1. CSE 486/586, Spring 2012 CSE 486/586 Distributed Systems Case Study: TOR Anonymity Network Bahadir Ismail Aydin Computer Sciences and Engineering University at Buffalo

2. CSE 486/586, Spring 2012 Outline Overview Users Onion Routing The Solution Hidden services The future of Tor How to install/use TOR? 2

3. CSE 486/586, Spring 2012 Overview Onion routing project of the U.S. Naval Research Laboratory Tor hides you among the other users on the network Use: Using Tor protects you against a common form of Internet surveillance known as "traffic analysis." What is traffic analysis? How does it work? 3

4. CSE 486/586, Spring 2012 Users Militaries use Tor –First designd with US Navy in mind Normal people use Tor Journalists and their audience use Tor Law enforcement officers use Tor Activists & Whistleblowers use Tor High & low profile people use Tor Business executives use Tor Bloggers use Tor IT Professionals use Tor 4

5. CSE 486/586, Spring 2012 Hide message source by routing it randomly Popular technique: Crowds, Onion Routing, TOR Routers don’t know for sure if the apparent source of a message is the true sender or another router Only secure against local attackers! Onion Routing

6. CSE 486/586, Spring 2012 R R4R4 R1R1 R2R2 R R R3R3 Bob R R R Sender chooses a random sequence of routers Some routers are honest, some hostile Sender controls the length of the path Goal: hostile routers shouldn’t learn that Alice is talking to Bob Alice Onion Routing

7. CSE 486/586, Spring 2012 R4R4 R1R1 R2R2 R3R3 Bob Alice {R 2,k 1 } pk(R 1 ),{ } k 1 {R 3,k 2 } pk(R 2 ),{ } k 2 {R 4,k 3 } pk(R 3 ),{ } k 3 {B,k 4 } pk(R 4 ),{ } k 4 {M} pk(B) Routing info for each link encrypted with router’s public key Each router learns only the identity of the next router Onion Routing

8. CSE 486/586, Spring 2012 Solution 8

9. CSE 486/586, Spring 2012 Solution 9

10. CSE 486/586, Spring 2012 Solution 10

11. CSE 486/586, Spring 2012 Hidden Services 11

12. CSE 486/586, Spring 2012 Hidden Services 12

13. CSE 486/586, Spring 2012 Hidden Services 13

14. CSE 486/586, Spring 2012 Hidden Services 14

15. CSE 486/586, Spring 2012 Hidden Services 15

16. CSE 486/586, Spring 2012 Hidden Services 16

17. CSE 486/586, Spring 2012 Future for TOR Tor can't solve all anonymity problems. As Tor's usability increases, it will attract more users, which will increase the possible sources and destinations of each communication, thus increasing security for everyone. We're making progress, but we need your help. Please consider running a relay or volunteering as a developer.running a relay volunteeringdeveloper 17

18. CSE 486/586, Spring 2012 How to install/use TOR? http://www.youtube.com/watch?feature=player_detail page&v=6xB_50VKxME#t=320shttp://www.youtube.com/watch?feature=player_detail page&v=6xB_50VKxME#t=320s https://media.torproject.org/video/2009-install-and- use-tor.ogvhttps://media.torproject.org/video/2009-install-and- use-tor.ogv 18