Searchable Encryption with Keyword-Recoverability

Ik Rae JEONG  Jeong Ok KWON  Dowon HONG  Dong Hoon LEE  

IEICE TRANSACTIONS on Information and Systems   Vol.E92-D   No.5   pp.1200-1203
Publication Date: 2009/05/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E92.D.1200
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Application Information Security
keyword search,  keyword-testability,  keyword-recoverability,  data-recoverability,  chosen ciphertext attacks,  

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Searchable encryption has many applications including e-mail systems and storage systems. The usefulness of searchable encryption derives from its support of keyword-testability. Keyword-testability means that a receiver of a ciphertext can test whether the ciphertext contains a specific keyword. Recently, Bellare et al. suggested an efficiently-searchable encryption scheme with keyword-recoverability as well as keyword-testability. Keyword-recoverability means that a receiver can extract the keyword from a ciphertext. All of the previous searchable encryption schemes have provided only keyword-testability. However, as explained by Bellare et al., no efficiently-searchable encryption scheme can provide even security against chosen keyword attacks. That is, Bellare et al.'s scheme assumes that no useful partial information about the keyword is known to the adversaries. In this paper, we suggest an SEKR (searchable encryption with keyword-recoverability) scheme which is secure even if the adversaries have any useful partial information about the keyword. Our scheme provides security against chosen ciphertext attacks which are stronger attacks than chosen keyword attacks. We also suggest an SEKR scheme for multi-keywords.