# Due Friday August 28th

For Friday, August 28th:

• Be aware that there’s a Cryptography Tools sheet available under Resources above.  It has a Vigenere square, among other things, to make adding mod 26 easy.
• Come up with a short (a few words) answer to the question “What’s the coolest math?”  This is your plaintext.
• Choose a 4-7 character word to use as a key.  Make it less than half the length of your plaintext.
• Encrypt the plaintext with Vigenere cipher (by hand, using the cryptography tools sheet if you like).
• Post your answer on the discord channel #ciphertexts in category STUDY GROUPS, along with the key.
• Choose another user’s post from #ciphertexts, and decrypt it (by hand).  Post the answer in the form “So-and-so thinks the coolest math is….”
• If by some chance you missed the daily post from yesterday, please catch up on it now.  Modular arithmetic is a bedrock concept for the rest of the course – absolutely crucial.
• I really do strongly encourage you to find partners to work with on discord.  You can watch the video below with someone so you can bounce ideas around.  Hop onto the text channel #study-room and just say “Hey all, I’m doing my daily post now.”  Chances are someone else might be around. Or just ask on there or on the #ask-the-hive channel when you have questions. 🙂
• Also, just be aware we are currently covering material that is in Chapter 2 of the text; you can use this as an added resource.  Chapter 3 contains some brief explanation of modular arithmetic.
• Watch my video Modular Arithmetic:  Under the Hood (17:26).  This gives an explanation for why everything works as described in the first video, so it should help demystify it a little.  And, it offers a glimpse of what type of mathematical proof I hope you can write, coming into the course.
• Therefore, your task is this:  study the proofs from the video to understand them, then turn off the screen and attempt to write the theorem statement and proof yourself, in your own words.  Turn on and compare, repeat, adjust, repeat.  This is not to hand in, but it’s an opportunity to get more comfortable with something we will rely on during the class.  Make sure none of the logical steps are mysterious — every one has a justification and a usefulness. Note: I could ask you to write these or similar proofs in an assessment.
• Your final task is to write me a brief note in today’s canvas dropbox about your comfort level with the proofs from the video.

# Due Wednesday August 26th

To do for Wednesday:

• Thank you for your patience exploring discord on Monday!  Wednesday will be more traditional. 🙂
• If you have not already, then view the welcome video for the course, and the discord intro video (both available on the main landing page in canvas), and get set up on discord.
• Read through Classroom Expectations in detail.  Make sure you are set up technologically and contact me with any concerns.  In particular, I’m hoping everyone will find discord useful.  But I am very willing to help with your individual needs.
• Make sure you have the textbook (Wade Trappe, Lawrence C. Washington, Introduction to Cryptography with Coding Theory, 2nd or 3rd edition).  While you procure it, the 2nd chapter is available on canvas.  I hope other chapters will be available from the library in electronic form, but this isn’t for sure yet.
• Note: the next activity is to watch a video and do an accompanying worksheet.  I strongly suggest working on this in groups, and collaborating on daily tasks with classmates in general.  To that end, I’ve set two designated times to meet on discord (check out the STUDY GROUPS category) to do the video with peers:
• Monday August 24th at 9 pm
• Tuesday August 25th at 6 pm
• The main activity for this daily post is to watch my video “Modular Arithmetic: User’s Manual” (9:22 mins:secs) and do the accompanying self-check worksheet.  Please show your work on the last problem.  Then upload a picture of the worksheet to the appropriate canvas dropbox to be checked for completeness.  (Note: you don’t need to print; you can work on a separate sheet of paper if desired.)

# Welcome to Coding and Cryptography!

Welcome to Coding and Cryptography!

I’m really looking forward to this course with you!

To prepare for the course, please do the following:

• Please log in to canvas and watch the welcome video.  In canvas you will also find the zoom link for our first meeting.
• In the menu items above, you will find the course syllabus content, so please visit each of those pages for further information about the course.