Almost Optimal Private Information Retrieval

  • Dmitri Asonov
  • Johann-Christoph Freytag
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2482)


A private information retrieval (PIR) protocol allows a user to retrieve one of N records from a database while hiding the identity of the record from the database server.

With the initially proposed PIR protocols to process a query, the server has to process the entire database, resulting in an unacceptable response time for large databases. Later solutions make use of some preprocessing and offline communication, such that only O(1) online computation and communication are performed to execute a query. The major drawback of these solutions is offline communication, comparable to the size of the entire database.

Using a secure coprocessor we construct a PIR scheme that eliminates both drawbacks. Our protocol requires O(1) online computation and communication, periodical preprocessing, and zero offline communication. The protocol is almost optimal. The only parameter left to improve is the server’s preprocessing complexity - the least important one.


Efficient realization of privacy services 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Dmitri Asonov
    • 1
  • Johann-Christoph Freytag
    • 1
  1. 1.Humboldt-Universität zu BerlinBerlinGermany

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