An extremely rare German four-rotor M4 Enigma cipher machine from the Second World War has set a new world auction record at a Christie's sale at Rockefeller Center in New York. The property of an American collector, it sold at for US$547,500, topping the previous record for a fully operational Enigma M4 used by the German U-boat forces during the war of US$463,500.
An M4 Enigma cipher machine may look like an old, badly designed typewriter in a wooden box, but finding one up for sale is a bit like finding a Faberge egg in the discontinued bin at the supermarket. They were one of the most closely guarded secrets of the Nazis during the Second World War and breaking the ciphered messages they generated was not only a number one priority for the Allies, but also spurred the development of modern electronic computers.
Out of 1,600 produced from 1941 until the end of the war, only around 100 M4 Enigmas survive to this day. Like all Enigmas, the M4's used a complicated series of electromechanical circuits running through banks of four removable rotors and plugs that could be programmed to produce an incredible number of unique sequences to foil decryption experts. After the previous M3 was compromised by Allied codebreakers, Admiral Doenitz ordered a more sophisticated machine, the M4, to be developed.
The M4 was used exclusively to send communications between the German Naval High Command and the U-boat wolf packs attacking Allied shipping. With its 153 trillion possible sequences, the Nazi High Command believed it to be almost unbreakable, but British decryption teams, which included computer pioneers Alan Turing and Tommy Flowers, used some of the earliest and most advanced computers to break the Enigma codes and read some of the Germans' most secret messages.
However, because most of the machines were used aboard U-boats, most were lost at sea as the boats were intercepted and sunk. Of those that remained, the Germans ordered them destroyed to keep them from falling into the hands of the advancing Allied forces and, after the war, the British destroyed their Engimas to preserve their code breaking secrets.
According to Christie's, the excellent shape and complete condition of the auction machine indicates that it was used at a command and communications facility on shore. The M4 Enigma was sold with a Kreigsmarine telegraph key and two facsimile user manuals.