Reducing the Servers Computation in Private Information Retrieval: PIR with Preprocessing

Private information retrieval (PIR) enables a user to retrieve a data item from a database, replicated among one or more servers, while hiding the identity of the retrieved item. This problem was suggested by Chor, Goldreich, Kushilevitz, and Sudan in 1995, and since then efficient protocols with sub-linear communication were suggested. However, in all these protocols the servers’ computation for each retrieval is at least linear in the size of entire database, even if the user requires only a single bit. In this paper, we study the computational complexity of PIR. We show that in the standard PIR model, where the servers hold only the database, linear computation cannot be avoided. To overcome this problem we propose the model of PIR with preprocessing: Before the execution of the protocol each server may compute and store polynomially-many information bits regarding the database; later on, this information should enable the servers to answer each query of the user with more effici...

• Type: Conference
• Year: 2000
• Where: CRYPTO
• Authors: Amos Beimel, Yuval Ishai, Tal Malkin
• Keywords: CRYPTO 2000, Cryptology, K-server Protocol, Private Information Retrieval, Standard Pir Model