Blockchain-Based Verifiable DSSE with Forward Security in Multi-server Environments

With big data and cloud computing development, data owners begin to outsource their large-volume data to remote servers to reduce local storage costs. Researchers have currently proposed some Dynamic Searchable Symmetric Encryption (DSSE) schemes that support efficient keyword searches on encrypted data with dynamic update operations. Unfortunately, most of them are constructed based on a single server architecture, which means that they cannot be used directly when multiple servers participate in the search process. Some schemes assume that the server is honest-but-curious, which cannot be guaranteed, especially in the multi-server scenario. This paper proposes a Blockchain-based Verifiable DSSE scheme with forwarding security in Multi-server environments. In the scheme, the data owner encrypts the partitioned files and randomly stores them in different servers from which a single server cannot recover any complete file. The use of blockchain and smart contracts to achieve reliable and verifiable search can detect malicious servers’ improper behaviors. Experimental evaluation show that the scheme achieves verifiable search, forward privacy with less leakage, and high search efficiency.