In cryptography, a scytale (; also transliterated skytale, skutálē "baton, cylinder", also σκύταλον]] skútalon) 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 Greece, and the 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 the parchment is wrapped to read the message.
To encrypt, one simply writes across the leather:
_____________________________________________________________| | | | | | | | I | a | m | h | u | | __| r | t | v | e | r |__| | | y | b | a | d | l | | | y | h | e | l | p | | | | | | | |_____________________________________________________________
so the ciphertext becomes, "Iryyatbhmvaehedlurlp" after unwinding.
Due to difficulties in reconciling the description of Plutarch with the earlier accounts, and circumstantial evidence such as the cryptographic weakness of the device, several authors have suggested that the scytale was used for conveying messages in plaintext and that Plutarch's description is mythological.
Nonetheless, any person intercepting a scytale message, and having heard about the method, could with little difficulty find out the rod size needed (a kind of brute-force attack); once knowing that, it would be easy to supplant the sender and forge new messages.
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