| 摘要 |
A time verification system capable of being readily constructed at low cost, without requiring a special arrangement for generating time information. A typical embodiment of this invention has a plurality of servers and a time verification device. The time verification device has: a segmented processing unit that segments an electronic document into a plurality of segmented data, using a secret sharing scheme; a distributed processing unit that sends each segmented data to a different server, and collects, from each server, each segmented data corresponding to the electronic document for which a time verification request has been received from a user; a restoration unit that restores the electronic document using the secret sharing scheme, on the basis of the collected segmented data; and an existence time calculation unit that, when the electronic document has been normally restored, calculates and outputs an existence time for the electronic document, on the basis of time stamps attached to each collected segmented data. |
