Patent ID: 7984302
Filing Date: 2011-07-19
Classification: H04L

Abstract:
1. An electronic document management apparatus, comprising: at least one processor coupled via a bus to a memory, wherein the at least one processor is configured to control: a first embedding unit configured to embed, into an electronic document to create a first embedded electronic document, digital signature long-term storage data and digital signature data for verifying validity of an electronic document including the digital signature long-term storage data; a second embedding unit configured to embed, into the first embedded electronic document to create a second embedded electronic document, time-stamp long-term storage data and time-stamp data for verifying validity of an electronic document including the time-stamp long-term storage data; a confirmation unit configured to confirm an object number of time-stamp data embedded in the second embedded electronic document when the second embedded electronic document is updated; a first obtaining unit configured to obtain embedded time-stamp long-term storage data and embedded time-stamp data among time stamps embedded in the second embedded electronic document, wherein the first obtaining unit obtains both the time-stamp long-term storage data and the time-stamp data by the object number of time-stamp data confirmed by the confirmation unit; a first verification unit configured to verify whether both the time-stamp long-term storage data and the time-stamp data obtained by the first obtaining unit have been tampered with, wherein, in a case where the first verification unit verifies that both a most recently embedded time-stamp long-term storage data and a most recently embedded time-stamp data have been tampered with, the first obtaining unit stops processing, and, in a case where the first verification unit verifies that both the most recently embedded time-stamp long-term storage data and the most recently embedded time-stamp data have not been tampered with, the first obtaining unit obtains a second most recently embedded time-stamp long-term storage data and a second most recently embedded time-stamp data relative to data previously verified by the first verification unit; a second obtaining unit configured to obtain, in a case where the first verification unit verifies that both the time-stamp long-term storage data and the time-stamp data obtained by the first obtaining unit have not been tampered with, digital signature long-term storage data and digital signature data embedded in the second embedded electronic document; a second verification unit configured to verify whether both the digital signature long-term storage data and the digital signature data obtained by the second obtaining unit have been tampered with; and a third embedding unit configured to, in a case where the second verification unit verifies that both the time-stamp long-term storage data and the time-stamp data have been tampered with, obtain a time-stamp certificate from a certificate authority, generate time-stamp long-term storage data and time-stamp data based on the time-stamp certificate, and embed the generated time-stamp long-term storage data and time-stamp data into the second embedded electronic document.