Authors:
Laltu Sardar
1
and
Subhra Mazumdar
2
Affiliations:
1
Institute for Advancing Intelligence, TCG-CREST, Kolkata, India
;
2
TU Wien and Christian Doppler Laboratory Blockchain Technologies for the Internet of Things, Vienna, Austria
Keyword(s):
Searchable Encryption, Keyword Search, Fair Payment, Smart Contract, No-Trust Assumption.
Abstract:
A searchable encryption (SE) scheme allows a client to outsource its data to a cloud service provider (CSP) without the fear of leaking sensitive information. The latter can search over the outsourced data based on the client’s query. Such a scheme prevents a malicious CSP from sending incorrect results. However, a malicious client can deny receipt of the correct result and wrongly blame the CSP. Existing SE schemes fail when the client acts maliciously. In this paper, we have studied searchable encryption schemes where none of the parties trust each other. We propose Fidelis, a novel blockchain-based SE scheme, with keyword-search functionality, that is verifiable by both parties. None of the parties can cheat, and an honest CSP gets payment upon providing the result. We implement and evaluate an instance of the protocol on real-life data using Ethereum as the blockchain platform, deploying it in the Ropsten test network. Upon comparing with existing schemes, we observe that our pro
tocol is efficient and scalable.
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