| 摘要 |
PURPOSE:To prevent a synchronizing signal from being detected easily by a third party, by transmitting an auxiliary signal for synchronization after modulation at a start position. CONSTITUTION:An enciphering part 1 enciphers and outputs data input according to a condition decided by a start position memory 2. Start position data stored in the start position memory 2 and the auxiliary signal for synchronization stored in a synchronizing auxiliary signal memory 3 are read out by clocks A and B respectively, and modulation is performed at an EXOR circuit 4 which performs the (exclusive OR) of those outputs, and a result is outputted. Reception data and the data of a synchronizing auxiliary signal memory 11 are collated bit by bit, and the output of a decision apparatus 15 is stored in an output register 16. The content of the output becomes the one which represents the start position. A cipher is decoded based on the start position data fetched in the output register 16 of enciphered data inputted to a register 12 after the synchronization being established.
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