» "Tunny" redirects here. For the fish, see Tuna. The Lorenz SZ 40 and SZ 42 (Schlüsselzusatz, meaning "cipher attachment") were German cipher machines used during World War II for teleprinter circuits. British codebreakers, who referred to encrypted German teleprinter traffic as "Fish", termed the machine and its traffic "Tunny". While the well-known Enigma machine was generally used by field units, the Lorenz machine was used for high-level communications which could support the heavy… (More on Tunny)