Zero-Knowledge Proof-Based Privacy-Preserving Smart Contracts for Healthcare

Blockchain enabled systems are more and more adopted in healthcare for secured processing of data, but current smart contract usage in healthcare leaks private patient data on execution. The contributions of this paper are two-fold: (1) it proposes a new framework that combines ZKPs with healthcare smart contracts/transactions to achieve full privacy preservation and (2) it discusses the security, usability, and the efficiency of the framework at the same time. Our proposed framework is based on zero-knowledge proof systems zkSNARKs (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge) and zkSTARKs (Zero-Knowledge Scalable Transparent Argument of Knowledge) tailored for computer on medical data without revealing effectively. We conduct extensive analysis and prototype implementation to show that our framework is able to achieve perfect privacy preservation at a 1.87% computational overhead increase with respect to standard smart contracts. The system processes over 10,000 medical records with sub-second verification times and that meet the HIPAA requirements. Experimental results in diverse healthcare applications attest to the efficacy of the approach in practice, and show the substantial gain of privacy preservation (99.8% retention rate) and computational efficiency over the state-of-art algorithms. This paper bridges the gap between blockchain’s transparency and healthcare’s privacy requirements, laying the groundwork for secure and privacy-preserving blockchain based healthcare applications.