US5915024A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic signature addition method, electronic signature verification method, and system and computer program product using these methods
Assignee: Toshiba Corp
•
Filing: 1997-06-17
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Granted: 1999-06-22
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Expires: 2017-06-17
Abstract
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.
Inventors
- 👤 Shoji Kitaori
- 👤 Yuichi Koganezawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:45
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/32; H04L9/3247; Y; Y10; Y10S; Y10S707/00; Y10S707/99941; Y10S707/99943
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
87 words
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.
Claim 2
Independent Claim
87 words
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.
Claim 3
Dependent Claim
45 words
A method according to claim 1, wherein the information for associating the divided document data with the electronic signature contains: information about division of document data contained in the divided document data; and non-encrypted information about division of document data contained in the electronic signature.
Claim 4
Dependent Claim
30 words
A method according to claim 1, further comprising the step of excluding from the document data an unprintable character appearing in the document data and storing the excluded unprintable character.
Claim 5
Dependent Claim
61 words
A method of verifying the electronic signature generated by the method of claim 1, comprising the step of, when the divided document data added with the electronic signature is contained in the received document data, determining the validity of the document for each divided document data on the basis of information for associating the divided document data with the electronic signature.
Claim 6
Independent Claim
85 words
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.
Claim 7
Independent Claim
85 words
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.
Claim 8
Dependent Claim
14 words
A method according to claim 5, wherein the predetermined character is an unprintable character.
Claim 9
Dependent Claim
27 words
A method according to claim 5, wherein the information for associating the electronic signature with the document data contains information associated with exclusion of the predetermined character.
Claim 10
Dependent Claim
64 words
A method of verifying the electronic signature generated by the method of claim 5, comprising the step of excluding the predetermined character from the document data on the basis of information for associating the electronic signature with the document data and determining the validity of the document data on the basis of the electronic signature and data from which the predetermined character is excluded.
Claim 11
Independent Claim
56 words
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.
Claim 12
Independent Claim
56 words
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.
Claim 13
Dependent Claim
79 words
A method according to claim 9, wherein the step of evaluating reliability comprises calculating a reliability value T by: T=(p k)×(m+1)×(m+2)× . . . ×(m+k)/(2 1) where p is the number of types of unprintable characters, m is the number of document characters, k is the number of printable characters, and L is the bit length of a message digest, and evaluating reliability of the signature information by comparing the obtained reliability value T and a predetermined threshold value.
Claim 14
Independent Claim
93 words
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.
Claim 15
Independent Claim
93 words
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.
Claim 16
Dependent Claim
49 words
An apparatus according to claim 11, further comprising means for making the information for associating the divided document data with the electronic signature contain information about division of document data contained in the divided document data, and non-encrypted information about division of document data contained in the electronic signature.
Claim 17
Dependent Claim
29 words
An apparatus according to claim 11, further comprising means for excluding from the document data an unprintable character appearing in the document data and storing the excluded unprintable character.
Claim 18
Dependent Claim
60 words
An apparatus for verifying the electronic signature generated by the apparatus of claim 1, comprising means for, when the divided document data added with the electronic signature is contained in the received document data, determining the validity of the document for each divided document data on the basis of information for associating the divided document data with the electronic signature.
Claim 19
Independent Claim
94 words
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.
Claim 20
Independent Claim
94 words
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.
Claim 21
Dependent Claim
14 words
An apparatus according to claim 15, wherein the predetermined character is an unprintable character.
Claim 22
Dependent Claim
30 words
An apparatus according to claim 15, further comprising means for making the information for associating the electronic signature with the document data contain information about exclusion of the predetermined character.
Claim 23
Dependent Claim
64 words
An apparatus for verifying the electronic signature generated by the apparatus of claim 15, comprising means for excluding the predetermined character from the document data on the basis of the information for associating the electronic signature with the document data and determining the validity of the document data on the basis of the electronic signature and data from which the predetermined character is excluded.
Claim 24
Independent Claim
57 words
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.
Claim 25
Independent Claim
57 words
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.
Claim 26
Dependent Claim
78 words
An apparatus according to claim 19, wherein said means for evaluating reliability calculates a reliability value T by: T=(p k)×(m+1)×(m+2)× . . . ×(m+k)/(2 1) where p is the number of types of unprintable characters, m is the number of document characters, k is the number of printable characters, and L is the bit length of a message digest, and evaluates reliability of the signature information by comparing the obtained reliability value T and a predetermined threshold value.
Claim 27
Dependent Claim
139 words
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.
Claim 28
Dependent Claim
139 words
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.
Claim 29
Dependent Claim
45 words
A product according to claim 21, wherein the information for associating the divided document data with the electronic signature contains: information about division of document data contained in the divided document data; and non-encrypted information about division of document data contained in the electronic signature.
Claim 30
Dependent Claim
37 words
A product according to claim 21, further comprising means for supplying to said computer system an instruction recorded on said recording medium to exclude an unprintable character appearing in the document data and storing the unprintable character.
Claim 31
Dependent Claim
81 words
A computer program product for causing a computer system to verify the electronic signature generated in claim 21, comprising: a recording medium; and means for, when the divided document data added with the electronic signature is contained in the received document data, supplying to said computer system an instruction recorded on said recording medium to determine the validity of the document for each divided document data on the basis of information for associating the divided document data with the electronic signature.
Claim 32
Dependent Claim
141 words
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.
Claim 33
Dependent Claim
141 words
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.
Claim 34
Dependent Claim
14 words
A product according to claim 25, wherein the predetermined character is an unprintable character.
Claim 35
Dependent Claim
26 words
A product according to claim 25, wherein the information for associating the electronic signature with the document data contains information about exclusion of the predetermined character.
Claim 36
Dependent Claim
87 words
A computer program product for causing a computer system to verify the electronic signature generated by the product of claim 25, comprising: a recording medium; and means for supplying to said computer system an instruction recorded on said recording medium to exclude a predetermined character from the document data on the basis of the information for associating the electronic signature with the document data and determine the validity of the document on the basis of the electronic signature and data from which the predetermined character is excluded.
Claim 37
Dependent Claim
94 words
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.
Claim 38
Dependent Claim
94 words
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.
Claim 39
Dependent Claim
86 words
A product according to claim 29, wherein said means for evaluating reliability causes said computer system to perform processing for calculating a reliability value T by: T=(p k)×(m+1)×(m+2)× . . . ×(m+k)/(2 1) where p is the number of types of unprintable characters, m is the number of document characters, k is the number of printable characters, and L is the bit length of a message digest, and evaluating reliability of the signature information by comparing the obtained reliability value T and a predetermined threshold value.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-06-21 | 2002-12-21 | 2003-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-06-21 | 2006-12-21 | 2007-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-06-21 | 2010-12-21 | 2011-06-22 | $7700.00 | Window Closed / Lapsed |