MASTERÂ Assignment
Libertas: A Backward Private Dynamic Searchable Symmetric Encryption Scheme Supporting Wildcard Search
Type : Master M-CS
Period: Apr, 2021 - Nov, 2021
Student : Weener, J. (Jeroen, Student M-CS)
Date Final project: Nov 5, 2021
Supervisors:
Abstract:
When outsourcing data, Searchable Symmetric Encryption schemes allow clients to query the server for their encrypted files without compromising data confidentiality. Several attacks against searchable encryption schemes have been proposed that leverage information leakage the schemes emit when operating. Schemes should achieve Forward and Backward Privacy to mitigate these types of attacks. Despite the variance of query types across SSE schemes, most forward and backward private schemes only support exact keyword search. In this research, we extend backward privacy notions and their underlying leakage functions to the Wildcard Search domain. Additionally, we present Libertas: a construction that provides backward privacy to any wildcard supporting scheme. If the scheme is forward private, this property is inherited. We prove security in the L-adaptive security model. We show that the performance overhead scales linearly with the number of deletions.