This document provides an overview of the Tor anonymity network. It discusses how Tor aims to conceal users' identities and online activity by routing data through at least three different routers, with encryption at each node except the beginning and end. The document outlines Tor's history and how it works, addressing its weaknesses, typical users, and licit and illicit uses. It also includes an agenda, abstract, timeline, and references.

1. Anonymity Network TOR
A Presentation by
Bahalul Haque
FH Kiel. M.Sc
Khaled Mosharraf
FH Kiel. M.Sc

2. Agenda
• Abstract
• Introducing the Tor Network
• Historical Background
• How does the Tor Network work?
• Goal
• Working Principal
• Weaknesses
• Users
• Licit and illicit users

3. Abstract
• This second-generation Onion Routing system addresses
limitations in the original design by adding perfect forward
secrecy, congestion control, directory servers, integrity
checking, configurable exit policies, and a practical design for
location-hidden services via rendezvous points. Tor works on
the real-world Internet, requires no special privileges or
kernel modifications, requires little synchronization or
coordination between nodes, and provides a reasonable
tradeoff between anonymity, usability, and efficiency.

4. Introducing the Tor Network
• Tor aims to conceal its users' identities and their online
activity from surveillance and traffic analysis by separating
identification and routing.
• This is done by passing the data through a circuit of at least
three different routers.
• The data that passes through the network is encrypted, but at
the beginning and end node, there is no encryption.

5. What is TOR ??

6. Historical Background
TOR control over its primary supply chain and afforded the opportunity to develop new products
In 2001, TOR acquired TP&T B.V.- Netherlands, renaming it TOR Processing & Trade B.V. TP&T provided a
new line of Specialty Aluminas with access to new markets and customers, as well as unique processing
technology that could be applied to other TOR products. It also provided a base for future sales
expansion.
• ORIGIN
Founded in 1973 by Benelite Corporation of America to develop and produce HITOX TiO2 pigment from
synthetic rutile made from the “Benelite Process”, the company was spun off and named HITOX
Corporation of America in 1980. In December 1988, the company became publically owned and traded on
NASDAQ under the symbol TORM.
• GROWTH
In 2000, the company was renamed TOR Minerals International, Inc. indicating its strategic direction and
global focus. The company acquired its major synthetic rutile supplier, Malaysian Titanium Sdn. Bhd. and
renamed it TOR Minerals Malaysia Sdn. Bhd. This purchase insured
• TODAY
TOR Minerals is a global producer of High Performance, Specialty Mineral products, focused on product
innovation and technical support. The mission is to bring high value products and superior levels of
service to customers to help ensure their success.

7. Timeline

8. Why do we need anonymity?
• To hide user identity from target web site
• To hide browsing pattern from employer or ISP
• To conceal our internet usage from hackers
• To circumvent censorship

9. How TOR Works

10. How TOR Works

11. R1
R2
R3
R4
srvr1
srvr2
R5
R6
one minute later
Working process

12. How Tor Works? --- Onion
Routing
• A circuit is built incrementally one hop by one hop
• Onion-like encryption
– ‘Alice’ negotiates an AES key with each router
– Messages are divided into equal sized cells
– Each router knows only its predecessor and successor
– Only the Exit router (OR3) can see the message, however
it does not know where the message is from
Alice Bob
OR2
OR
1
M
√M
M
OR3
M
C1 C2
C2 C3
C3
Por
t

13. Weaknesses
Using the following can disrupt the mechanism f anonymous
connection and can reveal the identity. Using these breaks the
communication chain and lead to leakage
• View Document
• Open flash object
• Use of add on in TOR browser

14. Weaknesses
• Using torrent In Tor also does the same thing as using flash
and add-on
• Anonymous payment or crypto payment is used while using
TOR. Bitcoin is used in general. This facilitates man in the
middle attack
• Using HTTP instead of HTTPS leads to vulnerability also.
Makes prone to wretapping

15. Weaknesses
• Redirecting to special servers over the telecom networks
increases man in the middle attack (only NSA can do it
presumably !!!)
• Control over one or more anonymous systems and internet
exchange pointe helps to de-anonymize the network 50
percent in over 3 months, almost 80 percent in over 6
months

16. Weaknesses
• Tor browser itself has some vulnerabilities.
• Based on Firefox. Recent versions are more prone to it.
• Heartbleed Bug has vulnerabilities in Open SSL cryptographic
software library. Leads to exfiltration

17. TOR Users
• Normal People
• Journalists and Audiences
• Law Enforcement Users
• Activists and Whistleblower
• High and Low Profile People
• Business Executives

18. Licit and illicit uses
• Tor is increasingly in common use by victims of domestic
violence and the social workers and agencies which assist them
• A growing list of news organizations are using
the SecureDrop software platform to accept material for
publication in a manner intended to protect the anonymity of
sources.
• It is endorsed by civil liberties groups as a method for
whistleblowers and human rights workers to communicate with
journalists

19. Licit and illicit uses (Contd.)
• Tor is used for matters that are, or may be, illegal in some
countries, e.g., to gain access to censored information, to
organize political activities,or to circumvent laws against
criticism of heads of state.
• Tor can be used for anonymous defamation,
unauthorized leaks of sensitive information and copyright
infringement, distribution of illegal sexual
content, selling controlled substances, money
laundering, credit card fraud, and identity theft.
• Ironically, Tor has been used by criminal
enterprises, hacktivism groups, and law enforcement
agencies at cross purposes, sometimes simultaneously

20. Dangers of using Tor Network
• "The more you hide the more somebody wants to know why.“
• While the inter-relay communications might be secure, the entry
and exit nodes are vulnerable to packet sniffing and
• The exit node decrypts the packet it received from its sibling on the
chain of nodes and receives your full plaintext request. This can be
easily seen by the operator of the exit node.
• Running an exit node is dangerous as all exit traffic, legal and illegal,
will be traced to your IP
• Anyone using TOR network is on the NSA watch list under
the Xkeyscore program.

21. References
• https://www.torproject.org/
• https://en.wikipedia.org/wiki/Tor_(anonymity_network)
• McCoy, Damon; Bauer, Kevin; Grunwald, Dirk; Kohno, Tadayoshi; Sicker, Douglas
(2008)."Shining Light in Dark Places: Understanding the Tor Network". Proceedings of the
8th International Symposium on Privacy Enhancing Technologies. 8th International
Symposium on Privacy Enhancing Technologies. Berlin, Germany: Springer-Verlag. pp. 63–
76.
• "Tor Project Form 990 2008". Tor Project. Tor Project. 2009. Retrieved 30 August 2014.
• "Tor Project Form 990 2007". Tor Project. Tor Project. 2008. Retrieved 30 August 2014.
• "Tor Project Form 990 2009". Tor Project. Tor Project. 2010. Retrieved 30 August 2014.
• Samson, Ted (5 August 2013). "Tor Browser Bundle for Windows users susceptible to info-
stealing attack". InfoWorld.
• Dingledine, Roger (7 April 2014). "OpenSSL bug CVE-2014-0160". Tor Project.
• Le Blond, Stevens; Manils, Pere; Chaabane, Abdelberi; Ali Kaafar, Mohamed; Castelluccia,
Claude; Legout, Arnaud; Dabbous, Walid (March 2011). "One Bad Apple Spoils the Bunch:
Exploiting P2P Applications to Trace and Profile Tor Users". 4th USENIX Workshop on
Large-Scale Exploits and Emergent Threats (LEET '11). National Institute for Research in
Computer Science and Control.

22. Q&A

23. Thank You