Fish (sometimes FISH) was the Allied codename for any of several German teleprinter stream ciphers used during World War II. While a large number of links were monitored, at least three different encryption systems were distinguished: Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ... The operation of A5/1, a LFSR-based stream cipher used to encrypt mobile phone conversations. ... World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrinations, and the use of new, extremely devastating weapons like the atom bomb. ...

• Tunny — the Lorenz SZ 40/42 from Lorenz Electric. Tunny traffic was read successfully at Bletchley Park, using the famous Colossus computer.
• Sturgeon — the Siemens and Halske T52 from Siemens. Although Bletchley Park managed to work out Sturgeon, they never read much of its traffic.
• Thrasher — the machine that generated this traffic does not appear to have been identified.

See also: Ultra For the fish, see Tuna. ... The Lorenz machine was used to encrypt high-level German military communications during World War II. British cryptographers at Bletchley Park were able to break the cipher. ... During World War II, British and American cryptographers at Bletchley Park broke a large number of Axis codes and ciphers, including the German Enigma machine. ... A Colossus Mark II computer. ... STURGEON exhibit at the National Cryptologic Museum. ... STURGEON exhibit at the National Cryptologic Museum. ... Siemens AG (NYSE: SI) is the worlds largest electronics company. ... Ultra (sometimes capitalised ULTRA) was the name used by the British for intelligence resulting from decryption of German communications in World War II. The term eventually became the standard designation in both Britain and the United States for all intelligence from high-level cryptanalytic sources. ...

References

• Wolfgang W. Mache, Geheimschreiber (Cryptology: Yesterday, Today and Tomorrow, Artech House, Norwood, 1987)
• Cipher A. Deavours and Louis Kruh, Mechanics of the German Telecipher Machine (also reprinted in Cryptology: Yesterday, Today and Tomorrow)
• Wolfgang W. Mache, The Siemens Cipher Teletype in the History of Telecommunications (reprinted in Selections from Cryptologia: History, People, and Technology, Artech House, Norwood, 1998)