Thursday, July 5, 2018

The Higgs memorandum - Compromise of State Department communications by the Finnish codebreakers in WWII

During WWII the US State Department used several cryptosystems in order to protect its radio communications from the Axis powers. For low level messages the unenciphered Gray and Brown codebooks were used.  For important messages four different codebooks (A1, B1, C1, D1) enciphered with substitution tables were available.

Their most modern and (in theory) secure system was the M-138-A strip cipher. Unfortunately for the Americans this system was compromised and diplomatic messages were read by the Germans, Finns, Japanese, Italians and Hungarians. The strip cipher carried the most important diplomatic traffic of the United States (at least until mid/late 1944) and by reading these messages the Axis powers gained insights into global US policy.

Germans, Finns and Japanese cooperated on the solution of the strip cipher. In 1941 the Japanese gave to the Germans alphabet strips and numerical keys that they had copied from a US consulate in 1939 and these were passed on by the Germans to their Finnish allies in 1942. Then in 1943 the Finns started sharing their results with Japan. 

Finnish solution of State Department cryptosystems

During WWII the Finnish signal intelligence service worked mostly on Soviet military and NKVD cryptosystems however they did have a small diplomatic section located in Mikkeli. This department had about 38 analysts, with the majority working on US codes.
Head of the department was Mary Grashorn. Other important people were Pentti Aalto (effective head of the US section) and the experts on the M-138 strip cipher Karl Erik Henriksson and Kalevi Loimaranta.

Their main wartime success was the solution of the State Department’s M-138-A cipher. The solution of this high level system gave them access to important diplomatic messages from US embassies in Europe and around the world. 

Operation Stella Polaris

In September 1944 Finland signed an armistice with the Soviet Union. The people in charge of the Finnish signal intelligence service anticipated this move and fearing a Soviet takeover of the country had taken measures to relocate the radio service to Sweden. This operation was called Stella Polaris (Polar Star).

In late September roughly 700 people, comprising members of the intelligence services and their families were transported by ship to Sweden. The Finns had come to an agreement with the Swedish intelligence service that their people would be allowed to stay and in return the Swedes would get the Finnish crypto archives and their radio equipment. At the same time colonel Hallamaa, head of the signals intelligence service, gathered funds for the Stella Polaris group by selling the solved codes in the Finnish archives to the Americans, British and Japanese. 

The Stella Polaris operation was dependent on secrecy. However the open market for Soviet codes made the Swedish government uneasy. In the end most of the Finnish personnel chose to return to Finland, since the feared Soviet takeover did not materialize. 

The Higgs memorandum

In September 1944 colonel Hallamaa met with L. Randolph Higgs, an official of the US embassy in Sweden and told him about their successes with US diplomatic codes and ciphers.

This information was summarized in a report prepared by Higgs, dated 30 September 1944.

The report can be found in the US National Archives - collection RG 84 ‘Records of the Foreign Service Posts of the Department of State’ - ‘US Legation/Embassy Stockholm, Sweden’ - ‘Top Secret General Records File: 1944’.

Higgs met with colonel Hallamaa on September 29 and the OSS officials Tikander and Cole were also present during their discussion.

Hallamaa stated that he was an administrator, not a cryptanalyst and about 10-12 of his men worked on US diplomatic codes.

His unit had solved the US codes Gray, Brown, M-138-A strip cipher and enciphered codebooks (probably the A1, B1, C1).

The high level M-138-A system had been solved mostly by taking advantage of operator mistakes such as sending strip cipher information on other systems that had already been broken or sending the same message in different strips one of which had been broken.

The strip cipher was considered a strong encryption system and had been adopted by the Finns for some of their traffic.

Important diplomatic messages from the US embassies in Switzerland, Sweden and Finland were read by the Finnish codebreakers.

Regarding Bern, Switzerland most of the messages dealt with intelligence matters:

Replying to my request for information regarding the contents of the messages from our Legation in Bern to the Department, Col. Hallamaa said the great bulk of them were intelligence messages dealing with conditions in Germany, France, Italy and the Balkans. He spoke in complimentary terms about ‘Harrison’s’ information service’.

Regarding Helsinki, Finland Hallamaa stated that thanks to the decoded diplomatic traffic they were always informed of current US policy initiatives:

Col. Hallamaa said that they always knew before McClintock arrived at the Foreign Office what he was coming to talk about’.

Hallamaa revealed a lot of confidential information to the Americans and volunteered to have some of his experts interviewed. 

The interview was conducted on friendly terms with Higgs stating; ‘Col. Hallamaa was most pleasant and seemed to be entirely frank and open regarding the matters discussed’.

Additional information: In November 1944 the US cryptanalysts Paavo Carlson of the Army’s Signal Security Agency and Paul E. Goldsberry of the State Department’s cipher unit interviewed Finnish officials regarding their work on US codes. Their report can be found here.

Friday, June 8, 2018

The Tanks of Operation Barbarossa

Boris Kavalerchik, tank expert and author of the Journal of Slavic Military Studies article ‘Once Again About the T-34’ has published a book on ‘The Tanks of Operation Barbarossa’.


When the Germans invaded the Soviet Union in 1941 the Red Army had four times as many tanks as the Wehrmacht and their tanks were seemingly superior, yet the Wehrmacht won the border battles with extraordinary ease the Red Armys tank force was pushed aside and for the most part annihilated. How was this victory achieved, and were the Soviet tanks really as well designed as is often believed? These are the basic questions Boris Kavalerchik answers in this absorbing study of the tanks and the tank tactics of the two armies that confronted each other at the start of the war on the Eastern Front. Drawing on technical and operational documents from Russian archives, many of which were classified until recently and are unknown to Western readers, he compares the strengths and weakness of the tanks and the different ways in which they were used by the opposing armies. His work will be essential reading for military historians who are interested in the development of armoured warfare and in this aspect of the struggle on the Eastern Front.

Q&A with Boris Kavalerchik

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

1) How did you become interested in WWII history and why did you decide to write a book on Soviet vs. German tanks during the 1941 campaign?

I've been reading and collecting books and magazines about all kinds of military hardware since I was 12 years old. In college, I had to go through military training and become a tank platoon's commander in reserve, so my knowledge of tanks became much deeper and more practical than before. After a while I started to realize that military hardware is nothing without the people who use it, and I began to pay much more attention to military history. 

The Great Patriotic War has always had special importance for people of the USSR, where I used to live. Many of my relatives, including my father, fought in that war, and some of them were KIA. Naturally, I have heard and read a lot about these historic events and become quite interested in them. Eventually, I co-authored a book about the Soviet Union and Germany's preparations for WWII, as well as that war's beginning. Tank warfare played a very important part in determining the outcome of these battles, so I decided to dedicate a separate study to this subject. That is how my book came to life.

2) What new information have you uncovered that differentiates your book from other similar studies?

In the USSR, only officially approved historians had access to the state archives. Moreover, their work had to go through government censorship and could only support the official point of view on history, which very often was far from reality. After the collapse of the Soviet Union all archives gradually became open to regular people who were interested in events from the past. More and more original archival materials began to be published and even became available online. As a result, I managed to find a lot of information which was classified until recently and had been generally unknown, especially to western readers. 

This information allowed me to reach quite different conclusions in comparison to widely held beliefs about Red Army's tanks during WWII based on old Soviet propaganda. As a mechanical engineer, I also analyzed and compared Soviet and German tanks from a purely technical standpoint, but from rarely used angles which as a rule got neglected. The results struck me as very unusual and I hope they will be of interest to my book's readers.

3) Do you think that WWII era armored vehicles truly played a decisive role in combat operations or has their contribution been exaggerated due to the ‘coolness’ factor?

I think that a very important role in WWII was played not by armored vehicles themselves but by armored forces which included not only tanks but motorized infantry, artillery, combat engineers, anti-tank and anti-aircraft units, and so on. Moreover, as a rule, armored forces fought successfully only in combination and cooperation with other services and branches of the armed forces. Tanks do have the ‘coolness’ factor, so many people mistakenly take them for wonder-weapons, capable of independently deciding the outcome of any battle. In reality, this is not the case. Nevertheless, tanks were a very significant part of the armed forces of all participants of WWII.

4) In your opinion what are the worst mistakes that popular history books make regarding German and Soviet armored vehicles and the Eastern Front in general?

In my opinion, some authors of popular history books mistakenly judge people of previous generations and their armored vehicles from today's point of view using modern criteria. Every tank, without exception, has both positive and negative aspects. In order to determine them it is necessary to know the purpose and objectives of these tanks, which were not the same in all countries or in all periods of time. So, before criticizing any tank from the past, one should determine why it was designed and built the way it was. After understanding all factors which influenced tank design in a particular time and country, we can judge these combat vehicles much more objectively.

Friday, June 1, 2018


In The Japanese FUJI diplomatic cipher 1941-43 I’ve added the following information under the paragraph ‘Pers Z effort’:

More information is available from the TICOM report DF-31B ‘How J.B. 57 Japanese Letter System Was Solved’, written by the cryptanalysts Annalise Huenke and Hans Rohrbach

The first break into system JB 57 came through two messages that had the same indicator (meaning they used the same transposition key). Once these were solved the system was identified as a transposed code, using a stencil.

Solution of this indicator led to the decipherment of more messages and dr Kunze (head of the ‘Mathematical Cryptanalytic Subsection’ of Pers Z) was able to use the information recovered in order to solve more message indicators. The inroads made by the solution of indicator groups led to the eventual recovery of the underlying code by the linguistic group and the current exploitation of this traffic.