Interesting Enigma article

Cryptologia: Enigma: the spoils of Gustave Bertrand, or “par où tout a commencé” by Jean-François Bouchaudy

Abstract

As early as 1931, Gustave Bertrand of the French intelligence services received from the traitor Hans Thilo Schmidt documents concerning the Enigma cipher machine. This machine was intended to equip all the German military forces. This is the beginning of an epic that has probably changed the History. The main documents collected by Bertrand have not been destroyed and are available in the archives of the French Army (SHD). This article describes and analyzes each of these documents, including the evolution of the Enigma and its procedures related in these documents. In conclusion, the article lists the findings that come from reading these originals and first and foremost the impact of having a cipher message with its plaintext on the British attempt to recover Enigma rotors wiring. Oddly enough, it seems that this message was not used by the Poles to break the Enigma.

Historical overview of the Enigma G cipher machine

‘Enigma G: The counter Enigma’ by David Kenyon & Frode Weierud

The article also has a reference to this interesting history of Abwehr radio communications:

‘Technik und Verfahren der Spionagefunkdienste’  (link from cdvant.org)

German cipher security reports from 1944

I have uploaded the following documents to my TICOM folder:

1). Report titled: ‘Überprüfung der Sicherheit eigener Geheimschriften’ dated 25 August 1944.

Source: Württembergische Landesbibliothek Stuttgart - Kapsel 137 / 14.

2). Report titled: ‘Niederschrift der Besprechung über Chiffrierfragen - 15.11.44’ dated 21 November 1944.

Source: German Foreign Ministry’s Political Archive - TICOM collection – file Nr 1.620 – ‘1938/45 Korrespondenz Dr. Hüttenhain’.

TICOM DF-174A

I’ve uploaded TICOM report DF-174A ‘Four papers by Fritz Menzer’.

The report has information on the Enigma cipher machine, the SG 39 cipher machine and the Enigma modification Lückenfüllerwalze.

The compromise of the Swiss diplomatic Enigma K cipher machine in WWII

In the course of WWII the Allied and Axis codebreakers attacked not only the communications of their enemies but also those of the neutral powers, such as Switzerland, Spain, Portugal, Turkey, Ireland, the Vatican State and others (1).

Switzerland was a traditionally neutral country but during the war it had close economic relations with Germany and it also acted as an intermediary in negotiations between the warring nations. Important international organizations like the Red Cross and the Bank of International Settlements were based in Switzerland.

Naturally both the Allies and the Germans were interested in the communications of the Swiss government.

Swiss diplomatic codes and ciphers

The Swiss Foreign Ministry used several cryptologic systems for securing its radio messages. According to US reports (2) several codebooks were used, both enciphered and unenciphered. These systems were of low cryptographic complexity but had an interesting characteristic in that the same codebooks were available in three languages.

French, German and Italian were the recognized official languages of Switzerland. The codebooks of the Swiss foreign ministry had versions in French, German and English.

Apart from codebooks the Swiss also used a number of commercial Enigma cipher machines at their most important embassies.

The Swiss Enigma K cipher machine

Since the 1920’s the Enigma cipher machine was sold to governments and companies that wanted to protect their messages from eavesdroppers.

The latest version of the commercial Enigma machine was Enigma K. In WWII this device was used by the Swiss diplomatic service and armed forces.

The device worked according to the Enigma principle with a scrambler unit containing an entry plate, 3 cipher wheels and a reflector. Each of the cipher wheels had a tyre, marked either with the letters of the alphabet or with the numbers 1-26, settable in any position relative to the core wheel, which contained the wiring. The tyre had a turnover notch on its left side which affected the stepping motion of the device.

The position of the tyre relative to the core was controlled by a clip called Ringstellung (ring setting) and it was part of the cipher key, together with the position of the 3 cipher wheels. 

The commercial version was different from the version used by the German Armed Forces in that it lacked a plugboard (stecker). Thus in German reports it was called unsteckered Enigma.

In 1938 the Swiss government purchased 14 Enigma D cipher machines, together with radio equipment. The next order was in 1939 for another 65 machines and in 1940 they received 186 Enigma K machines in two batches in May and July ’40. The Enigma cipher machines were used by the Swiss Army, Air Force and the Foreign Ministry (3).

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):

Cipher machines of WWII

In the period 1939-45 most countries enciphered their communications using hand methods (codebooks, transposition etc). Only a few countries used cipher machines.

The following list covers these countries and the specific models they used.

United States

SIGABA

SIGCUM/Converter M-228 T/P

SIGTOT T/P (one time tape system)

CCM - Combined Cipher Machine

M-209 (US version of the Hagelin C-38)

AT&T double tape machine

Hebern cipher machine (5 rotor version)

SIGFOY/M-325 (Enigma type)

Britain

Typex (Enigma type)

Rockex T/P (one time tape system)

CCM - Combined Cipher Machine

Poland

Lacida

Soviet Union

K-37 (Hagelin B-211 copy)

Pogoda or Pagoda (copy of US AT&T double tape machine)

M-100/101 T/P

France

Hagelin B-211

Hagelin B-211 modified

Hagelin C-38 (US M-209 version)

Hagelin C-36

Sweden

Hagelin B-211

Hagelin C-38

Norway

Hagelin C-38

Holland

Hagelin C-38

Enigma G

Portugal

Hagelin C-38

Switzerland

Enigma K

Germany

Kryha

Enigma K

Enigma G

Enigma I (plugboard machine)

Enigma M4 (4 rotor naval version)

SG (Schlüsselgerät) 41 (Hagelin type)

SZ-40/42 T/P

T-52 T/P

T-43 T/P (one time tape system)

Italy

Enigma K

Enigma G

Enigma I

OMI NISTRI

Hagelin C-38

Olivetti T/P

Japan

RED/Angōki Taipu-A

PURPLE/Angōki B-gata

JADE

CORAL

Enigma T

Finland

Hagelin C-36

Romania

Enigma G

Enigma I

Hungary

Enigma I

Slovakia

Enigma I

Bulgaria

Enigma I

Croatia

Enigma K

Spain

Enigma K

The Abwehr’s Enigma G cipher machine and Procedure 63

The Cryptologia article Mr. Twinn’s bombes is available from the Taylor and Francis website and it has some very interesting information on the Enigma G cipher machine, used in WWII by the German military intelligence service Abwehr.

The Enigma G was different from the version used by the German military since it did not have a plugboard. Also its stepping was more frequent due to the many notches in the rotors.

According to the article it was used by the following Abwehr networks:

1). Berlin, Madrid, Lisbon, Paris, Bordeaux

2). Berlin, Vienna, Budapest, Bucharest, Sofia, Salonika

3). Berlin, Vienna

4). Berlin with stations in Turkey

The device was issued with 3 rotors only (while the military version used 3 rotors from a set of 5). In some networks the rotors were rewired during the war.

Several indicator systems were used in the period 1941-44. Up to August 1942 the message key was enciphered twice on the Grundstellung (basic setting). The 8 letter sequence was the indicator at the start of the message. This was the same procedure used up to 1938 by the German Army and Airforce.

From August 1942 the double encipherment of the message key was dropped and instead it was enciphered on the Grundstellung only once.

In the period late 1943-early 1944 a new indicator procedure was introduced. This was part of new security regulations called Procedure 63 - ‘Verfahren 63’. The new system used two basic settings. One for the network and one for the station. The cipher clerk first enciphered the message key twice on the network’s basic setting and then enciphered the 8 letters again at the station’s basic setting.

It is interesting to note that an OKW/Chi report dated August 1944 says that Procedure 63 was not secure:

D) Agentenverkehr

Die Vorschrift Nr.63 genügt nur dann zeitgemässen Sicherheitsansprüchen, wenn auf jeder Linie nur wenig Verkehr auftritt. Es soll versucht werden eine bessere Vorschrift auszuarbeiten.

Es wird dafür gesorgt werden, dass alle anderen mit Enigma-Maschinen arbeitenden Behörden usw. nur die vom Ausschuss geprüften und zugelassenen Vorschriften benutzen.

Google translation:

D) Agent traffic

Regulation No.63 only meets current safety requirements if only little traffic occurs on each line. A better regulation is to be worked out.

It is necessary to ensure that all other authorities working with Enigma machines, etc., use only the regulations audited and approved by the Committee.

Breaking Enigma messages

Frode Weierud and Olaf Ostwald have written the interesting article ‘Modern breaking of Enigma cipher texts’ on modern techniques used in solving original Enigma messages from WWII.

ABSTRACT

“Breaking German Army Ciphers” is the title of a Cryptologia article from 2005, describing the lucky survival of several hundred authentic Enigma messages of World War II, and an account of a ciphertext-only cryptanalysis of a large number of these messages, leaving only a few (mostly short messages) unbroken. After reviewing the work done, and investigating the reasons for both lucky breaks and close misses, the modern ciphertext-only attack on Enigma messages is improved, especially on genuine ones with short lengths and/or many garbles. The difficulties of a proper measure for the candidate’s closeness to a plaintext are clarified. The influence on the decryption process of an empty plugboard and one with only a few correct plugs is examined. The method is extended by a partial exhaustion of the plugboard combined with an optimized hillclimbing strategy. The newly designed software succeeds in breaking formerly unbroken messages.

Frode has also summarized the previous efforts to solve these messages at CryptoCellar Tales.

The compromise of the Croat Enigma K cipher machine by the German Army’s codebreakers

Signals intelligence and codebreaking played an important role in WWII. British and American codebreakers solved many important Axis crypto systems and similarly their Axis counterparts also had their own successes.

Both the Allies and the Axis powers solved not only their opponents’ communications but also those of neutral powers and in some cases the communications of their own allies.

For example the German codebreaking agencies solved Japanese and Italian diplomatic ciphers during the 1930’s and in WWII.

The Germans also solved the messages of their minor allies. One such case concerns the Enigma K (commercial version) used by the Armed Forces of the Independent State of Croatia in WWII.

The Independent State of Croatia

The Kingdom of Yugoslavia was one of the states that were created when the old Austro-Hungarian empire collapsed at the end of WWI. The country covered a large area in the Balkans but was politically unstable since it was made up of a diverse group of peoples (Serbs, Croats, Slovenes, Montenegrins). 

In April 1941 the country was quickly defeated and occupied by German forces. The collapse of the Yugoslav state led to its partition into new states, subservient to the Axis powers.

One of them was the Independent State of Croatia, ruled by the Ustaše movement and its leader Ante Pavelić.

Although the Croat State was a puppet state of Germany its communications were targeted by the German Army’s codebreakers.

The German Army High Command’s codebreaking department

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. This was the German Army High Command’s Inspectorate 7/VI. 

Inspectorate 7/VI had separate departments for the main Allied countries, for cipher security, cipher research and for mechanical cryptanalysis (using punch card machines and more specialized equipment).

The codes of Balkan countries and of the Tito and Mihailović resistance movements (1) were worked on by Referat 6. This department also solved Croat communications in the period 1941-45 (2).

Yugoslav communications were also worked on by a small detachment under Lieutenant Wollny (Nachrichten Aufklärung Zug ‘W’) based in Belgrade and by the units of KONA 4 (Kommandeur der Nachrichtenaufklärung 4 - Signals Intelligence Regiment 4).

The Croat Enigma K cipher machine

According to German reports the Croatian forces used several cryptosystems, from Caesar cipher and simple transposition to 4 and 5-figure enciphered codes.

A more interesting system identified in Croatian radio traffic was the Enigma K cipher machine.

Since the 1920’s the Enigma cipher machine was sold to governments and companies that wanted to protect their messages from eavesdroppers.

The latest version of the commercial Enigma machine was Enigma K. In WWII this device was used by the Swiss diplomatic service and armed forces and also by the Croatian authorities.

The device worked according to the Enigma principle with a scrambler unit containing an entry plate, 3 cipher wheels and a reflector. Each of the cipher wheels had a tyre, marked either with the letters of the alphabet or with the numbers 1-26, settable in any position relative to the core wheel, which contained the wiring. The tyre had a turnover notch on its left side which affected the stepping motion of the device.

The position of the tyre relative to the core was controlled by a clip called Ringstellung (ring setting) and it was part of the cipher key, together with the position of the 3 cipher wheels.  

The commercial version was different from the version used by the German Armed Forces in that it lacked a plugboard (stecker). Thus in German reports it was called unsteckered Enigma.

The Croatian authorities first received 12 Enigma machines in July 1942 (3). More machines were purchased in 1943 and 1944. In the period November ’43 - March ‘44 Enigmas that had been used by the Condor Legion in Spain were rewired for the General Staff of the Croatian Home Defence Forces (Kroatischen Landwehr – Hrvatsko Domobranstvo) (4).

The reflector remained on the commercial wiring Ch 11 Tz 86, however the 3 cipher wheels received the new wiring Ch 11 Tz 364 a–c (5).

In total 12 new Enigma cipher machines and 29 rewired ones were prepared for Croatian use. In addition it is likely that another 44 machines were also delivered (6).

Solution of Croat Enigma K communications

Details on the solution of Croatian messages enciphered on the Enigma K are available from the postwar interrogation of Army cryptanalyst dr Buggisch and from the relevant entries in the War Diary of Inspectorate 7/VI.

Dr Buggisch, one of the top cryptanalysts of Inspectorate 7/VI, said in TICOM report I-92 ‘Final Interrogation of Wachtmeister Otto Buggisch’, p2-3

2. Solution of Croat Enigma. This was not an outstanding cryptanalytic achievement. The machine used was the K model, with three wheels and no stecker. The machines were made for the Croats by the firm of KROSKY and KRUGER, Berlin, which gave the wirings promptly to OKW/WNV in about 1941 or 1942. A single key was used throughout the entire Croat Army and area, and this consisted only of a list of 100 settings for a period of a month. As far as Buggisch knew the Ringstellung stayed always at AAA, and the wheel order at 1, 2, 3. Just to make sure, the Germans paid for one of the first keys used, and with this decoded traffic were able to establish stereotypes and solve almost 100% from the first.

The solutions were done entirely by hand with wiring charts, assuming a pet beginning (one third of all messages began with "MINORS") and assuming the left hand wheels and Umkehrwalz unmoving (only one notch per wheel as in the commercial model). The Croats also had pet indicators and so would furnish depths in case this method did not work. The setting was indicated directly by a two digit number unenciphered, so that the settings wore solved almost as fast as they came, and the traffic read currently from then on. Buggisch did not recall the contents in detail. 90% of it was uninteresting; there were some interesting messages about actions against Tito

Buggisch said the Germans had considered equipping the Croats With the military Enigma, as they did for HUNGARY, ROUMANIA, FINLAND and ITALY (and JAPAN, he thinks) in about 1942. However, they decided against this as they believed the corrupt CROATS would go right on selling the keys to British agents, while they, the GERMANS, would have to pay as well instead of solving free. (The possibility of a BRITISH solution obviously did not occur to Buggisch during this discussion of the K model.)

According to Buggisch one third of all messages began with the word ‘MINORS’. MINORS stood for ‘Ministarstvo Oruzanih Snaga’ - Ministry of Armed Forces of the Independent State of Croatia (7).

Thus this was high level traffic between the Ministry of Armed Forces and the regional military commands.

The war diary of Inspectorate 7/VI (8) confirms Buggisch’s statements and shows that in the period 1943-45 the Croatian Enigma was regularly read by the Germans.

Information from the War Diary of Inspectorate 7/VI

In June ’43 the report of Referat 13 (security of German cipher machines) said that the use of the commercial Enigma K machine had been identified in Croatian 5-letter cipher traffic and by using the wheel wirings supplied by the company Heimsoeth & Rinke together with known key documents it was possible to break into this traffic. Presumably ‘known key documents’ would have been the compromised documents that Buggisch mentioned in report I-92.

Bei einem kroatischen 5B-Verkehr wurde festgestellt, daß er mit einer handelsüblichen Enigma Modell K verschlüsselt ist. Ein Versuch mit den von der chiffriermaschinengesellschaft Heimsoeth & Rinke an Kroatien gelieferten Walzen ergab, daß tatsächlich die betreffenden Walzenschaltungen benutzt wurden. Unter Ausnutzung teilweise bekannter Schlüsselunterlagen gelang ein Einbruch und damit die Deutung der Schlüsseltechnik. Nach früher hier entwickelten Methoden wird eine laufende Entzifferung möglich sein.

In einer Besprechung am 8.6.43 wurden einige Entzifferungergebnisse über die handelsübliche Enigma mit dem Forschungsamt ausgetauscht. (Wm.Döring, Uffz. Rinow.)

In July ’43 the report of Referat 6 (Balkan countries) said that there was cooperation with Referat 13 (Wm. Buggisch) on the solution of the Croat Enigma. 23 indicators (for the initial position of the rotors) were recovered and transmitted to Lieutenant Wollny’s Nachrichten Aufklärung Zug ‘W’, together with a cipher machine for processing the accumulating material.

Von den mit Chiffriermaschine verschlüsselten kroatischen Sprüchen wurden unter Zusammenarbeit mit Referat 13 (Wm. Buggisch) 23 Kenngruppen (für Walzeneinstellung) gedeutet und mitsamt einer Chiffriermaschine fur Nachr. Aufkl.-Zug "W" zwecks Bearbeitung des dort anfallenden Spruchmaterials Herrn Oberleutnant Wollny übergeben. Die mit der Chiffriermaschine gelösten Sprüche wurden in einer umfangreichen VN-Meldung herausgegeben. (s.Schrb. Br.B.Nr. 1691/43 gKdos.)

The report of Referat 13 said that by solving the frequently used indicators it was possible to solve almost all the traffic.

Bei den kroatischen 5B-Sprüchen, die als Enigma-Sprüche (Modell K) erkannt wurden, konnten die häufig benutzten Kenngruppen erstellt werden, sodass fast der gesamte Verkehr mitgelesen werden kann.

A table contained in the Referat 6 report shows how many messages were processed during the month:

In August ’43 Referats 6 and 13 solved 16 indicator groups and transmitted them to Nachrichten Aufklärung Zug ‘W’ via teletype.

Referat 6:

Von den mit Chiffriermaschine verschlüsselten kroatischen Sprüchen wurden unter zusammenarbeit mit Referat 13 (Wm. Buggisch) 16 Einstellungsgruppen gedeutet und dem Nachr. Aufkl. Zug mit Fernschreibgspräch (G-Schreiber) am 10 und 17.8 zwecks Bearbeitung des dort anfallenden spruchmaterials mitgeteilt.

In September ’43, indicator groups continued to be solved and sent to the Wollny unit for direct exploitation. However according to the Referat 13 report the Croatian authorities changed the indicator system by having 10 new indicators valid for each day instead of the previous arrangement for 100 indicators valid for each quarter.

Nachdem die Kroaten von Vierteljährlichen Schlüsselwechsel (100 Schlüssel) zu täglichem Schlüsselwechsel (10 Schlüssel) übergegangen sind, erfordert die laufende Erstellung der schlüssel mehr Arbeit als bisher.

In October ’43, 13 indicators were sent to the Wollny unit. The report of Referat 13 says that the current solution of the indicators could be stopped. This would seem to imply that they got copies of the indicator tables, thus they didn’t need to solve them cryptanalytically.

Da die Schlüsselunterlagen zur kroatischen Enigma anderweitig besorgt werden, konnte die laufende Erstellung der schlüssel Mitte des Monats eingestellt werden.

In November ’43 the report of Referat 6 says that Croatian ciphers were solved (hand systems and cipher machine) and the results transmitted to Nachrichten Aufklärung Zug ‘W’.

Bearbeitung umfangreichen Spruchmaterials aus dem kroatischen Funkverkehr, Entzifferung einfacher Würfel und mit Chiffriermaschine verschlüsselter Sprüche. Herausgabe von 9 V.N.-meldungen aus diesem Verkehr. sämtliche hier erstellten Losungen und neuen überschlüsselungsarten wurden dem N.A.Zug "W" fernschriftlich oder schriftlich mitgeteilt.

In December ’43 there were organizational changes in Inspectorate 7/VI, with Referat 6 becoming Referat a5 and Referat 13 becoming Referat b2.

New indicators were recovered by departments a5 and b2. The report of b2 says that the solution of the Croat Enigma indicators had to be resumed because procurement was not yet possible in the new key period.

Referat b2

3. Enigma: Die erstellung der kroatischen Schlüssel wurde wieder aufgenommen, da die Beschaffung auf dem früheren Weg in der neuen Schlüsselperiode noch nicht möglich war.

Also in the second half of 1943 Referat 9, which was the Hollerith/IBM punch card section, did statistics on the Croatian Enigma traffic (Statistische Untersuchungen für kroatische Enigma für Wm. Buggisch) and on Croat language bigram and trigram statistics (Bi- und Trigrammstatistik aus kroatischen Klarsprüchen für Wm. Buggisch)

In February ’44, 18 indicator groups were solved.

The March ’44 report of Referat a5 says that the extensive Croatian Army traffic was tackled only at the forward unit Nachrichten Aufklärung.

Referat a5

Ehem. Südslawien - Freies Kroatien:

Bearbeitung des gesamten umfangreichen Heeres - Spruchmaterials ( einfache würfel, spaltencäsaren, Enigma) erfolgt nur noch bei N.A.

11 VN- Meldungen mit 208 Sprüchen

In April, May and June ’44 there seems to have been a halt on interception of this traffic. The April’ 44 report says that ‘for unknown reasons message interception has been discontinued as of 6.4’

Referat a5

Ehem. Südslawien - Freies Kroatien:

6 S- Meldungen mit 119 Sprüchen

Spruch aufnahme is mit  dem 6.4 aus unbekannten Gründen eingestellt worden, was sehr bedauerlich, da bei evtl. späterer Neubeobachtung erfahrungsgemäss die Ez. erheblichen Zeit- und Arbeitsaufwand erfordert.

Interception resumed in July ’44 with the report pointing out the negative consequences of losing touch with this traffic (‘The three-month interruption of interception makes itself felt in a disadvantageous manner’)

Referat a5

Ehem. Südslawien - Freies Kroatien:

Eingestellte Beobachtung am 1.7.44 wieder aufgenommen. Spruchanfall mässig. 48 Sprüche (einfache Würfel) entziffert, inhalt belanglos. Bearbeitung von 5Z- Sprüchen (vermutlich überschlüsselter 4Z-Code ) bisher ohne Erfolg. Die dreimonatige unterbrechnunh der Beobachtung  macht sich nachteilig bemerkbar. Angeforderte Schlusselunterlagen von Kdr 4 nicht eingegangen.

In August ’44 Referat b2 resumed work on the solution of the Enigma indicators.

Referat b2

Bei wieder aufgenommener Bearbeitung der kroat. Enigma konnten einige Schlüssel erstellt werden.

In September ’44, 7 indicators were recovered by Referat b2.

In October ’44 there was another organizational change with Referat a5 becoming Referat 3c and Referat b2 becoming Referat 1b.

During the month 5 indicators were created and results transmitted to KONA 4 (Kommandeur der Nachrichtenaufklärung 4 - Signals Intelligence Regiment 4) in the Balkans.

In November ’44 solutions increased with 33 indicators transmitted to Referat 3c.

Referat 1b

Erstellung von 33 Schlüsseln für kroatische Enigma und Weiterleitung an 3c.

In December ’44, 59 indicators were recovered.

In January ’45 Referat 3c became Referat 2c. The report of Referat 1b says that 47 keys for the Croat Enigma were solved and transmitted to Referat 2c.

In February ’45 the Ref 1b report simply says that a large number of keys for the Croatian Enigma was solved and passed on to Ref 2c.

Eine grössere Zahl von Schlüsseln für die Kroat. Enigma wurde gelöst und an Ref.2 c weitergegeben.

The final Ref 2c report from March ’45 says that 30 keys were recovered and 354 messages solved.

Referat 2c

1. Balkan- Freies Kroatien

a). Für die mit der Enigma verschlüsselten 5B-Sprüche des Kroatischen Heeres wurden 30 Schlüssel erstellt. Es wurden damit 354 Sprüche entschlüsselt.

Notes:

(1). The secret messages of Marshall Tito and General Mihailović

(2). Reports of Referat 6 – War Diary of Inspectorate 7/VI

(3). Correspondence with Frode Weierud.

(4). ‘Spanish Enigma: A History of the Enigma in Spain,’ p11

(5). ‘Spanish Enigma: A History of the Enigma in Spain,’ p11 and CroatianMachines.pdf

(6). Correspondence with Frode Weierud.

(7). Correspondence with dr Nikica Baric of the Croatian State Archives

(8). German Foreign Ministry’s Political Archive - TICOM collection - files Nr 2760-2761

Additional information:

The files of Inspectorate 7/VI, listed in TICOM report IF-272 - TAB ‘D’, include the following report on the Croatian Enigma in page 8:

Zusammengefasste Umkehrwalze. Kroatien. AA-AZ.

Walze I. II. III.

These should be the wirings for the reflector and the three wheels.

Acknowledgements: I have to thank Frode Weierud for his help in translating the relevant passages from the War Diary of Inspectorate 7/VI and for the information on the Croat Enigma orders and dr Nikica Baric for explaining the meaning of the term MINORS.

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.

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!

Update on Case Wicher

The following paragraph has been added in Case ‘Wicher’ – Information from the war diary of Inspectorate 7/VI.

The war diary of Inspectorate 7/VI, in the report of February 1942, says that an investigation of captured Polish files revealed deciphered German radio messages and this material was forwarded to Inspectorate 7/VI to clarify if the compromise was a result of treason or deciphering and if it was the latter to identify the compromised cipher system.

Book review - The triumph of Zygalski's sheets: the Polish Enigma in the early 1940

The solution of the German Enigma cipher machine by the codebreakers of Bletchley Park and the effect that this had on World War II became public knowledge in the 1970’s, with the publication of books like ‘The Ultra Secret’. Since then hardly a year goes by without a new book or movie coming out and claiming that the British codebreakers basically won WWII all on their own. Unfortunately the work of the Polish codebreakers has not received the same recognition, even though they were the first to solve Enigma messages in the 1930’s.

In the interwar period Poland had to face the hostility of a weakened Germany and a rising Soviet Union. The Polish military authorities knew that they had to keep a close eye their dangerous neighbors, so they built up an efficient codebreaking service, called Biuro Szyfrów. The Polish codebreakers played an important role during the Polish-Soviet War of 1919–21 by solving the ciphers used by the Red Army and learning of the enemy plans in advance.

Against Germany the department faced a serious problem due to the introduction of the Enigma machine in the late 1920’s. The solution of this device required scientific research undertaken by mathematicians and for this reason the department hired Marian Rejewski, Henryk Zygalski and Jerzy Różycki. Using material provided by the French intelligence service, the three of them were able to solve the Enigma in the early 1930’s.

Enigma Press has published a new book on Henryk Zygalski, called ‘The triumph of Zygalski's sheets: the Polish Enigma in the early 1940’ by Zdzisław J. Kapera.

The author has used Zygalski’s personal diary in order to reconstruct his work in Poland and then France plus he has included rare photographs from the archive of Anna Zygalska-Cannon.

The book covers Zygalski’s work for the Polish cipher bureau in the 1930’s, their evacuation to France in 1939, the solution of current Enigma traffic in 1940 (together with the British codebreakers) and his work for the signal intelligence service of Vichy France at PC Cadix. The last two chapters cover his escape to the UK (due to the German occupation of Vichy in late 1942), his assignment to the Polish radio intelligence unit near Stanmore and his postwar academic career at the University of Surrey.

The author has given particular attention to Zygalski’s cryptanalytic technique for the solution of Enigma traffic (Zygalski sheets) and he has also taken a look into why the intelligence gained from the Enigma did not play an important role during the fighting in Norway and France.

Overall this is a valuable contribution to Enigma historiography.

Q&A with Zdzisław J. Kapera

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

1). Can you give a summary of Enigma Press and the books you’ve published?

The Enigma Press is a scholarly publisher from Cracow - Mogilany. The Enigma Bulletin is one of series/journals printed irregularly and in limited number of copies maximum 150. Contents of the Enigma Bulletin you can find at the end of my book. We have also a Polish series of pamphlets on the Enigma story, but only two issues appeared, one being an introduction to the machine and the second is a brief biography of Rejewski. 

2). In the book you say that you consider Zygalski a personal hero. Can you expand on that and also explain what new information you were able to discover while researching this book?

I have always been thinking that besides Rejewski Zygalski should be presented in the full light. His sheets saved possibility to read Enigma after changes in January 1939. The British were unable to use them despite producing the full set of sheets (60 necessary copies) in November and December 1939. In my book I reconstructed from all available sources the turn of events in autumn and winter 1939/1940. I used the Polish, French and British sources together and compared them for the first time. Turing learned from Zygalski in mid January 1940 and the British also had an opportunity to read more and more. Without the period January to May 15, 1940 the British would start reading regularly Enigma many months later. Even if Enigma did not save Norway and France in this crucial period the British were able to put foundations for ULTRA.  

3). What is the current state of cryptologic historiography in Poland? Is there renewed interest in the accomplishments of the Polish codebreakers?

Very few people are now interested in the Enigma story as sources are very scattered. We expect that young historian Lukasz Ulatowski will write a history of the Polish Cipher Bureau in the 1920 and 1930s. 

4). What other topics do you plan to research for future books?

I am now working on the dangerous moment, the spring of 1940, when the reading the Enigma would be nearly exposed. Stupidity of some military committee of the Polish Government in Exile because of useless political revenge would help the Germans to discover reading Enigma. I plan to publish a pamphlet on the escape of the Polish cryptanalysts from the Vichy Cadix radio intelligence center and on the efforts of the Germans to protect Enigma against the WICHER operation.