Scytale

In cryptography, a scytale (/ˈskɪtəliː/, rhymes approximately with Italy; also transliterated skytale, Greek σκυτάλη "baton") is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message. The ancient Greeks, and the Spartans in particular, are said to have used this cipher to communicate during military campaigns.