Whose code was broken at Bletchley Park?

During the Second World War, codebreakers at Bletchley Park in England broke the ciphers of Nazi Germany, most famously the Enigma machine used by the German military and the even more complex Lorenz cipher used for high-level communications. A team including the mathematician Alan Turing designed machines called bombes to help crack Enigma settings, which changed daily. To break Lorenz, engineer Tommy Flowers built Colossus, considered the worlds first programmable electronic digital computer. Historians estimate the intelligence gained, codenamed Ultra, shortened the war by around two years and saved countless lives. The work remained secret for decades afterward.