Code-writing and code-breaking, also known as cryptography and cryptanalysis respectively, have been around for centuries: the ancient Greeks were said to have used ciphers, and secret codes played enormous roles in the Civil War, WWI and WWII. In this class, we'll look at a short history of cryptography, learn about different methods of code-writing, look at the mathematics behind some of the most difficult codes to crack, and try our hand at writing our own.