Cryptology ePrint Archive: Report 2014/509

Privacy preserving delegated word search in the cloud

Kaoutar Elkhiyaoui and Melek Onen and Refik Molva

Abstract: In this paper, we address the problem of privacy preserving delegated word search in the cloud. We consider a scenario where a data owner outsources its data to a cloud server and delegates the search capabilities to a set of third party users. In the face of semi-honest cloud servers, the data owner does not want to disclose any information about the outsourced data; yet it still wants to benefit from the highly parallel cloud environment. In addition, the data owner wants to ensure that delegating the search functionality to third parties does not allow these third parties to jeopardize the confidentiality of the outsourced data, neither does it prevent the data owner from efficiently revoking the access of these authorized parties. To these ends, we propose a word search protocol that builds upon techniques of keyed hash functions, oblivious pseudo-random functions and Cuckoo hashing to construct a searchable index for the outsourced data, and uses private information retrieval of short information to guarantee that word search queries do not reveal any information about the data to the cloud server. Moreover, we combine attribute-based encryption and oblivious pseudo-random functions to achieve an efficient revocation of authorized third parties. The proposed scheme is suitable for the cloud as it can be easily parallelized.

Category / Keywords: cryptographic protocols / Privacy preserving keyword search, delegation, cloud

Original Publication (with minor differences): Secrypt 2014

Date: received 27 Jun 2014, last revised 30 Jun 2014

Contact author: kaoutar elkhiyaoui at eurecom fr

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Version: 20140630:165125 (All versions of this report)

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