The scytale was a simple yet ingenious tool: a strip of parchment wound around a staff, the staff’s diameter determining the message length. You’d write the message along the strip, unwrap it, and only someone with a staff of the same diameter could read it. The Roman soldiers used it to send orders without arousing suspicion. If you want to try decoding one, bring me a staff and a strip, and we can see how the rhythm of the letters plays out.