Editing Fish (cryptography) (section)

{{For|the stream cipher published in 1993|FISH (cipher)}}
{{Use dmy dates|date=October 2019}}

[[File:Russian Fish.jpg|thumb|German prisoners prepare the "Russian Fish" for loading and shipment to England.<ref>{{cite book|title = The Ultra Americans: The U.S. Role in Breaking the Nazi Codes: Thomas Parrish: 9780812830729: Amazon.com: Books|isbn = 978-0812830729|last1 = Parrish|first1 = Thomas D.|year = 1986| publisher=Stein and Day |url-access = registration|url = https://archive.org/details/ultraamericansth00parr}}</ref>]]
'''Fish''' (sometimes capitalised as '''FISH''') was the UK's GC&CS [[Bletchley Park]] codename for any of several German [[teleprinter]] [[stream cipher]]s used during [[World War II]].<ref>{{ Harvnb | Mache | 1986 | pp = 230–242 }}</ref><ref>{{ Harvnb | Deavours | Kruh | 1986 | pp = 243–247 }}</ref><ref>{{ Harvnb | Mache | 1989 | pp = 97–117 }}</ref>  Enciphered teleprinter traffic was used between [[Oberkommando der Wehrmacht|German High Command]] and [[List of German army groups in World War II|Army Group]] commanders in the field, so its intelligence value ([[Ultra (cryptography)|Ultra]]) was of the highest strategic value to the Allies.<ref>{{ Harvnb | Copeland | 2006 | p = 47 }}</ref> This traffic normally passed over landlines, but as German forces extended their geographic reach beyond western Europe, they had to resort to wireless transmission.<ref>{{ Harvnb | Lewin | 2001 | p = 130 }}</ref>

Bletchley Park decrypts of messages enciphered with the [[Enigma machine]]s revealed that the Germans called one of their wireless teleprinter transmission systems "{{lang|de|Sägefisch}}" ('[[sawfish]]') which led British [[cryptographer]]s to refer to encrypted German [[Wireless telegraphy|radiotelegraphic]] traffic as "Fish." The code "Tunny" ('[[tunafish|tuna]]') was the name given to the first non-Morse link, and it was subsequently used for the Lorenz SZ machines and the traffic enciphered by them.