University of Waterloo
Anonymity systems preserve the identities of users as they access Internet data sources. The security of many such systems, such as Tor, relies on a model where the adversary does not have a global view or control of the network. A different problem is that of preserving access privacy for users accessing a large database over the Internet in a model where the adversary has full control of the database. Private Information Retrieval (PIR) schemes are designed to prevent an adversary controlling the database from being able to learn any information about the access patterns of users.