Origin and Nature of the Allied Cryptographic Advantage

During World War IIBy

Grant Musick

Enigma – The WWII Encryption Gold Standard

• Enigma is short hand for an entire family of rotor based machines

• Used by the Germans and some other countries

• Used for commercial, diplomatic and military traffic

• Japanese used it to a lesser extent, but had own codes (JN-25 and PURPLE)

Pre-War Activities

• There was a whole lot of spying going on by all countries

• U.S. identified Japan as a potential future adversary

• U.S. “obtained” Japanese naval code books throughout the 1920s

• U.S. sent naval personnel to Japan to learn Japanese language and culture.

Pre-War Activities (cont)

• 1929 Poles obtained a “mislabeled” German Enigma machine.

• 1932 Marian Rejewsky breaks Enigma encrypted traffic

• 1938 Rejewsky creates a “cryptologic bomb”, an electro-mechanical device that helps test possibly Enigma keys

Pre-War Activities (cont)

• In 1939 the Poles decide to share Enigma breaking techniques with British and French.

• Up until this point, British and French considered Enigma unbreakable.

• Without the Poles, Allied cryptanalysis would have been much, much harder.

Sharing is Good

• Poles shared with British and French

• British shared with U.S.

• British established Bletchley Park so their cryptanalysts could share with each other

• U.S. forced Army and Navy to share code-breaking duties and glory for greater efficiency

• Axis didn’t do this and paid the price

Smart People == Victory

• British actively gathered intellectual talent at Bletchley Park e.g. Alan Turing

• U.S. administered I.Q. tests to likely recruits to see which ones might have talent in the signal services

• Axis didn’t do this and paid the price

Industrialization – Age of the Machine

• Cryptologic Bomb and Collossus computers enabled semi-automated code breaking

• U.S. Industrial might was key to churning out machines to break codes.

The Joys of Gardening

• Allies held strategic initiative

• Made possible the use of dummy attacks to provoke radio traffic by Axis

• Military culture is very regimented, with procedures for everything

• So provoked traffic was analyzed against known responses to previous attacks.

• Known as “gardening” by the British

The Joys of Fishing

• Allies made a concerted effort to capture Axis cryptographic machines

• Strategic initiative made this possible

• 15 Enigmas captured during the war – seven from U-Boats and eight from surface vessels (spy trawlers and other covert merchant vessels)

Human Frailty

• People were as foolish then as they are today

• Axis operators didn’t change keys frequently or used things like their initials or girlfriends’ names

• Axis operators also sent test messages using the same key, e.g. “t”, for the entire message

In Closing

• “After the war, American TICOM project teams found and detained a considerable number of German cryptographic personnel. Among the things the Americans learned was that German cryptographers, at least, understood very well that Enigma messages might be read; they knew Enigma was not unbreakable. They just found it impossible to imagine anyone going to the immense effort required. When Abwehr personnel who had worked on Fish cryptography and Russian traffic were interned at Rosenheim around May 21, 1945, they were not at all surprised that Enigma had been broken, only that someone had mustered all the resources in time to actually do it. Admiral Dönitz had been advised that that was the least likely of all security problems.”

--From Answers.com “Cryptanalysis of the Enigma”