International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Protecting Data Privacy in Private Information Retrieval Schemes

Authors:
Yuval Ishai
Eyal Kushilevitz
Download:
URL: http://eprint.iacr.org/1997/006
Search ePrint
Search Google
Abstract: Private Information Retrieval (PIR) schemes allow a user to retrieve the i-th bit of a data string x, replicated in k>=2 databases, while keeping the value of i private. The main cost measure for such a scheme is its communication complexity. We study PIR schemes where in addition to the user's privacy we require data privacy. That is, in every invocation of the retrieval protocol the user learns exactly a single physical bit of x and no other information. Further, we require that even a dishonest user would not learn more than a single physical data bit. We present general transformations that allow translating PIR schemes satisfying certain properties into PIR schemes that respect data privacy as well, with a small penalty in the communication complexity. Using our machinery we are able to translate currently known PIR solutions into schemes satisfying the newly introduced, stronger privacy constraint. In particular we get: a k-database scheme of complexity O(log(n) n^{1/(2k-1)}) for every k>=2; an O(log(n))-database scheme of poly-logarithmic complexity; a 2-database computational PIR of complexity O(n^c), for every constant c>0. All these require only a single round of interaction.
BibTeX
@misc{eprint-1997-11288,
  title={Protecting Data Privacy in Private Information Retrieval Schemes},
  booktitle={IACR Eprint archive},
  keywords={},
  url={http://eprint.iacr.org/1997/006},
  note={Appeared in the THEORY OF CRYPTOGRAPHY LIBRARY and has been included in the ePrint Archive. yuvali@cs.technion.ac.il 10500 received May 4th, 1997.},
  author={Yuval Ishai and Eyal Kushilevitz},
  year=1997
}