Page 302 - The Secret War in the Italian front in WWI (1915-1918)

THE SECRET WAR ON THE ITALIAN FRONT IN WWI (1915 – 1918)

13.10 Specimen of fully filled R code (ISCAG Library)

According to the R instructions,

in no case should the code remain in service for more than a month. In normal circumstances,
it must be replaced every fifteen days or more often, when the flow of communications is
high or important actions have been finalised, or when there is a well-founded suspicion
that the enemy intercepted our communications, or even when the code is frequently used
for radiotelegraphic communications. Therefore, as soon as the Regiment Headquarters
distributes a new version, it should request a new one to its Division Headquarters and keep
it ready for immediate distribution.

The R code, as one could expect, was captured on several occasions by the Austro-Hungarians.
Among Ronge’s documents, a blank specimen appears captured in the area around Pasubio, but
without any instruction manual .
23
As for the D code, even when the enemy managed to capture a completed copy of R, it did not imply
the possibility of systematically decrypting dispatches, as both met the mentioned Kerckhoffs
principle which states that a cryptographic system must remain safe even when the enemy captures
it, unless he knows the key represented, in these cases, by the code groups extracted by lot and
frequently changed.

23 M. Ronge, Der Radiohorch, op cit., Annex 67.

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