Patent ID: 7080045

Claim:
An electronic revenue stamp issuing apparatus, comprising: request means for making a request for issuance of an electronic revenue stamp for a user-determined amount, said user-determined amount being a value or cost of the electronic revenue stamp, said request being made by a receiver; debit means for tracking remaining value of a prepaid amount, said prepaid amount being reduced, each time an electronic revenue stamp is issued, by said value or cost of said electronic revenue stamp; a judging means for judging whether the amount of said electronic revenue stamp to be issued is equal to or less than said prepaid amount; an issuing means for issuing said electronic revenue stamp as data on a document, said issuing means giving a serial number with said data to said electronic revenue stamp, said data containing a digital signature of said electronic revenue stamp issuing apparatus on a message, said message including the document which said electronic revenue stamp is attached to, the amount of said electronic revenue stamp, and an identifier of a receiver of said electronic revenue stamp, if said amount of said revenue stamp is judged to be equal to or less than said prepaid amount by said judging means; a balance amount reducing means for reducing said prepaid amount of said debit means by said value or cost of said electronic revenue stamp if said electronic revenue stamp is issued; a verifying means that is part of the stamp issuing apparatus, for receiving a digital certificate for making an electronic revenue stamp invalid, said digital certificate containing a digital signature of said receiver, and verifying whether said digital certificate is valid or not by using an identifier of said receiver and without communication with a data center; an amount increasing means for increasing said prepaid amount by an amount equal to the value or cost of said invalidated electronic revenue stamp; and an invalid electronic revenue stamp recording means for recording receipt of said digital certificate.