Polish-made replica of the German Enigma
Polish-made replica of the German Enigma

The Cipher Bureau (Biuro Szyfrów) was the interwar Polish General Staff's agency charged with both cryptography (the use of ciphers and codes) and cryptology (the study of ciphers and codes, particularly for the purpose of "breaking" them). It was formed in 1931 by the merger of pre-existing agencies. In December 1932, the Bureau began breaking Germany's Enigma ciphers. Over the next seven years, Polish cryptologists overcame the growing structural and operating complexities of the plugboard-equipped Enigma. The Bureau also broke Soviet cryptography. Five weeks before the outbreak of World War II, on 25 July 1939, in Warsaw, the Polish Cipher Bureau revealed its Enigma-decryption techniques and equipment (example pictured) to representatives of French and British military intelligence, which had been unable to make any headway against Enigma. This Polish intelligence and technology transfer would give the Allies an unprecedented advantage (see Ultra) in their ultimately victorious prosecution of the war. (Full article...)