A tight lower bound for restricted pir protocols

We show that any 1-round 2-server Private Information Retrieval Protocol where the answers are 1-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 de Wolf while avoiding their use of quantum techniques. Keywords. Private information retrieval, lower bounds, privacy Subject classification. 68Q17,

• Type: Journal
• Year: 2006
• Where: CC
• Authors: Richard Beigel, Lance Fortnow, William I. Gasarch
• Keywords: CC 2006, Information Retrieval Protocol, Lower Bounds, Private Information Retrieval, System Software