1. 2016 2학기 네트워크보안 김 창 훈 E-mail: kimch@daegu.ac.kr
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Office: 공) 7710A
Good afternoon ladies and gentlemen, Today, I would like to give an overview of network security.

2. 강 의 계 획 1
학습목표 2
강의내용 3
평가방법 4
레포트 4 5
Summary

3. Why Network Security? Protection Resource Inform.
1. Introduction to Network Security
Why Network Security?
Protection
Resource
Inform.
Attack prevention
Attack detection
Resource recovery
Open network
Unauthorized use
Denial of service
Electronic form
Eavesdropping
Forgery

4. What is Network Security?
1. Introduction to Network Security
What is Network Security?
Reaction
Detection
Prevention
Resource recovery
Use tools
Packet filtering
Access control
En/decryption
Crypto. checksum

5. Types of Security Attacks
Eavesdropping
Masquerade
Traffic Analysis
Attacks
Message Replay
Denial of Service
Message Modification

6. Passive Attacks 2. Security Attacks Characteristic
Detection is very difficult
Solution
Prevention using cryptographic technologies
Examples
Eavesdropping, Traffic analysis

7. Active Attacks 2. Security Attacks Characteristic
Quite difficult to prevent absolutely
Solution
Detect attacks and recover using security tools
Examples
Virus, Worm, Message replay

8. Security Services What Is Security Service? Types of Security Services
3. Security Services & Countermeasures
Security Services
What Is Security Service?
Countermeasures against with security attacks
Achieved by cryptographic technologies & security tools
Types of Security Services
Cryptographic based services
Authentication
Data confidentiality
Data integrity
Non-cryptographic based service
Access control

9. Cryptographic Based Service
3. Security Services & Countermeasures
Cryptographic Based Service
Requirements
Message transformation algorithm
Secret information to be used with algorithm
Methods for distribution of secret information
Specific protocol for a particular security service

10. Cryptographic Functions
3. Security Services & Countermeasures
Cryptographic Functions
Private Key
Public Key
Message en/decryption using one key
DES, AES, IDEA
Message en/decryption using two keys
Diffie-Hellman, RSA, ECC
Cryptographic
Functions
Hash Function
Random Number
Generator
Produce a fixed length message from variable length message
MD5, SHA
Provide unpredictable large numbers
LFSR, ANSI X9.17
Security protocols
SSL, IPsec

11. Private Key Cipher Model
3. Security Services & Countermeasures
Private Key Cipher Model
Functions
Message en/decryption
Countermeasure for eavesdropping attack
Operation
Simple data permutation and substitution
Advantages
Very fast and simple implementation is possible
Disadvantage
Requires very complex key management policies

12. Public Key Cipher Model
3. Security Services & Countermeasures
Public Key Cipher Model
Functions
Authentication and digital signature
Countermeasure for masquerade attack
Operation
Mathematical computations
Advantage
Simple key management
Disadvantage
Very slow compared to private key algorithm

13. Hash Function 3. Security Services & Countermeasures Functions
Generates cryptographic checksum
Message integrity
Countermeasure for message modification attack
Operation
Simple data permutation and substitution

14. Random Number Generator
3. Security Services & Countermeasures
Random Number Generator
Functions
Unpredictable pseudo random number generation
Countermeasure for replay attack
Operation
Repetition of private key algorithm
Application
Secure random session key generation

15. Non-cryptographic Based Service
3. Security Services & Countermeasures
Non-cryptographic Based Service
Functions
Countermeasure for denial of service
Requirements
Authentication for user’s permission
Packet filtering for worms, viruses, and other similar attacks

16. Research Trends 4. Research Trends Elements Characteristics
Sensor and sink node
Gateway
Middleware
Application server
Wireless device
Resource constrains
Different types of network

17. Design Considerations
4. Research Trends
Design Considerations
Processing Gap
Battery Gap
Processing
Battery
Use very slow microprocessors
Wireless device
Flexibility
Cost
Flexibility
Cost
Interconnect various types of network
Important factor
SW/HW Co-design
Basic cryptographic functions are implemented HW(ASICs/FPGAs)
Complex security protocols can be implemented as SW with HW function blocks

18. Summary Considered Network Security Types of Attacks
Passive attacks: prevention
Active attacks: detection and reaction
Two Countermeasures Are:
Cryptographic based service: information
Non-cryptographic based system: network resources
Research Trend Towards Sensor Network
Processing time
Power consumption
Flexibility for cryptographic algorithms and protocols
Cost for supporting security services

19. Thank You !