Patent ID: 7124294

Claim:
An electronic certificate system that uses an electronic certificate, comprising: a first user apparatus used by an issuee of the electronic certificate; a second user apparatus, connected with the first user apparatus over a network, that receives required data and the electronic certificate that are sent from the first user apparatus; and a certificate validity checking apparatus, connected with the network, that receives request information indicating a request to check for validity of the electronic certificate and validity check permission information indicating that checking for validity of the electronic certificate is permitted, which are sent from the second user apparatus; detects an expiration date of a validity check permit and an upper limit on a number of uses of the validity check permit based on the received validity check permission information; checks whether the expiration date has not passed and whether an accounted number of uses of the validity check permission is smaller than the upper limit; if the expiration date has not passed and the accounted number is smaller than the upper limit, checks for validity of the electronic certificate; and sends the result of the check processing to the second user apparatus.