Abstract:

The high value and sensitivity of medical data lead to the problems of access control,data security,effective supervision and privacy leakage in electronic medical data sharing.The traditional attribute-based encryption can solve one-to-many access control problems during data sharing,but there are still challenges that need to be solved,such as low efficiency,the invalidation of access policy once it changes slightly,and the leakage of sensitive information from the access policy.To solve the above problems,first,a scheme using the attribute-based encryption with the hidden access policy and proxy re-encryption is proposed,which can prevent privacy from being disclosed by the access policy,but also realizes more efficient and dynamic data sharing.Second,as for the issues of the centralized single point of failure,the lack of supervision in the process of data sharing,and the heavy storage load of blockchain,the scheme is integrated with the blockchain,smart contract and InterPlanetary FileSystem,and it can implement the low-overhead mode of the distributed storage of original data ciphertext off the chain and the sharing of the key information ciphertext on the chain.Then an architecture that supports flexible data supervision is established,which is suitable for decentralized medical data sharing scenarios.Finally,for the proposed scheme,the security proof and performance analysis including storage,computing and smart contract costs are conducted.The results show that the scheme can resist selective plaintext attack and collusion attack.In addition,privacy protection and effective supervision are added in the data sharing process,and at the same time,the efficiency of the proposed scheme is better than that of the existing data sharing schemes.

Key words: blockchain, attribute-based encryption, proxy re-encryption, smart contract, data sharing