Overview of 2016

During the year I continued to research several cases of cryptologic history. I got material from the US, British, German and Czech archives, I helped a lot of researchers by giving them information/files and I’ve also received some interesting material from my friends.

In January I had a look at some Unanswered questions of WWII cryptology and I presented information on the Compromise of a US cipher teleprinter in 1944.

In February I wrote about the German signals intelligence files in the Russian national archives and I added material on the compromise of OSS codes in WWII.

In March I presented more information on the possible exploitation of the Japanese PURPLE cipher by the German codebreakers. I also gave an overview of reports on the compromise of Allied communications in WWII.

In April I covered The ciphers of Czechoslovakia’s government in exile.

In May I added information in my essay on Case Wicher, I presented detailed information on the use of the M-138-A cipher by the US State Department and I posted Erich Hüttenhain’s statements on the solution of the M-138-A cipher from his unpublished manuscript ‘Einzeldarstellungen aus dem Gebiet der Kryptologie’.

In June I uploaded 3 missing pages from TICOM report I-22 and also the finding aid for the National Cryptologic Museum Library.

In July I looked back at all the information that I’ve uncovered these past few years in my essay July 2011 to July 2016 - 5 years of Christos military and intelligence corner and I wrote a review of ‘Code Warriors: NSA's Codebreakers and the Secret Intelligence War Against the Soviet Union’.

In August I added information on the US military attaché emergency double transposition cipher, I copied material from the British report FO 850/171 ‘Preparation of telegrams: use of code words: cypher machines and traffic: teleprinter services: en clair messages. Code 651 file 1 (to paper 4968)’ and added parts in my Typex essay and I uploaded Special Research History SRH-368 ‘Evaluation of the Role of Decryption Intelligence in the Operational Phase of the Battle of the Atlantic, U.S. Navy OEG Report #68’.

In September I gave an overview of the status of my recent FOIA cases, I added information on the Soviet analysis of the Enigma cipher machine and I located a NATO report critical of Hagelin C-type crypto machines.

In October I linked to two Australian reports detailing Japanese diplomatic and military codes of WWII. After receiving the book ‘KODY WOJNY. Niemiecki wywiad elektroniczny w latach 1907–1945’ I added some information from it in my essays on the German exploitation of Polish codes. Also during the month I uploaded the finding aid to the TICOM collection in the German Foreign Ministry’s Political Archive.

In November I added information on the history of US ciphers from the book ‘The history of codes and ciphers in the United States during the period between the world wars part ii. 1930-1939’ , I added information from the War Diary of Inspectorate 7/VI on the German analysis of Soviet cipher teleprinters of WWII and I uploaded several decoded Irish diplomatic telegrams from 1944.

In December I added information from the report ‘Dopady lúštenia šifrovacieho systému čs. londýnskeho MNO z rokov 1940-1945 na domáci odboj’ in my essay on The ciphers of Czechoslovakia’s government in exile.

Hopefully in 2017 I will be able to cover the few remaining cases of cryptologic history that interest me.

More information on the compromise of Czechoslovak ciphers in WWII

In The ciphers of Czechoslovakia’s government in exile I’ve added the following in the paragraph ‘Report on the compromise of the communications of the government in exile’:

The report ‘Dopady lúštenia šifrovacieho systému čs. londýnskeho MNO z rokov 1940-1945 na domáci odboj’, can be found in the archive of the Museum of the Slovak National Uprising in Banská Bystrica and in the Central Military Archive at Prague.

In the report Cigan analyzed the Czechoslovak STP cipher and found it insecure. In addition he proved the compromise of Czechoslovak ciphers by examining reports from the office of the high ranking SS official Karl Hermann Frank.

A report from November 1944 had a summary of Funkwabwehr (Radio Defense) operations and it said that during the previous month 8 radio links, whose cipher procedures could be solved, were kept under observation. Of special interest was traffic between the Protectorate and London regarding the preparations for the uprising.

In the month of October a total of 488 messages were solved and 8 cipher keys derived for the STP cipher.

In pages 37-41 Cigan directly compared the Funkawbehr decodes with some of the Czechoslovak telegrams found in the country’s national archives.

For example messages exchanged between the Minister of National Defense General Ingr and Ján Golian and Jaroslav Krátký in the Protectorate and with Heliodor Píka in Moscow.  

The author’s conclusion was that the use of insecure ciphers during wartime played an important role in undermining the operations of the Czechoslovak resistance movement and these events should be acknowledged by the country’s historians

Decrypted Irish telegrams from 1944

In The Irish Government Telegraph Code I’ve added some decrypted Irish diplomatic messages from 1944.

Source was the German Foreign Ministry’s Political Archive - TICOM collection – File Nr. 795 Irland 1944 Entschl. Verkehr (übersetzt) zw. d. versch. Irischen Botschaften.

Enigma research by the German Army’s codebreakers

In the period 1941-44 the cryptanalysts of the German army’s codebreaking department Inspectorate 7/VI investigated the security of the Enigma cipher machine.

I’ve copied the relevant passages from the War Diary of Inspectorate 7/VI and as soon as I get some accurate translations I’ll post the text.

Unfortunately I don’t have the files of the period 1939-40. However it is clear from the TICOM reports DF-190 that the double encipherment of the indicator was identified as a security weakness and that’s why it was changed in 1940.

Update

I’ve added the following in Soviet cipher teleprinters of WWII:

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.

Ok last one....

Ahahahahah

Top Kek

Update

I’ve added the following:

1). In US military attaché codes of WWII:

Military Intelligence Code No11 was a 5-letter codebook, printed in 1933. It was enciphered with substitution tables.

Source was the book ‘The history of codes and ciphers in the United States during the period between the world wars part ii. 1930-1939’.

2). In United States cryptologic security failures in WWII:

Under Military systems

The Military Intelligence Code No5 had been printed in 1918, Military Intelligence Code No9 in 1919, Military Intelligence Code No10 in 1927, Military Intelligence Code No11 in 1933 and Military Intelligence Code No12 in 1935.

The War Department Confidential Code No1 was introduced in the 1930’s. It was not a new codebook but rather the old Military Intelligence Code No5, provided with a new title page and supplement.

It seems that the War Department Confidential Code No2 also followed this system. According to a 1943 message of the Japanese military attaché in Hungary the War Department Confidential Code No2 was the same as the Military Intelligence Code No12.

Under Diplomatic and OSS systems

Apart from diplomatic messages their success against State Department systems also allowed them to read messages of other US agencies such as the OSS -Office of Strategic Services Bern station, Military Attaché in Switzerland. Office of War Information representative in Switzerland and possibly the Foreign Economic Administration, War Shipping Administration, Office of Lend-Lease Administration and the War Refugee Board.

Interesting articles

So far it’s been a slow year…

Here are some academic articles that I found interesting:

1). From Journal of Intelligence History: ‘Turkey’s intelligence diplomacy during the Second World War’

2). From Journal of Intelligence History: ‘Stay-behind operations, former members of SS and Wehrmacht, and American intelligence services in early Cold War Germany’

3). From Cryptologia: ‘Ludwig Föppl: ‘A Bavarian cryptanalyst on the Western front’

4). From Cryptologia: ‘Breaking “Tirpitz”: Cryptanalysis of the Japanese-German joint naval cipher’

5). From Cryptologia: ‘Deciphering ADFGVX messages from the Eastern Front of World War I’

6). From International Journal of Intelligence and CounterIntelligence: ‘Tolkachev Evidence Still Skimpy’

More freedom of information act responses from the NSA and the State Department

Recently I wrote about some of my old FOIA requests to the NSA that were processed during 2016.

Unfortunately their response was ‘a thorough search of our historical files was conducted but no records responsive to your request were located’.

In September and October I received two more letters from the NSA and State Department FOIA offices:

1). Professor Novopaschenny was head of the Russian section of Germany’s OKW/Chi (deciphering department of the Supreme Command of the Armed Forces). Novopaschenny was a former cryptanalyst of the Tsarist Navy and after the rise of the Communists he fled Russia and found work as a codebreaker in Britain (possibly for the Police/Scotland Yard). In the 1920’s he went to Germany where he met Wilhelm Fenner and together they reorganized OKW/Chi along mathematical/analytical lines.

In 2014 I requested any postwar reports/interrogations of dr Novopaschenny but it seems none are to be found as the response from the NSA FOIA office was ‘a thorough search of our files was conducted but no records responsive to your request were located’.

Fortunately there seems to be more information available online!

According to the recent Wikipedia page on Novopaschenny he was arrested by the Soviet authorities at the end of the war and died in 1950 in a camp near the Belorussian city of Orsha.

An unhappy end for a fascinating individual.

2). In 2015 I wrote the essay The compromise of the State Department’s strip cipher – Things that don’t add up… about the US cipher material transmitted from Finland and Germany to Japan during WWII.

These were solved alphabet strips and key lists for the US M-138-A cipher system.

The M-138-A cipher was used by the State Department for messages classified SECRET and (later in the war) CONFIDENTIAL.

These messages revealed that a large number of alphabets had been compromised, specifically the circular strips 0-1, 0-2, 0-3, 0-4, 0-5 and the specials 10-3, 10-1, 18-1, 4-1, 7-1, 33-1, Vichy, 38-1, 22-1, 20-3 (or 20-4) and 25-4.

That’s why I wrote:

‘These were just the strips mentioned in the Japanese traffic and not necessarily the only strips solved by the Axis (15). Yet the EASI volumes do not mention them. Nor do they mention which systems were solved by the Finnish codebreakers even though they had a detailed report on the subject. 

There is also no mention of specific embassies such as Moscow and Bern, whose messages were known to have been read by the Germans through the material found in the OKW/Chi archives and the OSS reports.

The EASI volumes are dated May 1946, so it is understandable that they only had general information on Axis codebreaking activities. Processing all the captured material would have taken years. Yet most of the information on the strip cipher was available since early 1945 (16). With the cooperation of the State Department it should have been easy to identify which embassies used these strips and for how long.’

After I wrote the essay I decided to investigate further so I requested the relevant information on the embassies that used these strips from the State Department’s FOIA office.

The response I received this month says:

‘Based on the subject matter of your request, we searched the record systems most likely to maintain responsive records: the central Foreign Policy Record Files and the Retired Inventory Management System records. After a thorough search of these systems conducted by professional employees familiar with their contents and organization, no records responsive to your request were located.’

It’s a good thing that I did my own research on the strip cipher earlier in the year!

Finding aid for the TICOM collection in the German Foreign Ministry’s Political Archive

Recently released TICOM material can be found in the TICOM collection of the German Foreign Ministry’s Political Archive.

I have uploaded the excel finding aid here. 

More information on the compromise of Polish codes in WWII

1). In The codes of the Polish Intelligence network in occupied France 1943-44 I’ve added:

Update: German decodes of the London-Grenoble traffic can be found in pages 793-877 of ‘KODY WOJNY. Niemiecki wywiad elektroniczny w latach 1907–1945’. They date from July 1943 to October 1944 and are signed ‘Szef II Oddzialu Sztabu’, ‘Marian’, ‘Alfred’, ‘Szef Ekspozytury II Oddzialu Sztabu’, ‘Lubicz’, ‘Vox’, ‘Los’, ‘Rawa’, ‘Klemens’, ‘Major Zychon’, ‘Mikolaj’, ‘Bernard’, ‘Biz’, ‘Zenon’.

2). In Polish Stencil codes and secret agent ‘’Knopf’’ I’ve added:

Update: German decodes of the Bern-London traffic can be found in pages 878-916 of ‘KODY WOJNY. Niemiecki wywiad elektroniczny w latach 1907–1945’. They date from October 1942 to September 1944 and are signed ‘Szef II Oddzialu Sztabu’, ‘Darek’, ‘Gano’, ‘Hugo’, ‘Mak’, ‘Orkan’, ‘Espe’, ‘Jerzy’

The French War Ministry’s FLD code - More clues…

I’ve written about the compromise of the French War Ministry’s FLD code by the codebreakers of the German High Command's deciphering department – OKW/Chi, however up to this point I hadn’t been able to find the official designation of this cryptosystem.

Recently I’ve discovered some clues that might clear things up.

According to the available sources this cryptosystem was used for ‘the cypher traffic between the French War Ministry and the army groups, armies and home authorities’.

The new finding aid to the TICOM collection of the German Foreign Ministry’s Political Archive has certain entries that read:

NR 3684 – ‘F4ZCUW 110’ German notes on the above French Defense Area cipher

NR 3615 – F4ZCUT’ German notes, 1931, on French code as above, used by the Defense Areas HQ’s from Schliersee.

The finding aid also mentions the French code F-90 which might have been the predecessor to F-110.

The French code F-110 is mentioned in one of Erich Huettenhain’s reports:

What was the French designation for the system that the Germans called F-110?

Possibly Code R.A.

The finding aid says:

NR 1736 – Code RA, French military code sheets and instructions for use. Various dates 1933-39 March and July 1940-42 from Schliersee.

Why do I think that Code RA was used by the French War Ministry and the Army Groups?

In the book ‘KODY WOJNY. Niemiecki wywiad elektroniczny w latach 1907–1945’, p1.046 there is a copy of a French report dated 16 April 1940.

It says:

Un code R.A. avec additif et son procede de surchiffrement (clef ZERO S.2.) pour permettre de correspondre a l'Intérieur de la Métropole avec les Autorités et Etats-Majors dotés de ce document (notamment commandants d' armes).

Google translation:

R.A. a code with additive and process for its super-encryption (key ZERO S.2.) To allow a match the interior of the metropolis with the authorities and with staffs of this document (including commanders of weapons).

I hope my friends in France will look into this case. I can’t solve everything by myself!

Reports on Japanese WWII codes and ciphers found in the Australian National Archives

Two very interesting reports detailing the main Japanese diplomatic and naval cryptosystems of WWII are available online via the Australian National Archives website.

To view the reports go to the National Archives site, click on ‘RecordSearch’, then click Advanced search for items and next to ITEM BARCODE enter 12127133 for the diplomatic report or 859305 for the Naval report.

1). The first report is titled ‘Special Intelligence Section report - Japanese Diplomatic ciphers’ and covers the codes and ciphers used by Japan’s Foreign Ministry, their characteristics and the success that the Anglo-American codebreakers had with each one.

2). The second report covers the codes and ciphers of the Imperial Japanese Navy and it is titled ‘Volume of technical records containing details of codes and cyphers’. The unofficial title is ‘The Jamieson report’.

Note that one of the systems mentioned is the JN-87 strip cipher. The Japanese thought so highly of the US M-138-A strip cipher that they copied it and used it with certain modifications!

Acknowledgements: I have to thank Professor Peter Donovan for informing me of the ‘Jamieson report’.

NATO not a fan of Hagelin cipher machines

Interesting report from the NATO online archive:

Mystics & Statistics – The Dupuy Institute blog

I’ve added a link to the Dupuy Institute blog.

Update

1). In Soviet codebreakers of WWII i added the following paragraph under Enigma:

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.

2). In Soviet signals intelligence and the German Enigma cipher machine i added:

According to the recent article ‘О ВКЛАДЕ СОВЕТСКИХ КРИПТОГРАФОВ В ПОБЕДУ ПОД МОСКВОЙ’, 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 new 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.

Another victory!

In my recent essay on The ciphers of Czechoslovakia’s government in exile I mentioned a report titled ‘Dopady lúštenia šifrovacieho systému čs. londýnskeho MNO z rokov 1940-1945 na domáci odboj’.

This report had information on the compromise of Czechoslovak communications and the impact on resistance activities.

It has taken me some time get a copy but thanks to my friend Jozef Krajcovic I finally have the report.

I will soon add some of this information in my essays on Czechoslovak ciphers.

Czechoslovak not Czech – my mistake…

I changed the title of my essay Svetova Revoluce and the codes of the Czech resistance into Svetova Revoluce and the codes of the Czechoslovak resistance.

What happened to my FOIA requests? Progress report

When I started researching WWII cryptologic history I not only copied stuff from the archives but I also requested a lot of material from the NSA’s FOIA office.

Although I have received some interesting reports from them (I-172, I-89, DF-111, DF-105, DF-176, DF-169) they are still reviewing a lot of the TICOM files that I’ve requested. Why do they need to ‘review’ material from the 1940’s? I don’t know.,,

So what’s the progress of these cases?

Let’s see, so far in 2016 i have received information on the following cases:

State Department M-138-A instructions

The M-138-A strip cipher system was used by the State Department during WWII for enciphering messages classified SECRET. The 1944 instructions can be found at NARA but the previous editions from 1939 and 1942 are not there (or at least I haven’t been able to find them).

The NSA FOIA office stated that ‘a thorough search of our archival files was conducted but no records responsive to your requests were located’.

However the 1939 instructions can be found in TICOM report DF-15 so that’s not a complete loss.

Note that the 1939 instructions describe the straight board system (30 letters taken from one cipher column) while the 1944 instructions state that channel elimination is to be used for each message.

Dr Wilhelm Vauck, head of Referat 12 (Agents section)

In 1942 the German Army’s codebreaking agency OKH/Inspectorate 7/VI created a new department tasked with the solution of enemy agents codes. This was Referat 12 (Department 12), headed by the mathematician dr Wilhelm Vauck. According to the short bio of dr Vauck found at the website of Dresden University he survived the war and was a POW for the years 1945-48.

I thought that in that period he would have been interrogated by the Allies about his wartime activities so I requested information from the NSA. The recent response was ‘a thorough search of our historical files was conducted but no records responsive to your request were located’.

Still it is possible that other agencies might have some information on Vauck. We’ll see…

Dr Herbert Lotze, head of Wa Pruef 7/IV/E

Dr Lotze was head of research on speech privacy systems at the German Army’s Ordnance, Development and Testing Group, Signal Branch Group IVe. His team solved the US Bell Labs A-3 speech scrambler and similar Soviet devices.

The response of the NSA to my request for any postwar interrogations of dr Lotze was ‘a thorough search of our historical files was conducted but no records responsive to your request were located’.

However there seems to be material on Lotze at NARA so this isn’t the end of this case.

Other cases

During the year I was able to copy from NARA some of the reports that I had requested from the FOIA office years ago. This is material that was given to NARA in 2015.

Apart from these cases there are about a dozen TICOM reports that are being reviewed by the FOIA office. Let’s hope that they are released soon.

SRH-368 ‘Evaluation of the Role of Decryption Intelligence in the Operational Phase of the Battle of the Atlantic’

The very interesting Special Research History SRH-368 ‘Evaluation of the Role of Decryption Intelligence in the Operational Phase of the Battle of the Atlantic, U.S. Navy OEG Report #68’ is available from the NSA website.

I’ve also uploaded the pdf to my Google drive and Scribd accounts.

Google drive link.

Scribd link.

Enjoy!

Wrong!

In the German Wikipedia entry on dr Werner Weber there is a mistake.

During WWII Weber worked at OKW/Chi (Oberkommando der Wehrmacht/Chiffrier Abteilung – Codebreaking department of the Supreme Command of the Armed Forces) and he solved important Japanese diplomatic cipher systems.

The first major system solved was the transposed code J-19 FUJI, used in the period 1941-43. Although some TICOM reports state that he was unable to solve the successor to FUJI this is not correct.

The next main system was also a transposed code (Japanese designation TOKI) and it was solved in the period 1943-45 by OKW/Chi and by the Pers Z agency (decryption department of the German Foreign Ministry).

Why did some Germans say in postwar interrogations that they could not solve it? I don’t know.

Why did the Allied interrogators believe them? I don’t know.

Just clearing things up… 

Typex security measures

In The British Typex cipher machine i added information from report FO 850/171 (mentioned in the book ‘Alan Turing: The Enigma’):

Countermeasures against cribbing

As an ENIGMA type device (with a reflector) Typex was also vulnerable to the plaintext-ciphertext attacks used by the Allied codebreakers against the German plugboard Enigma. In order to hinder such attacks several measures were employed, such as burying the address in the middle of the text, cyclic encipherment for short messages and insertion of random letters in the text.

For example report FO 850/171 ‘Preparation of telegrams: use of code words: cypher machines and traffic: teleprinter services: en clair messages. Code 651 file 1 (to paper 4968)’ (25) says:

‘When encyphering on the Typex machine, the encyphered version of a letter can never be the letter itself. This sometimes makes it possible to assign with absolute accuracy even a small number of words known or estimated to be in a message to the actual letters of the cypher version by which they are represented. To obviate this danger operators must from time to time press a key not demanded by the text of the message; the additional letters resulting will make the accurate fitting to the cypher version of a piece of clear text quite impossible. Such an insertion should be made on average once in every 10 words while the body of the message is being encyphered; it should be made on average once in every three words during the encypherment of the codress, the prefatory details and the beginnings and endings, whichever of the methods of encypherment in paragraph 25 is being followed; it should also be made on average once in every three words throughout very short messages when they have to be encyphered separately in Typex (see paragraph 27). The insertion should be made within words and not between them.’