WWII
histories of signals intelligence and codebreaking are currently focused on the
theatres where German and Japanese troops fought against the Anglo-Americans.
The influence of ULTRA intelligence on the Battle of the Atlantic, the North
Africa campaign, the Normandy invasion, the battle of Midway etc is mentioned
not only in specialized books but also in the popular histories of the war.
On the other
hand the Eastern
Front is completely neglected in this aspect, despite the fact that
millions of troops fought in countless battles and endured horrendous losses for
several years in the largest land campaign in history.
Codebreaking
and signals intelligence played a major role in the German war effort. We know
that the Army had 3 signal intelligence regiments (KONA
units) assigned to the three Army groups in the East (Army Group North,
South and Centre). In addition from 1942 another one was added to monitor
Partisan traffic. The Luftwaffe had similar units assigned to the 3 Air Fleets
(Luftflotten) providing aerial support
to the Army Groups.
Both the Army and the Luftwaffe also established central cryptanalytic departments
(Horchleitstelle Ost and LN Regt
353) for the Eastern front in East Prussia. So as we can see the Germans
certainly invested significant resources on sigint.
During the
war this effort paid off. We know that the German codebreakers could solve Soviet low, mid and (for a time) high level cryptosystems. We also know that they
intercepted the internal
radio teletype network carrying economic and military traffic. Traffic
analysis and direction finding also played a big role in identifying the Soviet
order of battle.
Having looked
at the German side we need to turn our attention to the Soviets. What were the
successes of the Soviet side in this shadow war?
Unfortunately
there is no clear answer to this question. The Soviet archives relating to
signals intelligence are closed and information on codebreaking is hard to find
and verify. This means that there are limited sources that a researcher can use and
in some cases it will be necessary to resort to deductive reasoning.
Prewar
developments
The Tsarist empire invested
considerable resources in the field of secret intelligence and codebreaking.
The agents of the feared Okhrana
monitored revolutionaries and other enemies of the regime and its ‘Black
Chamber’ (Cherniy Kabinet) could decode the telegrams of foreign ambassadors.
The new
Soviet state took over some of these codebreakers and put them back to work. In
1921 the Spetsial'niy Otdel (Special
Department) was created and it was housed in a building of the People's Commissariat
of Foreign Affairs on Kuznetskiy Most Street, Moscow. In 1935 it was moved to
the NKVD’s Lubyanka office complex. Security measures were draconian with the
personnel being told not to reveal even the location of their offices to their
relatives.
Head of the
department from 1921-37 was Gleb
Ivanovich Bokii, a loyal Bolshevik who had ruthlessly suppressed enemies of
the Soviet state during the Russian civil war. His
deputy was Major Pavel Khrisanfovich Kharkevich.
The Spetsodel
initially employed many former Tsarist codebreakers who were assisted in their
work by compromised cipher material provided by foreign spies. The Soviet
foreign intelligence service was able to recruit personnel with access to
cipher material in many countries during the 1920’s and 30’s.
During this
period the Soviet codebreakers were able to exploit the codes of several
foreign nations including Britain, France, Germany, Italy, Japan, USA, Poland
and many others. The main target was Japan due to the military incidents in the
Far East between the Soviet forces and the Kwantung Army.
Special operational groups of the Spetsodel were sent on these
operations. A small group went to Spain in 1936 were it succeeded in reading
the messages of Franco’s military forces and also of their spy network.
In early 1938 a group was sent to China to assist the Government forces
of Chiang Kai-shek in their fight against Japan. In the course of the following
months 10 Japanese tactical cryptosystems were solved.
In 1939 the
codebreakers were able to assist General Zhukov in the battle of Khalkhyn Gol by reading the code used by the
Kwantung Army.
The purges
of the 1930’s
The many
successes of the Special Department did not shield it from the purges of the
1930’s. During that period people from all aspects of Soviet society suffered
from accusations of spying and sabotage and there were show trials and executions.
The purges
crippled the cryptologic service since many of its workers were executed along
with the top administrators. Bokii was executed in 1937 with most of the
section heads and the Tsarist era personnel suffering the same fate.
These self
inflicted wounds came at the worst possible time since in September 1939
Germany invaded Poland and thus started World War II.
The Great
Patriotic war
In 1941 the
crypto service was redesignated as the 5th Department of the NKVD under the
efficient administrator Major Ivan Grigoryevich Shevelev.
The German
invasion led to the rapid expansion of the department and Shenelev recruited
some of the best mathematicians and technicians in the Soviet Union. According
to Matt Aid ‘By the end of World War II,
the 5th Directorate controlled the single largest concentration of
mathematicians and linguists in the Soviet Union.’
The Red Army
also had its own signal intelligence and codebreaking department under the
Chief Intelligence Directorate - GRU.
In 1930 the GRU decryption department became part of the Spetsodel but was
split off again in 1938.
In 1941 the
radio intelligence service was the 8th department of the Intelligence
Directorate of the Army General Staff. Head of the unit was Engineer 1st Rank
I.N. Artem'ev. The GRU controlled special radio battalions called OSNAZ. At the
start of the war there were 16 of these battalions.
How did the
Soviet radio intelligence organizations perform during the war?
Period
1941-42
We know that
in 1941 they were suffering from the loss of experienced personnel. It also
seems that the numerous GRU radio battalions were primarily tasked with monitoring
their own military forces for breaches of security and thus neglected to keep
foreign units under close observation.
The German
surprise attack caught the entire Soviet military in the process of
mobilization and movement of units. The great defeats of 1941 led to the loss
of equipment, cipher material and personnel. However it seems the Soviets were
also able to win some important victories in the radio war.
In the autumn
of 1941 a group led by NKVD cryptanalyst Sergei Tolstoy was able to solve the PURPLE cipher
machine used by the Japanese Foreign Ministry. The decrypts showed that Japan
would not attack the Soviet Union in support of the Germans. This information
allowed the Soviet leadership to concentrate all available resources against
Germany. Japanese diplomatic traffic continued to be read throughout the war
and provided important insights into the political and military developments in
Axis countries.
In the
military front there is no indication that German cipher machines were solved cryptanalytically
but in late 1941 the Soviets were able to capture Enigma machines and
documentation of the German Second Army. The information obtained might have
played a role in the Battle of Moscow.
Germany’s
Allies were easier targets. According to a recent book on Russian cryptology
the Army codebreakers were able to read messages exchanged between the Romanian
high command and General Manstein in the Ukraine during the period 1941-42.
The Soviet
Stalingrad offensive took advantage of the fact that the sides of the German
front were held by Romanian and Hungarian troops. It is not unreasonable to
assume that some of this information was acquired through signals
intelligence.
A report from
the
GRU to Stalin dated November 29, 1942 says that: ‘Direction finding of German army radio stations provided valuable
information about enemy groupings, their activities and intentions….The
cryptanalytic service of the Chief Intelligence Directorate of the Red Army
identified the main German and Japanese general military, police and diplomatic
ciphers, including 75 systems of German intelligence. More than 220 keys to
them, and more than 50,000 German messages were read…The research group of our
office has revealed the possibility of solving German messages enciphered on
the ‘‘Enigma’’ machine, and started to construct equipment, speeding up the
solution.’
The crypto
systems mentioned must have been the hand ciphers used at low and mid level by
the German military, police and Abwehr.
In 1942 there
was a major reorganization of the NKVD and GRU radio intelligence services. The
5th department took control of the evaluation and distribution of
Soviet crypto systems and also absorbed the GRU cryptanalysts.
The 8th
department concentrated on traffic analysis and direction finding in order to
reveal the order of battle of the German units.
Period
1943-45
In the second
half of the war the German forces were in retreat and the Soviets liberated the
occupied territories and ended the war by capturing Berlin. During this period
the Soviet military had a significant numerical advantage in troops and
equipment against the Germans. This makes it difficult to assess the importance
of signals intelligence in the Soviet victories since many different factors
were at play.
Still we do
know that through direction finding and traffic analysis the Soviets were able
to identify German formations and follow their movements. For example the
article ‘Spies, Ciphers and 'Zitadelle': Intelligence
and the Battle of Kursk, 1943’
says : ‘a captured intelligence
report of the Soviet 1st Tank Army dated 5 July 1943 revealed that radio
intelligence had identified the positions of the headquarters and units of II
SS Panzer Corps, 6th Panzer and 11th Panzer Divisions before the offensive
began. Other captured documents disclosed that 7th Panzer Division, XIII Corps
and Second Army headquarters had all been similarly ’fixed’ by Soviet radio
intelligence.’
The Soviet
codebreakers were definitely able to solve German hand ciphers and they must
have captured Enigma machines and their keylists when they encircled German
units (especially in the summer of ’44).
Help from
abroad
The Soviets
received assistance from two foreign sources. On the one hand the British
occasionally shared some of the intelligence that they acquired by breaking
German codes. The source was always camouflaged since the Brits did not want to
reveal their cryptologic successes to the Soviet government.
Apart from
general warnings about impending German actions the Brits also sent more
detailed reports. In April ’43 they transmitted a report sent by General von
Weichs to Foreign Armies East that revealed the main points of the German
plan for the battle of Kursk. In October of the same year they informed the
Soviet authorities about the Abwehr’s Klatt network.
Although the
British authorities were careful to hide the source of their reports the
Soviets already knew about Bletchley Park and the Enigma codebreaking through
their spy network. During WWII Kim Philby and Anthony Blunt passed along
information on Abwehr ciphers while John
Cairncross was able to infiltrate Bletchley Park.
According to ‘The Crown Jewels: The British Secrets at the Heart of the
KGB Archives’, p218-9 in 1942 apart from decrypted messages Cairncross was able
to get ‘two volumes of the secret
training manual on deciphering, a guide for the reading of the German Enigma
key codenamed TUNNY and a description of a machine constructed by the British
to read the Luftwaffe's cipher traffic’.
Tunny must refer to the SZ42 teleprinter and not Enigma. The part about
the machine used on the Luftwaffe cipher traffic could refer to the bombes but
it is not clarified in the book.
The information provided by Cairncross could have allowed the Soviet
codebreakers to overcome cipher research problems.
Working
backwards
Since we do not
have details on what systems the Soviets could exploit it might be best to work
backwards. By looking at the cryptosystems used by the Germans we can check if
their security was such that they would have resisted a well organized attack
by a group of mathematicians and linguists.
Overview
of Axis cryptosystems
Germany
Military
The German
military used cipher teleprinters of the SZ42, T52 and T43 types for top level
communications, the Enigma machine from regiment upwards and various hand
ciphers for frontline use.
Lorenz
SZ42
The main
radio-teletype machine used in the East was the Lorenz SZ42. This was
quite a complex machine and regular solution required the use of very advanced
cryptanalytic equipment. The Brits built the Colossus computer in
order to decode this traffic. The Soviets were probably unable to build similar
equipment but they could have decoded messages ‘in depth’ using hand methods.
This was the standard practice at Bletchley Park prior to the introduction of
high speed cryptanalytic equipment.
At this time
there is no information on Soviet analysis of German teleprinters.
Enigma
The plugboard Enigma
was used by the German Army, Navy and Airforce as their main cipher system.
Throughout the war its security
was upgraded with new procedures and modifications. Could the Soviets have
decoded Enigma traffic like Bletchley Park?
The GRU 1942
report says ‘The research group of our
office has revealed the possibility
of solving German messages enciphered on the ‘‘Enigma’’ machine, and started to
construct equipment, speeding up the solution’. However there is no mention
of actually decoding traffic.
This
possibility was examined by Geoff Jukes in a series of articles in the 1980’s.
However both his articles were based on inferential evidence and the responses
by Milner‐Barry and Ralph Erskine effectively
countered Juke’s arguments.
David Kahn who
interviewed KGB General Nicolai Andreev (head of the KGB’s sigint department in the 1970-80's) in
1996 was told that the Soviets knew how to solve the Enigma and although they
didn’t have bombes ‘it might have been possible to organize
people to replicate the mechanisms work’. From Andreev’s statement it is
not clear if this was actually done with real traffic.
The Soviets
definitely captured intact Enigma machines and valid keylists during the war.
Using them they would have been able to decode older traffic. However there is
no indication so far that they were able to recover the settings
cryptanalytically.
This information
seems to be confirmed by the war diary of the German Army’s Inspectorate 7/VI.
The March 1943 report of Referat 13 (security of German cipher machines) says that based on the published
radio dispatches from Stalingrad Inspectorate 7/VI was asked to give an opinion from the point
of view of decipherment.
Schlüsselüberwachung
Auf grund der veröffentlichten
Funksprüche asus Stalingrad wurde In 7/VI um ein allgemeines Gutachten gebeten,
das die Stellungnahme vom Standpunkt der Entzifferung enthält.
Thus it seems
that the Soviet effort to decrypt Enigma messages was identified early and
countered by the Germans.
Such a failure could be attributed to several factors:
1). They
started their analysis of the Enigma late in the war and thus could not exploit
the insecure signaling procedures of the period up to May 1940. In the period
1942-45 the Germans introduced many new security measures that would have made
a solution much more difficult than in 1939-40 when Bletchley Park made its
start.
2). Most of
the Enigma traffic in the East would be from Army units that traditionally had
a higher level of security than their Airforce counterparts. Army traffic
routinely caused problems for Bletchley Park, despite their large number of ‘bombes’.
Hand
ciphers
The German
army used hand ciphers at division level and below. For most of the war the
main systems were double Playfair and 3-letter field codes.
The double
Playfair- Doppelkastenverfahren was
a modification of the well known Playfair cipher but
instead of one square it used two. The text was broken up into digraphs and
they were enciphered using the two alphabet squares. According to Dr Fricke, a
German cryptologist who evaluated the security of Army systems, up to 1942 the
digraphs were enciphered only once but from that point on they were enciphered
twice. A report by Allied personnel who worked on this system says that ‘Each German division had its own set of
cipher boxes. It was assigned six different boxes for each day. These were
paired in different combinations for each day's eight three hour periods. In
effect, there were eight keys per day.’
The army also
used 3-letter codes. Initially these were used unreciphered but from 1942 they were enciphered with daily
changing trigraphic substitution tables.
Both these
systems had limited security. It is probably safe to assume that this traffic
was regularly solved by the Soviets and gave them tactical intelligence and OOB
data. However their success with military hand ciphers could not have lasted
for the entire war.
In 1944 the
double Playfair was replaced with the Rasterschlüssel
44, a transposition system using a stencil. The RS 44 had impressive
security for a hand cipher and confounded the analysts of Bletchley Park. The Soviet
codebreakers must have been similarly annoyed that the double Playfair was
replaced by such a secure cipher.
Radio
procedures
According to
German personnel the radio procedures of their units (callsigns, indicator
groups) were insecure and thus simply through traffic analysis and direction
finding the Soviets were able to identify enemy units and concentrate their
attacks at their flanks.
Intelligence services
The military
intelligence service Abwehr infiltrated
spies in the Soviet rear areas through WALLI I, a unit controlled by Major Hermann Baun. The ciphers used
by the Abwehr in the field were mostly transposition systems. The codebreaker
of Bletchley Park were able to solve Abwehr ciphers throughout the war. There
is no reason why these simple systems would resist solution by the Soviets. The
GRU report specifically mentions the Abwehr traffic: ‘….including 75 systems of German intelligence.’
Additional information on Abwehr ciphers was provided by the Cambridge
spy ring.
Central Abwehr stations also used a small number of Enigma G machines. The G (Counter) version did not have a plugboard since its
security laid in the irregular stepping system of the wheels. Bletchley Park
was able to solve this machine in late 1941 and the traffic was regularly read.
There is no indication that the Enigma G was solved by the Soviets, although it
would be theoretically possible (for example by using reencodements from hand
ciphers).
In one case we definitely know that the Soviets exploited the
communications of the Abwehr. In Sofia, Bulgaria the Klatt bureau gathered intelligence
from sources that were supposedly working inside the Soviet Union. The traffic
of the Sofia station was intercepted by the Brits who found the information
valuable. Through their spies inside British intelligence the Soviets learned
of the Klatt bureau and started intercepting the Vienna-Sofia traffic from
autumn 1941. According to ‘The Crown
Jewels: The British Secrets at the Heart of the KGB Archives’, p197 the Soviet
codebreakers were able to solve the cipher in July 1942 and found it to be ‘a letter cipher of a comparatively simple
system’. The same source says that the traffic on the Sofia-Budapest link
was also decoded.
The
intelligence service of the SS – Sicherheitsdienst recruited POW’s
and after a brief period of training and indoctrination sent them to the Soviet
rear on espionage and sabotage missions. This operation was called ‘Zeppelin’
and it was clearly a numbers game. The Germans did not expect their agents to
survive for long. The SD probably used several different cryptosystems, however
just like the Abwehr it seems that the most widely used one was double
transposition. Considering the limited training afforded to the ‘Zeppelin’
agents it is probably safe to assume that they would not be taught complex
cryptosystems. Just like the Abwehr there is no reason to assume that these
messages were secure from Soviet eavesdroppers.
Organisations
in the rear areas
Could the
Soviet radio intelligence services have gotten information on events in the
occupied areas of the Soviet Union? Although the Germans were well supplied
with radios they only used them when landlines were not available. In the East
they quickly built up a ground network using telephone cable and drehkreuz
lines. This means that most traffic in the rear areas would go by landline.
However some
organizations had to use the radio more often and their traffic could
potentially be exploited.
Police
The German
police - Ordnungspolizei
was a militarized organization and during the war several of their units served
as occupation troops in the East. Their radio communications were enciphered with
the simple and double Playfair system and from 1944 the RS44 stencil. According
to Major Schlake, head of communications in the Main office of the Ordnungspolizei, only a small number of Enigma machines (about 20) were used by the police.
According to ‘The history of Hut 6’ the Enigma was introduced in February 1944
for use by higher police officials in occupied Europe. The Brits called this
key ‘Roulette’ and were able to solve it mainly thanks to reencodements from
double Playfair.
There is no reason why the simple and double
Playfair would resist an attack by the Soviet codebreakers. The GRU 1942 report
says that police ciphers were identified and ‘valuable reports were obtained
about the fighting ability of partisans on territory occupied by the Germans.’
This information must have come from police reports.
German railways
The German
railways - Deutsche
Reichsbahn used a small number of rewired commercial
Enigma machines for radio traffic. The key used in Eastern Europe was named ‘Rocket’
by Bletchley Park and was first solved in early 1941.
The commercial Enigma was not as secure
as the military version because it lacked a plugboard. On the other hand the
wheels were wired separately for the Reichsbahn, so a cryptanalytic attack
would need to recover the wirings first.
So far there is no indication that the Soviet
codebreakers were successful with that task but it would be theoretically
possible since no special cryptanalytic equipment was needed.
German Allies
Apart from
German troops there were also Finnish, Romanian, Italian, Slovakian and
Hungarian units fighting in the Eastern front. Their contribution was important
especially in the period 1941-42, with numbers peaking in summer ’42 at roughly
850.000 troops.
These
countries used mainly hand ciphers so in theory their traffic should be
vulnerable to cryptanalysis. As has been mentioned previously the traffic of
the Romanian command was read in 1941-2 by the Soviet codebreakers.
The Germans
were aware of the insecurity of some of their Allies cryptosystems and in 1942
they gave them a number of plugboard Enigmas but still most of the traffic
would go through insecure systems. For example the cipher used by the Romanian
police was found to be very simple and it was a security risk since the police
routinely reported the movement of German units passing through their country.
Additional
research is needed to identify the cryptosystems used by the minor Axis nations
in the East and their exploitation by the Soviets.
Conclusion
The use of
signals intelligence and codebreaking by the Germans and Soviets in the Eastern
front is a subject that has received very little attention by historians so
far. The main reason was probably the lack of adequate sources. That excuse
might have been valid a few years ago but today the newly released TICOM
material allows the researcher to discover many details about the performance
of German sigint in the East.
When it comes
to the Soviet side we know that they performed well prewar but there is limited
information on the codesystems they solved during the war. The Soviet state
invested significant resources in its signal intelligence agencies and the NKVD
crypto department apparently gathered the top mathematicians and linguists in
the country. The collaboration of such a gifted group of individuals must have
led to the solution of numerous foreign cryptosystems.
Unfortunately
the information we have so far is limited and fragmentary. Perhaps more
information will be released in the future.
Sources: ‘The Mitrokhin archive’, ‘The
codebreakers’, ‘The Crown Jewels: The
British Secrets at the Heart of the KGB Archives’, ‘Russian cryptology’, ‘The
History of Information Security: A Comprehensive Handbook’ chapter 17-‘Eavesdroppers
of the Kremlin: KGB sigint during the Cold war’, ‘British intelligence in the
Second World War vol2 and vol4’, ‘Decrypted Secrets: Methods and Maxims of Cryptology’,
‘The history of Hut 6’ vol2, ‘Kursk 1943: A statistical analysis’, FMS
P-038 'German Radio intelligence' , FMS
P-132 ‘Signals Communications in the East - German experiences in Russia’, ‘The Soviet cryptologic service’, NSA report: ‘A World War II German Army Field Cipher and How We Broke It’, Cipher Machines and Cryptology, CryptoCellar Tales, Inspectorate 7/VI Kriegstagebuch, ‘О ВКЛАДЕ
СОВЕТСКИХ КРИПТОГРАФОВ В ПОБЕДУ ПОД МОСКВОЙ’
Various TICOM reports including DF-112, DF-292, I-20, I-91, I-121, I-129.
‘Cryptologia’ articles: ‘Summary Report of the State of the Soviet
Military Sigint in November 1942 Noticing “ENIGMA”’,’ Russian and Soviet
cryptology iv – some incidents in the 1930's’, ‘Soviet comint in the Cold war’
‘Journal of Contemporary History’ articles: ‘Foreign Armies East and
German Military Intelligence in Russia 1941-45’, ‘Spies, Ciphers and
'Zitadelle': Intelligence and the Battle of Kursk, 1943’
‘Intelligence and National Security’ articles: ‘The Soviets and Ultra’, ‘The
Soviets and Ultra: A comment on Jukes’ hypothesis’, ‘More on the Soviets and
Ultra’, ‘The Soviets and naval enigma: Some comments’, ‘Kōzō Izumi and the
Soviet Breach of Imperial Japanese Diplomatic Codes’.
Pics: Soviet flag found through Wikipedia
Acknowledgements: I have to thank Ralph Erskine for
sharing the ‘Intelligence and National
Security’ Enigma articles, Frode Weierud for information on the German
cryptosystems, Grebennkov Vadim Viktorovich for sharing information from his
book on Soviet cryptologic history and Anatoly Klepov for
general information on the history and achievements of the Soviet codebreakers.
