Breaking the Enigma Code
In 1938, Polish codebreakers continued to work on the Enigma code with fruitless efforts. Marian Rejewski was finally able to crack it with the assistance of German documents supplied to him by General Gustave Bertrand of the French army. (Rejewski)
General Gustave Bertrand of the French army, pictured after World War II. Photo courtesy of Wydawnictwo Polskie.
The Polish improved upon previous codebreaking techniques by using a machine called a bomba to find the Enigma settings instead of using hand techniques. The settings could be set into an Enigma machine or replica. When the enciphered message was then typed into the machine, the deciphered text would be revealed. (Rejewski).
Oral interview with Janice M. Bernario, a codebreaker at Bletchley Park. Interview courtesy of the Atlanta History Center.
Allied countries had difficulty cracking the Enigma; only the Polish had been successful so far in cracking the Enigma (unbeknownst to other Allies). (Dermot Turing) The Allies wanted to share cryptographical breakthroughs in order to crack the code.
"The French coaxed MI6, and via MI6's second-in-command, Stewart Menzies, GC&CS into a three-way codes and ciphers alliance for sharing knowhow and intelligence on codebreaking, involving the experts from GC&CS, from France's Deuxieme Bureau, and from Poland's Biuro Szyfrow." (The Codebreakers of Bletchley Park, 93)
The Polish were initially instructed not to share anything.
Hut 2 of Bletchley Park, the headquarters of GC&CS. Photo courtesy of Bletchley Park.
Workers of France's Deuxieme Bureau. Photo courtesy of Memoires de guerre.
With German invasion looming in July 1939, the Poles shared their breakthroughs on the Enigma. The Germans would invade soon after.
"Not only had Rejewski discovered the wiring - explaining to an incredulous know how he had done that - but the team, including codebreaker-mathematicians Jerzy Rozycki and Henryk Zygalski and engineer-codebreaker Antoni Palluth, had invented a wondrous range of machines and paper methods for finding the daily Enigma settings. The Poles showed their allies the machines they had created and how they worked...They explained everything." (The Codebreakers of Bletchley Park, 93)
In 1939 the Germans found evidence, including decrypts, that a Polish cryptanalytic organization, WICHER, had been reading the ENIGMA. Documents and interrogations did not reveal how the machine could have been read, and after some changes in the indicator system and pluggings, the matter was dropped. ~ Joseph Meyer, Der Fall WICHER
German horse artillery parading before the Polish Cipher Bureau. September 1939. Photo courtesy of Bundesarchiv.
Germans found evidence of read Enigma messages, and kept changing the device to keep it secure. They didn't know the revolutionary bomba device was being used to crack the code, but these changes nonetheless made existing bombas useless.
After the invasion of Poland on September 1st, 1939, the efforts to crack the changing Enigma code were passed over to Britain's Bletchley Park.
Rejewski's illustration of the Bomba kryptogiczna. Photo courtesy of Marian Rejewski.
