This document provides an overview of Tor's blocking-resistance design. It begins with background on Tor, including that it is open source software with over 1500 active relays and 200,000 daily users. It then outlines that it will discuss the expected adversaries against Tor (the threat model), properties of Tor that make it useful for blocking resistance, and modifications made to Tor to improve blocking resistance.

1. Tor blocking­resistance
design overview
Roger Dingledine
The Tor Project
https://www.torproject.org/
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2. Tor: Big Picture
● Freely available (Open Source), unencumbered.
● Comes with a spec and full documentation:
Dresden and Aachen implemented compatible Java
Tor clients; researchers use it to study anonymity.
● 1500 active relays, 200000+ active users, >1Gbit/s.
● Official US 501(c)(3) nonprofit. Seven funded
developers, dozens more dedicated volunteers.
● Funding from US DoD, Electronic Frontier
Foundation, Voice of America, Internews, Google,
NLnet, ...you?
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