Math Hacks for Scratch

6

Making Codes, and Cracking Them Too

Say you have a secret that you want to share with a friend. You could write it down and pass them a note, but somebody else might see it. Or you could whisper it to them, but somebody might overhear. Think how much better it would be if anyone else who intercepted your message couldn’t make sense of it. A secret code!

In this chapter, we’ll use Scratch to practice cryptography, the art of secret codes. We’ll write programs with a few different cryptographic techniques, consider their strengths and weaknesses, and use them to encode messages. Writing a message in code is only half the job, though. There has ...