Report on PIR with Low Storage Overhead

Private information retrieval (PIR) protocol, introduced in 1995 by Chor, Goldreich, Kushilevitz and Sudan, allows a user to retrieve a data item from a database without revealing which item is retrieved. Two main parameters of a PIR protocol are communication complexity, which is the total number of bits communicated between the user and the servers, and storage overhead, which is the ratio between the total number of bits stored on all the servers and the number of bits in the database. This report is based on the paper by Fazeli, Vardy and Yaakobi that is focused on the trade-off between these parameters in the information-theoretic setting. They showed that the storage overhead of a k-server PIR protocol can be arbitrarily close to the optimal value of 1 without sacrificing its communication complexity. They reduced the storage overhead parameter using coding technique instead of replication.