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