Suppose you had a secret message you needed to carry through hostile territory. You could write it on a piece of paper, but even if the message is in code it is possible that an enemy could find it and decipher it if you were captured.
Over 2500 years ago, Greek soldiers from the Spartan region devised a very clever way to conceal and encrypt messages that they wanted to carry from general to general – the Scytale (pronounced to rhyme with ‘Italy’).
In order to read a scytale, a long thin strap of leather would be wrapped around a wooden rod of a very particular diameter (like you see in the image above). The secret message is written crosswise on the strap, so that each letter of the message will fall on the next wrap of the leather. When the leather is unwrapped the letters appear to be meaningless gibberish and are only decipherable when the strap is wrapped around another rod of the exact same diameter. Each of the Spartan generals was issued one of these rods so that only they could read the messages.
To conceal the message even further, the messengers would wear the message strap as a belt with the letters on the inside. Even if they were captured, it was unlikely that any enemy would discover the message hidden inside their innocent looking belt.
So the next time you see a suspicious character with a fashionable belt around their waist they may be carrying a hidden message right in front of your eyes, so be suspicious.
If you missed last weeks transmission, read "How To See In The Dark" now. It's very useful. Try decoding a hidden Scytale message at Top Secret: License to Spy until September 5.