MtDB: A Decentralized Multi-Tenant Database for Secure Data Sharing

Abstract

Healthcare data sharing is fundamental for advancing medical research and enhancing patient care, yet it faces significant challenges in privacy, data ownership, and interoperability due to fragmented data silos across institutions and strict regulations (e.g., GDPR, HIPAA). Patients possess distributed records across multiple hospitals, each maintaining autonomous databases. Access to consolidated records by secondary entities mandates explicit patient consent while ensuring strict isolation between multi-tenant datasets, requiring fine-grained access control across organizational boundaries. Existing solutions exhibit critical limitations: blockchain-based databases lack robust fine-grained cryptographic enforcement of dynamic access policies, while TEE-enhanced systems suffer from synchronization overhead and poor scalability in distributed deployments. To bridge these gaps, we propose MtDB, a novel decentralized database architecture addressing secure data sharing in multi-tenant database ecosystems. MtDB employs blockchain for metadata coordination and sharing, IPFS for distributed data addressing, a universal SQL query interface for data access, and Intel SGX for integrity-protected query execution with enforced access control. We provide an open-source implementation demonstrating MtDB’s capabilities for secure, patient-centric healthcare data sharing while preserving ownership and enforcing policies. Experimental results show MtDB achieves 35 milliseconds query latency for indexed queries over 400M multi-tenant medical records while maintaining cryptographic security guarantees, with only 1.2–1.3× performance overhead compared to non-secure baselines.