Page 251 - The Secret War in the Italian front in WWI (1915-1918)

CHAPTER ELEVEN

January for communications with the Headquarters of the 16 Corps in Vlore, and with the
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Defence Attachés in London, Madrid, The Hague, etc .
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In February 1918, the Unit created a completely New SI Code .
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For all the remaining months of the war, it also maintained the SI carefully, often issuing
new coding and decoding tables. The Austro-Hungarian sources no longer mentioned this
codebook. At the end of the conflict, the Italian Intelligence Service included it among the
unbroken codes thanks to the “statements of personnel from the disbanded Austro-Hungarian
Army who worked in cryptographic offices” who had never heard of it .
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During 1918, the new SI code was also distributed to Army units outside the usual limited
‘circle’ around the Intelligence Service, until it spread to many Headquarters, as we will see
in the following pages of this book.

froM The “red” To The “sPecIal”

After the alarm and its temporary suspension in March 1916, the Red code had been reintroduced
into service after just over a month by adding simple additive over-encoding and by adopting a
different page numbering. However, these provisions were no significant obstacle to the Austrian
cryptanalysis.
In June 1917, another simple over-encoding was applied, which entailed swapping, in the code
groups, the position of the number of the page with the number of the word and adding ‘123’ to
each group of five digits. Three days later, this string was replaced with ‘55’, because an Officer
in the Headquarters of the 5 Army transmitted by radio the new key by a dispatch coded with the
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previous one, thus making it necessary to replace it . Simple additive keys could be discovered
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quickly.
Nevertheless, this modification to the Red Code, ever since named Special, was only an interim
solution, because after a short time, a radical change took place by introducing coding and decoding
tables, created by the Cryptographic Unit, as shown by the logs of Sections U in the 25 June entry:

Letter (sent) to the Ministry of War - Office of the Minister.
Please be informed that this Intelligence Service was tasked with drafting:
1- Special coding/decoding tables to be applied to the Special code. The tables should be
replaced periodically, or in case the code is lost. Distribution of the Special code should be
limited to the Headquarters of large units, intendancies, and 2 line services.
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2- A two-parts dictionary for lower commands, replacing the Pocket Military Cipher.
Sample tables for approval and distribution are attached; the dictionary will follow .
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Office of the General Staff of 15 January 1918), AUSSME, Series E2, env.110.
60 Section U logs, op. cit., 3 January, and 21 February 1918, AUSSME, Series D1, 101 D, Vol.360d.
61 Section R Logs, AUSSME, Series B1, 101 S Vol. 311d, 23 February 1918, Completamento della prefazione del nuovo
cifrario SI (Finalization of the new Code SI Introduction).
62 Intelligence Service, Attività dei reparti crittografici dell’Esercito austro ungarico durante la guerra, (Austro-Hungaric
Army Cryptographic Units activity during the War), signed by O. Marchetti, Prot. 951/A, 14 March 1919, AUSSME, Series
H4, Env.65.
63 The documentation relating to the ‘Special code’ with additive key is contained in AUSSME, Series F2 env.117. See in
particular: Headquarters, 5 Army, Telegram no. 2235, 7 June 1917; Circular Letters of the Ministry of War No. 2235, 7 June
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1917, and no. 2278, 10 June 1917.
64 Section U logs, op. cit., 25 June 1917, AUSSME, Series B1, 101 D, Vol. 349 d. The dictionary is the divisional D, which
the Cryptographic Unit prepared as described in the next paragraph.

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