Original URL: http://www.theregister.co.uk/2006/03/15/m4_project_message_break/

Codebreakers unravel second Enigma intercept

M4 Project targets last naval cipher

By John Leyden

Posted in Science, 15th March 2006 16:15 GMT

A distributed computing project has successfully cracked the second of three unbroken Enigma intercepts dating back to World War II. The naval codes resisted the best efforts of allied cryptographers but are beginning to fall to the combined forces of the net community, brought together by the M4 Project.

The second message to yield to the M4 Project fell on 7 March. A translation reveals little more than a routine observation report.

Found nothing on convoy's course 55°, [I am] moving to the ordered [naval] square. Position naval square AJ 3995. [wind] south-east [force] 4, sea [state] 3, 10/10 cloudy, [barometer] [10]28 mb [and] rising, fog, visibility 1 nautical mile. Schroeder

The first message to crack under M4, which fell on 20 February, was far more dramatic. The message corresponds with entries in the war diary of German Submarine U264.

Forced to submerge during attack, depth charges. Last enemy location 08:30h, Marqu AJ 9863, 220 degrees, 8 nautical miles, (I am) following (the enemy). (Barometer) falls (by) 14 Millibar, NNO 4, visibility 10.

So far efforts to break the remaining message have come to naught but project leaders remain confident it can be broken even though they are not certain which type of Enigma machine it was encoded using. A run through the entire search space corresponding to Army and M3 Enigma machines has failed to turn up any results.

Computer users interested in getting involved can download a client onto their PCs which takes advantage of idle processing time to perform number crunching in much the same way as the popular SETI@Home screen saver was used to analyse radio telescope signals from space in the search for extra-terrestrial intelligence. The name of the code breaking project, which started on 9 January, comes from the unconfirmed belief that the signals were encoded using a four rotor Enigma M4 device.

The signals analysed by the project were captured in the North Atlantic in 1942 and unearthed by amateur historian Ralph Erskine, who sent them off to journal Cryptologia in 1996 as a challenge to codebreakers. None of the messages are thought to be historically significant but all three set a formidable intellectual challenge to decipher.

The secrets of the intercepts eluded the boffins at Bletchley Park because of the switch from the Hydra (Doplhin) cipher-system to more complex Triton (Shark) cipher-system and the introduction of a more complex version of the Enigma machine at the height of the war in north Atlantic. Wartime efforts to crack the messages tried all combinations available on German army and three-ring Enigma machines but not those used by the more complex four-rotor Enigma M4 device. ®