Jerzy Witold Różycki (pronounced YEH-zhih VEE-told Roo-ZHITS-kee; July 24, 1909, Olshana , Kyiv province, Ukraine – January 9, 1942, near the Balearic Islands in the Mediterranean Sea) was a Polish mathematician and cryptologist who worked on solving German Enigma machine ciphers.

Różycki was a civilian cryptologist with the Polish Biuro Szyfrów (Cipher Bureau) from September 1, 1932, together with fellow Poznań University mathematics alumni and Cipher Bureau cryptology-course graduates Marian Rejewski and Henryk Zygalski.

After Rejewski made the initial breakthrough against the German military Enigma machine, Różycki and Zygalski likewise worked at ongoing development of methods and equipment to exploit Enigma decryption as a source of intelligence. Różycki invented the "clock" method, which sometimes made it possible to determine which of the machine's rotors was at the far right, that is, in the position where the rotor always revolved at every depression of a key.

More information about Różycki may be found in the article on Marian Rejewski.

References

• Władysław Kozaczuk , Enigma: How the German Machine Cipher Was Broken, and How It Was Read by the Allies in World War II, edited and translated by Christopher Kasparek, Frederick, MD, University Publications of America, 1984.
• "Różycki, Jerzy Witold," Polski słownik biograficzny (Polish Biographical Dictionary), vol. XXXII, Wrocław, Wydawnictwo Polskiej Akademii Nauk (Polish Academy of Sciences), 1989-1991, pp. 523-25.