1. Network Security Student: Lirong Wang Student ID: 122628 Instructor: Professor Anvari Winter 2003

2. Content What is Network Security Types of Network Security Security Attacks Encryption Application of Encryption in Network Security. Encryption/Decryption. Digital Signature Conclusion

3. Introduction Security technologies protect mission-critical networks from corruption and intrusion. Network security enables new business applications by reducing risk, and providing a foundation for expanding your business with Intranet, extranet, and electronic commerce applications.

4. Types Of Network Security Internet Security - From Infrastructure to Network to Computer Wide-Area Network Security - Bridge and Router Packet Filtering Local-Area Network Security - Tape Backup and LAN Admin. Computer Security - Power Protection and Special Mounting & Fastening Devices to Secure Computer Equipment

5. Security Attacks Interruption - the flow of information is blocked entirely Interception - In this attack, the normal flow of information is not affected, but an additional flow, generally to an unauthorized source, is created Modification - an unauthorized party not only gains access to but also changes the contents of message before it is received at the destination host Fabrication - an unauthorized party inserts counterfeit objects into the network.

6. Encryption One the most important automated tools for computer security Is a process that conceals meaning by changing intelligible messages into unintelligible messages. Can be achieved by means of either a code or a cipher Of equal importance to conventional encryption is public-key encryption.

7. Public key and Private key Public key: one of two keys used in an asymmetric encryption system. Public key is made public, to be used on conjunction with a corresponding private key. Private key: one of two keys used in an asymmetric encryption system. For secure communication, the private key should be only be known to its creator.

8. Encryption

9. Public-key encryption-cont. One key for encryption and another key for decryption. Advantage: Solves the problem of maintaining key security Disadvantage Much more complex than private key encryption Two or three orders of magnitude slow than private key encryption

10. Digital signature

11. Conclusion Network security protects data during their transmission and to guarantee that data transmissions are authentic We have four general categories of attack: interruption, interception, modification, and fabrication. Encryption is one of the most important automated tools for computer security. Public-key encryption and digital signature provide network security.

12. Reference William Stallings. Data and computer communication. Prentice Hall,1996. ISBN: 0-02-415425-3 William Stallings. Operating systems. Prentice Hall,1995. ISBN: 0-7803-1107-8 www.anvari.net http://www.microsoft.com/security

13. THANKS