1. CSCE 715: Network Systems Security
Chin-Tser Huang
University of South Carolina

2. About Me Chin-Tser Huang
Ph.D. in Computer Sciences, University of Texas at Austin
Research in network security, network protocol design and verification, distributed systems
My web page can be found at
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(C) 2009 Chin-Tser Huang

3. About You What’s your name? Where are you from? When did you join USC?
What are your research interests?
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4. About the Course
A grad-level course focusing on basics and issues in network security
First half will be lectures about elements of network security, cryptography backgrounds, and introduction to network security designs
Second half will be your chance to present what you have learned from key research papers
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5. Course Information Online
List of assigned paper and useful links are available on the page
Lecture slides will be available online too
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6. Why Should You Take This Course
Security is an increasingly important issue
You want to have basic knowledge about network security
You can learn latest attacks and newest skills to counter those attacks
You have a chance to implement the skills learned in the class
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7. Your Best Strategy
Come to every lecture to learn basic security problems and skills to counter them
Keep yourself exposed to articles related to network security to collect project ideas
Read each assigned paper and write good summary for each paper
Do not wait till last minute to prepare for exam or work on project
Enjoy the fun!
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8. What Can Go Wrong…
…when your computer y receive or is waiting for a message m? ?
Internet m x y
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9. Message Loss Adversary A can discard m in its transit A m x y
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10. Message Interception Adversary A can get a copy of m when m passes byx y
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11. Message Modification
Adversary A can arbitrarily modify the content of m to become m’ A m m’ x y
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12. Message Insertion
Adversary A can arbitrarily fabricate a message m, pretending that m was sent by x
src: x
dst: y A m x y
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13. Message Replay
Adversary A can replay a message m that has been sent earlier by x and received by y m A m x y
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14. Denial-of-Service Attack
Adversary A can send huge amount of messages to y to block m from arriving at y
In the case of botnet attack, the adversary instructs many bots to send messages to y simultaneously A m … … … … … …
????? x y
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15. More Scenarios
In one case, x wants y to be able to verify message m is sent by a legitimate party but not able to determine identity of x
src: ?
dst: y
Internet m x y
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16. More Scenarios
In another case, y wants to be able to prove to third party z that y receives message m from x z
x sent
to y m
Internet m x y
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17. Network Security Is Great…
Protect messages from interception in their transit
Provide desired level of privacy for user or data
Detect and discard messages that are modified, inserted, or replayed
Disallow unauthorized access to local system resource and sensitive data
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18. …But Hard To Achieve Many layers in network architecture
Many different media of network connection
Adversary’s location hard to determine
New attacks keep emerging
Cryptographic overhead
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19. Next Class Type of attacks Network security services
Formal specification and verification of network protocols
Read Ch. 1
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(C) 2009 Chin-Tser Huang