Efficient Indexing CP-ABE Mobile Healthcare Data Sharing Scheme with Policy Hiding

With the rapid development of mobile medical technology, ensuring the secure sharing of medical data has become a critical challenge. Traditional Attribute-Based Encryption (ABE) schemes achieve fine-grained access control but struggle with access policy exposure and heavy computational burdens during decryption. Rather than introducing new fundamental cryptographic primitives, this paper proposes a unified, system-level integration of policy-hiding CP-ABE, specifically optimized for resource-constrained m-Health environments. By synergizing policy-hiding techniques, a SipHash-based deterministic indexing mechanism, and verifiable outsourced decryption, the scheme transfers computation-intensive tasks to an edge agent while completely safeguarding policy privacy. Crucially, the proposed index matching achieves O(1) time complexity, which not only minimizes communication overhead but also ensures high scalability for large user populations. Theoretical and experimental analyses demonstrate that our scheme achieves an optimal and highly practical balance among security, privacy (with an acceptable and strictly bounded access pattern trade-off), and overall system efficiency for mobile medical data sharing.