Chapter 7: Network Security Chapter goals: O understand principles of network security o cryptography and its many uses beyond confidentiality o authentication o message integrity o key distribution O security in practice o firewalls o security in application transport network link layers 361.F2003
Comp 361, Fall 2003 7: Network Security 1 Chapter 7: Network Security Chapter goals: understand principles of network security: cryptography and its many uses beyond “confidentiality” authentication message integrity key distribution security in practice: firewalls security in application, transport, network, link layers
Chapter 7 roadmap 7.1 What is network security? 7.2 Principles of cryptography 7.3 Authentication 7.4 Integrity 7.5 Key distribution and certification 7.6 Access control: firewalls 7.7 Attacks and counter measures 7. 8 Security in many layers 361.F2003
Comp 361, Fall 2003 7: Network Security 2 Chapter 7 roadmap 7.1 What is network security? 7.2 Principles of cryptography 7.3 Authentication 7.4 Integrity 7.5 Key Distribution and certification 7.6 Access control: firewalls 7.7 Attacks and counter measures 7.8 Security in many layers
What is network security? Confidentiality: only sender, intended receiver should "understand"message contents o sender encrypts message o receiver decrypts message Authentication: sender, receiver want to confirm identity of each other Message Integrity: sender, receiver want to ensure message not altered (in transit, or afterwards without detection Access and Availability: services must be accessible and available to users 361.F2003
Comp 361, Fall 2003 7: Network Security 3 What is network security? Confidentiality: only sender, intended receiver should “understand” message contents sender encrypts message receiver decrypts message Authentication: sender, receiver want to confirm identity of each other Message Integrity: sender, receiver want to ensure message not altered (in transit, or afterwards) without detection Access and Availability: services must be accessible and available to users
Friends and enemies: Alice Bob. Trudy o well-known in network security world o Bob, Alice (lovers! )want to communicate "securely o Trudy(intruder)may intercept, delete, add messages Alice Bob channe data, control messages data secure secure data sender recelver Trudy 361.F2003
Comp 361, Fall 2003 7: Network Security 4 Friends and enemies: Alice, Bob, Trudy well-known in network security world Bob, Alice (lovers!) want to communicate “securely” Trudy (intruder) may intercept, delete, add messages secure sender secure receiver channel data, control messages data data Alice Bob Trudy
Who might Bob, Alice be? g.. well real-life bobs and alices o Web browser/server for electronic transactions(e., on-line purchases O on-line banking client/server O DNS servers D routers exchanging routing table updates O other examples? 361.F2003
Comp 361, Fall 2003 7: Network Security 5 Who might Bob, Alice be? … well, real-life Bobs and Alices! Web browser/server for electronic transactions (e.g., on-line purchases) on-line banking client/server DNS servers routers exchanging routing table updates other examples?