[Cryptography] Imitation Game: Can Enigma/Tunney be Fixed?

Adam Sampson ats at offog.org
Sat Jan 10 13:46:53 EST 2015

ianG <iang at iang.org> writes:

> I was told yesterday that during WWII the Germans had some success
> parking submarines over undersea cables from UK to US, and using
> acoustics to pick up traffic!?  Anyone got any references to that?

There's TICOM report I-186, "Interrogation of Oberpostrat Kurt
Vetterlein on attempted tapping of trans-atlantic cables", from December
1945. This is available from Christos Triantafyllopoulos' archive:

The report says:

"Abteilung VIII had conducted some experiments in the finding and
tapping of cables in the Baltic Sea. As a result of the experiments, it
was assumed that outgoing cable telegrams could be successfully
intercepted 50km. from the shore. [...]

No actual cases of the tapping of long-distance cables were known to
Vetterlein. He was told that it was planned to find the cables to
America [...] and if possible to tap and intercept them or destroy
them. This was to be done by dropping from a submarine a coil, which
could be used both for finding and interception [...] near to the

[...] He had also heard that the German Navy worked on the tapping of
foreign cables, but could offer no information or names connected with

So the Germans certainly developed and tested a way of doing this, and
intended to do it, but it's not clear whether they actually did it.

Christos' blog has lots of good discussion of WW2 German cryptanalysis
-- well worth a browse. I found TICOM I-38, discussed at the end of this
article, particularly interesting:

It describes an attack on the steckered Enigma developed by cryptanalyst
Hans-Joachim Frowein in late 1944, where he concludes that the 3-wheel
Army version was certainly breakable (given a short crib and a 70k-card
database -- "In practice, Hollerith machinery would be used") and the
4-wheel Naval version may well be.

There's a summary of German attacks on (and improvements to) the Enigma
in chapter 2 of this Army Security Agency report:


Adam Sampson <ats at offog.org>                         <http://offog.org/>

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