 :for other uses, see scytale (disambiguation). thumb|199px|right|a scytale in cryptography, a scytale (, rhymes approximately with italy; also transliterated skytale, greek ÏÎºÏÏÎ¬Î»Î· "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. the recipient uses a rod of the same diameter on which he wraps the parchment to read the message. it has the advantage of being fast and not prone to mistakes&mdash;a necessary property when on the battlefield. it can, however, be easily broken. since the strip of parchment hints strongly at the method, the ciphertext would have to be transferred to something less suggestive, somewhat reducing the advantage noted. ==encrypting== suppose the rod allows one to write four letters around in a circle and five letters down the side of it. the plaintext could be: "help me i am under attack". to encrypt, one simply writes across the leather: _____________________________________________________________ | | | | | | | | h | e | l | p | m | | __| e | i | a | m | u |__| | | n | d | e | r | a | | | t | t | a | c | k | | | | | | | | _____________________________________________________________ so the ciphertext becomes, "henteidtlaeapmrcmuak" after unwinding. ==decrypting== to decrypt, all one must do is wrap the leather strip around the rod and read across. the ciphertext is: "henteidtlaeapmrcmuak" every fifth letter will appear on the same line, so the plaintext becomes helpm...return to the beginning once the end is reached ...eiamunderattack after inserting spaces, the plaintext is revealed: "help me i am under attack". ==history== from indirect evidence, the scytale was first mentioned by the greek poet archilochus, who lived in the 7th century bc. other greek and roman writers during the following centuries also mentioned it, but it was not until apollonius of rhodes (middle of the 3rd century bc) that a clear indication of its use as a cryptographic device appeared. a description of how it operated is not known from before plutarch (50-120&nbsp;ad): :the dispatch-scroll is of the following character. when the ephors send out an admiral or a general, they make two round pieces of wood exactly alike in length and thickness, so that each corresponds to the other in its dimensions, and keep one themselves, while they give the other to their envoy. these pieces of wood they call scytalae. whenever, then, they wish to send some secret and important message, they make a scroll of parchment long and narrow, like a leathern strap, and wind it round their scytale, leaving no
Classical_ciphers Encryption_devices