Caesar's box is a method of simple encryption invented by Julius Caesar. Caesar invented this method in order to encode messages so that they wouldn't be able to be read if they fell into the wrong hands.
There is only one rule that a Caesar Box message must follow: the sum of the total number of characters has to be a perfect square, or a number whose square root is an integer. For example, an 9-character message is encryptable using Caesar boxes, because the message would have to be written in a 3 by 3 grid from top to bottom as follows:
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The message is "HOWAREYOU" (the spaces have been omitted to make the message nine characters long.) To encode the message, read it back horizontally from left to right in the grid, and you'd end up with "HAYOROWEU". Because of the nature of Caesar boxes, encrypting an encrpyted message decrypts the original message.
