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A seminar on
TOR NETWORK
By:
Shaik Arbaaz Ahmed
Under the Guidance of:Prof . Mujahid Irfan sir
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Contents
 What is TOR…?
 Why do we need anonymity?
 How normal Internet connection
works?
 How TOR network works?
 Decryption in TOR
 TOR Users
 Dangers of using Tor Network
 Conclusion
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What is TOR…??
 The Onion Routing
 Open source project
 Used for anonymity
 Supports only TCP
 No observer can tell where data comes
from/going
 Give access to dark-web and deep-web
 It route your traffic through 3 different
routers
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Why do we need anonymity?
 To hide user personal information
 Protect to user traffic from advertisers
 To hide browsing pattern from employer or ISP
 Protection from hackers
 Freedom from surveillance of government
 Freedom of Thought and Speech
 Freedom of Social and Political Activities
How normal Internet connection
works?
 Direct connection to the
internet
Server to Server connection
Traffic is not encrypted
anyone can intercept your
traffic
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How normal Internet connection
works?
 Internet packet have two parts
Header
Source address
 Destination address
Time
Cannot be hidden by encryption
 Datapayload
The request or messag
 Can be hidden by encryption
How TOR network
works?
Components of TOR
Client: the user of the Tor
network
Server: the target TCP
applications such
as web servers
Tor (onion) router: the special
proxy relays the application
data
Directory server: servers
holding Tor router information
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How TOR network works?
Onion-Routers/ Nodes
Sender chooses a random sequence of
routers
Some routers are honest, some controlled
by attacker
Sender controls the length of the
path
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How TOR network works?
Alice
Bob
√
M
OR2
M
M
C2 C3
OR1
C1 C2
M
OR3
C3
Port
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
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How TOR network works?
Cells
Traffic passes along these connections in
fixed-size cells
Each cell is 512 bytes
Header
circuit identifier (circID)
a command to do with the cell's payload.
Payload
Encrypted data
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Decryption in TOR
Decryption of an Onion
Tor circuit 4-3-5
OR-4 decrypts layer E[4u]
Finds next OR ip address
OR-3 decrypts layer E[3u]
Finds next OR ip address
OR-5 decrypts layer E[5u]
Finds targets ip address
Decrypted the data sends to target
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Encryption in TOR
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TOR Users
Normal People
Journalists and Audiences
Law Enforcement Users
Activists and Whistle-blowers
Business Executives
Cyber criminals
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Dangers of using Tor Network
Packet sniffing
Exit node sends Full Plain text request to the target
Running an exit node is dangerous
Anyone using TOR network is on the NSA watch list under
the XKEYSCORE
program
"The more you hide the more somebody wants to know why."
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Conclusion
 researches in last 30yrs has significance process
towards enabling anonymous communications on
internet
 Tor becomes most widely used anonymous network with its
speed
Tor supports mutual anonymity
 Tor resists local adversary effectively
 Tor anonymizes TCP streams, providing a high-throughput and
low- latency
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References
https://www.torproject.org/
https://svn.torproject.org/svn/projects/design-paper/tor-design.html
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Q&A
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ThankYou