Which naval cipher did Turing's Hut 8 mainly attack at Bletchley Park?

Turing's Hut 8 mainly attacked Naval Enigma, the German Kriegsmarine's version of the Enigma cipher machine. The work focused especially on messages exchanged by German surface ships and U-boats during the Second World War.

Naval Enigma was harder than many other Enigma systems because the German Navy used stricter operating procedures and a more complex indicator system. In 1940, Turing developed Banburismus to exploit statistical patterns in intercepted traffic and narrow the possible rotor arrangements before bombe machines tested them.

Hut 8 did not work alone. Hut 4 handled the translation and intelligence analysis of naval decrypts, while information from captured codebooks and key material helped the cryptanalysts recover periods of otherwise inaccessible traffic. In 1942, the German Navy introduced “Triton,” a fourth-rotor system used for important U-boat communications, creating a serious interruption in Allied reading of the messages. The alternatives are different cipher systems: Lorenz was used for high-level teleprinter traffic, Playfair was a manual cipher, and Purple was a Japanese system.