. . "The Lorenz SZ40, SZ42A and SZ42B were German rotor stream cipher machines used by the German Army during World War II. They were developed by C. Lorenz AG in Berlin. The model name SZ was derived from Schl\u00FCsselzusatz, meaning cipher attachment. The instruments implemented a Vernam stream cipher.British cryptographers, who referred to encrypted German teleprinter traffic as Fish, dubbed the machine and its traffic Tunny.The SZ machines were in-line attachments to standard teleprinters."@en .