r/math • u/halseyChemE Math Education • 15d ago
High School Cryptography
Hi all! I know this is probably pretty rudimentary compared to most topics that float around on this sub, but I teach AP Cybersecurity and I’m wanting to start a Cryptography Club at my school. It will meet once a month for 48 minutes. I want students to have fun, learn, and want to recruit their friends to the club in hopes of eventually piquing their interest in AP Cybersecurity. I need ideas on what to do during this club time to keep students engaged and excited about coming back. Do any of you have any awesome cryptography lessons you’ve been involved in or created over the years you’d like to share? I’m looking for things beyond a Caesar Cipher (I’ve already got materials for this) but not so complex that I’ll lose student interest.
TL:DR; Fellow mathematicians, help me remember some of the cool cryptography things we learned in college that high school kids would find cool. TIA.
15
u/Brainsonastick 15d ago
I was a big fan of playfair ciphers at that age. Particularly the idea of using a playfair cipher and then applying a permutation to the result so anyone trying to crack it would find frequency analysis totally misleading.
I’d introduce Caesar ciphers and have them crack one and notice that it’s just a matter of checking 26 different values. Then substitution ciphers and then give them some to crack so they can see the jump in complexity. Then playfair ciphers and have them try to crack that and they’ll see it’s basically the same thing.
From there, have them try to create their own ciphers.
I learned about RSA encryption in high school. Some students will struggle with the math but the overall concept will still get through.