During the Second World War German officials and military forces
used an innovative electro-mechanical device known as the Enigma
machine to protect their top-secret radio traffic. Though the
historical documents (held at the Public Record Office) remained
classified until the 1970s, the story of the breaking of the
Enigma cipher is now one of the most celebrated of the war. The
Enigma machine was invented by Arthur Scherbius and produced
commercially for the banking industry in 1918. The German Navy
saw its potential for military use and adapted the system of
rotors, keyboard and electrical wires. Resembling a typewriter,
the machine was portable and ideally suited to use in combat,
and was quickly adopted by all branches of the German armed
forces. made great strides in understanding the design of the
military Enigmas and even constructed several versions of the
machine. In 1939 the Germans began strengthening their system by
changing the cipher every day. The German Navy equipped their
Enigma machines with