirements in RTS. In addition, considering the large number of communication messages in RTS, we analyze the advantages of batch verification of signatures. In conclusion, the security of our proposal is validated under the random oracle model, and we evaluate the computational expenses associated with the algorithms via simulations on a laptop. The implementation outcomes demonstrate the practicality and viability of our scheme.