Timestamping system and timestamping program

A timestamping system comprising:

• a plurality of servers including a storage device;
• and a timestamping device being connected to each of the servers via a network and authenticating an existed time at which an event such that a plurality of data items are created at the same timing is considered to have at least occurred,
• wherein the timestamping device includes:
• a distributing processing unit transmitting the plurality of data items created at the same timing upon the event to the servers being different from each other, respectively, and collecting the data items corresponding to the event requested for timestamping from a user from each of the servers, respectively;
• and
• an existed time calculating unit calculating and outputting the existed time regarding the event based on the timestamps applied to each of the data items collected from each of the servers, and
• the server applies the timestamps to the data items transmitted from the timestamping system and stores the same in the storage device.

A timestamping system comprising:

• a plurality of servers having a storage device;
• and a timestamping device being connected to each of the servers via a network and authenticating an existed time at which an electronic document is considered to have at least created and existed,
• the timestamping device includes:
• a dividing processing unit dividing the electronic document into a plurality of divided data items by a secret sharing scheme;
• a distributing processing unit transmitting each of the divided data items to the servers being different from each other, and collecting each of the divided data items corresponding to the electronic document requested for timestamping from a user;
• a restoring processing unit restoring the electronic document by a secret sharing scheme based on each of the divided data items collected from each of the servers when the electronic document can be normally restored;
• and
• an existed time calculating unit calculating the existed time regarding the electronic document based on timestamps applied to the divided data items collected from the servers when the electronic document can be normally restored by the restoring processing unit, and
• the server applies a timestamp to the divided data transmitted from the timestamping system and stores the same in the storage device.

A timestamping program letting a computer function as a timestamping device in a timestamping system that includes:

• a plurality of servers having a storage device;
• and the timestamping device being connected to the servers via a network and authenticating an existed time at which an electronic document is considered to have at least created and existed,
• the timestamping program executing:
• a dividing processing of dividing the electronic document into a plurality of divided data by a secret sharing scheme;
• a distributing processing of transmitting the divided data items to the servers being different from each other to store the same and collecting each of the divided data items corresponding to the electronic document being requested for timestamping from a user from each of the servers;
• a restoring processing of restoring the electronic document by the secret sharing scheme based on each of the divided data items collected from each of the servers;
• and
• an existed time calculating processing of calculating and outputting the existed time regarding the electronic document based on timestamps applied by the servers to each of the divided data items collected from each of the servers when the electronic document can be normally restored in the restoring processing.