Electronic document authenticity assurance method and electronic document disclosure system

Abstract

An electronic document authenticity assurance technique and an information disclosure system both of which can compatibly realize the assurance of the authenticity of disclosure documents and the deletion of information inappropriate for disclosure. An electronic document is divided into constituent elements and an electronic signature is affixed to an arbitrary subset of a set including all the constituent elements. Otherwise, an electronic signature is affixed to data obtained by binding each of the constituent elements to information specifying the relationship between a respective one of the constituent elements and the structure of the electronic document. Otherwise, the hash values of the respective constituent elements are calculated and an electronic signature is affixed to data obtained by binding the calculated hash values together. Otherwise, random numbers generated for the respective constituent elements are bound together, then the hash values of the respective random-numbered constituent elements are calculated, and then an electronic signature is affixed to data obtained by binding the calculated hash values together.

1 - 15 . (canceled) 
   
   
       16 . An electronic document creation system in which a computer creates an electronic document whose authenticity is able to be verified by an authenticity assurance data from an original electronic document including a plurality of constituent elements,
 wherein:   the computer, by executing a first program, conducts the steps of:   dividing an original electronic document into the plurality of constituent elements;   calculating hash values on the plurality of constituent elements respectively by inputting the constituent elements to a cryptographic hash function;   creating hash value bound data in which hash values respectively calculated on the plurality of constituent elements are bound and generating one electronic signature corresponding to the hash value bound data;   generating the authenticity assurance data including the one electronic signature and position information indicating respective position of the constituent elements in the original electronic document; and   creating the electronic document whose authenticity is able to be verified including the original electronic document and the authenticity assurance data.   
   
   
       17 . A disclosure electronic document system in which a computer creates a disclosure electronic document from an electronic document whose authenticity is able to be verified that is created by the electronic document creation system according to  claim 16 ,
 wherein:   the computer, by executing a second program, conducts the steps of;   specifying undisclosure constituent elements not to be disclosed among the constituent elements including the electronic document whose authenticity is able to be verified;   calculating hash values on the plurality of the undisclosure constituent elements respectively by inputting the undisclosure constituent elements to a cryptographic hash function;   updating the authenticity assurance data by adding hash values calculated according to the disclosure constituent elements to the authenticity assurance data, and   creating a disclosure electronic document which does not include the specified undisclosure constituent elements, and includes one or more disclosure constituent elements which are the constituent elements not to be the undisclosure constituent elements and the updated authenticity assurance data.   
   
   
       18 . An authenticity verification system of a disclosure electronic document in which a computer verifies an authenticity of a disclosure electronic document created by the disclosure electronic document creation system according to  claim 17 ,
 wherein:   the computer, by executing a third program, conducts the steps of;   calculating hash values on the respective disclosure constituent elements included in the disclosure electronic document by inputting the disclosure constituent elements to the cryptographic hash function;   binding the calculated hash value according to the disclosure constituent elements and a hash value calculated according to the undisclosure constituent elements included in the updated authenticity assurance data in a order based on position information of the constituent elements included in the updated authenticity assurance data; and   verifying an assurance of the disclosure electronic document by verifying the electronic signature included in the updated authenticity assurance data with the use of the bound hash value.