How to alleviate the contradiction between the patient's privacy and the research or commercial demands of health data has become the challenging problem of intelligent medical system with the exponential increase of medical data. In this paper, a blockchain-based privacy-preserving scheme is proposed, which realizes secure sharing of medical data between several entities involved patients, research institutions and semi-trusted cloud servers. And meanwhile, it achieves the data availability and consistency between patients and research institutions, where zero-knowledge proof is employed to verify whether the patient's medical data meets the specific requirements proposed by research institutions without revealing patients’ privacy, and then the proxy re-encryption technology is adopted to ensure that research institutions can decrypt the intermediary ciphertext. In addition, this proposal can execute distributed consensus based on PBFT algorithm for transactions between patients and research institutions according to the prearranged terms. Theoretical analysis shows the proposed scheme can satisfy security and privacy requirements such as confidentiality, integrity and availability, as well as performance evaluation demonstrates it is feasible and efficient in contrast with other typical schemes.

中文翻译：

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基于区块链的医疗数据隐私保护和安全共享方案

随着医疗数据呈指数级增长，如何缓解患者隐私与健康数据的研究或商业需求之间的矛盾，成为智能医疗系统面临的挑战。本文提出了一种基于区块链的隐私保护方案，实现了患者、研究机构和半可信云服务器等多个实体之间医疗数据的安全共享。同时实现了患者与研究机构之间数据的可用性和一致性，采用零知识证明来验证患者的医疗数据是否符合研究机构提出的特定要求，同时不泄露患者隐私，然后采用代理重加密技术，保证研究机构可以解密中间密文。此外，该提案可以根据预先安排的条款，对患者和研究机构之间的交易执行基于PBFT算法的分布式共识。理论分析表明，所提出的方案能够满足保密性、完整性和可用性等安全和隐私要求，并且与其他典型方案相比，性能评估表明它是可行和高效的。