Oblivious keyword search

  • Authors:
  • Wakaha Ogata;Kaoru Kurosawa

  • Affiliations:
  • Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan;Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan

  • Venue:
  • Journal of Complexity - Special issue on coding and cryptography
  • Year:
  • 2004

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Abstract

In this paper, we introduce a notion of oblivious keyword search (OKS). Let W be the set of possible keywords. In the commit phase, a database supplier I commits n data. In each transfer subphase, a user U can choose a keyword w∈W adaptively and find Search(w) without revealing w to I, where Search(w) is the set of all data which includes w as a keyword.We then show two efficient protocols such that the size of the commitments is only O(nB) regardless of the size of W, where B is the size of each data. It is formally proved that U learns nothing more than search(w) and J gains no information on the keywords which U searched for. We further present a more efficient adaptive OTkn protocol than the previous one [19] as an application of our first OKS protocol.