JP2004248045A - Electronic signature system and its program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electronic signature system and its program that are capable of detecting that an alteration has been done if postscript and modification are added after a final signature. <P>SOLUTION: A signature area where an electronic signature is processed is indicated from among the signature areas provided beforehand in the electronic document data file of a signature target (S1). An electronic signature button is pushed down (S2). By comparing signature authority person information set beforehand in the signature area and certificate information (S3), if they are in discord with each other, an error massage is displayed (S7), while if they are in accord with each other, a signature formula is checked that is set beforehand in the signature area (S4). If being set in the signature formula 1, the signature is written using the signature formula for enabling a verification process that prevents the alteration even if the postscript and modification are added after the end of the signature (S5). If being set in the signature formula 2, the signature is written using the signature formula for enabling a verification process that allows the alteration if the postscript and modification are added after the signature (S6). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic signature system and an electronic signature program, and more particularly, to an electronic signature system and an electronic signature program that allow a plurality of signers to perform an electronic signature while adding or changing the contents of an electronic document.
[0002]
[Prior art]
Since the current digital signature of PDF allows multiple signatures, the original creator can add or change the file after signing the original. In other words, for a document that is transferred by a plurality of persons while writing, the individual sequentially transmits the document to the next signer while adding and adding an electronic signature to the same document being transferred (for example, (See Patent Document 1.)
[0003]
[Patent Document 1]
JP-A-6-315036
At this time, the appending / modifying person signs the original + its own change information. If the additional appending / modifying is performed directly on the original by overwriting, In the viewer, the contents after overwriting are displayed, and the contents of the original are hidden. The original data is stored in the document data that is sent sequentially, and each file that has been added or changed is also stored as an entity file, but if you do not check the change history that is also stored in the document data, The verifier cannot confirm which signer of the original data or multiple signers has added or changed what content.
[0005]
[Problems to be solved by the invention]
As described above, in the conventional electronic signature system, the verifier must add or delete the original data or the multiple signers without confirming the change history indicating which signer has added or changed what content. There was a problem that the changes could not be confirmed.
[0006]
Furthermore, in such a conventional electronic signature system, as described in the document (paragraph [0034]), the final signer checks the contents and signatures of all entity files after the drafter. Although the final decision can be made accurately, it is possible to add / change on the system even after the final signer's signature. Even if the signer's falsification after the signature becomes indistinguishable in the signature verification process, and if a third party overwrites or modifies the signature after the final signer's signature, there is no falsification in the signature verification process. However, there is a problem that the contents may be erroneously recognized as the contents created by the signer.
[0007]
The present invention has been made to solve such a problem, and an object of the present invention is to provide an electronic signature system and an electronic signature program that can recognize that there has been tampering if there is additional correction after the final signature.
[0008]
[Means for Solving the Problems]
The present invention provides an electronic signature system for performing an electronic signature on one or more signature areas provided in advance in an electronic document data file to be signed in accordance with preset signature authority information. Is determined by comparing the authority of the signer with the signature authority information, and determines whether the signer is authorized to sign the signature area. When the signature processing is performed, the signature scheme set in advance in the signature area may be the first signature scheme that does not alter the post-signature addition / change in the verification processing, or may be the post-signature addition / change after the verification processing. A signature scheme confirming means for confirming whether the signature scheme is a second signature scheme to be executed, and an electronic signature processing of the signer for the electronic document data file by the signature scheme confirmed by the signature scheme confirming means. Signature processing means for, in a signature scheme, as confirmed by the signature method confirming means is an electronic signature system comprising a signature verification unit for verifying the electronic signature processing performed by the signature processing unit.
[0009]
The present invention provides a signature file reading means for reading a digital document data file to be signed, and a signature area for performing a digital signature process from one or more signature areas provided in advance in the read electronic document data file. Signing area designation input means for designating the signing area, signing authority information reading means for reading the signing authority information preset in the signature area, and the signer's private key and the signer's signature authority information as attribute information. Private key / public key certificate acquisition means for acquiring a possessed public key certificate; signature authority information read by the signature authority information reading means; and private key / public key certificate acquisition means. The signer who performs the signature is compared with the signature authority information that is the attribute information of the obtained public key certificate, and the signer who has the authority to sign the signature area. Signer confirmation means for judging whether or not the signature is valid, and, if the signer confirmation means determines that the signature is proper, a signature scheme preset in the signature area is used in the verification process after the signature The signature method confirming means for confirming whether the first signature method does not falsify the appending / change or the second signature method falsifying the appending / change after the signature in the verification process, and the signer confirming means. When it is determined that the signature area is displayed with an imprint, and the signature method confirmed by the signature method confirmation means, using the secret key acquired by the secret key / public key certificate acquisition means, A signature processing unit for performing an electronic signature process on the electronic document data file; and a signature verification unit for storing a signature verification range for verifying the electronic signature process performed by the signature processing unit. An electronic signature system comprising a range storage means.
[0010]
In the case where a public key storage unit storing a public key paired with the secret key and the electronic document data file read by the signature target file reading unit have already been subjected to a digital signature process. And signature verification means for verifying the digital signature processing using the public key based on the signature verification range stored in the signature verification range storage means.
[0011]
Further, the apparatus further comprises an error message display means for displaying an error message when the signer confirmation means determines that the signer is not appropriate.
[0012]
The present invention also provides a signature file reading step for reading a digital document data file to be signed, and an electronic signature process from one or more signature areas provided in advance in the read electronic document data file. A signature area designation input step for designating a signature area; a signature authority information read step for reading signature authority information preset in the signature area; and a signer's private key and the signer's signature authority information as attributes. A private key / public key certificate obtaining step for obtaining a public key certificate possessed as information; the signing authority information read by the signing authority information reading step; and the private key / public key certificate obtaining Comparing the signature authority information, which is the attribute information of the public key certificate obtained in the step, with the signature authority, A signer confirmation step for judging whether or not the user has the authority to sign the area; and a signature scheme preset in the signature area when the signer confirmation step determines that the area is appropriate. A signature scheme confirming step for confirming whether the first signature scheme does not alter the post-signature addition / change in the verification process or the second signature scheme does not alter the post-signature addition / change in the verification process. When it is determined that the signature area is appropriate in the signer confirmation step, an imprint is displayed on the signature area and acquired by the secret key / public key certificate acquisition means in the signature method confirmed by the signature method confirmation means. A signature processing step of performing an electronic signature process on the electronic document data file using the obtained secret key; and Serial is a digital signature program for executing the signature verification range storage step in a computer for storing signature verification range for verifying the electronic signature processing.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows the configuration of an apparatus of an electronic signature system for performing multiple signature processing according to the present embodiment. The electronic signature system according to the present embodiment includes a computer as hardware and a program as software that causes the computer to function as an electronic signature system. The program may be installed in a computer, or may be stored in a storage medium readable by a computer.
[0014]
In FIG. 1, reference numeral 1 denotes a signature target file reading means for reading a digital document data file to be signed (hereinafter, referred to as signature target data). Reference numeral 2 denotes a case where the read signature target data has already been given an electronic signature. In addition, the signature verification means 3 for verifying the signature, the public key storage means 3 for storing the public key used for signature verification by the signature verification means 2, and the signature area (see FIG. (4) reference numerals 40 to 42) are selected from the document of the data to be signed and are specified by clicking with an input means such as a mouse or the like. Signature instruction input means 5 and 6 for inputting an instruction to perform electronic signature processing on the signature are signatures for reading attribute information such as signature authority information and signature scheme information set in the signature area in advance. The rear attribute information reading means 7 includes signature authority information preset in the signature area and signature authority information, which is attribute information in a public key certificate stored in the IC card 12 held by the signer. And a signer confirming means 8 for judging whether or not the signer performing the signature is appropriate as a person who has authority to sign the signature area is judged by the signer confirming means 7 to be appropriate. In this case, the signature method confirmation means 9 and 10 for confirming the signature method set in the signature area in advance are used for the signature area selected by the signer determined to be appropriate by the signer confirmation means 7. The imprint (signs 40a, 41a, and 42a in FIG. 4) is displayed, and the signature target data is encrypted using the secret key in the IC card 12 using the signature method confirmed by the signature method confirmation means 8. The first and second signature processing means for performing electronic signature processing by this means are: an IC card reader that reads a private key and a public key certificate stored in an IC card 12; 12 is an IC card; An error message display unit 14 for displaying an error message to the signer when the signer verification unit 7 determines that the signer is not appropriate. The display unit 14 includes a display or the like, and displays a file to be signed, an error message, or the like. It is.
[0015]
FIG. 2A is a diagram schematically showing an overall flow of a multiple signature process using the digital signature system according to the present embodiment. In the multi-signature process, the person in charge 110, section manager 111, manager 112, and verifier 113 shown in FIG. 2A sequentially use their own digital signature system according to the present embodiment to sign and sign, respectively. Perform verification processing. Specifically, as shown in FIG. 2A, first, an intermediate signature 1 for certifying that the person in charge 110 has issued the signature target data (original data) that has been issued, is performed. Then, a higher-level manager such as the section manager 111 checks the validity of the draft data (signature verification of the intermediate signature 1), adds missing information and the like, and creates an intermediate signature 2 for certifying that the check has been completed. Do. Further, a higher-level manager such as the manager 112 confirms the validity of the check by the section manager 111 (signature verification of the intermediate signature 2), and performs a final signature for certifying that the final authorization has been performed by adding missing information. . The verifier 113 verifies the final signed file to determine whether the final signature is by the director 112 himself or not and has not been tampered with after the final signature.
[0016]
In the present embodiment, two signature schemes are prepared as signature schemes, and each signature scheme is preset in a signature area, and by using these two signature schemes properly, the signature of the intermediate signer can be obtained. The postscript addition / change and the alteration after the signature of the final signer can be distinguished in the verification of the final signature. That is, for the intermediate signatures 1 and 2, the signature scheme 1 that does not alter the additional writing / change in the verification processing is selected, and for the final signature, the signature scheme 2 that alters the additional writing / change after the signature is selected in the verification processing. . The target of signature verification by the signature method 1 is only the data to be signed, and whether or not data has been added after the signature is performed, and even if there is additional data, the validity of the additional data is determined by the signature verification range. Be outside. Therefore, for example, even if an erasing line having a meaning that erases a part of the text of the signature target data of the intermediate signature 1 on the screen notation is added, it is not falsified. On the other hand, the target of the signature verification by the signature method 2 is not limited to the data to be signed, but also whether or not data is added after the signature is performed is also included in the signature verification range. That is, in the signature scheme 2, the data to be signed is the entire file, and if even one bit changes in the file, it is falsified. Due to the difference in this method, in the case of the final signature, if data is added after the signature, it can be automatically determined that there has been tampering at the time of signature verification by the verifier 113. Note that the signature verification range data indicating the signature verification range is generated when an electronic signature is performed, attached as attribute information (reference numeral 29 in FIG. 2B) of the file to be signed, and used for verification. The range for performing signature verification is automatically selected based on the signature verification range data, and verification processing is performed.
[0017]
FIG. 2B is a diagram showing a file generated as a result of the processing of FIG. 2A. The process flow of FIG. 2A will be described in more detail with reference to FIG. As shown in FIG. 2B, for the signature target data 20 of the intermediate signature 1 which is the original data, the person in charge 110 applies the signature to the signature area (reference numeral 40 in FIG. 4) of the person in charge 110. When the intermediate signature 1 is performed in accordance with the signature scheme 1 preset in the area, the signature data 21 of the intermediate signature 1 is attached. The signature data 21 is data obtained by encrypting the signature target data 20 using a secret key owned by the person in charge 110. Note that, since the intermediate signature 1 is applied by the signature method 1, the verification target at this time is only the signature target data 20, and the information is stored in the signature verification range data 29 shown in FIG. You.
[0018]
As shown in FIG. 3, a private key 30 and a public key certificate 31 are issued to each signer from a certificate authority that is a predetermined organization, and the public key certificate 31 has attribute information as attribute information. The signing authority information of the signer is stored. The signature authority information is a predetermined code set in advance for each position, indicating that the signer is a section manager if the signer is a section manager, and indicates that if the signer is a section manager.
[0019]
Further, the private key 30 and the public key certificate 31 are stored in the IC card 12 together with the imprint data of the imprints (reference numerals 40a, 41a, and 42a in FIG. 4) displayed on the electronic document to be signed at the time of digital signature, and are stored in the IC card 12. Distributed to As a result, the signature authority information to be confirmed at the time of the electronic signature, the secret key 30 for performing the signature, and the imprint data to be displayed for identifying the signer on the electronic document to be signed can be identified and used as a single pair.
[0020]
Next, an upper manager such as the section manager 111 verifies the validity of the signature target data 20 of the intermediate signature 1 (signature verification of the intermediate signature 1). Since the intermediate signature 1 is applied by the signature method 1, the verification target at this time is only the signature target data 20, and as described above, the information is stored in the signature verification range data 29 shown in FIG. Is stored in For this reason, the signature target data 20 is automatically selected as the signature verification range, and whether or not data is added after the signature data 21 of the intermediate signature 1 is created is outside the signature verification range of the intermediate signature 1. As a verification method, the signature verification means 2 reads out the public key paired with the secret key of the person in charge 110 from the public key storage means 3 and encrypts the signature target data 20 with the secret key of the person in charge 110. The decrypted signature data 21 is decrypted using the public key. The data obtained thereby and the original signature target data 20 are compared to verify whether the intermediate signature 1 is created by the person 110 in charge. As a result of the verification, if it is determined that the data is from the principal, missing information and the like are added as additional data 22 after the intermediate signature 1 and combined with the signature target data 20 to form one file. The file thus obtained is the signature target data 23 of the intermediate signature 2 to be signed by the section manager 111. In this way, when the section manager 111 performs the intermediate signature 2 for certifying that the check has been completed by using the secret key owned by the section manager 111 according to the signature scheme 1 preset in the signature area, the section manager 111 The signature data 24 is attached. The signature data 24 is similar to the signature data 21 and will not be described here. At this time, information indicating that the signature verification range of the intermediate signature 2 is only the signature target data 23 of the intermediate signature 2 is stored in the signature verification range data 29.
[0021]
Similarly, the section manager 112 checks the validity of the check by the section manager 111 (signature verification of the intermediate signature 2), that is, determines whether or not the intermediate signature 2 is signed by the section manager 111 himself, or the public key paired with the section manager 111 private key. Is read from the public key storage means 3 and is verified using it. Since the intermediate signature 2 is applied according to the signature scheme 1, the verification target at this time is only the signature target data 23 of the intermediate signature 2 by the signature verification range data 29, and after the signature data 24 of the intermediate signature 2 is created, Whether or not data has been added and the validity of the additional data, if any, are outside the signature verification range of the intermediate signature 2. As a result of the verification, if it can be confirmed that the data belongs to the person, the additional data 25 after the intermediate signature 2 is added as the missing information, and the signature target data 23 of the intermediate signature 2 and the additional data 25 after the intermediate signature 2 are added. And a final signature for certifying that the final permission has been granted to the signature target data 26 of the final signature obtained by combining By applying the final signature, signature data 27 of the final signature is attached. Since the signature data 27 is similar to the signature data 21 and 24, the description is omitted here. Note that the signature scheme of the final signature is the signature scheme 2 as described above. Therefore, as shown in FIG. 2, the verification target range by the verifier 113 is the signature target data 26 of the final signature and the additional data (falsification) 28 after the final signature, and the information indicating this is stored in the signature verification range data 29. Therefore, at the time of verification, both the final signature by the director himself and whether there has been any tampering after the final signature are verified.
[0022]
FIG. 5 is a flowchart summarizing the processing flow of the above-described embodiment. Hereinafter, the operation of the electronic signature processing of the electronic signature system according to the present embodiment will be described with reference to FIGS. In the present embodiment, as shown in FIG. 5, first, the electronic file to be signed is displayed on the display device 14 of the computer, and a plurality of signature areas 40 shown in FIG. To 42 (the person in charge signature area 40, the section signature area 41, and the section signature area 42), select the signature area to be signed by the user and input it to the signature area designation input means 4 (step S1). The selection / input method is performed by clicking with an input device such as a mouse. Next, the electronic signature button 43 constituting the signature instruction input means 5 displayed on the display screen of the display device 14 is depressed (step S2). Next, by inserting the IC card 12 storing the private key 30 and the public key certificate 31 (see FIG. 3) into the IC card reader 11, the signature authority preset in the signature areas 40 to 41 is set. The signer information and the signing authority information, which is attribute information of the signer's public certificate, are compared by the signer confirming means 7 (step S3). The signing authority information includes, for example, a list of codes indicating the positions, assuming that the authority to sign the section chief signature area 41 is a section manager and a section manager delegate. As shown in an example in FIG. 6, when a user whose position is not registered as signature authority information attempts to sign, it is determined by the comparison processing in step S3 that they do not match, and the process proceeds to step S7. In step S7, since it is not a person who can sign, the fact that the signature has been rejected is displayed by the error message display means 13, and the process is terminated. On the other hand, if it is determined by the comparison processing of step S3 that they match, the process proceeds to step S4. In step S4, the signature scheme confirmation means 8 confirms which of the signature schemes 1 and 2 the signature scheme preset in the signature areas 40 to 42 is. In the case of the signature system 1, the process proceeds to step S5, where the first signature processing means 9 performs the signature in the signature system 1 which can perform a verification process which is not falsified even if added or modified after the signature. On the other hand, in the case of the signature scheme 2, the process proceeds to step S6, where the second signature processing means 10 signs in the signature scheme 2 which can be verified to be falsified if added or modified after the signature.
[0023]
As described above, in the present embodiment, in the case of an intermediate signature, a signature is performed by the signature method 1 that enables verification processing that does not result in falsification even if added or modified after the signature, and in the case of a final signature, Since the signature is signed by the signature method 2 which can perform a verification process in which the data is falsified when added or modified after the signature, if there is any additional modification after the final signature, it can be recognized that the data has been tampered with.
[0024]
Also, since signature authority information and signature method information are set in advance in the signature areas 40 to 42 as attribute information, signatures other than the correct signer are canceled as error processing and the correct signer is canceled. In the case of (1), a signature by a preset signature method is enabled.
[0025]
【The invention's effect】
The present invention provides a signature file reading means for reading a digital document data file to be signed, and a signature area for performing a digital signature process from one or more signature areas provided in advance in the read electronic document data file. Signing area designation input means for designating the signing area, signing authority information reading means for reading the signing authority information preset in the signature area, and the signer's private key and the signer's signature authority information as attribute information. Private key / public key certificate acquisition means for acquiring a possessed public key certificate; signature authority information read by the signature authority information reading means; and private key / public key certificate acquisition means. The signer who performs the signature is compared with the signature authority information that is the attribute information of the obtained public key certificate, and the signer who has the authority to sign the signature area. Signer confirmation means for judging whether or not the signature is valid, and, if the signer confirmation means determines that the signature is proper, a signature scheme preset in the signature area is used in the verification process after the signature The signature method confirming means for confirming whether the first signature method does not falsify the appending / change or the second signature method not falsifying the appending / change after the signature in the verification process, and the signer confirming means, When it is determined that the signature area is displayed with an imprint, and the signature method confirmed by the signature method confirmation means, using the secret key acquired by the secret key / public key certificate acquisition means, A signature processing unit for performing an electronic signature process on the electronic document data file; and a signature storing a signature verification range for verifying the electronic signature process performed by the signature processing unit. Since the electronic signature system is provided with a certificate range storage unit, in the case of an intermediate signature, the signature is signed by the first signature method which can be verified without being falsified even if it is added or modified after the signature, and the final signature In the case of, the signature is made by the second signature method that can perform a verification process that becomes falsified when added or modified after the signature. Therefore, if there is additional correction after the final signature, it can be recognized that there has been tampering. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electronic signature system according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an overall flow of a multiple signature process using the digital signature system according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing an IC card storing a private key and a public key certificate used in the electronic signature system according to the embodiment of the present invention.
FIG. 4 is an explanatory diagram showing an example of a signature target file signed by the electronic signature system according to the embodiment of the present invention.
FIG. 5 is a flowchart showing a flow of an electronic signature process of the electronic signature system according to the embodiment of the present invention.
FIG. 6 is an explanatory diagram showing an example in which the signer is determined to be inappropriate in the electronic signature system according to the embodiment of the present invention;
[Explanation of symbols]
1 signature target file reading means, 2 signature verification means, 3 public key storage means, 4 signature area designation input means, 5 signature instruction input means, 6 signature area attribute information reading means, 7 signer confirmation means, 8 signature method confirmation means , 9 first signature processing means, 10 second signature processing means, 11 IC card reader, 12 IC card, 13 error message display means, 14 display device, 20 signature target data of intermediate signature 1, 21 signature processing data of intermediate signature 1 Signature data, 22 additional data after the intermediate signature 1, 23 signature data of the intermediate signature 2, 24 signature data of the intermediate signature 2, 25 additional data after the intermediate signature 2, 26 signature data of the final signature, 27 signature data of the final signature Signature data, 28 Additional data after final signature, 30 Private key, 31 Public key certificate, 40 Person in charge signature area, 41 Manager's signature area, 42 General manager Name area, 43 electronic signature button, 110 personnel, 111 managers, 112 Director, 113 verifier.

Claims (5)

An electronic signature system for performing an electronic signature on one or more signature areas provided in advance in an electronic document data file to be signed in accordance with preset signature authority information,
Whether the signer performing the signature has the authority to sign the signature area or not is determined by comparing the authority possessed by the signer with the signature authority information. When it is determined, the signature scheme preset in the signature area is the first signature scheme that does not alter the post-signature addition / change in the verification processing, or the post-signature addition / change after the signature in the verification processing is falsified. Signature scheme confirming means for confirming whether the signature scheme is the second signature scheme,
Signature processing means for performing a digital signature process of the signer on the electronic document data file with the signature method confirmed by the signature method confirmation means;
A digital signature system comprising: a signature verification unit that verifies the digital signature processing performed by the signature processing unit using the signature scheme confirmed by the signature scheme confirmation unit. Signature target file reading means for reading the electronic document data file to be signed;
Signature area designation input means for designating a signature area for performing an electronic signature process from one or more signature areas provided in advance in the read electronic document data file;
Signature authority information reading means for reading signature authority information preset in the signature area,
Secret key / public key certificate obtaining means for obtaining a private key of the signer and a public key certificate having signature authority information of the signer as attribute information;
The signature authority information read by the signature authority information reading means is compared with the signature authority information which is attribute information of the public key certificate acquired by the secret key / public key certificate acquisition means. Signer confirming means for judging whether or not the signer performing the signature has authority to sign the signature area;
If it is determined by the signer confirming means that the signature scheme is appropriate, the signature scheme set in advance in the signature area is a first signature scheme that does not falsify additional writing / change after the signature in the verification process. Signature scheme confirming means for confirming whether the second signature scheme for altering post-signature addition / change in the processing,
When it is determined that the signature is correct by the signer confirming means, an imprint is displayed on the signature area, and the private key / public key certificate is acquired by the private key / public key certificate acquiring means in the signature method confirmed by the signature method confirming means. Signature processing means for performing an electronic signature process on the electronic document data file using the secret key,
A signature verification range storage unit for storing a signature verification range for verifying the digital signature processing performed by the signature processing unit. Public key storage means for storing a public key paired with the secret key,
If the electronic document data file read by the signature target file reading means has already been subjected to an electronic signature process, the public key is stored based on the signature verification range stored in the signature verification range storage means. 3. The digital signature system according to claim 2, further comprising: a signature verification unit that verifies the digital signature processing using the electronic signature processing. 4. The electronic signature system according to claim 2, further comprising an error message display unit that displays an error message when the signer verification unit determines that the signer is not appropriate. A signature file reading step for reading the electronic document data file to be signed;
A signature area designation input step of designating a signature area for performing an electronic signature process from one or more signature areas provided in advance in the read electronic document data file;
A signature authority information reading step for reading signature authority information set in the signature area in advance,
A private key / public key certificate obtaining step of obtaining a private key of the signer and a public key certificate having signature authority information of the signer as attribute information;
The signature authority information read in the signature authority information reading step is compared with the signature authority information, which is attribute information of the public key certificate acquired in the private key / public key certificate acquisition step. A signer confirmation step of judging whether the signer performing the signature has authority to sign the signature area,
If it is determined by the signer confirmation step that the signature scheme is appropriate, the signature scheme set in advance in the signature area is a first signature scheme that does not falsify additional writing / change after the signature in the verification process. A signature scheme confirming step for confirming whether the second signature scheme for altering post-signature addition / change in the processing,
If it is determined by the signer confirmation step that the signature is appropriate, an imprint is displayed on the signature area, and the signature is obtained by the secret key / public key certificate acquisition means in the signature method confirmed by the signature method confirmation means. A signature processing step of performing an electronic signature process on the electronic document data file using the secret key.
An electronic signature program for causing a computer to execute a signature verification range storing step of storing a signature verification range for verifying the electronic signature processing performed in the signature processing step.

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