Trying to set up a cute demonstration of cryptography, here's what I'm envisioning so far:
I have a whiteboard, some number of students, and an equal number of different colored markers. On the whiteboard is a survey question, with possible 4 responses. One by one, each student writes something on the whiteboard with their own color to select their response.
But here's the catch:
- Each student's writing must commit them to one of the four choices.
- No other student should be able to figure out another student's selection, until...
- The students can reveal a piece of information that makes deciphering their choice possible.
So after all the students have gone up to the whiteboard, they can reveal their secret and let their choices be known.
What can they write on the board? This is an open-ended question, but I want to optimize for "elegance". I'm having a hard time articulating what I want, but I'll post my own answer and why I don't like my answer if that makes things more clear.