At the start
of WWII the Kingdom
of Greece, ruled by Ioannis Metaxas (head
of the 4th of
August Regime) followed a neutral foreign policy and tried to avoid taking
part in the conflict. However constant Italian harassment and provocations
(such as the sinking of the
cruiser Elli) and the transfer of Italian army units to Albania made it
clear that war could not be avoided for long.
In October
1940 Italian forces invaded Greece, in the area of Epirus, and
the Greek-Italian
war started. The Greek forces were able to contain the assault and the
Greek counterattack forced the Italians back into Albanian territory. After the
defeat of a major Italian offensive
in spring 1941 the front stabilized inside Albania.
At the time
Britain was overextended with obligations in Europe, Middle East and Asia.
However the British armed forces made a small contribution with an RAF
expeditionary corps. When more British forces started to
arrive in March 1941, their involvement gave Germany an excuse to become
involved in the conflict.
German
forces invaded
Greece in April 1941 and made rapid progress due to the fact that
almost the entire Greek Army was fighting in the Epirus area. The remaining
units and the small British forces transferred to Greece in March-April 1941
were unable to stop them. Then in May 1941 the Germans were also able to defeat
the Greek and British forces that had retreated to the strategic island of Crete.
Compromise
of Greek military codes
At this time
there is very limited information available on the cryptosystems used by the
Greek Armed Forces in WWII.
According to
TICOM report I-58 in early 1941 the codebreakers of the German Army’s signal
intelligence agency investigated a Greek 5-figure code enciphered with a 35
figure repeating additive sequence (2). Progress was made in the solution of
the cipher but the campaign ended just as the system was starting to be
exploited operationally.
c. Greek - In early 1941, B. solved a
5-letter code with a 7-cyclic recipherment (period of 35). Just getting to
operational speed when the campaign ended.
Information
on Greek
Airforce ciphers is available from TICOM report I-170 (3), written by Dr.
Otto Karl Winkler, a member of NAASt 4, which was the cryptanalytic centre of KONA
4 (Kommandeur der Nachrichtenaufklärung - Signals Intelligence Regiment). KONA
4 was a German Army signal intelligence unit assigned to cover radio traffic from
the Balkans and the Middle East.
In the report
dr Winkler said that in spring 1941 Greek AF single
transposition messages were solved and translated.
My first employment was on the
breaking and translating of Greek Air Force messages in Spring 1941. The unit
was in BUCHAREST at that time and later it was at BANJA KOSTENIC in Bulgaria.
C.O. was Hptm. SCHMIDT, head of the cryptography and translation department from
then until Autumn 1944 was Prof. Alfred KNESCHKE, a Professor of Mathematics from Saxony.
The Greek Air Force messages were a matter
of simple boxes, the text being sent in T/L groups. The indicator took the form
of 3 letters which were always in a given position, the first three T/L groups
and had to be knocked out before entering the cipher text in the clear box.
This was broken by writing out the cipher text in vertical strips of varying
depth and sliding them against each other until a few Greek syllables appeared above
one another. After the initial break it became clear that a large part of the
messages began with the words ‘parakalw', 'anaferw’ and ‘apesteilamen’ and that
the width of the box was as a rule between 15 and 22 columns. On the basis of
the above, initial words, all messages were tried out on the normal number of columns
and nearly everything was read. I had less to do with the actual evaluation,
firstly because the two departments were kept separate and secondly because we
were kept fully occupied with our own job. In any case the content of the
messages was usually of insignificant strategic value, although the continuous
check on officer personalities, deliveries of stores and knowledge of airfields
combined with D/F bearings indirectly contributed to considerable tactical
results.
According to dr
Winkler Greek Army and Navy codes were not broken until after the conquest of
Greece, when captured codes were read during the Battle of Crete. It
would seem that Greek military codebooks were captured in mainland Greece and
then used to solve Greek radio traffic during the Battle of Crete.
Regarding
Greek Navy ciphers there are translations of Greek naval radio messages in the
Italian state archives (4). Thus it seems that some Greek Navy communications
were read by the Italian
codebreakers.
The Greek
Government in Exile
After the
occupation of Greece by the Axis powers the King and the politicians that had
managed to leave the country constituted the Greek
government-in-exile, based in Cairo, Egypt. During the period 1941-44 the
Greek government and the military
forces that it controlled supported the Allied cause. Greek forces fought
in North Africa and in Italy, while the Greek Navy operated in the
Mediterranean in support of British operations.
In the diplomatic
field the goal of the Greek government was to promote Greek interests in the
Allied capitals and in the period 1943-44 to try and find an acceptable
solution to the problem posed by the rise of the Communist controlled EAM-ELAS
resistance movement in occupied Greece.
Greek
diplomatic codebooks
The Greek
foreign ministry used a series of codebooks in order to protect its sensitive
communications from eavesdroppers. These were the cryptographic lexicons 1927,
1931, Η (ITA), Φ (PHI) and Ι (IOTA).
Usually these
codebooks were used without additional encipherment, however when messages of
particular importance had to be transmitted then they were enciphered with
bigram substitution tables.
One
interesting characteristic of Greek diplomatic codes is that they allowed for inflection. Greek is
a highly
inflected language and in order for the plaintext to be encoded correctly
it was necessary to take this peculiarity of the Greek language into account. The
way the system worked was that an extra letter (or number) was added to each
codegroup in order to designate the grammatical form of the word in question.
Examples of
Greek diplomatic codebooks (5):
Lexicon
1927
Lexicon
1931
Lexicon Η (ITA)
Lexicon Φ (PHI)
Lexicon Ι (IOTA)
During WWII
Greek diplomatic communications were read both by the Allies and the Axis
powers.
US effort
According to
the NSA report SRH-361 ‘History
of the Signal Security Agency Volume Two The General Cryptanalytic Problems’
(6), Greek systems were worked on by a subsection of unit B-III-D of the Army
Security Agency.
This unit
initially worked on the communications of Far Eastern countries, specifically
Nationalist China and the Japanese controlled governments of occupied China,
Thailand and the Philippines. In April 1944 the functions of the unit were
extended to cover the traffic of Bulgaria, Croatia, Czechoslovakia, Greece,
Poland, Slovakia and Yugoslavia.
Greek traffic
was examined because the unit had a classical scholar who also knew modern
Greek. According to the report this was dr Aubrey Diller,
who was assisted by Mary Fennel, Lieutenant Praxythea M. Coroneos and Elaine
Pulakos.
In December
1944 the unit had about 50 workers, with 4 working on Greek ciphers. The Greek
codebook GRB (lexicon IOTA) had been copied by the FBI in an undercover
operation so messages on this system could be solved and translated without
delay.
Other systems
examined by the unit were the highly enciphered code GRA and a new codebook GRE
that was used during the San
Francisco conference. The latter code was enciphered with digraphic substitution
tables but some traffic was solved and several hundred codegroups recovered.
A table dated
September 1944, listing intercepts and decodes by country, shows that 1.333
Greek telegrams were received. Out of these 507 were original messages (the rest
duplicates), of which 427 were deciphered and 417 translated or summarized.
German
effort
Foreign
diplomatic codes and ciphers were worked on by three different German agencies,
the German High Command’s deciphering department – OKW/Chi, the
Foreign Ministry’s deciphering department Pers Z and the Air
Ministry’s Research Department - Reichsluftfahrtministerium Forschungsamt.
OKW/Chi
effort
At the High
Command’s deciphering department - OKW/Chi, Greek diplomatic systems were
worked on by a subsection of main Department V. Depending on the source the
unit was headed either by principal specialist Rudolf Seifert or by dr
Poestgens (7).
According to
Wilhelm Fenner (head of the cryptanalysis department of OKW/Chi), three Greek
codebooks were worked on (8).
Pers Z
effort
At the
Foreign Ministry’s deciphering department Pers Z Greek systems were worked
on by the group ‘Italy, Greece, Vatican, USSR’, headed by senior specialist (Oberregierungsrat)
dr Adolf Paschke.
According to
TICOM report I-22, paragraph 169 (9) three Greek codebooks were read by the
unit:
Greek:
there were three systems, all of which were read:
1) a clear 5 letter book, the fifth
letter of which was dummy; this carried most of the traffic.
2) a clear 4 letter book, used mainly
for traffic with Berne.
3) a four figure book used with bigram
substitution of 30 tables of 100 bigrams each. It was used between London and
Moscow, Washington, Cairo and Ankara. Traffic from London amounted to about 1 a
day. The bigram tables changed according to the date.
Forschungsamt
effort
At the Air
Ministry’s Research Department Greek systems were worked on by Abteilung 9,
Branch A, Section 2 (Czechoslovakia, Yugoslavia, Bulgaria, Greece, Albania) (10).
According to
dr Martin Paetzel (deputy director of Main Department IV - Decipherment) ‘just two plain codes were read’ (11).
Examples
of decoded Greek diplomatic messages
Decodes of Greek
telegrams can be found in the TICOM collection of the German Foreign
Ministry’s Political archive (12):
Worksheets
Translated
telegrams
Conclusion
In WWII Greek
radio communications were read by the Axis powers to a considerable extent.
During the
Battle of Greece it seems that the solution of Greek military codes did not
play a big role in the actual combat operations. However according to German
sources Greek communications were read during the Battle of Crete. If this is
true then the intelligence gained from reading Greek messages may have given
the Germans a significant advantage during that costly operation.
Greek
diplomatic codes were insecure and were read not only by the Axis powers but
also by the US and British codebreakers. Although Greece was a small country
its politicians and diplomats had regular meetings with Allied officials and
they were kept informed of important diplomatic and military initiatives. It is
reasonable to assume that some of that information was transmitted in insecure
Greek codes.
From the German
point of view it was a worthy investment to focus on the codes of small Allied
countries since they did not have the expertise or the resources needed to
secure their wireless communications.
Wilhelm
Flicke who was in charge of OKW/Chi’s Lauf intercept station wrote in his book
‘War Secrets in the Ether’ (13):
Hitler's attacks on the small states
of Europe from 1938 to 1941 had forced the governments of these countries to
take refuge abroad in order to continue efforts for the recovery of national
independence. Most of these governments in exile had gone to London. Here they
maintained little ministries and kept in touch with their representatives in
foreign countries, i.e. with their embassies, consulates, missions,
delegations, and the like. They made extensive use of radio telegraphy and thus
supplied raw material for the German intercept service. And this "raw
material" was - first class!
…………………………………………………………………………………………………………
Everything that the "big fry’’
(i.o. the governments or Great Britain, U.S.A, Soviet Union. etc.) strove to
keep secret, these "little fry" diligently tattled. It was fun to
read their messages. Poland and some of the Balkan governments were the worst.
Notes:
(1). German
Foreign Ministry’s Political archive - TICOM
collection - file Nr. 3.676 - Griechenland 1940 - Korresp. betr. Neue
milit. Schlüssel u. Vernichtung alter
(2). TICOM report I-58 ‘Interrogation of Dr. Otto Buggisch of OKW/Chi’
(3). TICOM
report I-170 ‘Report on
French and Greek Systems by Oberwachtmeister Dr. Otto Karl Winkler of OKH/FNAST
4’
(4). Archivio
dell' Ufficio Storico della Marina Militare, Rome
(5). US
National archives - collection RG457 - Entry 9032 - NR 664, 665, 666 'Greek
Cryptographic Lexicon I, O and I, NR 703, 704, 705, 706 'Greek Cryptographic
Lexicon Φ,
H, 1927, 1931, NR 2104 'Greek Cryptographic Lexicon'
(6) SRH-361 ‘History
of the Signal Security Agency Volume Two The General Cryptanalytic Problems’,
p190-196, p301.
(7). TICOM
report I-123
‘Interrogation Report on Rudolf Trappe (Civilian) of OKW/Chi’ and I-150
‘Report by Uffz. Heinz W. BEYREUTHER on the Organisation of OKW/CHI’
(8). TICOM
report DF-187B
‘The cryptanalytic successes of OKW/Chi after 1938’, p11-12
(9). TICOM
report I-22
‘Interrogation of German Cryptographers of Pers Z S Department of the
Auswaertiges Amt’, p20
(10). TICOM
report DF-241
‘Part 1’, p10
(11). TICOM
report I-25
‘Interrogation of five members of the RLM/Forschungsamt at Schloss Gluecksburg,
near Flensburg on 15th and 21st June 1945’, p8
(12). German
Foreign Ministry’s Political archive - TICOM
collection - files Nr. 2.256
Griechenland ‘’GC B 4251-450’’ Diplom. Verkehr Vollst. Entschlüsselt and
Nr. 781 Griechenland 1944 Entschl. Verkehr zw. zahlr. Griech. Konsulaten.
(13). War
Secrets In the Ether Part III by Wilhelm F. Flicke, p395-396
Acknowledgments: I have to thank Enrico
Cernuschi for sharing the messages from the Archivio dell' Ufficio Storico
della Marina Militare.
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