A Dynamic Decentralized Identity-Based Privacy Protection Scheme for Railway Passengers

The large-scale collection and circulation of passenger travel data in railway operations have dramatically heightened the risks of personal privacy leakage. In recent years, Decentralized Identity (DID) has become a vital component of privacy protection research for railway passengers by enhancing their autonomous control over identity information. However, existing DID-based railway passenger privacy protection schemes typically rely on static identifiers for continuous authentication within a single service domain. Consequently, different travel records can be linked into continuous spatiotemporal trajectories, directly exposing passengers’ real-world identities and resulting in severe privacy breaches. To address this issue, this paper proposes a trip-scoped dynamic DID-based privacy protection scheme for railway passengers. In this scheme, dynamic DID separates identity registration from the railway platform, and each DID’s lifecycle is strictly confined to a single trip, eliminating linkability through temporal correlation and behavioral pattern analysis. For selective disclosure at ticket purchase and gate verification, the scheme adopts the established BBS+ signature mechanism, allowing passengers to reveal only the minimum necessary verification information and achieving complete decoupling of identity authentication from travel trajectory data. Through security analysis and simulation experiments, the proposed scheme is demonstrated to be secure, effective, and feasible, offering a promising privacy protection solution for the railway industry.