SDTA: Secure Decentralized Trading Alliance for Electronic Medical Data.

The article focuses on the design and evaluation of a Secure Decentralized Trading Alliance (SDTA) for electronic medical data to enable efficient, fair, and privacy-preserving data sharing among hospitals. SDTA employs a consortium blockchain with a novel chain-net structure that records data digests and transactions to avoid duplicate data storage and ensure transaction fairness, while encrypted medical data are stored only once across hospital servers. The system integrates a dynamic searchable symmetric encryption (DSSE) scheme with an |$l$|-level access strategy to support secure, forward- and backward-private querying and updating of encrypted data according to user access levels. Comprehensive security analyses and experimental results demonstrate SDTA’s correctness, fairness, privacy protection, and efficiency, including the ability to search one million encrypted keyword-identifier pairs in approximately 0.04 seconds.