Introduction Overview

This video gives an overview of the experiences students will have in Chapter 2 of the CryptoClub Cipher Handbook as they learn to use the additive cipher. To encrypt with an additive cipher, we first change the letters to numbers and then add a key. Adding has the effect of shifting letters farther along in the alphabet, so an additive cipher is like a Caesar cipher that uses numbers.

With this cipher, students get plenty of practice with mental arithmetic and flexible thinking. They are also introduced to modular arithmetic, which is similar to the arithmetic used to tell time on clocks.