Title: A forward and backward secure conjunctive keywords dynamic searchable encryption scheme

Authors: Md. Asrar Ahmed; S. Ramachandram; Khaleel Ur Rahman Khan

Addresses: CSE Department, University College of Engineering, Osmania University, Hyderabad, 500007, Telangana, India ' CSE Department, University College of Engineering, Osmania University, Hyderabad, 500007, Telangana, India ' CSE Department, ACE Engineering College, Medchal, 501301, Telangana, India

Abstract: Dynamic searchable symmetric encryption (DSSE) allows a user to carryout search and update operations on the outsourced encrypted data on cloud. The recent research work in DSSE exposed many flaws in existing strategies by introducing leakage abuse attacks. To protect DSSE schemes from leakage, forward and backward privacy notions were introduced. In this paper, we propose a forward and backward secure chained dictionary-based indexing mechanism with support for conjunctive keyword queries. The proposed scheme uses a minimal leakage index design, requiring compact storage at client, easier update operations at server and removes entries of deleted files from index to ensure backward privacy resulting in reduced index size. It ensures that the searches followed by update operation do not violate query privacy. Rigorous security analysis and experimental evaluations show that our scheme achieves sub-linear search time and supports efficient update operations ensuring forward and backward privacy.

Keywords: forward privacy; backward privacy; dynamic SSE; outsourced data privacy; randomised query; conjunctive keyword search.

DOI: 10.1504/IJITST.2022.122073

International Journal of Internet Technology and Secured Transactions, 2022 Vol.12 No.3, pp.205 - 229

Received: 04 Jun 2020
Accepted: 21 Feb 2021
Published online: 08 Apr 2022 *

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