The scytala or scytale was one of the earliest instruments known, used for coding and decoding messages. It was used by the Ancient Spartans, and consisted of two rods with the same diameter. A strip of leather was wound round one of the rods and the message was then written on the leather. When it was unwound again it was just a meaningless jumble of letters. The messenger carried it as a belt, the side with the letters being worn inwards. The recipient, who had the other rod, then rewound the strip of leather to get the message.

This site (in French) http://www.jura.ch/lcp/cours/dm/codage/transpo/scytale.html has a scytala simulation program.

If I don't tell you the diameter of my "rod", can you read this message?

T ts sr.ien ruat ehhieeSc s iyld tteils pysO het t khe sl oatcnman d wnerr utfraycesciitio ossh tltes osfotwdoditetaaa sbd f hiif.tr hn ltaeevirona eaue oehgedeceugmt


Bingley

Bingley