Verifiable Encrypted Search with Forward Secure Updates for Blockchain-Based System

摘要

Enabling secure and reliable search over encrypted data is essential for data owners to protect their sensitive data from a compromised server. Recent advances in cloud computing are further pushing forward the development of this technique, known as searchable encryption. However, existing encrypted search schemes mainly consider a centralized setting, where a search is conducted in a traditional client-server model. How to apply searchable encryption schemes to an untrusted distributed setting like the blockchain environment remains to be explored. Meanwhile, the advanced security property like forward security is posing new challenges that traditional technologies are no longer sufficient to cope with. In this work, we explore the potential of blockchain technique and propose a novel dual index structure for forward-secure encrypted search with dynamic file updates. We show how to synthesize this design strategy in the context of blockchain-based storage systems and achieve both optimal search and update complexity. We also propose a verification scheme to verify the correctness of search results and customize an encrypted on-chain checklist to achieve strong data protection and lower the blockchain overhead. We implement the prototype on a Redis cluster and conduct performance evaluations on Amazon Cloud. Extensive experiments demonstrate the security and efficiency of the design.