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Transcript of Seminar Ppt
ONION ROUTING
Guided By: Smt. Geetha Raj. R
Seminar By: SOUMYA BALACHANDRAN
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What is Onion Routing?
An application independent infrastructure for traffic analysis resistant and anonymous internet connections.
Uses Public Key Exchange.
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GOAL
Primary• Strongly private
communication.• Cannot
determine the content of the message
Secondary• Anonymity
to sender and receiver
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OVERVIEW
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HOW SECRET MESSAGES ARE
SENT??
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Onion Routing exist in three phases
Connection Setup Data Movement Connection Termination
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1) Client application connects to
application proxy.
2) Packets are forwarded to onion proxy.
3) Onion is passed on to an
entry funnel.
4) At each onion router a layer of
onion is decrypted.
5) At exit funnel, the decrypted packet sent to destination TCP
host.
6) A status message sent
back to application proxy.
7) Connection terminated.
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HOW ONIONS ARE CREATED AND FORWARDED??
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Number all routers 1…N.
Public key Su (known to onion proxies).
Private key Sr (known only to routers)
Encryption function:- E[Key](data)
Decryption function:- D[Key](data)
Encrypted with public key and decrypted
with private key
D[Sr](E[Su](data)) = data.
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EXAMPLE
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Onion Created by proxy
E[4u](3’s IP address, E[3u](5’s IP address, E[5u](data))).
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Sender Activity
Receiver Activity
Sender Content
Receiver Content
SECURITY GOALS
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Observer
Disrupter
Hostile User
Compromised COR.
ADVERSARIES???
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WEAKNESS
Timing Analysis
•By analyzing the incoming and outgoing messages.
Intersection Attacks
•Nodes failure.
Predecessor Attacks
•Betrayal of compromised node.
Exit node sniffing
•Complete access to the content.
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COMPARISON WITH OTHER ANONYMOUS
WORKS
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Comparison related to
Anonymity mechanism
MIXES
REMAILERS
Connection based mechanism
ANONYMIZERS
CROWDS
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OR v/s Mixes
Time delay for traffic are limited for OR.
Traffic is multiplexed and is link encrypted.
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OR v/s Anonymizers
Traffic between the browser & anonymizer
sent in the clear.
Volume attack is possible by observers.
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Provides PERFECT FORWARD SECRECY.
Uses DIFFIE-HELLMAN KEY EXCHANGE.
Any router along the route can act as the exit
funnel.
Provides with Directory Servers.
Provides a service called “Hidden Services”.
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WHO USES Tor???
Family & friends.
Business.
Activists
Media
Military and law enforcements
CONCLUSION
The purpose of Onion Routing is to protect the anonymity.
Using Public Key Encryption, an onion is created which is sent over a set of routers to reach the destination.
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REFRENCES
[1].The Onion Routing Home Page. http://www.onion-router.net/
[2]. https://torproject.org/[3]. http://tor.eff.org/[4]. D. Goldschlag, M. Reed, P. Syverson. "Onion
Routing for Anonymous and Private Internet Connections," Communications of the ACM, vol. 42, num. 2, February 1999
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Thank you…
ANY QUESTIONS