Network security involves protecting computer networks through tools like firewalls, encryption, and digital signatures. Common security threats include TCP hijacking, packet sniffing, and unauthorized access to networks. Cryptography and steganography are methods used to secure communications and information. Cryptography involves encrypting data using techniques like public key infrastructure, while steganography hides secret messages within ordinary files like images or audio files. Both have benefits but also limitations, as strong encryption does not guarantee security if other vulnerabilities exist.

1. Network Security Cryptography & Steganograpy By Nikhil

2. A Security History Of The World Goths,vandals,huns Burglar by hacker

3. Why do we need security?

4. Introduction What is Network Security: Network security define the protection, safe guarding of the computers in the network by using security tools.

5. Who is vulnerable? Financial institutions and banks Internet service providers Government and Defense services Multinational corporations ANYONE ON THE NETWORK

6. Common security attacks and their countermeasures Finding a way into the network Firewalls TCP hijacking IPSec Packet sniffing Encryption (SSH, SSL, HTTPS)

7. Firewalls

8. TCP Attacks Say hello to sandy, Bob and Sam

9. TCP Attacks Sandy and Bob have an established TCP connection

10. TCP Attacks Sam lies on the path between Sandy and Bob on the network He can intercept all of their packets

11. TCP Attacks First, Sam must drop all of Sandy’s packets since they must not be delivered to Bob (why?) Packets The Void

12. TCP Attacks How do we prevent this? IPSec Provides source authentication, so Sam cannot pretend to be Sandy Encrypts data before transport, so Sam cannot talk to Bob without knowing what the session key is :-

13. Types of Secret Writing Secret writing Cryptography Steganography

14. Cryptography “ Strategy without tactics is the slowest route to victory. Tactics without strategy is the noise before defeat . ” Sun Tzu

15. Cryptography

16. example :-

17. Benefits of Cryptographic Technologies Data secrecy Data integrity Authentication of message originator Electronic certification and digital signature Non-repudiation

18. Potential Problems with Cryptographic Technologies? False sense of security if badly implemented Government regulation of cryptographic technologies/export restrictions Encryption prohibited in some countries

19. Steganography

20. Steganography –covered writing – is an art of hiding information Popular contemporary Steganography technologies hide information in images

22. How Secure are Today’s Encryption does not guarantee security! Many ways to beat a crypto system NOT dependent on cryptanalysis, such as: Viruses, worms, hackers, etc. Unauthorized physical access to secret keys Cryptography is only one of the elements of comprehensive computer security high overhead to hide relatively few info bits Technologies

23. Conclusion