FDRShare: A Fully Decentralized and Redactable EHRs Sharing Scheme with Constant-Size Ciphertexts

Blockchain-based Electronic Health Records (EHR) sharing schemes can enable the owner to outsource the encrypted EHR to the powerful but untrusted cloud such that only authorized users can search or access EHRs and check whether the cloud returns valid results or not. However, these existing schemes suffer from three substantial shortcomings that limit their usefulness: (i) a centralized Trusted Authority (TA) is introduced to manage keys, which fully conflicts with the decentralized nature of blockchain; (ii) the size of the encrypted EHRs is linear to the attribute set size, which poses challenges for the blockchain network; (iii) the efficiency of search seriously impacts the user experience, which hinders the deployment in practice. To address these issues, we proposed FDRshare, a fully decentralized EHRs sharing scheme with constant-size ciphertexts.