Study In Private Information Retrieval Protocal And Applications

Private information retrieval (PIR) is a strategy to protect individual privacy on the public network platform. When users retrieve information in the database, it will use certain method to prevent database server from knowing users queries information, and then protect users'privacy. The development and popularization of PIR is not only needing to enhance the privacy confidential technology, but also needing to improve people's privacy protection cognizance. In the real life, PIR has great application space in the field which has a higher request to privacy, such as patent database, medicine database, etc.This paper study focuses on three points: The first is studying PIR scheme under single server and multiple servers; the second is studying two typical protocols: PIR protocol based on trapdoor information and PIR protocol based on security coprocessor; the third is studying a typical application called Pynchon Gate system.In the part of studying PIR scheme under single server and multiple servers, we analyze the advantages and disadvantages of former schemes and then explore feasible PIR scheme considering comprehensive safety aspects. After these works, we use secret sharing protocol and homomorphism encryption and security communication technology, with considering the current complicated network environment and the possible malicious attack to user information, to design a proper PIR scheme under multiple servers.In the part of studying the typical PIR: The PIR protocol based on trapdoor information is the computational PIR protocol based on single server. It makes effort to reduce the computational complexity of computational PIR and to enhance the safety of protocol through optimizing algorithm. The PIR protocol based on safety coprocessor effectively introduces the concept of safety association processing, and optimizes the execution efficiency of inquiring data online and offline. It has a broad application prospects. This article analyzes and summarizes the core ideas and operation process of these two protocols.In the part of study the typical application: The Pynchon Gate system is an anonymous email retrieval system. It uses distributed credible privacy retrieval protocol to prevent malicious attacks by attacker, and then transfer the mails to anonymous receivers for ensuring the integrity and confidentiality of the mail. This is a typical application by using PIR protocol to resolve practical problems effectively. Through the analysis of PIR's application mode on this system, this article proposed a reasonable hypothesis about PIR protocol application mechanism.