Wednesday, September 4, 2013

Unanswered questions of WWII cryptology

So far i’ve covered many interesting cases of WWII signals intelligence and codebreaking but that doesn’t mean that there aren’t some mysteries that require more research.

What are they?

1). US State Department strip cipher
In the late 1930’s the US State Department adopted the M-138-A strip cipher as its high level crypto system. In 1937 the Japanese were able to copy the strip set 0-1 and they passed these to the Germans in 1941, who in turn shared them with the Finns in 1942. In the same period it seems that the Italians also got hold of some strips. How bad was the compromise of the State Department’s high level system?

That question is hard to answer because there is limited information available and it doesn’t seem like the Americans were really interested in learning the full extent of the compromise. Some documents that would shed more light on this affair are proving very hard to find…
The M-138 strip system was difficult to solve provided it was used properly. The State Department did not use it properly with the result that in 1943-44 most of the strip traffic could be read by the Germans and the Finns. I’ll write more about this in the future.

2). NKVD 5th Department codebreakers
In 1941 the NKVD’s codebreaking department was redesignated as the 5th Department under the efficient administrator Major Ivan Grigoryevich Shevelev. According to Matt Aid ‘By the end of World War II, the 5th Directorate controlled the single largest concentration of mathematicians and linguists in the Soviet Union.

What did these people do during the war? They couldn’t have spent all their time solving German low level hand ciphers. How many Axis and other foreign cryptosystems did they attack? How many could they solve? Did the ‘break’ foreign cipher machines like the Enigma or the Hagelin systems?
We simply don’t know. However it seems that a new book on WWII signals intelligence has been published in Russia recently. Unfortunately I don’t speak/read Russian…

3). Referat Vauck success
In 1942 the Germans organized a group tasked with solving enemy agents codes. This was department Vauck, named after its head dr Wilhelm Vauck. During the war they definitely solved enemy codes, usually those that had been physically compromised when the agent was arrested. However they also had some successes through cryptanalysis.

How successful were they during the war? Unfortunately we do not know. The relevant file in the British national archives HW 40/76 ‘Enemy exploitation of SIS and SOE codes and cyphers’ says that postwar files have been retained and my request for the release of the interrogations of dr Vauck has been rejected by the archives staff…

4). Forschungsamt information
I have already pointed out that the Anglo-Americans were able to capture many of the Forschungsamt higher-ups in 1945. Where is the information from their interrogations? Why wasn’t it released to TICOM authorities?

5). German Enigma investigations
The Germans constantly evaluated the security of their Enigma cipher machine. There were many studies on whether the daily key or parts of it could be retrieved through cryptanalysis. Those studies are the TICOM DF-190 to DF-190AN files.

I don’t have these but recently I was given a summary from Randy Rezabek of Ticom Archive. This file shows that the Germans had investigated several methods of attack on the Enigma and in many cases had calculated the time needed for a small team to carry them out. Many were within practical limits.
More research is needed to evaluate the German methods and the way they influenced their security measures.

6). Japanese Purple and Coral cipher machines
In the 1930’s the Japanese Foreign Ministry started using the PURPLE cipher machine as its high level system. PURPLE was solved by American and Soviet codebreakers. Did the Germans have any success with it? Until recently the answer was no.

However it seems there is more to this story.

The Coral machine was used by military attaches and the Anglo-Americans solved it in 1944. In the same year dr Steinberg of the German Army’s signal intelligence agency was transferred to OKW/Chi where he worked on a cipher machine used by the Japanese attaché. Did he manage to solve it?

TICOM report I-64 ‘Answers by Wm. Buggisch of OKH/Chi to Questions sent by TICOM’ saysB. thinks Steinberg (of 209 fame) solved some Jap machine traffic which was difficult but not so hard as Enigma. B. thinks it was traffic of the Jap Military Attache.

7). Soviet diplomatic code
The Soviet Union used a code enciphered with one time pads as its main diplomatic system during WWII. This system if used correctly is unbreakable.

Were the Germans able to read parts of this traffic? There are some strange statements in Allied and German reports…

8). M-209 decoding device
I’m surprised that no one has figured out how this machine worked!


  1. Albert Hess? The German general who escaped his prison via glider and was said to have a double? His tombstone reads something like 'it was worth the risk' Rudolph heiss may have been his name, he was even featured on unsolved mysteries. Check it out

    1. You mean Rudolf Hess? Yes that’s definitely an interesting story but here I mentioned some cases of cryptologic history, not general intelligence history.

    2. My bad

  2. For a thorough analysis of how to break the M209 see the book Cipher Systems - The Protection of Communications by HenryBaker & Fred Piper. It gives a detailed account of statistical methods to break this machine with examples.

    Benjamin Sidle

  3. "We simply don’t know. However it seems that a new book on WWII signals intelligence has been published in Russia recently."

    Pray tell, what is the book called?


    1. Good question. The book is ‘The cryptographic front of the (Second World) war’ by Butirsky, Larin and Shankin.