Hidden Code 5m5s2d

This is a good sort of code to write on a postcard or even stick on a noticeboard. It can look totally innocent and although anyone can see it, they won't suspect that there's a secret message hidden in there. The only person who can read the secret message will be your agent! d4n3x

There's a message hidden on this piece of paper. Can you spot it before we tell you the secret? 3p47m

If you can't work it out, then the secret is that you have to read every third word starting with "my". Have you got it now? Ouch!

However, if you want something a bit more secure, try one of the codes below.

Scrambled Codes 83d1h

Caesar Shift is one of the best known cipher systems. 3p5z2v

A cipher usually means that each letter is replaced by a different letter, and to decode a message you need to know the secret key.

A simple version of this system was used by the Roman Emperor Caesar to help him conquer the world. We'll show you how to use it and even make it better! 3c503g

Vigenere Grid is a very clever cipher system, similar to the Caesar Shift. It is so secure, it is still being used by real spies today. 266qh

The Vigenere system works with either a key word, a key sentence or even a whole key book. When the code is being used with a book, even computers can't break this one!

The Murderous Maths Home Page