BA-RMKABSE: Blockchain-aided Ranked Multi-keyword Attribute-based Searchable Encryption with Hiding Policy for Smart Health System

Abstract

Due to the popularity of electronic medical technology and the rapid rise of cloud storage technology, how to securely share medical data has become a research hotspot at present. Fast and efficient keywords search in medical cloud is the key first step to achieve it. However, untrusted servicer may return the false search results or the results related to some special commercial purpose. Additionally, privacy leakage in medical data will also damage the benefits of the users and primary data owners. Ensuring fair and accurate searching of shared data and protecting the privacy of medical data have become important in the medical sharing system. This paper aims at solving these problems and a search framework for smart health system is proposed. In the framework, two smart contracts, named search smart contract(SSC) and verify smart contract(VSC), are constructed based on Ethereum blockchain, which are used to match the user’s trapdoor with index and check the correctness of search results. To improve the search accuracy, we realizes a ranking multi-keyword search where it only returns the top-k documents which best meet the user’s needs. Additionally, a new attribute-based encryption(ABE) is introduced to keep confidentiality and access authority of the sharing data. And the proposed ABE supports the hiding policy which solves the privacy protection during the data share. For reducing the computing burden of the data user, the decrypted-cloud service assistant system is proposed. Security proof and performance comparisons prove the security and efficiency of the scheme.