CONFIDENTIAL
How do you keep your plans secret if you’re a king or queen and everyone would love to read your mail? Well, first you might try to hide your notes in some clever way.
Secret messages have been hidden in hairdos, sewn into clothes, written under paintings, and slid into shoes. The ancient Chinese wrote secrets on pieces of silk, which were then coated with wax and swallowed. (We’ll leave it to you to figure out how those messages were delivered!) But no matter how well hidden a message is, it can still be read if it’s found. What if you need something more secret?
Secret Writing
We’re talking about codes, of course. A code is a set of rules that hides the true message by substituting letters or mixing up words. That way, even if the message falls into unfriendly hands, it can’t be read. To do this, the writer uses a cipher, a formula for scrambling or substituting letters or symbols.
Great plan, you say, but if you swap the letters around, how will the person you’re sending it to be able to read it? To unlock the meaning of a coded message, you need to know how it. Say you received this message:
