Cryptology ePrint Archive: Report 2013/330

Trapdoor Privacy in Asymmetric Searchable Encryption Schemes

Afonso Arriaga and Qiang Tang

Abstract: We investigate the open problem, namely trapdoor privacy, in asymmetric searchable encryption (ASE) schemes. We first present two trapdoor privacy definitions (i.e. 2-TRAP-PRIV and poly-TRAP-PRIV) which provide different levels of security guarantee. Motivated by the generic transformation from IBE to ASE, we introduce two key anonymity properties (i.e. 2-KEY-ANO and poly-KEY-ANO) for IBE schemes, so that these properties directly lead to the resulting ASE’s 2-TRAP-PRIV and poly-TRAP-PRIV properties respectively at the end of a transformation. We then present a simplified Boyen-Waters scheme and prove that it achieves IBE-IND-CPA, IBEANO (anonymity), and 2-KEY-ANO security in the random oracle model. Finally, we extend the simplified Boyen-Waters scheme to be based on pairings over composite-order groups and prove that the extended scheme achieves poly-KEY-ANO security without random oracles.

Category / Keywords: public-key cryptography / Searchable Encryption, Trapdoor Privacy, Anonymous IBE

Date: received 29 May 2013

Contact author: qiang tang at uni lu

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Version: 20130602:170325 (All versions of this report)

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