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During the Second World War, codebreakers at Bletchley Park in England read German messages encrypted with the Enigma and Lorenz cipher machines. To do it, they built some of the first computing machines, including Colossus, the world's first programmable electronic digital computer.

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Bletchley Park, a country house north-west of London, was the wartime home of Britain's codebreakers, and about three-quarters of its staff were women. The work built on Polish success: five weeks before the war, Poland's Cipher Bureau showed British and French experts how it had broken Enigma. From 1940, electromechanical machines called Bombes, designed by Alan Turing and improved by Gordon Welchman, raced through possible Enigma settings. A different cipher, the Lorenz machine used by the German High Command, was attacked with Colossus, built by the Post Office engineer Tommy Flowers; it broke its first message in February 1944, and an improved model was working days before the Allied landings in Normandy. The historian Harry Hinsley, himself a Bletchley veteran, estimated that this work shortened the war by two to four years; others think the gain was smaller and impossible to measure. It all stayed secret until the 1970s.

Türkçe oku
İkinci Dünya Savaşı'nda İngiltere'deki Bletchley Park'ın şifre çözücüleri, Enigma ve Lorenz makineleriyle şifrelenmiş Alman mesajlarını okudu. Bunun için ilk hesaplama makinelerinden bazılarını geliştirdiler; dünyanın ilk programlanabilir elektronik dijital bilgisayarı Colossus da bunlardan biriydi.

Londra'nın kuzeybatısındaki bir malikâne olan Bletchley Park, savaş yıllarında İngiliz şifre çözücülerin merkeziydi; çalışanlarının yaklaşık dörtte üçü kadındı. Çalışmalar Polonya'nın başarısına dayanıyordu: Savaştan beş hafta önce Polonya Şifre Bürosu, İngiliz ve Fransız uzmanlara Enigma'yı nasıl çözdüğünü göstermişti. 1940'tan itibaren Bombe adlı elektromekanik makineler, Enigma'nın olası ayarlarını büyük bir hızla taradı; bu makineleri Alan Turing tasarlamış, Gordon Welchman geliştirmişti. Alman Yüksek Komutanlığı'nın kullandığı Lorenz makinesinin şifresi ise Colossus'la çözüldü. Colossus'u İngiliz Posta İdaresi'nin mühendisi Tommy Flowers yapmıştı. Makine ilk mesajını Şubat 1944'te çözdü; geliştirilmiş modeli de Müttefiklerin Normandiya Çıkarması'ndan birkaç gün önce çalışmaya başladı. Kendisi de Bletchley'de çalışmış olan tarihçi Harry Hinsley, bu çalışmaların savaşı iki ila dört yıl kısalttığını tahmin etti; başka tarihçilere göre kazanç daha küçüktü ve böyle bir süre ölçülemez. Bütün bunlar 1970'lere kadar gizli kaldı.

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Background reading: Bletchley Park
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