Electronic signature addition method, electronic signature verification method, and system and computer program product using these methods
First Claim
1. 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.
1 Assignment
0 Petitions
Accused Products
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.
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Citations
30 Claims
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1. A method of adding an electronic signature to document data, comprising the steps of:
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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. - View Dependent Claims (2, 3, 4, 14)
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5. A method of adding an electronic signature to document data, comprising the steps of:
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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. - View Dependent Claims (6, 7, 8)
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9. A method of evaluating reliability associated with alteration of document data with an electronic signature, comprising the steps of:
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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. - View Dependent Claims (10)
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11. An apparatus for adding an electronic signature to document data, comprising:
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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. - View Dependent Claims (12, 13)
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15. An apparatus for adding an electronic signature to document data, comprising:
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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. - View Dependent Claims (16, 17, 18)
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19. An apparatus for evaluating reliability associated with alteration of document data with an electronic signature, comprising:
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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. - View Dependent Claims (20)
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21. A computer program product for causing a computer system to execute processing for adding an electronic signature to document data, comprising:
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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. - View Dependent Claims (22, 23, 24)
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25. A computer program product for causing a computer system to execute processing for adding an electronic signature to document data, comprising:
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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. - View Dependent Claims (26, 27, 28)
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29. A computer program product for causing a computer system to evaluate reliability associated with alteration of document data added with an electronic signature, comprising:
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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. - View Dependent Claims (30)
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Specification