Cloud computing has transformed healthcare by enabling efficient storage and management of large-scale medical data. However, outsourcing sensitive patient information to third-party servers introduces critical privacy and security risks. Traditional cryptographic approaches like searchable encryption provide partial protection but are vulnerable to leakage-based attacks and suffer from high computational overhead. To overcome these limitations, we implement ECMO (Efficient Cloud-based Medical Outsourcing)—a novel protocol that integrates ordered additive secret sharing and index permutation to securely outsource medical data while preserving privacy and access pattern confidentiality. Our ECMO system is developed using the MERN stack (MongoDB, Express.js, React.js, Node.js), offering a secure web interface for uploading, storing, and searching encrypted medical files. By splitting keyword mappings across distributed shares and permuting index access, ECMO prevents inference attacks even on untrusted servers. Experimental results show excellent performance, with 500 keyword store operations averaging only 42.5 μs, proving ECMO's effectiveness, scalability, and suitability for secure healthcare data outsourcing.

Keywords: Cloud Computing, Medical Data Security, ECMO Protocol, Additive Secret Sharing, MERN Stack.