Fish (cryptography)
ALLIED CODENAME FOR ANY OF SEVERAL GERMAN TELEPRINTER STREAM CIPHERS USED DURING WORLD WAR II
Fish cyphers; Fish ciphers; Fish (cipher); Fish (cypher); FISH (cryptography)
Fish (sometimes FISH) was the UK's GC&CS Bletchley Park codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies.