Editing Lorenz cipher (section)

==History==
After the Second World War, a group of British and US cryptanalysts entered Germany with the front-line troops to capture the documents, technology and personnel of the various German signal intelligence organizations before these secrets could be destroyed, looted, or captured by the Soviets. They were called the [[TICOM|Target Intelligence Committee]]: TICOM.{{sfn|Parrish|1986|p=276}}{{sfn|Rezabek|2017|loc=I Introduction: Origin of TICOM}}

From captured German cryptographers Drs Huttenhain and Fricke they learnt of the development of the SZ40 and SZ42 a/b.{{sfn|Huttenhain|Fricke|1945|pp=16-19}} The design was for a machine that could be attached to any teleprinter. The first machine was referred to as the SZ40 (old type) which had ten rotors with fixed cams. It was recognised that the security of this machine was not great. The definitive SZ40 had twelve rotors with movable cams. The rightmost five rotors were called ''Spaltencäsar'' but named the ''Chi'' wheels by [[W. T. Tutte|Bill Tutte]]. The leftmost five were named ''Springcäsar'', ''Psi'' wheels to Tutte. The middle two ''Vorgeleger'' rotors were called ''Mu'' or motor wheels by Tutte.

The five data bits of each [[ITA2]]-coded telegraph character were processed first by the five ''chi'' wheels and then further processed by the five ''psi'' wheels. The cams on the wheels reversed the value of a bit if in the raised position, but left it unchanged if in the lowered position.