Friday, September 1, 2017


In The Japanese FUJI diplomatic cipher 1941-43 I’ve added the following:

1). In ‘Allied exploitation of the improved J series codes’:

When the new J-19 system was introduced the US codebreakers were already familiar with the basic characteristics of the cipher and Rowlett quickly made important discoveries regarding the underlying code. However solution of the daily key settings was a difficult problem, especially since more resources were put into the solution of the traffic sent on the PURPLE cipher machine.

2). In ‘Australian effort’:

Progress in 1941 was slow and up to February 1942 the only keys solved were those for messages whose content was known (for example messages reporting the departure of ships). However in 1942 things progressed rapidly.

In March ‘42 a member of the British Foreign Office from Singapore who possessed an excellent knowledge of Japanese joined the section. At the same time personnel of the unit developed elaborate cryptanalytic methods for recovering the daily settings and by May ‘42 the section was able to read virtually all FUJI traffic and ‘all bigrams, except those of very rare occurrence, and most tetragrams had been recovered’.

3). In ‘OKW/Chi effort’:

The OKW/Chi designation for FUJI was system J-13/J2B4BCüRuW (Japanese 2-letter and 4-letter code with stencil and transposition – Raster und Würfel). FUJI messages were first solved thanks to a repeat message sent from Paris to Tokyo. The first message and the repeat had the same plaintext (with small variations) and they had both been enciphered with the same key. This mistake facilitated their solution and the basic characteristics of the system were identified.

The solution of the daily transposition settings and the different stencils was taken over by personnel of the mathematical research department, specifically by the mathematician dr Werner Weber.

According to Part 3 of the report I-181 ‘Homework by Dr Werner Weber of OKW/Chi’, Weber started working on Japanese diplomatic messages in July ’41 and he identified the system as a transposed code. The underlying code for some of the messages was the previously solved LA code, thus they could be read. The rest of the messages had a new code.

Solution of the new system and recovery of the code proceeded slowly in 1941. In September ’41 Weber was allocated a small staff to help him with the Japanese traffic and by February ’42 some material could be read. During the year the new system was solved and most of the circular and European/Middle East traffic could be read. In the period summer ’42 to summer ’43 the previous year’s indicators were reused and the old transposition keys and stencils were either repeated or were modified in a predictable manner (with some exceptions).

Tuesday, August 29, 2017

Info on Greek Army codes

A Greek file dated 1938 (1) mentions the following Army cryptosystems: small unit code 1937, large unit code 1937, small unit code 1938, mobilization code 1937, cryptographic lexicon 1935. 

Monday, August 21, 2017

Missing page from TICOM I-137

The TICOM report I-137 ‘Final report written by Wachtmeister Otto Buggisch of OKH/Chi and OKW/Chi’ that I recently uploaded was missing page 2.

Thankfully the NSA FOIA office has sent me the page, thus I have re-uploaded the file.

Missing page:

Tuesday, August 15, 2017

Book review – ‘TICOM: The Hunt for Hitler’s Codebreakers’

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. These operations remained hidden from the public till the 1970’s, when several books finally acknowledged the Allied codebreaking successes.

Since then countless books have been written about the Allied codebreakers, their successes and their contribution to the overall war effort.

Information about the similar successes of the Axis codebreakers is much harder to find since the relevant material only started to be declassified in the 2000’s.

The material that has been declassified reveals that at the end of the war in Europe the US and UK authorities were interested in finding out as much as possible about the operations and successes of the German codebreaking organizations. For this reason the TICOM (Target Intelligence Committee) project was created. The goal was to send small teams into Germany in order to capture the German codebreakers and their archives.

A new book has been published that covers the operations and findings of the TICOM teams sent to Germany at the end of WWII. ‘TICOM: the Hunt for Hitler’s Codebreakers’ by Randy Rezabek is available in both paperback and e-book format.

The book starts in 1944, when the Anglo-Americans expecting the war to end soon had started planning for the capture of enemy sigint personnel and archives.  The joint US-UK effort was codenamed TICOM and six teams were formed to go into Germany and search for the German signal intelligence personnel and archives.

The operations of the individual TICOM teams are covered in the following chapters. Travelling through a war ravaged Germany they had to improvise and take risks in order to locate their targets. The teams managed to retrieve important enemy personnel and files, including the entire codebreaking unit of the German Foreign Ministry. Other great successes were the capture of a ‘Kurier’ burst-radio communications device in Northern Germany, multichannel radio-teletype demodulators found buried in a camp in Rosenheim and the retrieval of the OKW/Chi archive, found in metal boxes at the bottom of lake Schliersee in Bavaria.

The author not only describes the operations of the TICOM teams but also explains the organization, personalities and achievements of the German codebreakers.

The book contains maps and several rare photographs of personnel and material from that era. There is also an appendix with an overview of the different codes and ciphers used in WWII.

Q&A with Randy Rezabek

The author was kind enough to answer some of my questions.

1). How did you become interested in WWII cryptologic history and why did you decide to write a book about the TICOM operation?

Many years ago (35+) I was saving in the Navy and was stationed at a Naval Security Group intercept site running the local photo lab. I had a clearance and learned a bit through osmosis, but it wasn’t until I read Bamford’s book The Puzzle Palace that things became clear about what we were up to. I maintained an interest in things Sigint even though life moved on in different directions.
About 2010 I was diagnosed with MS and that created physical limitations on many of my activities, so I focused on TICOM as a pastime that could focus on.
I first learned about TICOM through another Bamford book Body of Secrets, also the account in The Ultra Americans by Parrish. I found the whole topic fascinating but little researched in the literature. Since then I have acquired a personal library of 150 or so volumes on Signit, intelligence and military communications.
Since nobody else had written a book on TICOM I thought that was a worthwhile goal.

2). How hard was it to find information about the TICOM teams and the information they gathered?

About the time I got serious about this I started doing follow ups with NSA and NARA. It was around this time that TICOM documentation started being released. It was a very slow process, especially with the NSA FOIA requests, they often took years, and by the time they replied the requested documentation had been released to NARA anyway. The release of “European Axis Signal Intelligence…” was a great boon to researchers. In addition to the overview, I compiled a list of 150 or so TICOM reports that were cited in the footnotes, this gave me a guide on what to look for. I also hooked up with some other researchers in the field, such as Ralph Erskine, Frode Weierud and you. I made the acquaintance with David Kahn, who was a great inspiration, and met and corresponded with Stephen Budiansky, all have helped me find sources and sharpened my knowledge.
Otherwise it was a matter of patience watching the slow drip, drip of releases over the years. NARA was a great help, when I started out there was no use of the Term TICOM in the descriptors. But by 2012 they had reorganize lot of the catalog and put the newer TICOM stuff into their own entries.

3). You said in the book that the reasons why TICOM remained classified into the 21st century is perhaps its greatest secret. Do you think it was simple bureaucratic inertia or something else?

At this point I think it was inertia. After the end of the cold war there was no real need to keep it secret from a security viewpoint. Human sources were long retired or dead, technologies and techniques were long superseded, and the use of captured German intelligence information against the Soviets would be obvious to even the most clueless observer.. But the law says a secret is a secret until properly declassified, even if everyone knows about it. And declassification is a laborious process with little priority: as I say in the book “nobody in the NSA ever got fired for not revealing a secret.”

4). Are you going to write more books on the subject?

At this point I think I have pretty well exhausted the topic. I tried to include as many details as possible in it to provide a guide to future researchers. If something comes out in future released that alter the story then I may do a follow up article or two. However, publishers don’t see enough profit in the story to bother, that why I had to publish it myself.

More TICOM reports

The NSA FOIA office has released the following TICOM reports:


Saturday, August 5, 2017


1). In The secret messages of Marshall Tito and General Mihailović I added the Journal of Slavic Military Studies article: ‘The Key to the Balkans: The Battle for Serbia 1944’ in the sources.

2). In Svetova Revoluce and the codes of the Czechoslovak resistance I added information from the report ‘Dopady lúštenia šifrovacieho systému čs. londýnskeho MNO z rokov 1940-1945 na domáci odboj’ and a short biography of Karol Cigan (from the essay 'STP cipher of the Czechoslovak in-exile Ministry of Defence in London during WWII’ by Štefan Porubský).

Wednesday, August 2, 2017

Compromise of Greek military and diplomatic communications in WWII

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.


Tuesday, August 1, 2017

War By Numbers

Christopher A. Lawrence of the Dupuy Institute has published the book ‘War by Numbers Understanding Conventional Combat’.

Available from Potomac books and Amazon.

War by Numbers assesses the nature of conventional warfare through the analysis of historical combat. Christopher A. Lawrence (President and Executive Director of The Dupuy Institute) establishes what we know about conventional combat and why we know it. By demonstrating the impact a variety of factors have on combat he moves such analysis beyond the work of Carl von Clausewitz and into modern data and interpretation.

Using vast data sets, Lawrence examines force ratios, the human factor in case studies from World War II and beyond, the combat value of superior situational awareness, and the effects of dispersion, among other elements. Lawrence challenges existing interpretations of conventional warfare and shows how such combat should be conducted in the future, simultaneously broadening our understanding of what it means to fight wars by the numbers.

Table of contents

Preface                                                                                          ix
Acknowledgments                                                                         xi
Abbreviations                                                                                xiii
Understanding War                                                                        1
Force Ratios                                                                                   8
Attacker versus Defender                                                             14
Human Factors                                                                             16
Measuring Human Factors in Combat: Italy 1943-1944               19
Measuring Human Factors in Combat: Ardennes and Kursk       32
Measuring Human Factors in Combat: Modern Wars                  49
Outcome of Battles                                                                       60
Exchange Ratios                                                                          72
The Combat Value of Superior Situational Awareness                79
The Combat Value of Surprise                                                   121
The Nature of Lower Levels of Combat                                      146
The Effects of Dispersion on Combat                                         163
Advance Rates                                                                            174
Casualties                                                                                   181
Urban Legends                                                                           206
The Use of Case Studies                                                            265
Modeling Warfare                                                                        285
Validation of the TNDM                                                               299
Conclusions                                                                                 325
Appendix I: Dupuy’s Timeless Verities of Combat                       329
Appendix II: Dupuy’s Combat Advance Rate Verities                  335
Appendix III: Dupuy’s Combat Attrition Verities                            339
Notes                                                                                            345
Bibliography                                                                                  369

Sunday, July 30, 2017

Comrade detective

This is awesome!

Comrades, it is your patriotic duty to report to the authorities anyone who doesn’t see this TV series. 

Thursday, July 13, 2017

Working on the Dark Side of the Moon: Life Inside the National Security Agency

A new book on the NSA has been published recently. The book in question is ‘Working on the Dark Side of the Moon: Life Inside the National Security Agency’ by Thomas Reed Willemain.

Maitland, FL (May 19, 2017) –Working on the Dark Side of the Moon provides the first, ground-level look inside the super-secret National Security Agency (NSA) and a shadowy think tank affiliated with it. The author, a software entrepreneur and statistics professor, volunteered for a year-long sabbatical tour of duty in the NSA. He ended up spending several years moving between the business and academic worlds and the secret world. This book records his impressions of people and places never before described in such intimate detail.

A deeply personal account of the years spent within the most secretive organization in the world, Working on the Dark Side of the Moon explores the range of emotions an outsider experiences while crossing over to the “inside.” It also shows the positive side of an Agency whose secrecy hides dedicated men and women devoted to protecting the country while honoring the Constitution.

Willemain writes, "The very secrecy that enables NSA to be effective also cripples its ability to explain its positive contributions. Into this void are projected grossly distorted views of what NSA does and what NSA people are like. This book puts a human face on the people who work in this secret world: their character, motivations, frustrations, sense of humor. Readers can develop a more balanced and nuanced view of NSA and its people."

About the Author

Dr. Thomas Reed Willemain served as an Expert Statistical Consultant to the National Security Agency (NSA) at Ft. Meade, MD and as a member of the Adjunct Research Staff at an affiliated think-tank, the Institute for Defense Analyses Center for Computing Sciences (IDA/CCS). He is Professor Emeritus of Industrial and Systems Engineering at Rensselaer Polytechnic Institute, having previously held faculty positions at Harvard’s Kennedy School of Government and Massachusetts Institute of Technology. He is also co-founder and Senior Vice President/Research at Smart Software, Inc. He is a member of the Association of Former Intelligence Officers, the Military Operations Research Society, the American Statistical Association, and several other professional organizations. Willemain received the BSE degree (summa cum laude, Phi Beta Kappa) from Princeton University and the MS and PhD degrees from Massachusetts Institute of Technology.

His other books include: Statistical Methods for Planners, Emergency Medical Systems Analysis (with R. C. Larson), and 80 articles in peer-reviewed journals on topics in statistics, operations research, health care and other topics.

Q&A with Thomas Reed Willemain

The author was kind enough to answer some of my questions.

1). Can you give an overview of your career prior to working for the NSA?

I’ve had overlapping careers:  About 40 years as an academic, and about 30 years as a software entrepreneur. I have been a professor at Massachusetts Institute of Technology, Harvard Kennedy School of Government, and Rensselaer Polytechnic Institute. I am now Professor Emeritus of Industrial and Systems Engineering at RPI. I am also co-founder and Senior Vice President/Research at Smart Software, Inc. in Boston. A common thread has been the study of statistics, forecasting -- anything involving randomness.

2). How/why did you consider working for the NSA?

I was looking for a challenging and useful sabbatical leave. I’d previously spent a sabbatical leave at the Federal Aviation Administration and made some contributions there, even though I’d not had any formal background in aviation. I was wary of applying to NSA, since I was not in synch with the Bush administration. But I wanted another period of public service. I also knew that there would be no more intriguing place for a statistician to work. And I suspected, correctly, that when I came back to RPI I would have more to contribute to my students. That turned out to be correct, in that my courses were richer (and more computational) afterwards.

3). What did you expect working at the NSA would be like and were your expectations accurate or not?

I was very wrong about some things. One was politics, or the lack thereof. I mentioned my misgivings about President Bush. The woman who handled the sabbatical program was very diplomatic and not put off by my questions. When I finally met her in person, it turned out that she was a lesbian with an “Anybody but Bush” bumper sticker on her car – not at all fitting my stereotype of an NSA person. During the McCain-Obama election campaign, the bumper stickers in the vast parking lots were about 50:50, and there was no whiff of politics inside the wire. The only person who talked (incessantly) about the election was somebody from another country embedded with us. I did expect a high level of expertise, and that was definitely true.

Something I should have expected but did not was how radically different the culture was from my university life. I was going back and forth between “inside” and “outside”. The academic culture encourages the question “Hey, what are you working on?” I had to learn to not ask that question on the inside unless it was behind a locked door, and not always then.

Now, the NSA is a big place. And one of the people described in my book pointed out that I was in the Research Directorate, which is more like a playground for uber-geeks than most of the rest of the Agency, where a mix of civilians and service members grind out massive amounts of work every day. So my book must present a partial picture of “Life inside the National Security Agency”. I may have been the proverbial blind man feeling the best part of the proverbial elephant.

4). Why did you decide to write a book about your experiences working for the NSA and was it difficult to gain approval from the agency?

I’ll be 70 years old soon, and I found myself slowing down on the math side of things, so I looked for another way to contribute. I had a plan to begin substituting my words for my equations, and writing the book would be a good way to test the feasibility of that plan. But I was also motivated by a desire to continue serving as best I could. Most every depiction of NSA in the media has been negative, and distorted stereotypes about the people and the Agency are rampant. I wanted to offset that with an insider’s look at the reality. The Snowden affair in particular prompted me to try to offset that. It turned out that, without knowing what I was contributing to, some of my technical work helped the Agency offset some of the damage Snowden did. The book let me do more on that front.

Getting the book cleared through NSA’s pre-publication review was a slow-motion crucifixion. It delayed the book by five months and blacked out about 15% of the book. There was some lying and bullying involved. Call it a character-building moment. I wrote about the process in the LawFare blog and discussed it with the House Permanent Select Committee on Intelligence, who were already reviewing the pre-pub process. The basic problem is that the process knows only one word: “No”. I tried to get the strategic communications people involved so there would be someone to say “Yes” to the idea of permitting a pro-Agency book to be published, but so far no luck. The Agency claimed, with perhaps dubious legality, that anybody described in my book, though anonymously, could require me to remove them from the book. If they had all done so, there would have been no book. But only one insisted that she be removed. She is now a large black rectangle.

5). What new information is available from your book compared to previous studies of the NSA?

I’m fairly certain that this is the only grunt-level memoir of service in the NSA. There are a few faux-memoirs that are works of fiction. Folks at the top levels have written books (e.g., Michael Hayden), but daily life below the top has been, well, rather like the dark side of the moon. There have been policy-oriented and history-oriented books about NSA, but not people-oriented books. So what it feels like to work there has been mysterious. Much of my book is centered on descriptions of about 40 people that I worked with, and the book is about their stories as much as mine. I also paid a lot of attention to comparing life inside against life outside, especially regarding the intellectual and administrative climates (including personnel evaluation systems). There are not many “insider/outsider” stories to tell, and mine is the only one in print.

Actually, part way through my time inside, several of us academics were “traded” to NSA-affiliated think tanks. So my book is also the first to expose the inner workings of the Institute for Defense Analyses Center for Computing Sciences. That must be the world’s most comfortable SCIF, and it’s full of sharp, colorful characters. I think the director of IDA/CCS was even more opposed to publication of my book than the NSA itself, even though my book might be very helpful to recruiting people to take my place there.

6). What is your opinion on the recent Snowden revelations regarding the NSA interception of US civilian communications?

I have mixed feeling about Snowden, mostly negative. Perhaps some of his motivation was idealistic. But what he did was very damaging to the tracking of foreign targets, so he definitely belongs in jail. He also appears to be a narcissistic liar. He permitted a persona to be presented in the movie “Snowden” that was just not true. As I watched the movie, I kept thinking “That’s not true. And that’s not true. And that doesn’t really happen.” For instance, I write about my struggles to pass the repeated exams I had to take to certify that I knew about the practical implementation of the Fourth Amendment prohibitions as applied to foreign intelligence. The public should know how seriously the Agency regards those things. It is certain that something as powerful as the NSA bears constant watching, but facts ought to be the basis for judgment.

Sunday, July 9, 2017


1). I’ve made some corrections and also changed the title in The Japanese FUJI diplomatic cipher 1941-43 (for example instead of saying the Germans or OKW/Chi solved the code I mention the specific department etc)

2). I uploaded the file containing the Japanese decodes of US diplomatic traffic from Diplomatic records Office, Tokyo, ‘U.S.-Japan Relations, Miscellaneous Diplomatic Correspondence-Special Information File’ (A-1-3-1, 1-3-2). Link here.

Also fixed the broken links in Japanese codebreakers of WWII.

Saturday, July 1, 2017

The quest for the missing NAASt 5 reports - Update

In April I said that I’ve been trying to locate the two missing reports of NAASt 5, which was the cryptanalytic centre of KONA 5 (Kommandeur der Nachrichtenaufklärung - Signals Intelligence Regiment).

KONA 5 covered Western Europe and the cryptanalysts of NAASt 5 were able to solve the US M-209 cipher machine in 1944.

According to the TICOM report IF-272 - TAB ‘D’ the following NAAS 5 reports survived the war:

E-Bericht Nr. 1/44 der NAAst 5 dated 10.1.44

E-Bericht Nr. 2/44 der NAAst 5

E-Bericht Nr. 3/44 der NAAst 5 (Berichtszeit 1.4-30.6.44)

E-Bericht 4/44 der NAAst 5 (Berichtszeit 1.7-30.9.44) dated 10.10.44 

E-Bericht der NAAst 5 (Berichtszeit 1.10.44-30.12.44) dated 14.1.45

The first three can be found in the US national archives, collection RG 457 - Entry 9032 - box 22, titled ‘German deciphering reports’.

Unfortunately the last two (covering the second half of 1944) are not there.

Initially the NSA FOIA office told me that the NAASt 5 reports had been transferred to the US National archives as part of transfer group TR-0457-2016-0014. However when the NARA FOIA office checked these files they were unable to locate any report titled E-Bericht NAAs 5.

I then asked the NSA FOIA office again about these files, since it seems they made a mistake and I was told to check transfer group TR-0457-2017-0010.

Now the response from the NARA research office regarding this transfer group has been the following:

‘We have received the records of which you speak and they must first of all undergo formal accessioning and any necessary preservation. Then they will need to be archivally described and professionally arranged before they will be available for research.   ALL of those steps will depend on how many previous accessions are in line to be processed.

Although you have the most up-to-date information on these record transfers, our archival processing steps must be done prior to making the records available for public use.’

So it seems that I’ll have to wait for NARA to process the transfer group TR-0457-2017-0010 and then they can search it for the NAASt 5 reports (assuming they are there).

Thursday, June 22, 2017

German signals intelligence successes during operation Barbarossa

On June 22 1941 the military forces of Nazi Germany attacked the Soviet Union, thus starting the largest land campaign in history.

Codebreaking and signals intelligence played a major role in the German war effort. Army and Luftwaffe units relied on signals intelligence in order to monitor enemy units and anticipate major actions.

For a summary of German signal intelligence operations read Compromise of Soviet codes in WWII.

Saturday, June 10, 2017

Information on the Enigma cipher machine found in the War Diary of Inspectorate 7/VI

During WWII the German Army made extensive use of signals intelligence and codebreaking in its operations against enemy forces. German commanders relied on signals intelligence in order to ascertain the enemy’s order of battle and track the movements of units.

The German Army’s signal intelligence agency operated a number of fixed intercept stations and also had mobile units assigned to Army Groups. These units were called KONA (Kommandeur der Nachrichtenaufklärung - Signals Intelligence Regiment) and each had an evaluation centre, a stationary intercept company, two long range signal intelligence companies and two close range signal intelligence companies.

The KONA units did not have the ability to solve complicated Allied cryptosystems. Instead they focused on exploiting low/mid level ciphers and even in this capacity they were assisted by material sent to them by the central cryptanalytic department in Berlin. This was the German Army High Command’s Inspectorate 7/VI

The War Diary of Inspectorate 7/VI

Some files of the German army signal intelligence service survived WWII and were retrieved in 1947 from a camp in Glasenbach, Austria, where they had been buried at the end of the war.

The War Diary of Inspectorate 7/VI for the years 1939-45 can be found in the US National Archives, in collection RG457 and in the TICOM collection of the German Foreign Ministry’s Political Archive.

The reports of departments 1, 7, 13 and F occasionally have information on the Enigma cipher machine (both commercial and plugboard versions).

Initially department 1 was responsible for general cryptanalytic research but in 1941 department 7 was created to look into the security of German cipher systems. For a time both 1 and 7 did general crypto research. In November 1942 department 13 was created and from then on department 7 dealt solely with German hand systems, while department 13 was responsible for German cipher machines. In 1943 department F (Forschung/Research) was created to do general cryptanalytic research.

I’ve copied the relevant passages from the War Diary and used google translate. However many terms were not translated correctly so it was up to Frode Weierud, an expert on Enigma history, to correct these passages.

Thus I present the War Diary entries dealing with the Enigma machine for the years 1941-45 (I’m afraid I don’t have the files of 1939-40):

Friday, June 9, 2017

Secure ciphers - Insecure messages

In the construction and use of tactical cryptosystems there are two conflicting requirements. One is security and the other is ease of use. If a system is highly secure but hard and time consuming to use then important messages might be secure from cryptanalysis but they could arrive too late, with disastrous consequences. On the other hand if a system is extremely easy to use but insecure then the messages will get through on time but the enemy will also be able to read them.

The Slidex code, used by the US and British armies in WWII was easy to use but it could be solved in a few hours by the German codebreakers.

However the British Army’s double transposition cipher and the US Army’s M-209 cipher machine were basically secure systems, since they could only be solved through mistakes in encipherment. It seems that contrary to regulations the Allied troops did not always use these systems in the field since it took too long to encipher their messages.

UK example

Letter from the War Office to the Commanders in Chief 21st Army Group, Home Forces, Middle East, Persia-Iraq (dated February 1945):

I am commanded by the Army Council to inform you that further consideration has been given to the suitability for operational purposes of the Low-Grade cipher "Double Transposition" which was introduced for use throughout the Army by War Office letter 32/Tels/943 dated 5th November, 1943.
2. Experience shows that while this cipher affords adequate security, unit personnel find it difficult and slow to operate. There is, therefore, a tendency to avoid the use of cipher with a consequent possibility of overstrain of other safe means of communication or the use of wireless in clear to a dangerous extent.
3. It has, therefore, been decided to adopt a new Low Grade cipher, called LINEX, details of which are given in appendices A to D, in place of Double Transposition.’

US example

Report of interview with S/Sgt, Communications Section 79 Inf Div, 7th Army. (dated March 1945):

"The US Army code machine #209 was found to be something that hampered operations. It would take at least half hour to get a message through from the message center by use of this code machine and as a result the codes of particular importance or speed, for instance mortar messages, were sent in the clear."

Sources: British national archives WO 193/211 ‘Wireless, cable and signal (including cipher) communications: policy and codes: action from report of Godwin-Austen Committee’, US national archives - collection RG457 - Entry 9032 - box 1.024 - US COMSEC reports.

Saturday, May 27, 2017

The compromise of Greek partisan radio communications in WWII

A history lesson

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.

In the period 1941-44 Greece was split into three occupation zones, controlled by Italy, Germany and Bulgaria.  This measure fractured the Greek economy and together with hyperinflation and loss of value of the paper currency led to the collapse of the economy.
Greece was a poor agricultural country prior to WWII. The war of 1940-41, the splitting of the country into three occupation zones and the confiscation of goods by the occupying powers led to the impoverishment of an already poor population.

Greek resistance groups

Under these circumstances several resistance groups were formed by Greek patriots in order to oppose the Axis powers.

Small groups operated in urban centers but the bigger ones could only survive in the countryside where the presence of Axis troops was limited.

The main ones were the military wing of the Greek Communist Party - ELAS (Greek People's Liberation Army) and the liberal EDES (National Republican Greek League).

The resistance forces organized by the Communist Party were ostensibly created in order to oppose the Axis rule and liberate Greece but in reality their main goal was to eliminate their liberal rivals, unify all resistance groups under communist control and gain power in postwar Greece (1).

During the period 1943-44 the Communist forces showed more interest in attacking and destroying other resistance groups than in attacking the occupiers. One of their most infamous acts was the destruction of the EKKA (National and Social Liberation) resistance group and the execution of its commander Dimitrios Psarros.

The ΕΑΜ ELAS movement grew in power during the occupation for several reasons. Compared to the other resistance groups it had an advantage in that it was tightly controlled by the Communist Party, an organization that knew how to operate in adverse conditions. The main achievement of the communists was that they managed to get British backing for their operations. British liaison officers were transported to Greece and British money and arms supported the ΕΑΜ ELAS movement.

In addition to British support, with the collapse of Italy in September 1943, several Italian military units in the Balkans surrendered to the partisans and the capture of their heavy weapons (mortars, artillery, machine guns) gave ΕΑΜ ELAS the ability to conduct regular military operations.

Radio communications and ciphers of the ELAS movement

According to German sources ELAS radio communications began to be intercepted by the units of KONA 4 (Kommandeur der Nachrichtenaufklärung - Signals Intelligence Regiment) in early 1944.

KONA 4 was a German Army signal intelligence unit assigned to cover radio traffic from the Balkans and the Middle East. In the period 1943-44 the unit was able to decode a large volume of Yugoslav partisan traffic.

The quarterly reports of the unit for 1944 (2) show that Greek communist radio traffic was worked on by NAZ G (Nachrichten Nahaufklärungszug - Close Range Signal Intelligence Platoon).

The report Ez Bericht 1944/II says that in April 1944 radio traffic of the Greek communist groups from the areas Volos, Lamia and Olympus was intercepted. The messages were sent in 4-figure and 5-letter groups. The first procedure was a letter to figure Caesar cipher and it was discontinued by the end of April. The second procedure was double transposition with the same key used for both cages. Both were solved and 240 messages read.


Mitte April wurde erstmalig ein griechischer kommunistischer Bandenfunkverkehr mit Funkstellen im Raum Volos - Lamia und im Olymp-Gebiet festgestellt. Seither sind hauptsächlich zwei Arten von Chisprüchen der Elas (Griechisches Volksbefreiungsheer)- Verkehre angefallen: 4Z- und 5B-Sprüche.

a) 4Z-Sprüche.
Statistische Untersuchungen des Spruchmaterials ergaben eindeutige Hinweise auf ein mehrfach belegtes 2Z-Cäsar-Verfahren, das in seinen verschiedenen Schlüsselformen durch 4Z-Kenngruppen bezeichnet wird. Es wurden schliesslich fünf derartige 2Z-Buchstaben-Silben-Cäsaren gelöst. Bereits Ende April wurde dieses Verfahren ausser Kraft gesetzt.

b) 5B-Sprüche. 
Die in grösserem Umfange zwischen dem Obkdo. der Elas und der Gruppe der Divisionen Makedoniens mit ihren unterstellten Einheiten abgesetzten 5B-Sprüche wurden als Klartext-Verwürfelungen erkannt. Untersuchungen auf einfache Verwürfelungen waren erfolglos. Erst als zwei nahezu textgleiche Sprüche mit gleicher 4Z-Kenngruppe auftraten, von denen der eine die mit einer Spalten-vertauschung versehene Wiederholung des anderen war, konnte die Losung erstellt und der Spruch als Doppelwürfelverschlüsselung gelöst werden. Die folgende Entschlüsselung aller mit dieser Losung verzifferten Sprüche ergab, dass der Verschlüssler beim Obkdo der Elas besonders für volle Würfel eine Vorliebe hat. Diese Annahme bestätigte sich, als festgestellt wurde, dass darüber hinaus sogar qruadratische Würfel vorlagen, für die eine einfache Lösungsmöglichkeit besteht. In arderen Fällen lagen der Verschlüsselung halbquadratische Würfel zugrunde. Solche können gleichfalls gelöst werden, da in zwei Halbzeilen des waagerecht eingetragenen Chitextes oft eine bekannte Unterschrift gefunden werden kann. Unter Ausnutzung dieser Verschlüsselungsschwächen des Gegners wurden bisher 20 Doppelwürfelosungen erstellt.
In der Berichtszeit wurden insgesamt ca 240 Sprüche mitgelesen die wertvolle Aufschlüsse über den organisatorischen Aufbau, die militärische Gliederung und die militärischen Aktionen der kommunistischqp Banden im griechischen Raume gaben.

ELAS radio-traffic

Mid-April radio communications of a Greek Communist gang , with radio stations in the area of Volos - Lamia and Olympus, was detected for the first time. Since then, mainly two kinds of cipher messages in the ELAS traffic (Greek people's Liberation Army) have turned: 4-figure and 5-letter messages.

a) 4-figure messages.
Statistical investigations of the intercepted material gave clear indications of a multiply occupied 2-figure Caesar system, which in its various cipher forms is identified by 4-figure indicator. Finally five such 2-figure letter-syllable Caesars were solved. Already at the end of April this procedure was cancelled.

b) 5-letter messages.
The 5-letter messages, which in larger extent were sent between the ELAS headquarter and the group of divisions in Macedonia with its subordinate units, were recognized as plaintext transpositions. Studies based on simple transpositions were unsuccessful. It was not until two nearly textually equal messages with the same 4-figure indicator group occurred, of which one could be seen as a column swapped repetition of the other, that an answer was found and the message solved as a double transposition. The following decryption of all the enciphered messages with this solution revealed that the cipher clerk at ELAS headquarter had a special preference for complete transposition rectangles. This assumption was confirmed when it was found that it even square transposition templates was used, for which there exist a simple solution. In other cases, the enciphering was based on using half-square transposition templates. Those can equally be solved because in two half-lines of the vertically entered ciphertext one often will find a well-known signature. So far 20 double transposition solutions have been created using these encryption weaknesses of the enemy.
During the period under review a total of about 240 messages were read which gave valuable insights into the organizational structure, the military plans and the military action of the Communist rings in the Greek area.

The report Ez Bericht 1944/III says that double transposition continued to be used in ELAS radio communications. Due to poor cipher practices this system could be solved. In the reporting period about 120 keys were solved and 2.200 messages read.

Elas bewegung

Sämtliche Funkverkehre der Elas-Bewegung im griechischen Raume verwenden nach wie vor die Dopelwürfelverschlüsselung. Aus der bereits im letzten Bericht erwähnten Vorliebe der gegnerischen Schlüssler für volle Würfel hat sich ein gangbarer Weg zur Lösung dieser Doppelwürfel finden lassen. Unter Verwendung bereite bekannter Unterschriften wurden die Würfellosungen gefunden an quadratischen, doppelquadratischen, halb- und viertel-quadratischen Würfeln, ferner an längen- und lösungsgleichen Würfeln und Würfeln mit Spaltenvertauschung, Dass in einer Anzahl von bereits entzifferten Sprüchen auch Hinweise auf neue Losungen gegeben wurden, erleichterte die Entzifferungsarbeit beträchtlich.

Mit ca. 120 Losungen konnten in der Berichtszeit nahezu 2.200 Sprüche mitgelesen werden,

ELAS movement:

All radio traffic of the ELAs movement in the Greek area still uses the double transposition system. From the preference of the enemy cipher clerks for complete transposition squares, as mentioned in the last report, a practical method of solving this double transposition has been found. By using well-known signatures solutions were found for square, double square, half - and quarter square transposition templates, as well as solutions to same length and solution-equal transposition templates and templates with column swapping.
The decipherment work was eased considerably by the fact that a number of already decrypted messages also gave hints about new solutions. With about 120 solutions nearly 2,200 messages could be read during the reporting period.

The last report Ez Bericht 1944/IV says that approximately 50% of the messages were read:

Elas Bewegung

Der griechische Bandenfunk wurde ausschliesslich von NNA Zg G bearbeitet, der sich in der Berichtszeit 2 Monate auf dem Rückzug befand. Im letzten Vierteljahr 1944 wurde als einziges Verfahren der Doppelwürfel verwendet . Ungefähr 50% der angefallenen Sprüche wurden mitgelesen. Für ca. 30 Kenngruppen wurden die Losungen  erstellt.

ELAS movement

The Greek agent radio traffic was processed exclusively by NNA Zg G who, during the reporting period, had already been on the retreat for 2 months. In the last quarter of 1944 the only method used was double transposition. Approximately 50% of the attacked messages were read. Solutions were found for about 30 characteristic groups (indicators).

Dr. Otto Karl Winkler and TICOM report I-170

Additional information on the exploitation of ELAS communications is available from the TICOM report I-170 ‘Report on French and Greek Systems by Oberwachtmeister Dr. Otto Karl Winkler of OKH/FNAST 4’ (dated January 1946).

The report was written by Dr. Otto Karl Winkler, a member of KONA 4. Dr Winkler was in charge of decoding and translating the Greek messages and in pages 4-6 he stated about his work:

The unit moved to BELGRADE in Autumn 1943, thence, in August 1944 to PERNITZ near WIENER NEUSTADT, However, I received a new task in Spring 1944 with the appearance of Greek messages sent by ELAS. In the course of our two year stay in Athens I had been able to learn modern Greek almost perfectly, on the basis of a knowledge of classical Greek and spurred on by love for and interest in Greece. In addition my duties had provided me with a certain experience of cryptography and a good translation technique. Thus I was put in charge of Greek cryptography and was assisted in the actual cryptographic work by Uffz. Diether STROBL from BERLIN, an English interpreter and technical student. I had held the rank of Wachtmeister since Christmas 1943.

Regarding the cipher systems used he also mentions the 2-figure Caesar system and the double transposition cipher. Solution of the latter depended on the poor practices of the ELAS cipher clerks:

Double transpositions are regarded as a secure type of cipher and are therefore used by many British agents. To the best of my knowledge the unit never succeeded in breaking one and only occasional captured material has rendered it possible to read some traffic retrospectively. For the sake of security it is essential to avoid using complete or even square boxes, typical beginnings or endings of messages and constantly recurring addresses and signatures, to use each key as little as possible and as far as possible to have different keys for each box of the pairs The Greeks overlooked all these rules right up to the end, with the result that messages in the same setting and with the same number of groups (Elementeanzahl) cropped up.

The solution of these messages provided valuable information about the organization, personalities and operations of the ELAS partisan forces:

In any case we succeeded in breaking 50 – 60% of the traffic tackled and as important messages were always retransmitted on several links with different keys, we were able to build up an almost complete picture of the build-up, organization and composition of EAM and ELAS, to compile lists of their leading personalities and officers and to inform the competent German political and military authorities in good time about many planned military and political actions, acts of sabotage, ambushes, dynamitings, etc. I can only remember a few details and cannot reproduce examples systematically as the evaluation of the material wan not my job, which consisted only of deciphering, decoding and translating the available material.

Radio traffic of British liaison officers in Greece

Apart from ELAS communications the Germans were also able to read some of the messages sent by British liaison officers assigned to the Greek partisans. The German Army’s codebreaking agency OKH/Inspectorate 7/VI was able to decode some of these messages in the period 1943-44 (3).

The British authorities kept in contact with partisan groups in the Balkans through liaison officers sent by the intelligence services SIS and SOE. These small teams transmitted traffic by radio to their controlling stations in Cairo, Egypt and Bari, Italy. The cryptosystems used were double transposition and the War Office Cypher, enciphered with one time pads.
Some of the encoded radio traffic of British officers in the Balkans was exploited by the Germans. They were able to read messages both through captured material and by cryptanalysis. 

The reports of KONA 4 show that some cipher material was captured in the field and messages read. For example in 1943:

Field units had to rely on captured material in order to read British agents transmissions but this was not necessarily true of the central department. The reports of Inspectorate 7/VI show that this traffic (special traffic to Cairo with indicator GESH) was first solved in June 1943 by Referats 6 and 12:

Traffic continued to be read till November 1944 but it seems this was mostly from the team assigned to the headquarters of General Mihailović and from the liaison officers in Greece. 

For example:

September ’43:

April ’44:

July ’44:


In the period 1941-44 the Greek population suffered under a triple occupation by Italian, German and Bulgarian forces. The collapse of the Greek State, of the economy and the falling living standards led many Greeks to take up arms against the occupiers.

This situation gave the Greek Communist Party an opportunity to build up a large partisan movement in the countryside and use it to monopolize the anti Axis resistance in Greece. With support from the British and after capturing Italian heavy weapons in 1944 the Communists were one step away from gaining power in the country.

During this period the German authorities were aware of the growing strength of the partisan movements in the Balkans but they did not have the military forces needed to permanently destroy them. Instead their forces garrisoned strategic areas and urban centers.

Both in Yugoslavia and in Greece they were able to monitor the military operations and political maneuvers of the partisan movements through signals intelligence.

In 1944 the German Army’s signal intelligence agency was able to solve a large part of the ELAS radio traffic. Their success was possible mainly due to the many mistakes made by the ELAS cipher clerks. This traffic provided valuable intelligence on the ELAS organization, personalities and planned military and political actions.


(1). A good summary of the main issues surrounding the goals of the Communist party and EAM ELAS can be found in ‘Εμφύλια πάθη: 23+2 νέες ερωτήσεις και απαντήσεις για τον Εμφύλιο’ - Στάθης Ν. Καλύβας, Νίκος Μαραντζίδης (2016)

(2). KONA 4 - Ez Bericht 1944/II, Ez Bericht 1944/III, Ez Bericht 1944/IV (NARA - RG 457 - Entry 9032 - box 22 - ‘German deciphering reports’)

Additional information:

1). In TICOM report I-170, p9 an example is given of the ELAS double transposition cipher. 

The sample message reads:


My translation: ‘For Macedonian group of divisions – Day – STOP we request that you report immediately if the five officers of the British mission have arrived STOP Stefanos Sarafis’.

Stefanos Sarafis was the military commander of the ELAS forces.

2). It seems that the Greek communist military forces continued to use insecure cipher systems even in the late 1940’s. An FBI report dated August 1950 (4) says the AFSA (Armed Forces Security Agency) was working on the following Greek communist crypto systems:

These were monome-dinome substitution (enciphered with additive) and single and double transposition, similar in concept to the systems used in 1944.

It is reasonable to assume that the use of insecure ciphers by the communists was exploited by the Greek Army and US agencies during the Greek Civil War.

Acknowledgments: I have to thank Frode Weierud for translating the KONA 4 summaries and Randy Rezabek for sharing his copies.