Boolean Key-aggregate Searchable Encryption with Hierarchical Time Validity for Cloud Storage Services

Abstract

The key-aggregate searchable encryption (KASE) [TC’2016] enables a data owner to share any set of selected documents with any group of users in cloud storage. Nevertheless, existing KASE solutions neglected the practical situation of categorized storage of documents that lead to inefficient expressive keyword search over shared documents. Moreover, they rarely considered the property of time controlled data sharing, where a data owner cannot specify corresponding time validity period of shared documents. To address the problems, this work presents a TC-KASE scheme for practical categorized storage of documents, supporting time controlled data sharing and boolean keyword search over shared data. Compared to state-of-the-art solutions, TC-KASE runs 85× (resp. 860×) faster for document searching with #keywords=10 and s-term=10 (resp. s-term=1), where s-term is the least frequent keyword in the query. Technically, the performance gain derives from a semi-generic construction of TC-KASE that roughly combines oblivious cross-tags protocol and time-based direct revocation strategy. Additionally, we introduce a new “adjusted matching” technique to match encryption tuples and a token that adjusted from an aggregate token. Overall, our experiment confirms that TC-KASE achieves practical performance while supporting new properties, which is conducted over real-world dataset on a cloud platform (our codes are available at https://github.com/Kai9009/Codes).

Keywords

Cloud Storage / Group Data Sharing / Key-Aggregate Encryption / Searchable Encryption

RIGHTS & PERMISSIONS

Higher Education Press 2026

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