To make provable the existence and contents of an electronic document without limitation even after the expiration of validity of an electronic certificate and to prove the existence and contents of that electronic document even when the original is not kept.
Client computers EE1, EE2 and EE3 keep an original ORG2 and a registration number NUM returned at the time of registering an electronic document DOC and directly apply for a proof while using the original ORG2 or indirectly apply for the proof while using the registration number NUM. The server computer of a notarial agency NA applies time information T1 and the signature of the notarial agency to the registered electronic document and preserves it in a preserving device DB as the original ORG. The notarial agency responds to the direct or indirect proof application with time information T2 and T3 at the time of proving, the signature of the notarial agency and a certification sentence.
TOYODA HIDEKI
NAGANO HIROMI
SUZAKI SEIICHI
