The ancient Spartans encrypted messages by means of a simple mechanical device called a scytale. The code writer would wrap a strip of leather or parchment in a tight, spiral fashion around a staff and then write a message on the material along the staff. When unwrapped, the strip of leather appeared to contain just meaningless letters. But when the intended receiver wound the material around another staff of exactly the same diameter as the original, he could read the text. Adding a touch of steganography, the messenger would sometimes disguise the strip as a belt, wearing it with the letters on the inside.

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Ancient Spartan scytale