| 摘要 |
1,170,100. Digital transmission systems. THOMSON-CSF. 29 Dec., 1966 [30 Dec., 1965], No. 58234/66. Heading H4P. A ciphering and deciphering unit is timeshared between a receiving channel, containing data to be deciphered, and a transmitting channel, containing data to be ciphered. Received ciphered data passes to a buffer store and also to a logic arrangement to ensure synchronism of operation. When the store is filled and the cipher-decipher unit is free the store is read out, the data passing via a switch to the cipher-decipher unit, which deciphers the data. At the end of the deciphering cycle the content of the cipher-decipher unit is stored in a second store until the next deciphering cycle, and the current content of the store, which is that of the cipher-decipher unit at the end of the previous ciphering cycle, is read out to the cipher-decipher unit so making it ready for the subsequent ciphering cycle. Data to be ciphered passes from a third store to the cipher-decipher unit via a switch controlled by the logic when the store is full and the cipher-decipher unit is free. The data is then ciphered and transmitted, after which the content of the cipher-decipher unit replaces that in the second store, so readying the cipher-decipher unit for the subsequent deciphering cycle. |
