To create your cryptogram puzzle, follow the steps below and click the “Create My Cryptogram” button when you are done. Puzzlemaker uses PNG image files which are only viewable in Netscape and Internet Explorer browsers version 4.0 or higher.

It looks like a whole lot of nonsense, right? Well, to many people, for many hundreds of years, it was nonsense - and the simple substitution cipher worked just fine to keep secret documents just that: secret.

Between 1966 and 1974, the Zodiac killer provided more than 20 written communications to police officials, some including ciphers that have not been cracked to this day, including Z340.