Qu'est-ce (qui) est purple - définition
![Red]] analog is also visible](https://commons.wikimedia.org/wiki/Special:FilePath/American first purple analog 1.jpg?width=200 "Red]] analog is also visible")
![Front panel of the March 1944 improved U.S. Army PURPLE analog. The three rows of indicator lights show the position of the rotor in each stage. a removable plugboard in the center selects the alphabet. A six-position switch selects the stepping order and buttons on the box at top center are used to set the initial position of each rotor. Exhibit at the [[National Cryptologic Museum]]](https://commons.wikimedia.org/wiki/Special:FilePath/PURPLE analog, improved version of March 1944 - National Cryptologic Museum - DSC07847.JPG?width=200 "Front panel of the March 1944 improved U.S. Army PURPLE analog. The three rows of indicator lights show the position of the rotor in each stage. a removable plugboard in the center selects the alphabet. A six-position switch selects the stepping order and buttons on the box at top center are used to set the initial position of each rotor. Exhibit at the [[National Cryptologic Museum]]")
![Side view of recovered Type 97 fragment. The three [[stepping switch]]es implemented one stage of the "twenties" cipher, with 25 [[permutation]]s of 20 letters encoded by the mass of wires underneath.](https://commons.wikimedia.org/wiki/Special:FilePath/Purple code machine 3.jpg?width=200 "Side view of recovered Type 97 fragment. The three [[stepping switch]]es implemented one stage of the \"twenties\" cipher, with 25 [[permutation]]s of 20 letters encoded by the mass of wires underneath.")
![7 December 1941]]. Note the hand-written calculations at the upper right which deduce the initial positions of the rotors and the stepping order from the message indicator.](https://commons.wikimedia.org/wiki/Special:FilePath/Purplemsg.PNG?width=200 "7 December 1941]]. Note the hand-written calculations at the upper right which deduce the initial positions of the rotors and the stepping order from the message indicator.")
![reverse engineered]] by the United States Army's [[Signal Intelligence Service]] in 1940.](https://commons.wikimedia.org/wiki/Special:FilePath/Type 97 cypher machine.jpg?width=200 "reverse engineered]] by the United States Army's [[Signal Intelligence Service]] in 1940.")
![Six level telephone [[stepping switch]] similar to the type used by SIS to build its first Purple. analog. On display at [[The Telephone Museum]].](https://commons.wikimedia.org/wiki/Special:FilePath/WE 206A stepping switch wipers.agr.jpg?width=200 "Six level telephone [[stepping switch]] similar to the type used by SIS to build its first Purple. analog. On display at [[The Telephone Museum]].")
Wikipédia
In the history of cryptography, the "System 97 Typewriter for European Characters" (九七式欧文印字機) or "Type B Cipher Machine", codenamed Purple by the United States, was an encryption machine used by the Japanese Foreign Office from February 1939 to the end of World War II. The machine was an electromechanical device that used stepping-switches to encrypt the most sensitive diplomatic traffic. All messages were written in the 26-letter English alphabet, which was commonly used for telegraphy. Any Japanese text had to be transliterated or coded. The 26-letters were separated using a plug board into two groups, of six and twenty letters respectively. The letters in the sixes group were scrambled using a 6 × 25 substitution table, while letters in the twenties group were more thoroughly scrambled using three successive 20 × 25 substitution tables.
The cipher codenamed "Purple" replaced the Type A Red machine previously used by the Japanese Foreign Office. The sixes and twenties division was familiar to U.S. Army Signals Intelligence Service (SIS) cryptographers from their work on the Type A cipher and it allowed them to make early progress on the sixes portion of messages. The twenties cipher proved much more difficult, but a breakthrough in September 1940 allowed the Army cryptographers to construct a machine that duplicated the behavior (was an analog) of the Japanese machines, even though no one in the U.S. had any description of one.
The Japanese also used stepping-switches in systems, codenamed Coral and Jade, that did not divide their alphabets. American forces referred to information gained from decryptions as Magic.
