Lecture 40 Computer Security

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Lecture 40Computer Security

• Phillip G. Bradford
• Computer Science Department
• The University of Alabama

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Outline

• Final Exam Review
• Final Exam 8-May-03
• 1130 to 200 in our usual room
• Any questions?
• Brief Intro to Wireless Security

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Exam Review

• Old Exams
• Final
• Question Session!

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Why is Wireless Different?

• Broadcast Model
• Less Computational Power
• Other Constraints
• Lack of Physical Security
• Mobile
• Different Venues
• Cell Phones
• Short Haul (802.11b)
• Ubiquitous and Pervasive Computing

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Why is Wireless Different?

• Very attractive for adding networks without
  cabling
• Power Issues

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Why is Wireless Different?

• Attacks
• Physical Attacks are easier
• Denial of Service Attacks
• Beware of Avalanche Effect!
• Location (In the case of Mobile Devices)
• Worm Holes

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Why is Wireless Different?

• End-to-End Encryption?
• Link-Level Encryption?
• Conference Calls More Interesting
• Similar to UDP

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A Start

• Frequency Hopping
• Classical
• Vulnerable to Physical Insecurity
• One-Time Pads
• WEP
• Problems
• IV
• Considered Cracked
• Need some resources to crack it!

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WTLS Wireless Transport Level Security

• For WLANs
• Based on TLS 1.0 (SSL 3.1)
• Replace 802.11bs WEP
• Protocol
• Client and Server Authentication
• Encrypts Wireless Data Streams

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WTLS

• Follows TLS very closely
• Negotiate Security Parameters
• Determine Mode
• Send Data
• Also, in link-layer security
• Interesting that TLS does not deal with UDP, yet
  WTLS deals with such issues