JP2004080335A - Digital signature device, digital signature system, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a system in which a digital signature can be imparted after confirming the content of the document data, and the time signing the contract can be specified. <P>SOLUTION: Contract document data written in a specified data format, e.g. HTML, is acquired by means of a Web browser 101, and converted at a text converting section 102 into text data which is then displayed on a specified display screen at a display processing section 104. A signature imparting person confirms the displayed content and then a digital signature is imparted to the contract document data at a digital signature generating section 105. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for adding an electronic signature to document data.
[0002]
[Prior art]
At present, documents are frequently exchanged as electronic data due to the development of the Internet and the like. At this time, an electronic signature is given to the document data in order to secure the authenticity of the document data.
[0003]
[Problems to be solved by the invention]
However, when document data (for example, contract data) is displayed as Web content on the Internet and an electronic signature is attached to the displayed content, the signer gives the content displayed on the Web page. Is checked before the digital signature is added. At this time, it was not possible to confirm that all the document contents were displayed on the Web page.
That is, there is a case where the provider of the original document publishes a part of the document data as hidden on the Web page. There is a problem that an electronic signature is added to the document data without being recognized.
[0004]
Also, when a contract is exchanged between the parties, the contract between the remote parties will be concluded when the notice of consent is issued by law, so when the contract with the electronic signature is sent from the other party of the contract The contract will be concluded with.
In this regard, when a contract is concluded using a network, when trying to identify the date and time when the terminal of the other party transmitted the contract data with the electronic signature, the current time normally held by the terminal of the other party is used as a reference It is possible.
However, when the time held by the terminal of the other party is not accurate or has been intentionally tampered with, there has been a problem that it is extremely difficult to specify and prove the exact contract conclusion time. .
[0005]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and problems, and provides a mechanism capable of confirming the contents of document data and adding an electronic signature, and specifying the time of the exchange. The task is to
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, an electronic signature providing apparatus according to the present invention is an apparatus for a signer to apply an electronic signature to document data, and converts document data created in a predetermined data format. Acquisition means for acquiring, when the acquired document data is in a data format other than text data, conversion means for converting the document data to text data, so that the signer can confirm the contents of the document data, A display control means for displaying the text data on a predetermined display device, and an electronic signature grant for giving an electronic signature to the document data based on an instruction for giving an electronic signature from the signer who has confirmed the display contents. Means.
[0007]
The electronic signature assigning means may assign an electronic signature to the text data converted as the document data.
[0008]
The display control means further includes an extracting means for extracting a part matching the predetermined document format from the converted text data, and the display control means displays the text data of the part extracted by the extracting means in a predetermined display. You may make it display on a device.
Further, the document data may be contract document data.
[0009]
An electronic signature system according to the present invention is a system including a management center for managing document data and an electronic signature device configured to be communicable with the management center, wherein the management center is provided with an electronic signature. Storage means for storing the document data and its transmission time data, and management means for storing and managing at least the document data and the transmission time data to which the electronic signature device has been attached and to which an electronic signature has been added, in the storage means The electronic signature device has an acquisition unit that acquires document data created in a predetermined data format, and, when the acquired document data is in a data format other than text data, converts the document data into text data. Converting means for converting the text data into a predetermined display device so that the signer can confirm the contents of the document data. Display control means for displaying, electronic signature giving means for giving an electronic signature to the document data based on an instruction for giving an electronic signature from the signer who has confirmed the display content, and time for measuring the current time Processing means for transmitting time data at the time of transmitting document data by referring to the time processing means, and transmitting the obtained time data and the document data with the electronic signature to the management center; It is characterized by having processing means.
[0010]
Further, the transmission processing means generates transmission signature data for transmission based on the document data to which the digital signature is added and the transmission time data, and converts the generated transmission signature data to the document data to which the digital signature is added. The transmission center data may be transmitted to the management center together with the transmission time data, and the management unit of the management center may store and manage the transmission signature data together with the document data and the transmission time data in the storage unit.
[0011]
The management center measures time and determines whether the time notified from the electronic signature device matches the measured time.
And a time distribution unit for notifying the electronic signature device of a time correction instruction when the time notified from the electronic signature device is not appropriate, wherein the time processing unit In addition to notifying the management center, the time measured may be synchronized with the time of the management center in response to a correction instruction from the management center.
[0012]
Further, the management center may further include a verification unit that verifies the electronic signature and / or transmission signature data attached to the contract.
[0013]
A computer program according to the present invention is a computer program for causing a computer to function as a device for a signer to give an electronic signature to document data. Acquiring the acquired document data, converting the acquired document data into text data when the acquired document data is in a data format other than text data, and enabling the signer to confirm the contents of the document data. A process of displaying the text data on a predetermined display device, and a process of giving an electronic signature to the document data based on an instruction to give an electronic signature from a signer who has confirmed the display content. Is executed.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment in which an electronic signature device and a computer program according to the present invention are applied to a system for exchanging a contract via the Internet will be described below with reference to the drawings.
FIG. 1 shows an outline of the overall configuration of a system according to the present embodiment.
In FIG. 1, a system according to the present embodiment includes a management center 3, a signer terminal 1 used by an electronic signature holder configured to be connectable to the management center 3 via a network such as the Internet, and a contract. It is composed of a contract creator terminal 5 used by the creator, a third party terminal 6 used by a third party, and an IC card 2 configured to be connectable to the signer terminal 1.
[0015]
The contract creator terminal 5 and the third party terminal 6 are configured by computers, and are configured to be able to access the management center 3 and the predetermined Web server 4 via the Internet using a predetermined Web browser. ing.
Note that the contract creator terminal 5 and the third party terminal 6 can be configured by a so-called personal computer, mobile phone terminal, PDA (Personal Digital Assistance), or the like.
[0016]
FIG. 2 shows functional blocks of the signer terminal 1, the IC card 2, and the management center 3.
In FIG. 2, a management center 3 is a device for managing contract data exchanged between an electronic document creator and an electronic signature grantor.
The management center 3 is constituted by a computer, and as shown in FIG. 2, a contract database 300, a key generation unit 301, an IC card issuing unit 302, a verification processing unit 303, a management unit 304, a time distribution unit 305, It comprises a time management unit 306, a receiving unit 307, and a transmitting unit 308.
[0017]
The contract database 300 is a database of contract data and the like.
The contract database 300 includes contract data, electronic signature data added to the contract data, time data indicating the date and time when the contract was sent from the signer, and the time when the contract data was transmitted. It is configured to store and manage transmission signature data and the like.
[0018]
The key generation unit 301 performs a process of generating a signature grantor secret key and a corresponding public key, a data transmission secret key and a corresponding public key by a predetermined key generation algorithm.
Here, the signer private key is a private key held by the signer who gives a signature to the document, and the data transmission private key is used to attach a transmission signature to transmission data transmitted to the management center 3. Secret key.
[0019]
The IC card issuing unit 302 stores the signer private key, the data transmission secret key, and the like generated by the key generation unit 301 in the IC card 2 and performs a process of issuing the key.
[0020]
The verification processing unit 303 can perform verification processing of the electronic signature data added to the contract data and the transmission signature at the time of transmission.
As this processing, the verification processing unit 303 checks whether the electronic signature attached to the contract data can be properly decrypted by the signer's public key, and checks whether the transmission signature attached to the transmission data is This can be performed by verifying whether or not decryption can be properly performed using the public key.
[0021]
The management unit 304 performs processing of storing and managing the contract data with electronic signature, time data, and transmission signature data transmitted from the signature grantor terminal 1 in the contract database 300.
In addition, the management unit 304 performs processing for providing the contents of the contract data and the like in response to an inquiry request from the signer, contract creator, or a third party.
[0022]
The time distribution unit 305 receives the time distribution request from the signer terminal 1 and, if it is determined that the time held by the signer terminal 1 is not appropriate, sends the time to the signer terminal 1. Time correction notification and the like can be performed.
The time management unit 306 manages the time serving as a reference for the delivery time of the contract by using a predetermined timer, and can perform a process of determining whether the time notified from the signature grantor terminal 1 is correct.
[0023]
The receiving unit 307 and the transmitting unit 308 perform data transmission / reception processing based on a predetermined protocol with the signer terminal 1 and the third party terminal 6 via a network such as the Internet.
[0024]
The IC card 2 includes a CPU (Central Processing Unit), and a memory such as a ROM and an EEPROM capable of storing a program executed by the CPU and predetermined parameter values.
In this memory, the signer's private key and the data transmission private key issued by the management center 3 can be stored, and in accordance with an instruction from the signer's terminal 1, management of these key data, key An arithmetic processing unit 201 that performs arithmetic processing using data and the like can be configured.
[0025]
The signer terminal 1 constitutes an electronic signature device according to the present invention, and an output device such as a display, not shown, and an input device such as a keyboard and a mouse are connected to the signer terminal 1.
The signer terminal 1 is composed of a computer, and includes a CPU, a computer program executed by the CPU, an internal memory such as a ROM and a RAM for storing the computer program and the like, and an external storage device such as a hard disk drive. 2 can be configured.
[0026]
The Web browser 101 performs processing for browsing a Web page provided by the Web server 4 and acquiring information.
The web browser 101 can display a web page including contract data created in HTML (Hyper Text Markup Language) format or the like, and can acquire data.
[0027]
The text conversion unit 102 performs a process of converting data posted on a Web page including contract data created in a predetermined data format provided on the Web page into text data.
The text conversion unit 102 performs a process of converting contract data created in a data format such as HTML, PDF (Portable Document Format), or a bitmap file into plain text data without fonts or style information. Can be.
[0028]
The extraction processing unit 103 performs a process of extracting a part that matches a predetermined document format from the contract data converted into text data.
As this processing, for example, the extraction processing unit 103 may detect a header and a footer in a text-converted document and extract only the text data included therein.
[0029]
The display processing unit 104 performs a process of displaying the converted text data of the contract on a screen of a predetermined display, and providing the text so that the signer can confirm the content.
As this processing, the display processing unit 104 displays the portion extracted by the extraction processing unit 103 on a predetermined Web page, and displays a message for confirming whether or not the signer gives the digital signature. It may be.
[0030]
The digital signature creating unit 105 checks the contract document data of the text data and, when instructing the digital signature to be given, generates a digital signature of the signature grantor and attaches it to the document data. I do.
As a process of generating the electronic signature, for example, the electronic signature creation unit 105 can generate the electronic signature by a predetermined algorithm using the signature grantor private key held by the IC card 2.
[0031]
The IC card control unit 106 performs a process of controlling the IC card 2 by notifying the IC card 2 of a predetermined control command such as an operation processing command using the signature grantor private key.
[0032]
The transmission data processing unit 107 performs a process of generating a transmission signature for data transmitted to the management center 3. As this processing, for example, the transmission data processing unit 107 generates a hash value of transmission data (text data of a contract, generated digital signature data and time data thereof), and based on the generated hash value. The transmission signature can be generated by a predetermined algorithm using the data transmission secret key held by the IC card 2.
[0033]
The time synchronizer 108 measures the time with a predetermined timer and performs a process for synchronizing the time with the management center 3 side.
As a process for synchronizing the time, for example, the time synchronizing unit 108 synchronizes with the time notified from the management center 3 based on NTP (Network Time Protocol), and the management center 3 Considering the signer terminal 1 as an NTP server, a checksum is added to the current time to notify the management center 3 and the management center 3 checks whether or not this is within a predetermined error range. Is also good.
[0034]
The receiving unit 109 and the transmitting unit 110 perform data transmission / reception processing based on a predetermined protocol with the management center 3 via a network such as the Internet.
[0035]
Next, an embodiment of a digital signature processing method will be described.
First, the overall processing flow will be described with reference to FIG.
In FIG. 1, as a preliminary process, the management center 3 issues the IC card 2 to the signer (S1).
At this time, the key generation unit 301 of the management center 3 generates the signer private key, the public key and the data transmission private key and the public key, and the IC card issuing unit 302 generates the generated signer private key and the transmission key. Issuance processing is performed by storing the secret key in the IC card 2. The public key corresponding to the secret key stored in the IC card 2 is held by the management center 1.
On the other hand, the contract creator uses the contract creator terminal 5 to register the contract in an arbitrary Web server 4, and publishes the contract on a Web page (S2).
[0036]
In this state, the signer uses the signer terminal 1 to access a Web page on which the contract is posted, and causes the Web browser 101 to display Web content data including the contract data (S3). .
The signer terminal 1 converts all the data including the contract data displayed on the Web page into text data, extracts only the contract portion from the converted text data, and extracts the extracted contract. The text data of the portion is displayed on the display, and it is confirmed with the signer whether or not to give the digital signature (S4).
When the signer confirms the contents of the displayed contract and instructs to give an electronic signature, the signer terminal 1 uses the signer private key stored in the IC card 2 to sign the contract. An electronic signature is attached to the text data (S5).
[0037]
Further, the signer terminal 1 requests the management center 3 to deliver the current time at a predetermined timing, and synchronizes with the delivery time of the management center 3 in response to the request (S6).
This synchronization process may be performed periodically between the management center 3 and the signer terminal 1, or may be performed only when an electronic signature is requested by the signer.
[0038]
When the time synchronization is completed, the signer terminal 1 displays the current time held by the signer terminal 1 and, when the signer selects and instructs the transmission of the contract data, the signature is given. The grantor terminal 1 generates an electronic signature (transmission signature) for data transmission using the data transmission private key stored in the IC card 2 (S7).
Then, the signer terminal 1 transmits the generated transmission signature, contract data, the digital signature of the signer, and the time data to the management center 3 (S8).
Accordingly, in the management center 3, the management unit 304 stores and manages the contract data with the electronic signature, the transmission signature data, and the time data in the contract database 300.
[0039]
When the contract creator, the signer, or a third party requests verification of the signed contract data and transmission time as necessary (S9), in the management center 3, the verification processing unit 303 By verifying the electronic signature of the contract with the public key of the user and verifying the transmission signature with the public key for data transmission, the falsification of the contract and the transmission time is verified, and the verification result is notified (S10). To end.
[0040]
Next, a detailed process flow of the signature grantor terminal 1 from when the signature grantor acquires the contract data to when the digital signature is assigned will be described with reference to FIG.
In FIG. 3, the signer activates the Web browser 101, accesses a Web page provided by the Web server 4, and acquires Web content data including contract data posted on the Web page (S101).
When the data acquisition is completed, the text conversion unit 102 determines whether the data format of the acquired data is text data (S102).
[0041]
If the result of the determination is that the data is not text format data, the text conversion unit 102 converts the acquired content data including the contract data into text data (S103).
[0042]
After the conversion into the text data is completed, or when it is determined that the content data is the text data in the above-described processing of S102, the extraction processing unit 103 extracts a portion matching the contract format from the text data. It is extracted (S104).
This extraction can be performed, for example, by the extraction processing unit 103 detecting a predetermined header or footer representing a contract portion in the text data.
[0043]
When the extraction is completed, the display processing unit 104 outputs and displays the extracted contract data on a display screen (S105).
Then, the display processing unit 104 displays a message or the like for confirming whether to apply an electronic signature to the contract data, and confirms whether to apply the electronic signature to the contract (S106).
As a result of the confirmation, if the signature grantor selects not to attach the electronic signature, the display processing unit 104 stops the processing and ends.
[0044]
When the signer gives an instruction to select the digital signature, the digital signature creating unit 105 acquires the contract data displayed on the screen (S107) and generates a hash value of the contract data (S108). ).
The electronic signature creation unit 105 generates an electronic signature to be attached to the contract data by using the signer private key held by the IC card 2 via the IC card control unit 106 (S109).
The electronic signature creation unit 105 combines the text data of the contract and the electronic signature data, edits the data into a predetermined electronic certificate format (S110), and ends the process.
[0045]
Next, a detailed process for synchronizing the time between the signer terminal 1 and the management center 3 will be described with reference to FIG.
In FIG. 4, the time synchronization unit 108 of the signer terminal 1 issues a time distribution request to the management center 3 via the transmission unit 110 (S201).
When a time distribution request is made, the time distribution unit 305 of the management center 3 receives this request via the reception unit 307, notifies the signature grantor terminal 1 of the current time via the transmission unit 308, and Are requested to be synchronized (S202).
[0046]
The time synchronizing unit 108 of the signer terminal 1 receives the time notified via the receiving unit 109, and displays the received time on the screen (S203).
The time synchronization unit 108 regards the signer terminal 1 as an NTP server and the management center 3 as a client, and attaches a display time and a checksum to the signer terminal 1 (S204). The notification is sent to the management center 3 via S205 (S205).
[0047]
In the management center 3, when the time and the checksum are notified and received via the receiving unit 109, the time distribution unit 305 synchronizes the time on the management center 3 side with the virtually notified time (S206).
The time management unit 306 corrects the time of the checksum addition from the virtually synchronized time (S207), and compares the corrected time with the original accurate time managed by the management center 3 side. The difference is obtained (S208).
[0048]
As a result of the comparison, the time management unit 306 determines whether or not the difference is within a predetermined error range (S209). If the difference is outside the error range, the time distribution unit 305 indicates that the time is not synchronized. To the signature grantor terminal 1 (S210).
[0049]
If the difference is within the predetermined error range, the time management unit 306 checks the checksum (S211), and the time distribution unit 305 notifies the signer terminal 1 of time synchronization completion. (S212).
Then, the signer terminal 1 and the management center 3 repeat the processing from S201 to S211 for a predetermined period (for example, after several seconds to several tens of seconds), and perform the signer terminal until this repetition processing is performed. It runs on its own using the timer of the time synchronization unit 108.
[0050]
Next, detailed processing when the signer terminal 1 transmits contract data and the like to the management center 3 will be described with reference to FIG.
In FIG. 5, the transmission data processing unit 107 refers to the timer of the time synchronization unit 108 to acquire the time synchronized with the management center 3 (S301).
Further, the transmission data processing unit 107 combines the signed text data of the contract with the acquired time data (S302), and generates a hash value from the combined data based on a predetermined algorithm (S303). .
[0051]
The transmission data processing unit 107 generates a transmission signature from the hash value generated by using the data transmission secret key held by the IC card 2 via the IC card control unit 106 (S304).
Then, the transmission data processing unit 107 combines the contract data with the electronic signature, the time data, and the generated transmission signature, and edits the data into a predetermined transmission data format (S305). When the editing is completed, the transmission data processing unit 107 transmits the edited data to the management center 3 via the transmission unit 110 (S306), and ends the processing.
Thus, the contract data with electronic signature, time data, and transmission signature data received by the management unit 304 of the management center 3 can be stored and managed in the contract database 300.
[0052]
As described above, according to the present embodiment, the contract data created in a predetermined data format such as HTML is acquired by the Web browser 101, and the acquired contract data is converted into text data by the text conversion unit 102. The converted text data is displayed on a predetermined display screen by the display processing unit 104, and after the signer confirms the displayed content, the electronic signature creation unit 105 applies an electronic signature to the contract data. Since the signature is given, the signer can give the digital signature after confirming the contents of the contract in text display.
As a result, for example, even if the contract creator includes content that is not displayed in the HTML document, the content is displayed as text data when converted to text, and therefore, the signer can be provided with the signature. After confirming the contents, an electronic signature can be given.
[0053]
In addition, if the electronic signature creating unit 105 assigns an electronic signature to the contract data converted into text data and registers it in the management center 3, the contents confirmed by the signer can be obtained. The content to which the digital signature is to be added always matches, and it is possible to prevent the discrepancy between the confirmed content and the content to which the digital signature is added.
[0054]
Further, if the extraction processing unit 103 extracts a part that matches a predetermined contract format from the converted text data, and the display processing unit 104 displays only the text data of the extracted part, The signer can accurately confirm the contents of the contract to be signed.
[0055]
In addition, since the transmitting unit 110 and the receiving unit 109 communicate with the management center 3 and the time of the signer terminal 1 is synchronized with the time of the management center 3 by the time synchronizing unit 108, the signature is It is possible to know the exact time at which the digital signature was given by the grantor terminal 1.
[0056]
In addition, since the management center 3 manages the contract data with the electronic signature in a database, the possibility that the contract is falsified is reduced and the burden of the parties managing the contract data is reduced. Can be reduced.
In addition, since the management center 3 verifies the contract data and the like, it is possible to objectively prove the time at which the signer gave the document transmission, and to clarify the contract establishment time. .
Also, even when the contract creator or the like alters the contents of the contract or the transmission time of the signature grantor, the verification processing unit 303 of the management center 3 assigns the signature to the contract with the signature grantor public key. By verifying the electronic signature and the transmission signature using the data transmission public key, it is possible to verify whether the electronic document and the transmission time have been tampered with, thereby preventing tampering.
[0057]
In the above-described embodiment, an embodiment in which a contract is made has been described. However, the present invention is not limited to this, and can be widely applied to a case where a digital signature is attached to document data. .
[0058]
Further, in the present embodiment, an example has been described in which an electronic signature and a transmission signature are generated in the signer terminal 1, but these signatures may be generated in the IC card 2.
Further, the signer private key and the data transmission private key may be directly attached to the signer terminal 1 without using the IC card 2, or other tamper-resistant cryptographic operations may be performed. It may be stored in a processing device.
[0059]
Also, in the present embodiment, an example has been described in which the management center 3 generates the signer private key and the data transmission private key. However, the signer himself generates these private keys and handles these private keys. May be transmitted to the management center 3.
[0060]
The computer program for the signer terminal 1 or the management center 3 according to the present embodiment may be stored in a computer-readable medium (FD, CD-ROM, etc.) and distributed, or may be superimposed on a carrier wave to provide a communication network. It is also possible to distribute via.
When the OS (Operating System) shares the functions of the signer terminal 1 or the management center 3 or realizes the functions of the signer terminal 1 or the management center 3 jointly with the OS, only the parts other than the OS are used as computer programs. May be stored in a computer-readable medium, or the computer program may be distributed.
[0061]
【The invention's effect】
According to the present invention, it is possible to add a digital signature after confirming the contents of document data, and to specify the time of the exchange.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating a system according to an embodiment to which an electronic signature device and a computer program according to the present invention are applied.
FIG. 2 is a functional block diagram of a signer terminal, an IC card, and a management center according to the embodiment.
FIG. 3 is a processing flow showing a detailed processing flow from the time when the signer terminal acquires the contract data to the time when the electronic signature is added by the signer terminal according to the embodiment;
FIG. 4 is a processing flow showing a detailed processing flow when the signer terminal according to the present embodiment synchronizes time with the management center.
FIG. 5 is a processing flow showing a detailed processing flow when the signer terminal according to the embodiment transmits data to the management center.
[Explanation of symbols]
1 Signer terminal
2 IC card
3 management center
4 Web server
5 Contract creator terminal
6 Third party terminals
101 Web browser
102 Text converter
103 Extraction processing unit
104 Display processing unit
105 Electronic Signature Creation Unit
106 IC card control unit
107 transmission data processing unit
108 Time synchronization unit
109 Receiver
110 transmission unit
201 arithmetic processing unit
300 Contract Database
301 key generation unit
302 IC card issuing unit
303 verification processing unit
304 Management
305 Time distribution unit
306 Time management unit
307 Receiver
308 Transmitter

Claims (9)

An apparatus for a signer to give an electronic signature to document data,
Acquisition means for acquiring document data created in a predetermined data format;
When the acquired document data is in a data format other than text data, conversion means for converting the document data into text data,
Display control means for displaying the text data on a predetermined display device so that the signer can confirm the contents of the document data;
An electronic signature assigning unit that assigns an electronic signature to the document data based on an instruction to assign an electronic signature from the signer who has confirmed the display content;
An electronic signature device comprising: The electronic signature applying means applies an electronic signature to the text data converted as the document data.
The digital signature device according to claim 1. Extracting means for extracting a part matching the predetermined document format from the converted text data,
The display control means causes a predetermined display device to display the text data of the portion extracted by the extraction means,
The electronic signature device according to claim 1. The above document data is contract data,
The digital signature device according to claim 1. A system comprising a management center for managing document data and an electronic signature device configured to be able to communicate with the management center,
The above management center,
Storage means for storing document data to which an electronic signature is added and transmission time data thereof,
Management means for storing and managing at least the document data and the transmission time data to which the digital signature is transmitted from the electronic signature device and to which the digital signature is added,
The electronic signature device,
Acquisition means for acquiring document data created in a predetermined data format;
When the acquired document data is in a data format other than text data, conversion means for converting the document data into text data,
Display control means for displaying the text data on a predetermined display device so that the signer can confirm the contents of the document data;
An electronic signature assigning unit that assigns an electronic signature to the document data based on an instruction to assign an electronic signature from the signer who has confirmed the display content;
Time processing means for measuring the current time;
Transmission processing means for acquiring time data at the time of transmitting document data with reference to the time processing means, and transmitting the acquired time data and the document data with the electronic signature to the management center; ,
An electronic signature system, characterized in that: The transmission processing means generates transmission signature data for transmission based on the document data to which the digital signature is added and the transmission time data, and transmits the generated transmission signature data to the document data to which the digital signature is added and the transmission data. Sent to the above management center with time data,
The management means of the management center stores and manages the transmission signature data together with the document data and the transmission time data in the storage means.
An electronic signature system according to claim 5. The above management center,
Time management means for measuring time, and determining whether the time notified from the electronic signature device conforms to the time being measured,
If the time notified from the electronic signature device is not appropriate, the electronic signature device further includes a time distribution unit that notifies the electronic signature device of a time correction instruction,
The time processing means notifies the management center of the measured time, and synchronizes the measured time with the time of the management center in response to a correction instruction from the management center.
The electronic signature system according to claim 6. The management center further includes a verification unit that verifies the electronic signature and / or transmission signature data attached to the contract.
The digital signature system according to claim 5. A computer program for causing a computer to function as a device for a signer to apply an electronic signature to document data,
Against the computer
A process of acquiring document data created in a predetermined data format;
When the acquired document data is in a data format other than text data, a process of converting the document data into text data;
Displaying the text data on a predetermined display device so that the signer can confirm the content of the document data;
A process of giving an electronic signature to the document data based on an instruction to give an electronic signature from the signer who has confirmed the display content;
A computer program that executes

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