1) Field of the Invention
The present invention relates to a technology for issuing and granting an electronic signature.
2) Description of the Related Art
With advance of the technology, digitalizing the paper documents and saving the data of the paper documents digitalized are required. By digitalizing the paper documents, the space to save the paper documents is economized and the data of the paper documents are managed electronically. However, the electronic data has a problem that the electronic data can be falsified without leaving any trace. When the data is exchanged socially and commercially, the data-reliability and data-integrity are required socially and commercially by determining whether the data is falsified.
So far, the apparatus for granting electronic signature that creates the electronic signature using the public-key encryption method and grants the electronic signature to the electronic data has been made to solve this problem. The electronic signature that is granted to the electronic data indicates whether the electronic data is falsified.
The apparatus for granting electronic signature that uses the public-key encryption method creates the electronic signature using the secret key, and the certificate authority sets the expiration date for the secret key to have the higher-reliable secret key by expiring the secret key when needed.
An example of the apparatus for granting electronic signature is disclosed in Japanese Patent Application Laid-Open No. 2002-230202. The apparatus for granting electronic signature that uses the public-key encryption method creates the electronic data and the electronic signature from the paper documents that are acquired from the user of the service. While sending the electronic data and the electronic signature that are created to the user, the service provider saves both the electronic data and the electronic signature corresponding to the paper documents, so that the service provider guarantees the relationship between the paper documents and both the electronic data and the electronic signature.
The digitalization of the especially important paper documents must be performed correctly. However, the possibility of the failure of the digitalization exists actually. For example, when the scanner digitalizes the paper documents, the dirt on the paper may cause the scanner to miss the data. Another example is that the optical character reader (OCR) may recognize the wrong character. In these cases, the electronic data needs to be processed properly to redeem the failure of the digitalization.
The electronic document with the failure of the digitalization is less reliable, so that the paper documents still need to be saved, that is, the space for the paper documents can not be economized. To have the higher-reliable electronic document, the paper documents must be digitalized by the user who has the suitable knowledge and ability.
However, in the conventional apparatus for granting electronic signature, the reliability of the paper documents digitalized are determined by whether the electronic signature is granted, that is, the secret key is used. However, who knows the owner of the secret key has enough ability to digitalize the paper documents?
For example, in the conventional technology, the service provider saves the paper documents and both the electronic data and the electronic signature corresponding to the paper documents, and guarantees the relationship between the paper documents and both the electronic data and the electronic signature. However, the secret-key owner who does not have the authority to grant the electronic signature to the electronic data sometimes creates the electronic data and the electronic signature. Therefore, the relationship between the paper documents and both the electronic signature and the electronic data has not been guaranteed certainly.
The problem of the conventional technology is the lower reliability of the electronic signature, because the conventional apparatus for granting electronic signature does not determine whether the owner of the secret key has the authority to grant the electronic signature. Accordingly, determining whether to grant the electronic signature based on the secret-key owner's authority has been required.
In other words, the apparatus for granting electronic signature that grants the authority based on both the knowledge and the ability of the secret-key owner has been required to guarantee the proper digitalization.