What was the Polish Cipher Bureau?

The Cipher Bureau was a unit of the Second Department of the Polish General Staff responsible for signals intelligence, cryptography, and cryptanalysis. Created from pre-existing agencies in mid-1931, it achieved historic success by breaking Germany's Enigma ciphers in December 1932. Weeks before World War II, the Bureau shared its techniques and equipment with French and British intelligence, giving the Allies a vital advantage.

What we know

• The Cipher Bureau was formed in mid-1931 by the merger of pre-existing agencies within the Second Department of the Polish General Staff. [2]
• In December 1932, the Cipher Bureau began successfully breaking Germany's Enigma ciphers. [2]
• Cryptologist Marian Rejewski designed a special-purpose machine called the bomba around October 1938 to break Enigma ciphers. [4]
• On July 25, 1939, five weeks before World War II, the Bureau revealed its Enigma decryption techniques and equipment to French and British intelligence. [2]

Where to go next

• how it workedHow did Marian Rejewski break the Enigma machine?
• a case in pointWhat was the Enigma double machine?
• what followedHow did the Ultra intelligence program shape World War II?
• whenWhat role did the Cipher Bureau play in the Polish-Soviet War?
• the bigger pictureHow did the electromechanical rotor mechanism of the Enigma work?
• an unexpected connectionHow a commercial cipher device became a military secretThe Enigma machine was originally developed to protect commercial and diplomatic communications before being heavily adopted by Nazi Germany for top-secret military operations.

Sources

• [1]Cipher Bureau (Wikidata Q267599) · CC0 1.0
• [2]Cipher Bureau (Poland) · CC BY-SA 4.0
• [3]Polish Enigma double · CC BY-SA 4.0
• [4]Bomba (cryptography) · CC BY-SA 4.0
• [5]Enigma machine · CC BY-SA 4.0