How do secret codes and ciphers hide a message?
The Key Game
How do secret codes and ciphers hide a message?
Imagine you write a note that says MEET AT NOON. You don't want anyone but your friend to read it. So you scramble it into nonsense — QHHW DW QRRQ — and only your friend knows how to un-scramble it back. That little trick, repeated and refined for thousands of years, is the whole art of secret codes.
The simplest cipher just shifts the alphabet. Slide every letter forward by three: A becomes D, B becomes E, and so on. So "CAT" turns into "FDW." Julius Caesar used a trick like this, which is why people still call it the Caesar shift. The number you shift by is your secret — that's called the key.
