Editing Ultra (cryptography) (section)

====Lorenz cipher====
{{Main|Cryptanalysis of the Lorenz cipher}}
In June 1941, the Germans started to introduce on-line [[stream cipher]] [[teleprinter]] systems for strategic point-to-point radio links, to which the British gave the code-name [[Fish (cryptography)|Fish]].{{sfn|Gannon|2006|p=103}} Several systems were used, principally the [[Lorenz cipher|Lorenz SZ 40/42]] (codenamed "Tunny" by the British) and [[Siemens and Halske T52|Geheimfernschreiber]] ("Sturgeon"). These cipher systems were cryptanalysed, particularly Tunny, which the British thoroughly penetrated. It was eventually attacked using [[Colossus computer|Colossus]] machines, which were the first digital programme-controlled electronic computers. In many respects the Tunny work was more difficult than for the Enigma, since the British codebreakers had no knowledge of the machine producing it and no head-start such as that the Poles had given them against Enigma.<ref name="haigh">{{cite journal | url=http://cacm.acm.org/magazines/2017/1/211102-colossal-genius/fulltext | first=Thomas | last=Haigh | title=Colossal Genius: Tutte, Flowers, and a Bad Imitation of Turing | journal=[[Communications of the ACM]] | volume=60 | issue=1 | date=January 2017 | pages=29–35 | doi=10.1145/3018994| s2cid=41650745 | url-access=subscription }}</ref>

Although the volume of intelligence derived from this system was much smaller than that from Enigma, its importance was often far higher because it produced primarily high-level, strategic intelligence that was sent between Wehrmacht high command ([[Oberkommando der Wehrmacht]], OKW). The eventual bulk decryption of Lorenz-enciphered messages contributed significantly, and perhaps decisively, to the defeat of Nazi Germany.<ref name="Hinsley 1993 8">{{Harvnb|Hinsley|1993a|p=8}}</ref><ref name="Brzezinski 2005 18">{{harv|Brzezinski|2005|p=18}}</ref>  Nevertheless, the Tunny story has become much less well known among the public than the Enigma one.<ref name="haigh"/>  At Bletchley Park, some of the key people responsible for success in the Tunny effort included mathematicians [[W. T. Tutte|W. T. "Bill" Tutte]] and [[Max Newman]] and electrical engineer [[Tommy Flowers]].<ref name="haigh"/>