| 摘要 |
1,010,430. Cyphering and decyphering. ANSTALT EUROPAISCHE HANDELSGESELLSCHAFT. Nov. 9, 1961, No. 40173/61. Heading H4P. In a cyphering system each " clear " letter, from either a keyboard M or a tape LS, Fig. 1, is converted C into a number of pulses equal to the serial number of the letter in the alphabet, a " key " letter, e.g. from a key-tape B, is similarly converted, and the two pulse trains are added (modulus 26) in a counter D, the resulting sum (modulus 26) being converted E into a " cypher " letter having a serial number in the alphabet equal to the sum (modulus 26), and this " cypher " letter is transmitted F.G.N. in a telegraphic code to a distance. For decyphering a similar arrangement is used except that the " key " letter is subtracted. The system described also includes a counting H and programme J device which inserts two " space " signals between each block of five " cypher " letters and " carriage return " and " line feed " signals between each group of ten blocks. In the decyphering arrangement of the equipment shown a device I is provided which detects any technical signals such as " line feed ", " space " and the line, and stops the feed of key letters from the tape B since such technical signals form no part of the cyphered text. (The apparatus only cyphers letters and each cyphered letter is a further letter). Also, as described, the letter " W " is replaced by the letters "VV", thereby leaving W free to be used as a space symbol.
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