Tor is an anonymity network that allows users to access the internet anonymously. It works by routing connections through a series of volunteer relays run by other Tor users, making it difficult to trace the connection back to the original user. There are three types of relays - entry/guard relays, middle relays, and exit relays. Data is encrypted multiple times and sent through the relays, with each relay decrypting one layer of encryption. This prevents any single relay from knowing both the IP address of the user and the destination they are connecting to. Tor provides anonymity but is slower than a VPN. A VPN provides privacy by masking the user's IP address but does not provide the same level of anonymity as Tor since

1. Information Security Using
Onion Routing(TOR)
-By Kaustubh Joshi
A Seminar On

2. Contents :
• Introduction
• Overview Of Tor
• Working
• Tor Vs. VPN
• Application
• Conclusion
• References

3. Introduction:
• What is information security?
• Need of Information Security?
• What is Hidden Web?
• What are the Techniques to Access Hidden Web?

4. What is Tor and how does it work Exactly?
• Tor is an anonymity , low-latency , volunteer based network that
provides free software designed to allow you to access the internet
anonymously.
• Tor is acronym for “The Onion Router”
• Tor works by bouncing connections from your computer to
destinations through a series of relays.

5. Tor Network Overview:

6. What are the tor relays?
• Entry/Guard Relay : This is entry point of Tor network. Relays are
selected to serve as guard relays after being around for a while, as
well as having shown to be stable.
• Middle Relay : Middle relays are exactly the middle nodes used to
transport traffic from guard relay to exit relay. This prevents the guard
and exit relays from knowing each other.
• Exit Relay : These relays are exit point at the edge of Tor network .
They send traffic to final destination intended by client.

7. How tor works with help of relays:

8. Tor 3-layered Encryption:

9. Tor Encryption Flow :
• Step 1 : Client Encrypts the data in 3 different layers using 3 different DH(Diffie-Hellman)
keys.
• Step 2 : This Encrypted cell is then sent to Guard Relay in Random Hopping.
• Step 3 : Guard Relay use its Decryption Key and Decrypt one layer of cell. After Decryption
cell is routed forward to another relay randomly until key matches with MiddleRelay.
• Step 4 : On Middle Relay, one layer is Decrypted again using Decryption Key and Cell is
routed to next Relay until key matches with Exit Relay.
• Step 5 : When Cell Reaches exit relay,it decrypts the final layer using its private key. After
Decryption it gets plain text showing address of destination node desired by user.
• Step 6 : Response is then sent back in reverse manner from Exit relay to Client. As client
knows each key, it Decrypts the data.

10. Without Tor

11. With Tor

12. Tor Vs. VPN
TOR(Onion Routing) VPN(Virtual Private Network)
Tor gives you Anonymity. VPN gives you Privacy.
No-one can trace you to external IPs visited. The VPN provider can record your internet activity.
Very slow. Fast.
Free. Costs money.
Not Suitable for P2P Filesharing. Ideal for P2P Filesharing.
No protection from Malwares. Provides Malware Protection.

13. Applications :
Who Uses Tor?
• Normal Peoples
• Journalists
• Law Enforcement Officer
• Activist or/And Whistleblowers
• Militaries
• High profile Peoples

14. Conclusion :
As we saw, Information Security is becoming more aggressive issue day
by day and the techniques to achieve it are expanding.
In this seminar we have learned about how exactly we become
anonymous by using onion routing technique.

15. References :
[1]. TorBridge Discovery: Extensive Analysis and Large - scale Empirical Evaluation Zhen Ling, Junzhou
Luo, WeiYu,Ming Yang,and Xin wenFu
[2]. TorWard: Discovery, Blocking, and Traceback of Malicious Traffic Over Tor Zhen Ling, Junzhou Luo,
Member,IEEE, Kui Wu, Senior Member, IEEE, Wei Yu, and Xinwen Fu
[3]. How to Find Hidden Users :A Survey of Attacks on Anonymity Networks Esra Erdin,Chris Zachor ,and
Mehmet HadiGunes
[4]. http://jordan-wright.com/blog/2015/02/28/how-tor-works-part-one/
[5]. The Tor Project, Inc. (2015). Tor: Anonymity Online. [Online]. Available : https://www.torproject.org/
[6]. https://thetinhat.com/tutorials/darknets/tor-vpn.html
[7]. http://lifehacker.com/what-is-tor-and-should-i-use-it-1527891029