| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital certificate issue system that can update a digital certificate for a plurality of number of times without being attendant with increase in a data amount and complicated decoding processing and facilitate the management of its term of validity. SOLUTION: The digital certificate issue system generates a key pair KP<SB>X</SB>being a pair of a private key and a pubic key whose term of validity at each of unit period N years is twice the unit period at a point of time X, generates new key pairs KP<SB>X+1</SB>, KP<SB>X+2</SB>, -KP<SB>X+i</SB>by each of the unit period N years N after that, encrypts attachment information such as a message digest and an existing date or the like decoded by a digital certificate generated before every time of generation by using the key pair newly generated to update the digital certificate, increases the data amount for the case and simplifies the decode processing thereby facilitating the management of term of validity. COPYRIGHT: (C)2004,JPO
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