History

The following calendar will be populated with links to worksheets, videos, activities and daily posts, so you can catch up on anything you’ve missed and revisit important material.

  • Friday, August 28th:
    • What we did in class: We began with cryptanalysis of Vigenere cipher.  Then we discussed one-time pads. Slides from class.
    • Here’s a video I made that hopefully clarifies the cryptanalysis.
    • Here’s some more detail about variations on the method to solve Vigenere ciphertexts.  It’s also in Chapter 2 of your text.
    • After-class daily post link: Due Mon Aug 31st
  • Wednesday, September 2nd:
    • What we did in class:  We discussed wartime ciphers (ADFGXV and Enigma), as well as DES/AES and some terminology for classical cryptography.  Here are notes from class.
    • After-class daily post link:  Due Fri Sept 4th
  • Friday, September 4th:
  • Wednesday, September 9th:
  • Friday, September 11th:
    • What we did in class today:  We introduced the notions of multiplicative order, primitive root, multiplicative generator, and discrete logarithm, and the discrete logarithm problem.  Here are class notes
    • After-class daily post link:  Due Mon Sept 14th
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  • Monday, September 14th:
    • What we did in class today:  We introduced public-key cryptography (as compared to symmetric key cryptography), and the Diffie-Hellman Key Exchange.  We characterized the unit group as those elements coprime to the modulus.  Here’s the first page of notes (I sadly lost the rest of them but you can see them on the canvas video).  Then we worked on a worksheet.  Here’s a Jamboard version.
    • After-class daily post link:  Due Wed Sept 16th
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  • Wednesday, September 16th:
    • What we did in class today:  We proved that the unit group is made up of those residues which are coprime to the modulus.  We defined Euler’s phi function.  We discussed Gauss’ method of finding multiplicative inverses.  We gave a little teaser for the next method of solving the discrete logarithm problem.  Here are notes.
    • After-class daily post link:  Due Fri Sept 18
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  • Friday, September 18th:
    • What we did in class today: We did an activity to discover how to most efficiently compute modular exponents.  We covered successive squaring and the double-and-add (AKA square-and-multiply) algorithm.  Here are notes.
    • After-class daily post link: Due Mon Sept 21