Marian Rejewski, mathematician, cryptographer, participating in codebreaking of “Enigma”
Born: August 26, 1905, Bydgoszcz, Prussian partition of Poland (presently Poland)
Died: February 13, 1980, in Poland
Higher education. In 1923 Rejewski started studying mathematics at the Adam Mickiewicz University in Poznan (Poland). After finishing he went for one year to Goettingen (Germany) to study actuarial mathematics.
Teaching. Upon return to Poland he taught at the Poznan University. The earliest Polish work on the intercepted German machine ciphers had begun already in 1928, right after the system's introduction by the German Army. Polish Intelligence had obtained examples of the commercial Enigma machine but quickly found that the German Enigma was different in detail from the commercial version.
However, no progress was made during the next four years.
Begins work at the Cipher Bureau. On September 1, 1932, Rejewski and his two somewhat younger colleagues, Jerzy Rozycki, and Henryk Zygalski began work as regular employees at the Cipher Bureau (Biuro Szyfrow) in Warsaw which was part of 2nd Section (Military Intelligence) of the General Staff. To be sure they were first all given, along with twenty-odd their fellow-students, a rudimentary training in code breaking during a special course, organized by the military. Their real aim was to find crypto logical talents, the most promising of which was considered Marian Rejewski.
During the first few weeks, the young mathematicians worked on relatively simpler German Navy codes. In early-October, 1932, Rejewski was given a separate room and told to take a closer look at a pile of the Enigma-researchers.
Initial work on Enigma. He was also supplied with an obsolete commercial Enigma machine, initial type, which had been bought in Germany. In 1931 and 1932 the French cryptographer Gustave Bertrand obtained priceless information about the German Enigma from a spy, Hans-Thilo Schmidt, known by the code name Asche. The French were unable to use this information to break into the German Enigma traffic. It was also passed to the British who were also at this time unable to break into Enigma. Finally Bertrand passed the information to Polish Intelligence who had not revealed how far they had got with their attack on Enigma. This information, which included German operating instructions for Enigma and two sheets of monthly key settings enabled Rejewski to deduce the internal wheel wiring for all three wheels, but only after he had made an inspired leap of imagination. The problem was the order of the 26 wires connecting the keyboard to the fixed entry disc at the right hand end of the three wheels. In the commercial Enigma, which the Polish team possessed, the wiring order clockwise round the entry disc was the order of the keys on the keyboard, QWERTZUIO... Rejewski had realized that the wiring order must be different on the German Forces Enigma, but had no way of finding out what the order was. The inspired leap of imagination was to suppose the Germans had, in their logical way, just used ABCDEFG... as the order. He tried this and it worked and he could now work out from his equations the internal wiring of the three wheels and the reflector.
Replicas of Enigma built. The deduction of the internal wiring of the wheels was a spectacular feat by Rejewski. It enabled the Polish cryptographers to build replicas of the German Enigma machine which could then be used to decipher the intercepted Radio messages once the Enigma configuration and the message settings had been deduced.
That was the next problem. Rejewski had shown that his characteristics could be deduced from a day's radio traffic when the Germans were double enciphering the Enigma message settings. Now the Polish cryptographers had to produce a catalogue of these characteristics for every wheel order and every wheel start position, 26x26x26x6 entries,(no less than 105,456 in all!), in order to deduce the Enigma configuration for that day.
This began in earnest when Rejewski realized the applicability of some properties of permutations to his analysis of the German machine cipher. Rejewski quickly showed that mathematical techniques could be used to attack the problem of finding the message key by exploiting the German's cryptographic error in repeating the message key at the start of a transmission. For most crypto graphical methods repetitions are the weak spot. Rejewski looked therefore for a pattern. In the case of Enigma broadcasts the keywords were the repetitive patterns. As an example: GQF- the keyword; GQFGQF – the double keyword; VDSPLK- the encoded information, put at the beginning of the real information.
Code broken. Marian Rejewski, Jerzy Rozycki, Henryk Zygalski and other cryptoanalysts from BS4, broke into Kriegsmarine code in November 1932.
Fully decrypted Enigma texts were read by BS4 since mid January 1933.
During Roehm's Putsch in June 1934 Enigma messages were read within minutes from their interception. During two weeks long cryptographic exercises organized at BS4 in January 1938 up to 75 percent of secret German communication was decrypted within hours from interception. In 1939 he created a programmable electro-mechanical decoding machine named "Bomba", the predecessor of the British "bombes" and early computers like the Colossus computer. They devised a machine which they called a Cyclometer. This consisted of, in effect, two Enigma machines side by side with their right hand wheels offset by three places.
Then in September 1938 the Germans changed the Enigma procedures for enciphering message keys. They no longer started the message key encipherment from one standard set of wheel positions set for the whole 24 hour period, but asked the Enigma operator to choose a different encipherment start, known as the indicator, for each message sent and to transmit the chosen indicator with the double enciphered message setting in the header of the German message.
This meant that Rejewski's characteristics no longer worked because they depended on all message key encipherments being from the same wheels start positions. In July 1939 with the invasion of Poland imminent, the Polish cryptographers decided to share their Enigma results with the French and British code breakers.
Meeting at the Kabacki Woods. At a meeting in the Kabacki Woods near Pyry just outside Warsaw all was revealed to the utter astonishment of the French and British. The Polish team gave them copies of the German Enigma machine and revealed the details of the Cyclometers, Bombas and Zygalski sheets.
Most of documents published in the 'Enigma File' were collected by Col. Wladyslaw Kozaczuk, an author who in 1967 revealed that Enigma was no secret for Allied intelligence services.
Wehrmacht correspondence was decrypted efficiently up to November 1938 and Sicherheitsdienst up to 1st July 1939. Once Chi-Dienst upgraded German Enigmas BS4 lost its possibilities and between November 1938 and summer 1939 only one in ten Wehrmacht dispatch was read.
Code breakers work in France.In October 1939 evacuated from Poland BS4 code breakers resumed their work as Equipe Z with Gustave Bertrand and his French team at Chateau Vignolles just outside Paris. On 17th January 1940 Equipe Z as the first Allied code breaking team broke wartime Enigma daily key and immediately passed its findings to Bletchley Park (England). Bletchley Park began its mass code breaking work.
Equipe Z was active until November 1942 when Wehrmacht occupied Vichy and German RDF vehicles were spotted near its premise.
Rejewski in England.They had to flee France in 1942/43 and some of them, including Rejewski succeeded reaching England. The doors to Bletchley Park, the site of the English code breakers remained however closed for them. Three years later, in his "Enigma: the Greatest Puzzle of the War 1939-1945”, General Gustave Bertrand supplied ample corroboration for the Polish. Meanwhile, Bertrand's book, which ascribes "all the credit and all the glory" for breaking the German machine cipher to the Poles, was totally ignored by the British.
Rejewski returns to Poland.After the WWII Rejewski returned to Poland in 1946. He was re-united with his wife and two children. He wrote a book about his work during the breaking of Enigma. This book remains unpublished. Polish Mathematical Society has honored him with a special medal. Rejewski died in 1980 in Warsaw and is buried there in the Powazki Cemetery.
* 1. D. Kahn, Enigma Unwrapped. New York Time Book Review, 29.XII.74
Tech. Univ. Freiberg
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