Ultra (cryptography)
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Ultra was the designation adopted by British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at
Enigma machine out of its wooden box
Lorenz SZ42 machine with covers removed
Part of Japanese PURPLE machine
A typical Bletchley intercept sheet, before decryption and translation
Cryptanalysis of the Enigma
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Cryptanalysis of the Enigma ciphering system enabled the western Allies in World War II to read substantial amounts of Morse-coded radio communications of the Axis powers that had been enciphered usin
Ultra (cryptography)
…virtually unbreakable; in practice, shortcomings in operation allowed it to be broken. The term "Ultra" has often been used almost synonymously with "Enigma decrypts". However, Ultra also encompassed decrypts of the German Lorenz SZ 40/42 machines that were used by the German High Command, and the Hagelin machine…
The Enigma machine was used commercially from the early 1920s and was adopted by the militaries and governments of various countries—most famously, Nazi Germany.
The plugboard (Steckerbrett) was positioned at the front of the machine, below the keys. In the above photograph, two pairs of letters have been swapped (A↔J and S↔O). During World War II, ten leads were used, leaving only six letters 'unsteckered'.
Marian Rejewski c. 1932, when he first broke Enigma
Zygalski sheet