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| ==Video==
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| The video for the lecture given on November 25, 2015 [http://homeostasis.scs.carleton.ca/~soma/os-2015f/lectures/comp3000-2015f-lec21-25Nov2015.mp4 is now available].
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| ==Notes== | | ==Notes== |
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| <pre>
| | * Explain generating, format of patches for reports |
| Lecture 21
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| ----------
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| no last assignment
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| What is research?
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| * Asking questions and figuring out the answers
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| * Questions are much more important than answers
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| * Questions are much *harder* than answers
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| What question you ask determines what answer you'll get
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| The research literature
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| - many many publications
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| - hard to tell what is any good
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| Reseachers know who to trust in their area, and, how in general to determine trust
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| - do spot checks for obvious errors, based on what you do know
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| - do they give full details about what they did? could you reproduce it?
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| - surprising results require extraordinary evidence
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| If you're outside the field, look at
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| - publication reputation
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| - citation counts and quality
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| to learn more about operating systems research...
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| what are the well-respected venues?
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| Conferences, not journals
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| USENIX OSDI
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| ACM SOSP
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| When should you *really* look at the research literature?
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| You're trying to solve a hard problem and aren't sure what approach to take.
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| * look to see what other people have done in response to similar problems!
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| What about computer security?
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| * even more publications
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| But there's a truth to research...
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| - most of it isn't any good
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| Why?
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| - a lot of research doesn't work in practice
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| - a lot of conclusions are premature
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| Computer security research is mostly bad
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| Cryptography is mostly bad. And dangerous.
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| * easy to implement
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| * hard to implement well
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| If you make a mistake, your crypto is worse than useless
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| * security cannot be specified or completely defined
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| * attacks exploit details that you didn't think about
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| Timing attacks
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| Game in encryption: encrypt and decrypt without disclosing the plaintext or the key
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| For many encryption algorithms, execution time is a function of the plaintext and/or key
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| Watch how long a computer takes to encrypt something, and you can figure out the key
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| 1970's, Data Encryption Standard (DES)
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| - first developed by IBM
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| - "fixed" by the NSA
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| - halved the key (much easier to break)
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| - fiddled with the constants in the algorithm
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| Any security technology may improve and reduce your security at the same time
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| security is confidentiality, availability, and integrity
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| Example: encrypting a hard disk
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| Why not use biometrics
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| - fingerprints
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| - facial recognition
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| It is all about your threat model
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| - any technology helps with certain risks and harms versus others
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| - what do you care about?
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| Tradeoffs are inherent to technology
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| </pre>
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