Cryptanalysis
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Cryptanalysis refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic security systems and gain access to the contents of encrypted messages, even if the cryptographic key is unknown.
Reconstruction of the appearance of cyclometer, a device used to break the encryption of the Enigma machine. Based on sketches in Marian Rejewski's memoirs
The decrypted Zimmermann Telegram.
The Bombe replicated the action of several Enigma machines wired together. Each of the rapidly rotating drums, pictured above in a Bletchley Park museum mockup, simulated the action of an Enigma rotor.
Colossus computer
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Colossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program.
A Colossus Mark 2 computer being operated by Wrens. The slanted control panel on the left was used to set the "pin" (or "cam") patterns of the Lorenz. The "bedstead" paper tape transport is on the right.
A Lorenz SZ42 cipher machine with its covers removed at The National Museum of Computing on Bletchley Park
The Lorenz SZ machines had 12 wheels, each with a different number of cams (or "pins"). Wheel number 1 2 3 4 5 6 7 8 9 10 11 12 BP wheel name ψ1 ψ2 ψ3 ψ4 ψ5 μ37 μ61 χ1 χ2 χ3 χ4 χ5 Number of cams (pins) 43 47 51 53 59 37 61 41 31 29 26 23
Cams on wheels 9 and 10 showing their raised (active) and lowered (inactive) positions. An active cam reversed the value of a bit (0→1 and 1→0).