Marian Rejewski

Marian Rejewski
Rejewski, c. 1932
Born	Marian Adam Rejewski (1905-08-16)16 August 1905 Bromberg, German Empire
Died	13 February 1980(1980-02-13) (aged 74) Warsaw, People's Republic of Poland
Occupation	Mathematician, cryptologist
Known for	Solving the Enigma-machine cipher
Awards	Order of Polonia Restituta, Grand Cross War Medal 1939–1945 Knowlton Award IEEE Milestone award.

Marian Adam Rejewski [ˈmarjan reˈjefski] (16 August 1905 – 13 February 1980) was a Polish mathematician and cryptologist who reconstructed the Nazi German military Enigma cipher machine sight-unseen in 1932. The cryptologic achievements of Rejewski and colleagues Jerzy Różycki and Henryk Zygalski enabled the British to begin reading German Enigma-encrypted messages at the start of World War II, seven years after Rejewski's original reconstruction of the machine. The intelligence that was gained by the British from Enigma decrypts formed part of what was code-named Ultra and contributed—perhaps decisively—to the defeat of Germany.

In 1929, while studying mathematics at Poznań University, Rejewski attended a secret cryptology course conducted by the Polish General Staff's Cipher Bureau (Biuro Szyfrów), which he joined in September 1932. The Bureau had had no success in reading Enigma-enciphered messages and set Rejewski to work on the problem in late 1932; he deduced the machine's secret internal wiring after only a few weeks. Rejewski and his two colleagues then developed successive techniques for the regular decryption of Enigma messages. His contributions included the cryptologic card catalog, derived using the cyclometer that he had invented, and the cryptologic bomb.

Five weeks before the German invasion of Poland in 1939, Rejewski and colleagues presented their achievements to French and British intelligence representatives summoned to Warsaw. Shortly after the outbreak of war, the Polish cryptologists were evacuated to France, where they continued breaking Enigma-enciphered messages. They and their support staff were again compelled to evacuate after the fall of France in June 1940, and they resumed work undercover a few months later in Vichy France. After the French "Free Zone" was occupied by Germany in November 1942, Rejewski and Zygalski fled via Spain, Portugal, and Gibraltar to Britain. There they enlisted in the Polish Armed Forces and were put to work solving low-grade German ciphers.