Hardening distributed and encrypted keyword search via blockchain

Chengjun Cai, Xingliang Yuan, Cong Wang

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearch

31 Citations (Scopus)


Distributed storage platforms draw much attention due to their high reliability and scalability for handling a massive amount of data. To protect user and data privacy, encryption is considered as a necessary feature for production systems like Storj. But it prohibits the nodes from performing content search. To preserve the functionality, we observe that a protocol of integration with searchable encryption and keyword search via distributed hash table allows the nodes in a network to search over encrypted and distributed data. However, this protocol does not address a practical threat in a fully distributed scenario. Malicious nodes would sabotage search results, and easily infiltrate the system as the network grows. Using primitives such as MAC and verifiable data structure may empower the users to verify the search result, but the robustness of the overall system can hardly be ensured. In this paper, we address this issue by proposing a protocol that is seamlessly incorporated to encrypted search in distributed network to attest and monitor nodes. From the moment a node joins the system, it will be attested and continuously monitored through verifiable search queries. The result of each attestation is determined via a standard quorum-based voting protocol, and then recorded on the blockchain as a consensus view of trusted nodes. Based on the proposed protocols, malicious nodes can be detected and removed by a majority of nodes in a self-determining manner. To demonstrate the security and efficiency, we conduct robustness analysis against several potential attacks, and perform performance and overhead evaluation on the proposed protocol.

Original languageEnglish
Title of host publicationProceedings - 2017 IEEE Symposium on Privacy-Aware Computing - PAC 2017
Subtitle of host publicationWashington DC, DC, USA 1-3 August 2017
EditorsNinghui Li, Kui Ren, Ahmad-Reza Sadeghi
Place of PublicationPiscataway NJ USA
PublisherIEEE, Institute of Electrical and Electronics Engineers
Number of pages10
ISBN (Electronic)9781538610275
Publication statusPublished - 2017
Externally publishedYes
EventIEEE Symposium on Privacy-Aware Computing 2017 - Washington, United States of America
Duration: 1 Aug 20173 Aug 2017
Conference number: 1st


ConferenceIEEE Symposium on Privacy-Aware Computing 2017
Abbreviated titlePAC 2017
Country/TerritoryUnited States of America
Internet address

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