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

[Adam Sampson]

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:
http://chris-intel-corner.blogspot.gr/

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
cable.

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

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:
http://chris-intel-corner.blogspot.gr/2014/05/naval-enigma-compromise-and-spy-in.html

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:
https://www.nsa.gov/public_info/_files/european_axis_sigint/volume_2_notes_on_german.pdf

Cheers,

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