Qmcs 490 class today
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QMCS 490 - Class Today. Handing back the exam Projects Certificates and Chaining SSL and “Spot the Plaintext”. Exam. 76 points total Median: 88% (-9 points); Lowest: 82% Let’s work through the problems Problem 2 first – it’s easy Just about everyone got it

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QMCS 490 - Class Today

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Qmcs 490 class today

QMCS 490 - Class Today

  • Handing back the exam

  • Projects

  • Certificates and Chaining

  • SSL and “Spot the Plaintext”

R. Smith - University of St Thomas - Minnesota


Qmcs 490 class today

Exam

  • 76 points total

  • Median: 88% (-9 points); Lowest: 82%

  • Let’s work through the problems

  • Problem 2 first – it’s easy

    • Just about everyone got it

    • I wanted to see physical security in sensible places

    • I wanted to see access control policies/procedures

      • Locks, access cards, whatever

      • Specify who gets in and who is excluded

R. Smith - University of St Thomas - Minnesota


Problem 1

Problem 1

  • Tradeoff study

    • You don’t list shared features!

    • I.e. choose between jeep and Hummer

      • 4WD

      • Gasoline powered

      • Internal combustion engine

      • Seats for driver and passengers

  • Which is most common today for linking sites?

  • If I didn’t come away convinced, you got 4 points off.

  • If you listed shared features, 2 points off

  • IDEALLY: 2 “real” reasons for/against each

    • Less than that, or wrong direction, and I took 4 points

  • R. Smith - University of St Thomas - Minnesota


    Problem 1 rough answer

    Problem 1 rough “answer”

    • Link encryption

      • Established technology (so says the book)

      • Potential crypto protocol weaknesses (replay, etc.)

      • Expensive to deploy – renting dedicated links (so says the book)

      • Expensive to add new links – new hardware EVERYWHERE

    • IPSEC crypto

      • More complex technology (so says the book)

      • Broader protections (anti replay, anti tamper)

      • Cheaper to deploy – just need an Internet connection

      • Cheaper to expand – just add the new site’s hardware

    R. Smith - University of St Thomas - Minnesota


    Problems 3 and 4

    Problems 3 and 4

    • What are the 3 types/classes of firewall?

    • Problem 3: how can the different classes be used by a government to suppress information?

      • Points for identifying ‘real’ mechanisms

      • Points for linking it to information worth suppressing

        • Political items and commentary

        • Culturally inappropriate material (porn)

    • Problem 4: how can dissidents or other troublemakers circumvent these 3 firewalls?

      • At least 1 practical example for each for getting access

      • Not interested in plain old troublemaking

    R. Smith - University of St Thomas - Minnesota


    Project schedule

    Project Schedule

    • Team and project THIS WEEK

      • Tell me next Tuesday

      • What you’re doing; who you’re working with

    • Three page Outline by December 4

      • Major ‘facts and elements’ of the topic

      • List of information sources you will use

    • Final Project Due last week of class

    R. Smith - University of St Thomas - Minnesota


    Continuing with certificates

    Continuing with Certificates

    • Can someone tell me how a certificate works?

    • How does Firefox/Explorer, etc, validate a server certificate?

      • Crypto credentials

      • URL

    • How does ‘certificate chaining’ work?

      • Commercial certification authorities

      • Web of trust and confidence in keys

    R. Smith - University of St Thomas - Minnesota


    How ssl works

    How SSL Works

    • How do we use RSA to share secret keys?

    • Where is the plaintext?

    • What if we use RC-4 for encryption?

    • Generating distinctive keys from limited entropy

    R. Smith - University of St Thomas - Minnesota


    That s it

    That’s it

    • Questions?

      Creative Commons License

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    R. Smith - University of St Thomas - Minnesota


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