Alastair Denniston
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Commander Alexander Guthrie Denniston was a Scottish codebreaker, deputy head of the Government Code and Cypher School and hockey player. Denniston was appointed operational head of GC&CS in 1919 and
Alastair Denniston in 1926
Cipher Bureau (Poland)
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The Cipher Bureau was the Second Department of Polish General Staff unit charged with SIGINT and both cryptography and cryptanalysis. The precursor of the agency that would become the Cipher Bureau wa
General Staff building (Saxon Palace), destroyed in World War II. The arcade still shelters Tomb of the Unknown Soldier, before which stood Thorvaldsen's equestrian statue of Prince Józef Poniatowski. In this building, from 1932, the Cipher Bureau broke the German plugboard military Enigma.
Enigma, an electro-mechanical rotor machine with scrambler comprising entry drum, three rotors, and reflector. This military model also has a plugboard.
Marian Rejewski when he first reconstructed Enigma
A Zygalski perforated sheet (1938)