Presented at the first PhutureCon (2014) (http://phuturecon.com) in Denver, CO.

1. How it works to keep you safe online
Phuturecon 2014
IceQUICK
ParkBenchIndustries.com

2. Who am I
 Former USAF NOC admin (Active Duty and Contractor)
 Windows/Solaris/Linux admin
 IT process architect (ITIL)
 Not a developer (Tor is written in C)
 Tor Experience
 User for 10+ years
 Relay node admin for ~3 years

3. This presentation
Combined from a variety of sources
No tricks, vulnerabilities, hacks
Not ‘breaking news’
Why I trust the network
Why you should contribute

4. What is Tor?
 Network of virtual tunnels
 Privately Browse Internet
 FREE!
 Used by…
 Journalists
 Activists
 Censorship circumventing
citizens
 Military intel analysts
 Law enforcement
 Whistleblowers
 Bloggers
 http://www.torproject.org/ Privacy-contious

5. Tor History
 ~1995 - Naval Research Lab as “Onion Routing”
 2002 - Converted to TOR “The Onion Router”
 Code open-sourced
 2006 – Tor Project Formed
 501(c)(3) research-educational non-profit
 Today: 60%+ of funding still from US Government

9. Technologies Used
 PKI
 Public/Private Keys
 Hashing / Signing
 Diffie-Hellman key exchange
 PFS – Perfect Forward Secrecy
 DHT – Distributed Hash Table
 For hidden services /.onions

10. Life of a session
 Client to Node 1(Guard)
 Perform DH Key Exchange
 Acquire PFS Session Key
 Use Node 1(Guard) to repeat process to Node 2(Relay)
 Use Node 2(Relay) to repeat process to Node 3 (Exit)
 Use Node 3 to contact internet resource
 Create new path every 10 minutes
 Will route existing TCP sessions through existing paths
 Repeat…

11. DH Key Exchange
 Key Exchange
 Client gets the node’s public key from directory
 Client sends the first half of DH handshake encrypted with node’s
public key
 Node receives, decrypts it, using its private key
 Node has first half (client’s) of two-way DH handshake
 Node completes second half of the handshake, creating session
key
 Hashes the resulting session key and signs it with it private key
 Node sends to client – both parties now have the session key
 Verify Session Key
 Client believes session key came from the router
 Client decrypts session key using router's public key
 Will only work if session key was signed with the router's private
key

12. Uses
 Web Browsing
 DNS
 Most services using TCP
 Chat, Mail, etc.
 Hidden Services
 E.g. http://j8hlg2sh2hoasdh8.onion/

13. What can you do?
 Run a Relay
 Exit node or not
 Home cable modem
 VPS
 Tor Cloud – Amazon
 Help Develop
 C, C++, Python, Java
 OnionTip.com
 BTC to node operators
 Defend its use

14. Questions?

15. Enjoy!
@IceQUICK
icequick@parkbenchindustries.com
@DC970