German code breaking in World War II

Last updated

German code breaking in World War II achieved some notable successes cracking British naval ciphers until well into the fourth year of the war, [1] using the extensive German radio intelligence operations during World War II. Cryptanalysis also suffered from a problem typical of the German armed forces of the time: numerous branches and institutions maintained their own cryptographic departments, working on their own without collaboration or sharing results or methods. This led to duplicated effort, a fragmentation of potential, and lower efficiency than might have been achieved. [2] There was no central German cryptography agency comparable to Britain’s Government Code and Cypher School (GC&CS), based at Bletchley Park. [3]

Contents

History

Departments

In Germany, each cryptographic department was responsible for cryptanalytic operations. They included:

While most contributed little to the German war effort, the Navy's OKM did have some remarkable successes in breaking Allied codes. The 2. Abteilung der Seekriegsleitung included the Marinenachrichtendienst (M.N.D.) and its III. Abteilung, radio intelligence. The B-Dienst (Beobachtungsdienst, "surveillance service",) and the xB-Dienst ("decryption service") were able to break into several important Allied radio communication circuits.

B-Dienst

The B-Dienst, created in the early 1930s, had broken the most widely used British naval code by 1935. When war came in 1939, B-Dienst specialists had broken enough British naval codes that the Germans knew the positions of all British warships. They had further success in the early stages of the war as the British were slow to change their codes. The B-Dienst could regularly read the Broadcast to Allied Merchant Ships (BAMS) code, which proved valuable for U-boat warfare in the early phases of the Battle of the Atlantic. In February 1942, B-Dienst broke the code used for communication with many of the Atlantic convoys. [4]

Before the US entered the war at the end of 1941, B-Dienst could also read several American codes. This changed after April 1942, when the US Navy changed their code systems, but earlier, the ability to read American message traffic contributed to the success of Operation Paukenschlag (Operation Drumbeat), the destructive U-boat attacks off the American East Coast in early 1942.

In 1941, the US Navy refused, for security reasons, to equip the British Navy with their ECM Mark 1 encryption devices, so the British Admiralty introduced "Naval Cypher No. 3" for Allied radio communication and convoy coordination in the Atlantic. The B-Dienst concentrated on deciphering the new code, in September 1942 and from December 1942 to May 1943, 80 percent of the intercepted radio messages were read but only 10 percent were decrypted in time to take action. [5]

The British Naval Cypher No. 5 is also known to have been broken by the B-Dienst, as were various low-grade British Naval and Air codes, including COFOX, MEDOX, FOXO, LOXO, SYKO, Air Force code and Aircraft Movement code. The US "Hagelin" M-209 field cipher machine and the French "Anglp"[ clarification needed ] code were also often read.

In addition, B-Dienst cracked Soviet and Danish code systems.

Radiotelephone interception

Apart from the notable successes of the German navy's decryption services, there were also some useful results from other institutions. For example, the Reichspost was able to descramble scrambled voice transmission of transatlantic radiotelephone conversations between the USA and Great Britain. For this purpose, an interception and descrambling facility was built in Noordwijk, near the Hague in occupied Holland. From 1940, the Mail Service's descrambling specialists intercepted and understood classified telephone conversation between President Roosevelt and the British Prime Minister Winston Churchill. [6]

The scrambler worked by voice inversion around a chosen frequency, so that the high frequencies become low and vice versa. It was impossible for a casual listener to break. However the Germans, by recording the telephone message on a BASF tape recorder, could quickly identify the scrambling method by playing the tape a few times through the few possible combinations of coding, to unscramble it. [7]

In 1943 the facility relocated to a purpose built bunker facility in Valkenswaard, south of Eindhoven to avoid a potential commando raid on the northern coast. Valkenswaard remained operational until August 1944 when the facility had to relocate to Germany to avoid the advancing British. [8] The most important intercept was a conversation discussing on 29 July the pending Italian surrender, weeks before the event took place on 3 September 1943, giving the Germans time to plan the occupation of Italy and disarming of Italian soldiers. The interception potential thereafter decreased, as did the number of phone calls intercepted. [9]

This was not codebreaking, but an adjunct to it - the exploitation of understanding of a sophisticated technology for the purpose of data interception.

Co-operation with Italy

Another success was the OKW/Chi 1941 cryptanalysis of the "Black" code used by US diplomats. Due to this, a huge interception facility in Lauf (Bavaria) could decrypt communication between US diplomats and Washington DC. The specialists in Lauf concentrated on messages from Bonner Fellers relating to the North African Campaign, so they could pass information to Feldmarschall Erwin Rommel about Allied plans and operations. The Germans also received the "Black" code from the Italians; Italian spies had photographed the code tables in the US embassy in Rome in September 1941. While the Germans appreciated the gift from their ally, they did not explain that they were already able to read "Black" code messages.

In general, however, German performance in code breaking was weak due to the fragmentation of responsibility and specialized personnel.[ citation needed ] The Navy's B-Dienst was an exception to the rule, although its successes largely ended when the Allies began using more sophisticated encryption methods by 1943.

See also

Related Research Articles

<span class="mw-page-title-main">Ultra (cryptography)</span> British designation for intelligence from decrypted enemy communications

Ultra was the designation adopted by British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at the Government Code and Cypher School (GC&CS) at Bletchley Park. Ultra eventually became the standard designation among the western Allies for all such intelligence. The name arose because the intelligence obtained was considered more important than that designated by the highest British security classification then used and so was regarded as being Ultra Secret. Several other cryptonyms had been used for such intelligence.

<span class="mw-page-title-main">Fish (cryptography)</span>

Fish was the UK's GC&CS Bletchley Park codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies. This traffic normally passed over landlines, but as German forces extended their geographic reach beyond western Europe, they had to resort to wireless transmission.

The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well. Every Japanese code was eventually broken, and the intelligence gathered made possible such operations as the victorious American ambush of the Japanese Navy at Midway in 1942 and the shooting down of Japanese admiral Isoroku Yamamoto a year later in Operation Vengeance.

Cryptography, the use of codes and ciphers to protect secrets, began thousands of years ago. Until recent decades, it has been the story of what might be called classical cryptography — that is, of methods of encryption that use pen and paper, or perhaps simple mechanical aids. In the early 20th century, the invention of complex mechanical and electromechanical machines, such as the Enigma rotor machine, provided more sophisticated and efficient means of encryption; and the subsequent introduction of electronics and computing has allowed elaborate schemes of still greater complexity, most of which are entirely unsuited to pen and paper.

Magic was an Allied cryptanalysis project during World War II. It involved the United States Army's Signals Intelligence Service (SIS) and the United States Navy's Communication Special Unit.

TICOM was a secret Allied project formed in World War II to find and seize German intelligence assets, particularly in the field of cryptology and signals intelligence.

The Cipher Bureau was the interwar Polish General Staff's Second Department's unit charged with SIGINT and both cryptography and cryptanalysis.

<span class="mw-page-title-main">Cryptanalysis of the Enigma</span> Decryption of the cipher of the Enigma machine

Cryptanalysis of the Enigma ciphering system enabled the western Allies in World War II to read substantial amounts of Morse-coded radio communications of the Axis powers that had been enciphered using Enigma machines. This yielded military intelligence which, along with that from other decrypted Axis radio and teleprinter transmissions, was given the codename Ultra.

Cryptography was used extensively during World War II because of the importance of radio communication and the ease of radio interception. The nations involved fielded a plethora of code and cipher systems, many of the latter using rotor machines. As a result, the theoretical and practical aspects of cryptanalysis, or codebreaking, were much advanced.

Alfred Dillwyn "Dilly" Knox, CMG was a British classics scholar and papyrologist at King's College, Cambridge and a codebreaker. As a member of the Room 40 codebreaking unit he helped decrypt the Zimmermann Telegram which brought the USA into the First World War. He then joined the Government Code and Cypher School (GC&CS).

<span class="mw-page-title-main">Hut 8</span> Section of Bletchley Park codebreaking station, England

Hut 8 was a section in the Government Code and Cypher School (GC&CS) at Bletchley Park tasked with solving German naval (Kriegsmarine) Enigma messages. The section was led initially by Alan Turing. He was succeeded in November 1942 by his deputy, Hugh Alexander. Patrick Mahon succeeded Alexander in September 1944.

The B-Dienst, also called xB-Dienst, X-B-Dienst and χB-Dienst, was a Department of the German Naval Intelligence Service of the OKM, that dealt with the interception and recording, decoding and analysis of the enemy, in particular British radio communications before and during World War II. B-Dienst worked on cryptanalysis and deciphering (decrypting) of enemy and neutral states' message traffic and security control of Kriegsmarine key processes and machinery.

With the rise of easily-intercepted wireless telegraphy, codes and ciphers were used extensively in World War I. The decoding by British Naval intelligence of the Zimmermann telegram helped bring the United States into the war.

The Cipher Department of the High Command of the Wehrmacht was the Signal Intelligence Agency of the Supreme Command of the Armed Forces of the German Armed Forces before and during World War II. OKW/Chi, within the formal order of battle hierarchy OKW/WFsT/Ag WNV/Chi, dealt with the cryptanalysis and deciphering of enemy and neutral states' message traffic and security control of its own key processes and machinery, such as the rotor cipher ENIGMA machine. It was the successor to the former Chi bureau of the Reichswehr Ministry.

The Research Office of the Reich Air Ministry was the signals intelligence and cryptanalytic agency of the German Nazi Party from 1933 to 1945. Run since its inception by Luftwaffe chief Hermann Göring, the Research Bureau was a Nazi Party institution rather than an official Wehrmacht-run military signals intelligence and cryptographic agency.

The German Naval Intelligence Service was the naval intelligence department of the Germany Navy and had a long history, going back to the naval aspirations of German emperor Wilhelm II in 1899.

<span class="mw-page-title-main">Wilhelm Tranow</span>

Wilhelm Tranow was a German cryptanalyst, who before and during World War II worked in the monitoring service of the German Navy and was responsible for breaking a number of encrypted radio communication systems, particularly the Naval Cypher, which was used by the British Admiralty for encrypting operational signals and the Naval Code for encrypting administrative signals. Tranow was considered one of the most important cryptanalysts of B-service. He was described as being experienced and energetic. Little was known about his personal life, when and where he was born, or where he died.

General der Nachrichtenaufklärung was the signals intelligence agency of the Heer, before and during World War II. It was the successor to the former cipher bureau known as Inspectorate 7/VI in operation between 1940 and 1942, when it was further reorganised into the Headquarters for Signal Intelligence between 1942 and 1944, until it was finally reorganised in October 1944 into the GdNA. The agency was also known at the OKH/Gend Na, GendNa or Inspectorate 7 or more commonly OKH/GdNA. Inspectorate 7/VI was also known as In 7 or In/7 or In 7/VI and also OKH/Chi.

General der Nachrichtenaufklärung Training Referat was the training organization within the General der Nachrichtenaufklärung (GDNA), the military signals intelligence agency of the Wehrmacht during World War II. Initially established from May 1941, it continued teaching until September 1944. Until 1942, the work of the Training Referat was not fully exploited and only a small beginners course was taught.

The Servizio Informazioni Segrete was the intelligence service of the Royal Italian Navy. SIS was instrumental in moulding Italian Army's operations during the Second Italo-Ethiopian War and the Battle of the Mediterranean, primarily due to its cryptanalysis successes and undercover operations.

References

  1. ↑ Marchant, Herbert "Secrets of Station X2 The Observer , 15 October 1978
  2. ↑ Rezabek, Randy (2017), TICOM: the Hunt for Hitler's Codebreakers, Independently published, ISBN   978-1521969021, archived from the original on 2022-05-26, retrieved 2018-02-26
  3. ↑ Overcamer, Arvo. "German Code Breaking of WWII". feldgrau.com.
  4. ↑ Mallmann-Showell, Jak P. (2003), German Naval Codebreakers, Annapolis, MD: Naval Institute Press, ISBN   0-7110-2888-5
  5. ↑ HyperWar Foundation: Compromise of Allied Codes and Ciphers by German Naval Communication Intelligence http://www.ibiblio.org/hyperwar/ETO/Ultra/SRH-009/SRH009-6.html
  6. ↑ "CHAPTER VII World War II: Establishing the Circuits of Victory". 3 April 2006.
  7. ↑ "SCRAMBLED PHONES". 8 December 2019.
  8. ↑ "Brabant farmstead Valkenhorst housed 1943 German spy station" . Retrieved 16 December 2023.
  9. ↑ "The Churchill-Roosevelt Forgeries". December 2002.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.