Research On The Privacy Protection Of Medical Health Data Based On Blockchain

With the rapid development of information technology and the popularization of medical informatization,medical and health data are growing at an alarming rate.Rational use of these data will play a very important role in health monitoring,disease diagnosis and drug research and development.However,the consequent privacy security issues should also be taken seriously.Most of the existing medical institutions use databases or cloud servers to centrally store medical and health data,which is vulnerable to single point of attack,resulting in privacy data leakage.At the same time,a large number of medical and health data are scattered in various medical institutions,which makes it difficult to achieve cross-institution and cross-platform data sharing.Blockchain,with its characteristics of decentralization,openness,transparency and immutability,provides a good technical support for the privacy protection of medical and health data and the information exchange between different medical institutions.Based on the application scenario of electronic health records(EHR),the research on the use of content extraction signature algorithm and the use of blockchain to achieve the safe storage and sharing of EHR data is carried out.Firstly,aiming at the problems of low security and low computational efficiency of existing content extraction signature schemes,a new content extraction signature scheme based on certificateless public key cryptosystem(CL-CES)is proposed,which uses the point multiplication operation on elliptic curve to replace the complex bilinear pairing operation.The proposed scheme can achieve the function of partial data hiding,and users can extract signatures without viewing the complete content of the document.Then,the scheme is proved to satisfy the unforgeability under the random oracle model.Compared with other schemes,the proposed scheme has high computational efficiency and has great application potential in the scenario of protecting the privacy of medical and health data.Secondly,based on the CL-CES scheme proposed above,a blockchain-based EHR data secure storage and sharing scheme is designed.The new designed scheme adopts the storage mode of combination of on-chain and off-chain,the complete EHR data is stored in the IPFS file system and returned the unique hash value,while the alliance blockchain is only responsible for saving the hash value.At the same time,the fuse mechanism and credit rating are introduced into the CPBFT consensus mechanism to reduce the possibility of malicious nodes becoming consensus nodes.Combined with the simplified consistency protocol and proxy re-encryption technology,the secure sharing of medical and health data is realized.The security analysis and performance analysis show that the proposed scheme has obvious advantages in data security,privacy protection,download speed and so on.