en:nema
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+ | ====== NEMA / T.D. ====== | ||
+ | **NEMA / T.D.**; " | ||
+ | The delivery of the last [[Enigma_K|Enigma]] cipher machines ordered in Germany was more and more delayed, as World War II borke out. So employees of the national cipher office developed a technically improved cipher machine, which was to be manufactured by Zellweger AG, Uster. | ||
+ | |||
+ | Two prototypes were built in 1943 and successfully tested in fall 1944. The mechanically improved machine was built in spring 1945 as "NEMA Model 45" in a total of 640 machines. These machines came into service in 1947, and they were used by the Swiss army and the Federal Political Department (Swiss ministry of foreign affairs) for more than 20 years. | ||
+ | {{: | ||
+ | ===== Specifications ===== | ||
+ | * [[Principle]]: | ||
+ | * [[Modes]]: Rotor machine, one reflector wheel, four permutation wheels, five stepping wheels | ||
+ | |||
+ | ==== Power Supply ==== | ||
+ | {{ : | ||
+ | * [[Accumulator / Batteries]]: | ||
+ | * [[Mains]]: 110 - 250 V AC power | ||
+ | |||
+ | ==== Dimensions ==== | ||
+ | * 332 x 384 x 148 mm, 10.7 kg | ||
+ | |||
+ | ==== Accessories ==== | ||
+ | * Second lamp field | ||
+ | * Case with reserve wheels ** Res. Rolls to T.D. ** | ||
+ | |||
+ | ===== Operation ===== | ||
+ | Similar to the [[Enigma K|ENIGMA]], NEMA is a rotor-type ciphering machine with a lamp panel; the machine is more complex in comparison to the ENIGMA and offers better key security. | ||
+ | |||
+ | The NEMA is equipped with one **reflector wheel**, which is not moved, but only adjusted to the basic position, **five stepping wheels** and **four permutation wheels**. In contrast to the ENIGMA, the wheels notches to move the next wheel in irregular intervals, which greatly increases the key security. The stepping and the permutation wheels can be mounted and inserted into the machine in different orders, the key consists of the order of the wheels and a keyword which has to be set with adjusting the wheels in the initial position; this keyword of ten letters and was trnasmitted in the beginning of a telegram and repeated at its end. | ||
+ | |||
+ | When one of the 26 letter keys is pressed down, one of the 26 letters will light up on the lamp panel, depending on the setting of the wheels determined by the initial keyword. Each time a key is pressed, the stepping and permutation wheels are rotated at irregular intervals. | ||
+ | |||
+ | The text to be encrypted is entered on the typewriter keyboard and the ciphertext is copied from the lamp panel and written on a telegram form, which is handed over to the radio operator to be transmitted. | ||
+ | |||
+ | In this kind of mechanical ciphering, one letter is substituted by another, when the same key for the same plaintext letter is pressed several times, it will be replaced by different letters in the ciphertext. The fact that a letter can never be replaced by itself is a weak point of the rotor cipher machines. | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | ===== Technical Principle ===== | ||
+ | Mechanical cipher machine with one reflector wheel, four permuting wheels and five stepping wheels. | ||
+ | |||
+ | ==== Tube Assembly ==== | ||
+ | No electronic valves are used. | ||
+ | |||
+ | ==== Development ==== | ||
+ | The NEMA was developed by the Swiss army's cipher bureau and manufactured by the [[Zellweger|Machine Factory Uster, Zellweger AG]], which had some experience in precision mechanics, but had never dealt with ciphering technology before. | ||
+ | |||
+ | The entire production took place in a secret project, only a few employees were allowed to wire the wheels in a secret shelter. Since all cases of Swiss Army equipment in the arsenal must carry a label to be reconized from the outside, the NeMa case got the abbreviation T.D., which stands for **" | ||
+ | |||
+ | ==== Component Layout ==== | ||
+ | The machines in the instruction material (for the training of the soldiers) are equipped with other wheels than the KMob machines: these, marked with sticker "To be used only in war mobilization", | ||
+ | * ** Training machines ** (so-called " | ||
+ | * ** War machines ** (so-called "KMob machines" | ||
+ | * ** Machines for the embassy communication** (so-called " | ||
+ | |||
+ | The " | ||
+ | The " | ||
+ | |||
+ | The cipher machines were used in 1948 - 1979 in the army and in the EPD. The NEMA procedure was declassified in 1992 (ie secrecy abolished) and the machines were sold to the public in May 1994 in the Zeughaus Meiringen for liquidation. | ||
+ | |||
+ | {{gallery>: | ||
+ | |||
+ | ===== Technical Manuals ===== | ||
+ | * {{ : | ||
+ | |||
+ | ==== Additional Information ==== | ||
+ | * Das Fernmeldematerial der Schweizerischen Armee, Band 10, Codes und Chiffrierverfahren, | ||
+ | * [[http:// | ||
+ | * [[https:// | ||
+ | * [[https:// | ||
+ | * [[https:// |
en/nema.txt · Zuletzt geändert: 2019/11/24 20:24 von 127.0.0.1