Candle in the Dark: COMINT and Soviet Industrial Secrets, 1946-1956

The study ‘Candle in the Dark: COMINT and Soviet Industrial Secrets, 1946-1956’ by Carol B. Davis is available for download from the NSA website.

This version (unlike the copy at the Cryptologic Museum’s Library) is complete!

Compromise of Soviet codes in WWII

Signals intelligence and codebreaking played an important role in WWII. British and American codebreakers solved many important Axis crypto systems, such as the German Enigma machine and the Japanese Navy’s code JN25. 

Historians have not only acknowledged these Allied successes but they’ve probably exaggerated their importance in the actual campaigns of the war.

Unfortunately the work of the Axis codebreakers hasn’t received similar attention. As I’ve mentioned in my piece Acknowledging failures of crypto security all the participants suffered setbacks from weak/compromised codes and they all had some successes with enemy systems. 

Britain, the Soviet Union and the United States did not have impenetrable codes. In the course of WWII all three suffered setbacks from their compromised communications.

After having dealt with the United States and Britain it’s time to have a look at the Soviet Union and their worst failures. 

Move along comrade, nothing to see here

Compromises of communications security are usually difficult to acknowledge by the countries that suffer them. For example since the 1970’s countless books have been written about the successes of Bletchley Park, yet detailed information on the German solution of Allied codes only started to become available in the 2000’s when TICOM reports and other relevant documents were released to the public archives by the US and UK authorities.

In Russia the compromise of their codes during WWII has not yet been officially acknowledged and the archives of the codebreaking organizations have remained closed to researchers. This is a continuation of the Soviet policy of secrecy.

The Soviet Union was a secretive society and information was tightly controlled by the ruling elite. This means that history books avoided topics that embarrassed the regime and instead presented the officially sanctioned version of history. Soviet era histories of WWII avoided references to codes and ciphers and instead talked about ‘radio-electronic combat’ which dealt with direction finding, traffic analysis and jamming (1).

After the fall of the Soviet Union several important government archives were opened to researchers and this information has been incorporated in new books and studies of WWII. However similar advances haven’t taken place in the fields of signals intelligence and cryptologic history. Unlike the US and UK that have admitted at least some of their communications security failures the official line in Russia is that high level Soviet codes were unbreakable and only unimportant tactical codes could be read by the Germans. Even new books and studies on cryptology repeat these statements (2).

However various sources such as the TICOM reports, the war diary of the German Army’s signal intelligence agency Inspectorate 7/VI and the monthly reports of the cryptanalytic centre in the East Horchleitstelle Ost clearly show that the Germans could solve even high level Soviet military and NKVD codes.

More information from ‘It Wasn’t All Magic’

The recently released United States Cryptologic History: ‘It Wasn’t All Magic: The Early Struggle to Automate Cryptanalysis, 1930s – 1960s’ has some interesting information in pages 266-7 regarding the Japanese Purple cipher machine and the Soviet Longfellow cipher teleprinter.

Purple was used by the Japanese Foreign Ministry since the late 1930’s but after the war it seems that it continued to serve the Emperor! Apparently this time it was used to generate random diplomatic one-time pads. According to the report: ‘Somewhat later, Japan's reintroduction of the Purple machine to generate one-time pads for its diplomats proved quite useful to America's SIGINT monitors.’

The Soviet Longfellow cipher teleprinter was such an important target for the American codebreakers that very advanced cryptanalytic equipment was built to decode its messages:

‘Much more ambitious was Hiawatha. In late 1947 electronic potentials finally came together with a cryptanalytic opportunity to force the release of massive funding for the long-sought Electronic Super Bombe. The elusive electronic matrix finally seemed ready, and at the same time enough had been learned about Longfellow to think that a bombe would allow continuous reading of its messages.’

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‘The attack on Longfellow was thought to be just a prelude to reading the rest of Russia's most valuable communications. The Cold War, it seemed, was to have its own Ultra.’

Unfortunately this breakthrough could not be taken advantage of because the Soviets removed Longfellow from service in 1948!

‘Howard Campaigne, was furious with the Americans as well as the Soviets. When he learned that ERA's electronic bombe project was terminated, he wrote: "If we had complete coverage [of Longfellow] from the beginning [1943] we probably could have been reading their communications by 1945. If we had supported this by the analytic machinery recently planned, we could have broken out most of the available traffic. The entire story is one of 'too little too late'. This system was in use for five years, yet we were not ready to read it in quantity until it disappeared."

 If Campaigne is right and Longfellow was introduced in 1943 then it must have been the machine the Soviets called M-101.

Soviet codebreakers of WWII

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.

The Soviet codebreakers also took part in the Spanish Civil War, the Sino-Japanese war and the battle of Khalkhyn Gol.

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 8^th 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 5^th department took control of the evaluation and distribution of Soviet crypto systems and also absorbed the GRU cryptanalysts.

The 8^th 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. 

On the contrary the recent article ‘О ВКЛАДЕ СОВЕТСКИХ КРИПТОГРАФОВ В ПОБЕДУ ПОД МОСКВОЙ’, says that in late 1942 the Soviet codebreakers analyzed the Enigma cipher machine and developed ways of solving it. However their efforts failed in January 1943 due to German security measures.

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.

Pseudo and inartistic folk songs

Thanks to help from Ralph Erskine another interesting file turns up. Now we all know the evils of communism. Gulag, censorship, propaganda, Party rule etc etc

However there are some things that cannot be tolerated.

 

‘The love of Stepan Razin’ inartistic? You’ve crossed the line there comrade!

Report on the war industry of the Soviet Union

There is a file at NARA called SOVIET UNION, SURVEY OF THE RECORDS OF THE BAND I (NR 3708 CBTM13 20293A 19420201).

It is a German estimate of Soviet industrial production in 1942. I assume that some of the information on this report comes from monitoring the internal radio and radio-teletype traffic between industrial centers.

It would be interesting to compare the data on this report (and others like it) with the ‘official’ numbers from Soviet/Russian sources. Unfortunately I could only copy the first pages of this large report (~300 pages):

 

Russian Fish intelligence – A case of quantity over quality

As I’ve mentioned before the internal Soviet radioteletype network was intercepted during the 1930’s and 1940’s by the Germans and postwar by the Americans.

The intercepted plaintext traffic concerned economic and military matters and was of vital importance in finding out what was happening inside the Soviet Union.

However the Russian Fish intelligence was definitely a case of quantity over quality. This is clearly mentioned in several TICOM reports and matches the American assessment during the early cold war period.

Alexis Dettmann, head of cryptanalysis at the German Army’s cryptanalytic centre in the East -Horchleitstelle Ost, says in TICOM DF-112:

‘The monitoring and deciphering of internal radio traffic was not an assignment of army signal intelligence units but necessarily messages of internal networks were solved and worked on. Special offices in the former German army were occupied among other things with the reception of messages of Baudot circuits, the value of the results however belonged in a different sector. Even in the years 1938/39 a relatively simple devise was constructed which made it possible to reproduce directly on typewriters the Baudot messages which in part ware transmitted by high-speed transmitters. The results from the point of view of content in no wise corresponded to the expectations. Of the entire traffic monitored at great expense at best 10% was useful for economic leaders while military-political matters constituted hardly 1%.. The major portion of these messages was like the content of the long distance telephone messages and contained private or business affairs. It was learned that all these circuits were not only monitored and controlled by the NKVD but in many cases were directed by it, and that in all probability the GUP-NKVD was also responsible in large measure for the issue of cryptographic material for internal radio traffic.’

Otto Buggisch, a member of the cipher machine department of the German army’s signal intelligence agency, gives the same percentage in TICOM I-58:

‘Further on Russian Baudot – B. says that one Dipl. Ing. Gramberg came to group IV with him from In 7/VI (Army Signal Intelligence) and was used to translate the intercepted clear text in Russian Baudot. ‘’ 90% of it was unimportant’’.

The relative lack of importance of each individual message was also recognized by the Americans. According to NSA history ‘The Invisible Cryptologists: African-Americans, WWII to 1956’:

‘The ASA. effort to exploit Russian plaintext traffic began in 1946 with the part-time assignment of several linguists to the target. At that time, however, the Agency's emphasis was on the translation of encrypted messages, and the employment of scarce Russian linguists on plain text was judged to be unwarranted. Later, in May 1947, the effort was revised at the Pentagon. Individuals without security clearances or with partial clearances would sift through volumes of messages and translate all or parts of those determined to have intelligence value. Placed in charge of this group was Jacob Gurin, an ASA Russian linguist who had immigrated to the U.S. with his parents at the age of three.

……………………………………………………………………………………………………………………………………………

From the Agency's inception under William Friedman, its business was the breaking of codes and ciphers. Once the underlying text was revealed, individual messages were translated, and, after a reporting mission was established, selected ones were published on 3" x 5" cards. While individual decrypted messages could be extremely valuable, plaintext messages were most often preformatted status reports that were insignificant when considered singly. Jack Gurin was convinced that if these messages were assembled and analyzed in the aggregate, they could yield valuable information on Soviet defense capabilities.’

 

For both the Germans and Americans the limited value of single messages was leveraged by the huge intercept volumes.

FMS P-038 ‘German Radio intelligence’ says: ‘At the experimental station the volume of recordings, which were made available to the cryptanalysis and evaluation sections of the Armed Forces Cryptographic Branch and the Evaluation Control Center of OKH, averaged ten million transmissions a day.’

Information on the  Anglo-American interception is available in NSA history ‘On Watch: Profiles from the National Security Agency’s past 40 years’:

‘In addition to manual Morse, the Soviets were using a good deal of [redacted] among others. The Soviet plaintext problem was a SIGINT success story from the beginning, from the design of electro-mechanical processing equipment that could handle each new Soviet development to the painstaking analysis of the intercepted communications. A joint American-British effort against these communications in the nineteen-forties led to high intercept volume and new engineering challenges in the face of proliferating Soviet [redacted] techniques.

At one time the United States and Britain together were processing as many as two million plaintext messages a month, messages containing everything from money orders to birthday greetings. The production task was awesome, with analysts manually leafing through mountains of page copy, meticulously screening millions of messages. [redacted] The investment paid off, leading, to an encyclopedic knowledge of what was going on in the Soviet Union. Over 95 percent of what the United States knew about Soviet weaponry in the nineteen-forties came from analysis of plaintext radioprinter traffic. Almost everything American policy makers learned about the Soviet nuclear energy and nuclear weapons programs came from [redacted] radioprinter traffic, the result of fitting together thousands of tiny, selected pieces of the jig saw puzzle.’

 

Soviet cipher teleprinters of WWII

At the start of the Soviet-German war the cipher machines used by Soviet authorities were the K-37 ‘Crystal’ (a modified Hagelin B-211) and the cipher teleprinters B-4 and M-100.

Few details about these machines are known. I have covered the K-37 here. An article in agentura.ru says that the B-4 was built in the 1930’s and used in Spain during the civil war, in the Far East border incidents with Japan and in the Russo-Finnish war of 1940.

A modernized version of the B-4 called M-100 was built in 1940 and installed in American busses in order to provide mobility (it weighed 141kg). By the summer of 1941 there were 96 sets of the M-100 in service.

In 1943 a more compact version of the M-100 was built and given the designation M-101.

The agentura piece does not give details on the characteristics of these machines.

German interception of Soviet radio-teletype networks

During the 1930’s the SU started to use radio-teletype. Since 1936 the Germans had equipment that automatically intercepted and printed this traffic.

From TICOM reports it seems that the military networks used 2-channel teleprinters while the economic links used multichannel systems.

The 2-channel links employing cipher T/P assigned one channel for the cipher traffic and the other for operator ‘chat’.

There were at least three agencies that intercepted this traffic.

1). The Army Ordnance, Development and Testing Group, Signal Branch Group IV C  -  Wa Pruef 7/IV C at an experimental station in Hillersleben-Staats.

2). The Forschungsamt, an agency reporting directly to Hermann Goering.

3). The Army’s signal intelligence agency OKH/GdNA/In 7/VI (General der Nachrichtenaufklaerung) and its Group VI - OKH/GdNA Group VI.

Forschungsamt success in 1943

In 1943 the Forschungsamt informed the Army agency of their success in reconstructing a Soviet cipher teleprinter used between Moscow and the Fronts. This machine was solved because during every pause seven characters of pure ‘key’ were transmitted. A meeting was held in September 1943 between Councilor Paetzel (head of the FA’s cipher research department), Councilor Kroeger (the FA’s cipher machine specialist) and the Army agency’s Dr Pietsch (head of the mathematical research department) and Doering (head of cipher machine research).

The Soviet machine had 6 wheels. Five enciphered the respective Baudot impulses while the sixth controlled their movement.

The wheels had the following positions (pins):

wheel I – 49

wheel II – 47

wheel III – 46

wheel IV – 45

wheel V – 41

wheel VI – 43

The Soviet scrambler corresponded to the left portion of the German SZ 40/42 cipher attachment. The Forschungsamt people stated that they would build a copy of this machine in order to decrypt this traffic more efficiently.

More details about the Forschungsamt solution of the Soviet cipher teleprinter are given by Bruno Kröger in TICOM reports DF-240 and DF-241. Kröger was the FA’s cipher machine expert and during the war he solved not only the Soviet machine but also the Swiss diplomatic Enigma K.

The Soviet cipher teleprinter was used on 2-channel networks and the FA’s Technical Division was able to build equipment that automatically intercepted and printed this radio traffic. The cipher text was then examined by Kröger’s department and it was discovered that during transmission pauses the Russian letter П was enciphered seven times in succession. Messages interrupted by transmission pauses were examined and their first and last seven characters analyzed in order to uncover the operating principles of the device.

Through this cryptanalytic procedure it was possible to find out that the machine had 6 wheels that stepped regularly, then their pin arrangement was identified and with the daily key recovered all the day’s traffic could be solved.

This success however turned out to be short lived since in late 1943 the Soviet cipher machine was modified and no pure ‘key’ was transmitted during transmission pauses. It seems that from then on this traffic was only examined by the Army’s Inspectorate 7/VI.

Efforts of the Army signal intelligence agency

The Army agency Inspectorate 7/VI assigned its own unit to intercept and evaluate this traffic. This was Group VI operating during 1942-44 from Loetzen, East Prussia.

Unteroffizier Karrenberg, the member of that unit assigned to work on the cipher teleprinter said in postwar interrogations that this traffic was first intercepted in 1940 in Warsaw. However it was not systematically collected and analyzed till summer 1943. They called this traffic ‘Bandwurm’ because of the non-repeating cipher.

There were 8 T/P links from the Army Fronts to Moscow plus 2-3 Airforce links and a link to the Far East command. It was also used by the NKVD. There was no direct T/P link between the individual Front staffs. Instead messages had to be routed through Moscow.

According to Karrenberg the machine had two settings a large and a small. The large setting gave a simple substitution because the wheels did not turn. This was used for operator ‘chat’. The small setting gave an endless column substitution since the wheels moved.

In TICOM report I-153 he says: ‘In Autumn 1944 both the end of 'adder' and every pause in the cipher proper was preceded by seven key letters [redacted]. Then the traffic went off the air and reappeared in December with no external change except that the seven ‘residue' letters had been reduced to three, suggesting a modification of the machine’. In TICOM report I-30 he says that the attachment had 5 small wheels driven by a large one with a period of 43.

These were the same characteristic observed in the machine analyzed by the Forschungsamt. However another OKH cryptanalyst named Buggisch says that the FA machine and the ‘Bandwurm’ were different.

Buggisch was assistant to Doering in the cipher machine research section of Inspectorate 7/VI. In his interrogation TICOM I-64 he says that the cycle of one wheel was 37 and the others 30-80. The machine was analyzed by the mathematics department and a cryptanalyst Troeblicher or Troebliger played a leading part. Thanks to a ‘compromise’ of 8 messages enciphered with the same settings 1.400 characters of pure ‘key’ were recovered. However they were not able to solve the machine because they lacked the manpower.

Unfortunately Buggisch left the OKH agency in June 1944 so he did not know anything more.

The Germans may have failed to solve this machine but they were able to decode messages ‘in depth’ by anagramming. A machine was built that automatically printed the Baudot traffic in Hollerith/IBM cards and these were searched for repeats but with limited success.

The intercepted messages contained reports on Soviet and German military dispositions, statements by POW's, signal intelligence reports, reports for TASS and SOVINFORMBUREAU, letters concerning postings, transfers, promotions, weather situation reports and supply manifests.

Information from the War Diary of Inspectorate 7/VI

More details are available from the monthly reports found in the War Diary of Inspectorate 7/VI.

In July 1943 a report by dr Pietsch says that the examination of Russian Baudot material revealed cipher teleprinter traffic and an effort was made to copy this traffic either by LNA (Leitstelle der Nachrichtenaufklärung in Loetzen) or Staats (Wa Pruef 7/IV C). Processing was to be carried out at Referat 13:

(2) Die eingehende Beobachtung der Baudot-Aufnahmen ergab, daß neben normalen Klar- und Chitexten auch Material anfällt, daß als eigentlicher Fernschreibschlüsselverkehr anzusprechen ist. Es wurden Maßnahmen verabredet, um das Material in einer zur Bearbeitung geeigneten Form (Lochstreifen, Einbeziehung des Verständigungsverkehrs) nach Berlin zu bekommen. Eine tiefergehende Bearbeitung dürfte nur an Ort einer Empfangsstelle (LNA oder Staats) möglich sein. Ob man jedoch beim Fehlen jeder Geräte-Kenntnis über primitive Feststellungen hinauskommen kann, bleibt abzuwarten. Über die weitere Entwicklung wird Referat 13 berichten.

In August ’43 the tapes with the Baudot traffic were examined but investigations could not be carried forwards due to the limited traffic and the many errors due to bad reception.

In September ’43 dr Pietsch and dr Doering (head of Referat 13) met with their Forschungsamt counterparts Councilors Paetzel and Kroeger (the FA’s cipher machine specialist), to discuss the Soviet cipher teleprinter problem.

Investigations continued and in November ’43 the analysts of Referat 13 succeeded in solving a long message and recovering the pure ‘key’:

6. Russischer Baudot--‐Verkehr. Es gelang, für einen längeren Spruch den reinen Schlüssel zu erstellen und damit den Geheimtext zu lösen. Schlussfolgerungen über den Bau und die Wirkungsweise der Schlüsselfernschreibmaschine konnten bisher nicht daraus gezogen werden.

In December ‘43 the departments were renamed, with Referat 13 becoming Referat b2. A second message was solved and investigations continued:

6. Russischer Baudot--‐Verkehr. Aus einem zweiten Spruchmaterial wurde stückweise der reine Schlüssel ermittelt. Weitere Materialen wurden laufend untersucht.

In February and March ’44 departments b1 (general research into cipher machines) and b2 (former 13) worked on the teleprinter problem, examining the Soviet 4-letter and 5-letter Baudot traffic and the movement of the cipher wheels of the device:

Referat b1

3. Russischer Baudot--‐Verkehre: Neu in Angriff genommen wurde die Untersuchung von russischen 4B--‐ und 5B--‐Sprüchen, die in Baudot--‐Fernschreibverkehren auftreten. Die Untersuchungen befinden sich noch im Anfangsstadium.

Referat b2

5. Russischer Baudot--‐Verkehr: Die Untersuchungen über die gegenseitige Abhängigkeit der einzelnen Impulse des reinen Schlüssels wurden an weiterem Spruchmaterial fortgesetzt.

In April ’44 department b1 stated that through analysis of the indicator groups the Soviet Baudot traffic could be subdivided into three distinct groups. The first being probably a cipher machine unlike the second and the third unclear:

 3. Russischer Baudot--‐Verkehre: Durch Kenngruppenuntersuchungen gelang Trennung des Materials in drei Gruppen, von denen die erste im Gegensatz zur zweiten möglicherweise von einer Maschine stammt, während das dritte Verfahren völlig ungeklärt ist.

The report of department b2 shows that there was a meeting at Wa Prüf 7 to better organize the interception of this traffic. Investigations on the recovered pure key continued.

In the following months investigations continued but no breakthrough was achieved. There were complaints about the limited traffic intercepted.

In December ’44 four messages in depth were solved and pure key analyzed:

Russische Baudot verkehre

Aus dem anfallenden material könnte ein kompromiss von 4 phasengleichen sprüchen  gefunden werden, der zum grössten Teil gelöst wurde. Mit Untersuchungen am reinen schlüssel wurde begonnen.

In January ’45 investigations of the recovered pure key continued and in February more in depth messages were solved:

Russische Baudot verkehr

An der lösung weiterer phasengleicher sprüche wurde gearbeitet; ausserdem wurden die untersuchungen am reinen Schlüssel fortgesetzt.

The last report, of March ’45 says that investigations continued:

Russische Baudot verkehr

Die untersuchung der russischen Baudot-verfahren wurde fortgesetzt.

The Poets series cipher machines

In the immediate postwar period the Anglo-Americans were able to solve at least two Soviet cipher teleprinters. These were given the names Coleridge and Longfellow.

Coleridge was used on military networks in the European part of the Soviet Union. By March 1946 it had been solved. The Coleridge decrypts provided important intelligence about the Soviet military’s order of battle, training activities and logistical matters.

The other system, Longfellow, was reconstructed by July 1946 and the settings were first retrieved in February 1947.

It seems both machines were ‘lost’ in 1948 when the Soviets introduced emergency changes in their cryptologic systems.

It is not clear if Coleridge and Longfellow had a connection with the cipher machines that the Germans attacked during the war.

Coleridge may have been the system the Germans called ‘Bandwurm’.

Primary sources:

From TICOM I-2 ‘Interrogation of Dr. Huettenhain and Dr. Fricke at Flenshurg,21 May 1945’, p2

... they also have another machine„ funkfernschreiber, which encodes during transmission. it uses the international five impulse teleprinter code.

Q. Did the Russians use this machine much?

A. It became increasingly important during the last 1 ^1/2 years.

Q. What units used it?

A. Only the highest staffs, press and diplomatic services.

From TICOM DF-240 ‘Characteristics, Analysis and security of cryptographic systems’ - Parts III and IV, p37-39

Both texts indicated the pauses in transmission by - - - - - etc.  The cipher tape has the peculiarity that in passing from the preliminary call-up to the transmission pause, the Russian letter Π, represented in the radio alphabet by + + + + +, occurs seven times.

…………………………………………….

Now since it was natural to assume that in this transition to and from cipher texts the same letter Π= + + + + + likewise appeared seven times in each case but vas no longer recognizable due to the encipherment the first and last seven cipher values of all cipher texts interrupted by transmission pauses were subjected to special study. Since the machine, once the daily key had been set up, was used very frequently during the course of the day for sending cipher text with numerous pauses in transmission without any new daily key being set up, rather numerous fragments of a length of seven letters were available at known intervals of greater or lesser lengths.

…………………………………………….

From this it could be concluded that the first seven and the last seven letters of each secret text came from enciphering the letter Π= + + + + + seven times and hence these fragments of cipher text represented pure key text. The following study of these fragments of pure key text led to a recognition of the fact that the first impulses show the same repeated picture in the chain of plus and minus impulses at an interval of 37, the second impulses at an interval of 39, the third impulses at an interval of 41, the fourth and fifth at an interval of 43 and 45 respectively (the intervals may have been 35, 37, 39, 41, 43). This showed the length of the five cipher wheels and their cam pattern according to the day’s setting. Each cam crest caused the inversion of the plain impulse into its opposite while a cam trough left a plain impulse unchanged. The wheels regularly moved one step after each cipher letter.

With this the decipherment of the cipher text had been accomplished. The reconstruction of the cam pattern of the wheels, which was set up new each day, was easily accomplished.

From TICOM DF-241 ‘The Forschungsamt’- Part I, p25

18. The Russian radio [2-channel] cipher machine with a channel for plain text and a channel for cipher text could be studied after the Technical Division had constructed a receiving device which at the same time removed the scrambling. The five elements of the radio alphabet [bands] ware enciphered singly through five wheels which move evenly. The wheels could be set up new each day corresponding to the daily key; but the period was constant and invariable. It was possible to solve this completely.

From TICOM DF-241 ‘The Forschungsamt’- Part IV, p38

It need only be mentioned here that the 2-channel cipher machine was withdrawn from use a few days after the Forschungsamt succeeded in solving it. When the machine was put into use again some weeks later, the cipher device of the cipher channel had been so altered that solution by the previous method was no longer possible since, when switching the machine from procedure traffic to cipher text and between a pause in transmission and cipher text, the switching became effective at once and the idling period of 7 elements had dropped out. That the same machine was involved was proven only by the receiver device which still broke up the scrambled text into a clear and a cipher text in the same manner as before. Because OKH had great interest in this traffic and its own receivers did not work perfectly, and because further detailed work at this time (Autumn 1943) in the Forschungsamt was not possible, OKH received all new traffic on this machine for processing. 

From TICOM I-30 ‘Report on Interrogation of  Uffz. Karrenberg  at Steeple Claydon on 7th July 1945 at 11.00 am’, p2

The subject of this interrogation was confined to Karrenberg’s work on Russian Baudot letter ‘strip’, traffic known to the Germans as ‘BANDWURM’ and not to be confused with Russian 5-letter, traffic also carried on Baudot lines.

The Germans had not captured any of the apparatus used but considered that it consisted of two parts: 1) a Baudot-teleprinter with the letters of the Russian alphabet (excluding q and 'g') and figure and letter shift making 32 characters in all; 2) a cipher attachment consisting of 5 small wheels driven by one large wheel.

Each of the small wheels had a pattern of positive and negative impulses and each wheel worked in conjunction with one of the five impulses produced by pressing a key of the teleprinter, the effect being to add a positive or negative impulse to each of the five impulses produced by the letter being sent. This in effect means adding a letter of key to the clear letter to produce a cipher letter.

Depths were frequent on the traffic intercepted by the Germans, but they do not seem to have made any attempt to reconstruct the wheel patterns. In the case of the driving wheel they came to the tentative conclusion that it had a period of 43. The preambles of messages were always enciphered which resulted in stereotyped and known beginnings to messages. The machine setting for a message was indicated by means of a two figure number which presumably referred to a table of settings; a different table was used each day.

Before the actual start of a message a passage of operator's chat was sent enciphered by the addition of a constant letter to each letter of the clear text. This letter was then sent en clair- and repeated three times. The object of this was to see that the receiver had his machine net up correctly.

The system was used by the Army and Air Force and to a lesser extent by the N.K.W.D.

From  TICOM I-153 ‘Second Interrogation of Uffz. Karrenberg of OKH on the Baudot-Scrambler Machine (Bandwurm)’, p2

P.W. stated that he believed the ‘Bandwurm’ traffic was first intercepted in 1940 in Warsaw. As far as he had been able to make out no interest had then been taken in it. The first actual knowledge we had of a traffic with the same external features (chat. indicators, eto.) was in summer 1943 when the first real interest was taken in it and the traffic was sent to Berlin for analysis. He understood that it went to a Dr. Pietsch and Doering.

There were a number of links usually varying according to the number of armies (Frontstaebe). The maximum number was 8. One end of each link was always in Moscow, the other would be mobile, and move with the armies. There were also one or two Airforce links. There was also supposed to be a link with the Far East. Traffic was heavier from the ‘outstations’ to Moscow.

and page 3

In Autumn 1944 both the end of 'adder' and every pause in the cipher proper was preceded by seven key letters [redacted]. Then the traffic went off the air and reappeared in December with no external change except that the seven ‘residue' letters had been reduced to three, suggesting a modification of the machine. In general it is clear that some of the features of the key at least have not changed in the last nine months.

From TICOM I-64 ‘Answers by Wm. Buggisch of OKH/Chi to Questions sent by TICOM’ , p2-3

1. Russian Systems 

In 1943 B heard that the Forschungsamt (no individual names given) had claimed some success on a Russian teletype machine, and had re-created the action of the machine. It was a machine with a very long cycle being not prime but the product of several smaller cycles--like the SZ42. B. did not know the cycle of all of the individual wheels or any other details. He heard this from DOERING, who was then doing his research on the T-52, but liaison with the FA was bad anyway (Major Mettig was particularly opposed to the SS taint) and the next he heard was that the traffic found by the FA had stopped. B. remembered only that the cycle of one wheel was 37; the others, he thought, varied widely from 30-80.

Late in 1943 and increasingly in 1944 OKH itself began to intercept non-Morse, 5-impulse traffic (called ‘Hughes’ by B.). The Mathematics Referat went to work on it, with TROEBLICHER playing a leading part. At the end of 1943 the Russians created a ‘kompromiss’, giving a depth of about 8 messages with the same setting. With this they were able to recover 1400 letters of pure key and at the same time to ascertain that the traffic being passed was the 5-figure code, with regular station chat enciphered at the same time on the machine (Suggests a machine in constant motion as described by Karrenberg).Part of the depth was created within the same long message, so that the machine had a cycle, at least in this one case of about 1450 letters. The actual number was thought to be very significant by the Germans, as it was prime and so could not be the product of smaller cycles in any way that they could imagine. This differentiated it from the machine which the FA had broken. The Germans postulated either a single tape machine like the T43 or a machine in which the motions of the wheels influenced each other,1 and 2 affecting 3, 3 affecting 5, etc. as in the T52. They were never able to prove one theory or the other. (B. apologized for this. Said they did not have enough mathematicians to tackle the fascinating problem of determining what the motion must be to create this cycle. Seemed quite convinced that there would be a unique solution to the problem.) After this experience they devised Hollerith machinery to locate depths, but in fact they only found three or four more cases and none of these gave additional cycle evidence or even furnished as much pure key as the first one. B. left the section in June 1944. He thinks the traffic slumped off in the summer of 1944 and LNA took steps to try to improve the reception, as they believed the traffic was still there. TROEBLICHER was detailed to this end of the work at this time. B. stressed one fact which had surprised him, that they had never had information about either of these machines (he assumed that the one the FA broke was not the same because of the difference on cycles.) from PW or agent sources.

B. said in passing that their own security idea on the subject of wheel machines of this sort was that the cycle should not be the product of smaller periods(as in Hagelin) even if this was long. Mutual influence of wheels should be used to avoid this, but at the same time care must be taken that too short a period was not created in the process. This in fact had apparently been done by the Russians, but the fact that it was not repeated suggested to him that they might have seen the weakness and corrected it.

Troeblicher is mentioned in CSDIC (U.K.) SIR 1717, appendix A as Troebliger (Uffz). He worked in Group IV, Referat 1b as an analyst on Russian Baudot traffic.

Sources: CSDIC (U.K.) SIR 1717, SI-32 ‘Special intelligence report’,  ‘European Axis Signal Intelligence in World War II’ vol2 and vol4, TICOM reports I-2, I-64, DF-98, I-30, I-153, I-169, I-173, DF-240, DF-241, ‘The Secret Sentry: The Untold History of the National Security Agency’, Intelligence and National Security article: ‘Behind Venona: American signals intelligence in the early cold war’, Soviet cryptographic service 1920-1940 , Kriegstagebuch Inspectorate 7/VI

TICOM reports I-2, I-64, DF-98, DF-240, DF-241 can be found in my TICOM folder, reports I-30, I-153, I-169, I-173 can be downloaded from TICOM Archive.

Acknowledgments: It was Frode Weierud who first pointed to me the German interest in the Soviet teleprinter and the characteristics of the machine solved by the Forschungsamt in 1943. Credit also goes to Randy Rezabek for finding and uploading to the internet the interrogations of Karrenberg since they contain lots of information on the cipher machine.