LiveIndex: An Index-Driven Hybrid-Storage Blockchain Framework for Cross-Domain Data Governance

Online user interactions produce privacy-sensitive data, necessitating data governance frameworks that respect user-defined privacy preferences. Nevertheless, the centralized storage and management of such preferences encounter significant interoperability challenges across different domains. By combining on-chain and off-chain storage paradigms, hybrid-storage blockchains have developed into a reliable infrastructure. Their value lies not only in ensuring secure data storage, but also in providing a practical foundation for data governance, especially in complex and cross-domain environments. In this paper, we propose LiveIndex, an index-driven hybrid-storage blockchain framework for cross-domain data governance. First, we design an on-chain data index based on distributed chameleon hash (DCH) to enable efficient off-chain data governance. This index incorporates essential elements, including metadata tags, data addresses, privacy ciphertexts, and group signatures. Second, we employ asymmetric searchable encryption (ASE) to protect privacy by converting analysis policies into search trapdoors and embedding privacy attributes into ciphertexts, thereby supporting compliant and secure data analysis. Third, we integrate proxy re-encryption (PRE) to strengthen control over cross-domain data, using re-encryption keys to ensure secure data authorization. Finally, we implement and evaluate LiveIndex on public datasets. The results show time overheads ranging from milliseconds to microseconds, demonstrating the practicality and efficiency in real-world scenarios.