Biuro Szyfrów 4, the German section of the Polish Cipher Bureau
:For the Polish organization see Biuro Szyfrów, for the U.S. intelligence agency see Black Chamber.
During the Polish-Soviet War (1919-1921), Mazurkiewicz as early as 1919 broke the most common Russian cipher for the Polish General Staff's cryptological agency.
Beginning in 1929, the modest shop, ten minutes' walk from the General Staff building, which housed the Cipher Bureau, was transformed into AVA.
Before World War II, Pyry was also the seat of the Polish General Staff's Cipher Bureau, the agency that before the war was the only one in the world to break the German Enigma cipher (beginning in December 1932).