DSE-RB: A Privacy-Preserving Dynamic Searchable Encryption Framework on Redactable Blockchain

With the development of various applications of blockchain, blockchain-assisted searchable encryption technology has received wide attention as it can eliminate misbehaviours of malicious servers through the verification and incentive mechanism of blockchain. However, most existing solutions update the encrypted data by means of appending new transactions, which does not scale and wastes resources. In this paper, we explore the potential of redactable blockchain and propose a privacy-preserving dynamic searchable encryption framework (DSE-RB), which is a general scheme that guarantees reliable queries and updates on encrypted data. In particular, we first use transaction-level editing technology to achieve a more flexible update operation of encrypted data without additional transactions while avoiding the waste of storage on the chain. To better support practical applications, we use an index partition method to divide the traditional binary tree index into a plurality of sub-indexes and introduce the concept of polynomials to simplify the whole access control mechanism. We define the security model and conduct repeated experiments on real data sets to test the efficiency. Experimental results and theoretical analysis show the practicability and security of our scheme.