| 摘要 |
PURPOSE:To obtain a random number generator with high security by providing a rewrite means rewriting at least one digit of a digital pattern into the sum of at least two digits of the said digital pattern in the ciphering communication. CONSTITUTION:A ROM 341 is a 16X8 bit ROM and outputs an 8-bit stored in an address to an address input 4-bit. A selector 342 decides which bit among the said 8 bits is to be selected by a part of a key pattern inputted from an input terminal 343. ROMs 321, 322 are 16X7 bit ROMs. The key pattern consists of 60 bits and they are inputted to 301-302 by 3-bit each. The output of the ROM 322 is fed back and subject to exclusive OR (EOR) by an exclusive OR element at the most significant bit 332 of the shift register 331 and the result is inputted to the least significant bit of the shift register 331. The output random number is an output once per 8 times among the outputs of the ROM 321.
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