| 摘要 |
PURPOSE:To prevent the deviation of synchronism of a special code even in case of bit deviation between transmission data and reception data by detecting a signal indicating the divisions of data blocks and generating the special code by this signal to decode a cipher. CONSTITUTION:Ciphered reception data is inputted from an input terminal 11 and is inputted to a block signal generating part 1 and an exclusive OR circuit 3. The generating part 1 monitors a block division signal in reception data and detects this signal to output a block signal 101. At the time of receiving the block signal 101, a special code generating circuit 2 generates the decoding special code within a time shorter than a time corresponding to the length of one block. The special code generated by this circuit 2 is inputted to the exclusive OR circuit 3 for the purpose of decoding ciphered data in the next block.
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