computational complexity

, Volume 15, Issue 1, pp 82–91 | Cite as

A tight lower bound for restricted pir protocols

Original Paper


We show that any 1-round 2-server Private Information Retrieval Protocol where the answers are one bit long must ask questions that are at least n−2 bits long, which is nearly equal to the known n−1 upper bound. This improves upon the approximately 0.25n lower bound of Kerenidis and deWolf while avoiding their use of quantum techniques.


Private information retrieval lower bounds privacy 

Subject classification.



Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Birkhäuser Verlag, Basel 2006

Authors and Affiliations

  • Richard Beigel
    • 1
  • Lance Fortnow
    • 2
  • William Gasarch
    • 3
  1. 1.Department of Computer and Information SciencesTemple UniversityPhiladelphiaU.S.A.
  2. 2.Department of Computer ScienceUniversity of ChicagoChicagoU.S.A.
  3. 3.Department of Computer Science and Institute for Advanced Computer StudiesUniversity of MarylandCollege ParkU.S.A.

Personalised recommendations