Tor: Anonymity and Access to Services Despite Censorship

Tor is an overlay network for anonymizing interactive communications such as web browsing, remote login, and chat. Originally designed by and for the Naval Research Laboratory to protect government communications, Tor has grown to a network of about a thousand volunteer-operated nodes around the globe and a user base of hundreds of thousands protecting their corporate, educational, military, law enforcement, and individual activities. The nonprofit Tor Project has also been funded by various sources to promote human rights and fight censorship. In this presentation we will describe Tor and its application in these areas. In particular we will focus on the design of hidden services, which can be accessed from anywhere even though the client does not know the server's location. This makes them difficult to attack or block. We will also focus on the recently-developed design for blocking resistance that provides clients access to Tor and the Internet in general in circumstances when access to public resources is restricted.