Digital document management system, digital document management method, and digital document management program

A digital document management system that manages document information created and registered in a digital form, comprising:

• a partial identification information generation section that divides the document information into a plurality of parts and generates partial identification information that represents, in an identifiable manner, the respective parts of the document information based on information included in the respective parts;
• a digital signature creation section that creates a digital signature to be appended to the document information using the partial identification information;
• a management section that manages the document information;
• and
• a verification section that verifies the validity of the managed document information, wherein
• at the registration time of new document information, the management section manages a digital signature created by the digital signature creation section in association with the document information and, at the correction time of the document information, it acquires partial identification information related to a corrected part of the document information before correction, allows the digital signature creation section to create a digital signature to be appended to the corrected document information, and manages the digital signature and partial identification information related to the corrected part of the document information before correction in association with the corrected document information, and
• the verification section uses the partial identification information and digital signature managed in association with the corrected document information by the management section and partial identification information newly created from the corrected document information by the partial identification information generation section to perform the verification.

A digital document management method that manages document information created and registered in a digital form by a computer, comprising:

• a partial identification information generation step that divides the document information into a plurality of parts and generates partial identification information that represents, in an identifiable manner, the respective parts of the document information based on information included in the respective parts;
• a digital signature creation step that creates a digital signature to be appended to the document information using the partial identification information;
• a management step that manages the document information;
• and
• a verification step that verifies the validity of the managed document information, wherein
• at the registration time of new document information, the management step manages a digital signature created by the digital signature creation step in association with the document information and, at the correction time of the document information, it acquires partial identification information related to a corrected part of the document information before correction, allows the digital signature creation section to create a digital signature to be appended to the corrected document information, and manages the digital signature and partial identification information related to the corrected part of the document information before correction in association with the corrected document information, and
• the verification step uses the partial identification information and digital signature managed in association with the corrected document information by the management step and partial identification information newly created from the corrected document information by the partial identification information generation step to perform the verification.