Explore an in-depth analysis of the Tor network and circumvention techniques in this invited talk from Crypto 2011 at the University of California, Santa Barbara. Delve into the fundamentals of Tor, its threat model, and the crucial distinction between anonymity and encryption. Examine how different user groups, including law enforcement, journalists, and activists, benefit from anonymity. Investigate the current state of internet privacy and the challenges faced by simple relay designs. Learn about the basic Tor architecture, including its centralized directory protocol and bridge discovery methods. Analyze the goals of potential attackers and the various threats to anonymity. Discuss the impact of publicity on anonymity networks and the importance of advocacy and education. Gain insights into measuring bridge reachability and other key components of circumvention technologies.
Tor and Circumvention: Lessons Learned, by Roger Dingledine
Overview
Syllabus
Intro
What is Tor?
Threat model: what can the attacker do?
Anonymity isn't encryption: Encryption just protects contents.
Anonymity isn't just wishful thinking...
Anonymity serves different interests for different user groups.
Law enforcement needs anonymity to get the job done.
Journalists and activists need Tor for their personal safety
Current situation: Bad people on the Internet are doing fine
The simplest designs use a single relay to hide connections.
But a single relay (or eavesdropper!) is a single point of failure.
Alice makes a session key with R1 ...And then tunnels to R2...and to R3
The basic Tor design uses a simple centralized directory protocol.
How do you find a bridge?
Attacker's goals
What we're up against
Flash is dangerous too
Publicity attracts attention
Advocacy and education
Measuring bridge reachability
Other components
Taught by
TheIACR
