Electronic signature addition method, electronic signature verification method, and system and computer program product using these methods
AssigneeKabushiki Kaisha Toshiba
InventorsShoji Kitaori, Yuichi Koganezawa
Life of this patent
Estimating the term…
Abstract
An apparatus for adding an electronic signature to document data includes a delimiter character detector for dividing the input document data into a plurality of divided document data by using as a delimiter a predetermined character appearing in a document represented by the document data, a digest generator and an encrypter for generating an electronic signature based on the divided document data for each divided document data, and a signature-added message generator for generating the divided document data, the electronic signature based on the divided document data, and information for associating the divided document data with the electronic signature.
Claims30
A method of adding an electronic signature to document data, comprising the steps of:
- dividing the document data into a plurality of divided document data using as a delimiter a predetermined character appearing in a document represented by the document data;
- generating an electronic signature for each of the divided document data on the basis of the divided document data;
- and
- storing the divided document data, the electronic signature based on the divided document data, and information for associating the divided document data with the electronic signature.
A method of adding an electronic signature to document data, comprising the steps of:
- storing the document data upon excluding a predetermined character appearing in a document represented by the document data;
- generating an electronic signature on the basis of the document data from which the predetermined character is excluded;
- and
- storing the document data from which the predetermined character is not excluded, the electronic signature, and information for associating the electronic signature with the document data from which the predetermined character is not excluded.
A method of evaluating reliability associated with alteration of document data with an electronic signature, comprising the steps of:
- obtaining a total number of printable characters in the document data and a total number of unprintable characters in the document data;
- and
- evaluating reliability on the basis of the total numbers of printable and unprintable characters.
An apparatus for adding an electronic signature to document data, comprising:
- input means for the document data;
- means for dividing the input document data into a plurality of divided document data using as a delimiter a predetermined character appearing in a document represented by the document data;
- means for generating an electronic signature based on the divided document data for each divided document data;
- and
- means for outputting the divided document data, the electronic signature based on the divided document data, and information for associating the divided document data with the electronic signature.
An apparatus for adding an electronic signature to document data, comprising:
- input means for the document data;
- means for storing the document data upon excluding a predetermined character appearing in a document represented by the document data;
- means for generating an electronic signature on the basis of the document data from which the predetermined character is excluded;
- and
- means for storing the document data from which the predetermined character is not excluded, the electronic signature, and information for associating the electronic signature with the document data from which the predetermined character is not excluded.
An apparatus for evaluating reliability associated with alteration of document data with an electronic signature, comprising:
- means for obtaining a total number of printable characters in the document data and a total number of unprintable characters in the document data;
- and
- means for evaluating reliability on the basis of the total numbers of printable and unprintable characters.
A computer program product for causing a computer system to execute processing for adding an electronic signature to document data, comprising:
- a recording medium;
- means for supplying to said computer system an instruction recorded on said recording medium to divide the document data into a plurality of divided document data by using as a delimiter a predetermined character appearing in a document represented by the document data;
- means for supplying to said computer system an instruction recorded on said recording medium to generate an electronic signature based on the divided document data for each divided document data;
- and
- means for supplying to said computer system an instruction recorded on said recording medium to store the divided document data, the electronic signature based on the divided document data, and information for associating the divided document data with the electronic signature.
A computer program product for causing a computer system to execute processing for adding an electronic signature to document data, comprising:
- a recording medium;
- means for supplying to said computer system an instruction recorded on said recording medium to exclude a predetermined character appearing in a document represented by the document data and store the excluded predetermined character;
- means for supplying to said computer system an instruction recorded on said recording medium to generate an electronic signature on the basis of the document data from which the predetermined character is excluded;
- and
- means for supplying to said computer system an instruction recorded on said recording medium to store the document data from which the predetermined character is not excluded, the electronic signature, and information for associating the electronic signature with the document data from which the predetermined character is not excluded.
A computer program product for causing a computer system to evaluate reliability associated with alteration of document data added with an electronic signature, comprising:
- a recording medium;
- means for supplying to said computer system an instruction recorded on said recording medium to obtain a total number of printable characters in the document data and a total number of unprintable characters in the document data;
- and
- means for supplying to said computer system an instruction recorded on said recording medium to evaluate reliability on the basis of the total numbers of printable and unprintable characters.
Dependencies are inferred from the claim text.