Security Encyclopedia


The name Bombe generally refers to a device that British cryptologists used to decipher encrypted German military communications during World War II. 

Bombe was used to reveal some of the settings of the Germans’ Enigma machine, which was used for the encryption. With some basic understanding of the Enigma device workings, the British and Allied forces were able to substitute, omit, and reverse engineer the methods their German counterparts used to encipher sensitive information of a strategic nature. The success ascribed to this British military and academic decryption effort using the Bombe, its successive iterations, and syndicated Allied devices shortened WWII by as much as two years, by some estimates. 

Many people contributed to the thought and production behind the Bombe. The device is most often attributed to groundbreaking, foundational work by the Polish cryptologist Marian Rejewski, known as the “bomba”, of the Biuro Szyfrów (Cipher Bureau), as he devised and constructed the first successful bombe. It then benefited more generally and materially through the work of British multidisciplinary scientist Alan Turing, who worked at the UK Government Code and Cypher School (GC&CS), Bletchley Park, it benefited from improvements by British mathematician Gordon Welchman, working at same. 

The Bombe and the British era, the Turing-led project, were popularized in the 2014 film The Imitation Game starring Benedict Cumberbatch.


“In WWII cryptographers, mathematicians, and other scientists responded to the Allies’ call to break Germany’s use of Enigma to encrypt sensitive military communications. From their project came the creation of the Bombe decryption device, negating the Germans’ longtime advantage of surprise and secrecy.”