JP2007150447A - Electronic document management apparatus, and electronic document management program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the reliability of an electronic document before giving a time stamp. <P>SOLUTION: An electronic document management apparatus 100 includes a signature generating section 104 for generating an electronic signature for the electronic document; an electronic document storage section 114 for storing the electronic signature and the electronic document so that they are correlated; a tampering detecting section 108 for detecting whether the electronic document has been tampered on the basis of the electronic signature generated by the signature generating section 104; and a time stamp acquiring section 106 for acquiring a time stamp to be given to the electronic document. After a predetermined time elapses between an instruction of acquiring a time stamp and completion of acquiring the time stamp by the time stamp acquiring section 106, the time stamp acquiring section 106 continues time stamp acquiring processing on the condition that the tampering detecting section 108 has detected that the electronic document has not been tampered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electronic document management apparatus and an electronic document management program.

  In recent years, electronic signatures that detect tampering of electronic documents and prove the creator have been used as techniques to replace conventional handwritten signatures and seals. A time stamp is used as a technique for proving the confirmation time of an electronic document.

  Processing of the time stamp is performed, for example, when the data transmission side (user) generates a hash value of the electronic document, transmits the hash value to a time server that is a third party, and registers the data on the time server side, This is performed by a procedure of transmitting a receipt indicating that data has been registered from the time server side to the user (for example, Patent Document 1).

Further, as an example of a long-term signature format corresponding to the electronic document law, there is one specified in IEEE RFC3126 (Electronic Signature Formats for long term electronic signatures). In such a long-term signature format, an electronic signature is first given to an electronic document, a time stamp is given, a certificate revocation list (CRL: Certificate Revocation List) is given, and then a time called an archive time stamp is given. A stamp is given.
JP 2004-304338 A

  By the way, when making a time stamp assignment request from the data transmission side to the time stamp server, there is a case where the time stamp cannot be acquired immediately after an error occurs due to, for example, a communication failure. In the long-term signature format, it may take time to acquire the revocation list in order to wait for the revocation information of the certificate to be reliably reflected in the revocation list. In such a case, there may be a time lag between when the time stamp acquisition request is first made and when the time stamp is actually given. In such a case, if the electronic document is tampered with before the time stamp is given, even if the process for giving the time stamp is performed, accurate verification cannot be performed later.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for ensuring the reliability of an electronic document before giving a time stamp in an electronic document management apparatus for giving a time stamp to an electronic document. It is to provide.

According to the present invention,
An electronic document storage unit for storing electronic documents;
A tamper detection unit that detects the presence or absence of tampering with the electronic document stored in the electronic document storage unit;
A reception unit for receiving an instruction to acquire a time stamp to be given to the electronic document;
After obtaining a time stamp to be given to the electronic document and after a predetermined time elapses from when the accepting unit accepts the time stamp obtaining instruction until the time stamp obtaining is completed, the falsification detecting unit A time stamp acquisition unit that continues the time stamp acquisition process on the condition that the electronic document has not been tampered with;
An electronic document management device is provided.

According to such a configuration, when the time stamp to be given to the electronic document is acquired, if the electronic document is falsified or changed, the time stamp acquisition process can be stopped. Thereby, it is possible to prevent the time stamp from being added in advance to an electronic document whose contents are changed before the time stamp is added and cannot be correctly verified later. For this reason, for example, when a time stamp cannot be acquired due to some error and the time stamp re-acquisition processing is performed, if the electronic document has been tampered or changed at that time, it is detected and the time stamp acquisition processing is canceled. Therefore, unnecessary time stamp issue processing can be prevented.
Here, “the time stamp acquisition is completed after the reception unit receives the time stamp acquisition instruction” includes the first time stamp acquisition instruction reception (that is, the time stamp request The completion of acquisition of a final time stamp is also included. In this case, after obtaining the electronic signature and the time stamp first, when obtaining the revocation list of the electronic certificate used for the electronic signature, the process of obtaining the final time stamp is performed again. At this time, there is a case where final time stamp acquisition processing is waited until the revocation information of the electronic certificate is reflected in the revocation list. In such a case, it takes time from the acquisition instruction of the first time stamp to the completion of the final time stamp acquisition. However, if the electronic document is altered or changed, the final time stamp The acquisition process can be canceled.

  The electronic document management apparatus of the present invention further includes a signature generation unit that generates an electronic signature for the electronic document, and the electronic document storage unit can store the electronic signature in association with the electronic document. The tampering detection unit can detect whether or not the electronic document has been tampered with based on the electronic signature generated by the signature generation unit.

In the electronic document management apparatus of the present invention, the falsification detection unit includes an electronic signature generated for the electronic document stored in the electronic document storage unit after the predetermined time has elapsed, and the electronic document storage unit By comparing the electronic signature stored in association with the electronic document, it is possible to detect whether the electronic document has been tampered with.
In the electronic document management apparatus of the present invention, the time stamp acquisition unit generates a hash value of the electronic signature associated with the electronic document and acquires a time stamp generated based on the hash value. The electronic document management apparatus may further include a hash value storage unit that temporarily stores the hash value. The tampering detection unit stores a hash value calculated based on the electronic signature stored in association with the electronic document in the electronic document storage unit after the predetermined time has elapsed, and is stored in the hash value storage unit By comparing the hash value of the electronic signature with the electronic signature, it is possible to detect whether the electronic document has been tampered with.

  In the electronic document management apparatus of the present invention, the time stamp acquisition unit generates a hash value of the electronic signature associated with the electronic document and acquires a time stamp generated based on the hash value. The electronic document management apparatus may further include a hash value storage unit that temporarily stores the hash value. The time stamp acquisition unit uses the hash value stored in the hash value storage unit when the falsification detection unit detects that the electronic document has not been falsified after the predetermined time has elapsed. A time stamp can be obtained. Thereby, the time stamp acquisition process can be simplified.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, in an electronic document management apparatus that gives a time stamp to an electronic document, it is possible to ensure the reliability of the electronic document before the time stamp is given.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

FIG. 1 is a block diagram illustrating a configuration of an electronic document management apparatus according to the present embodiment.
The electronic document management apparatus 100 includes an electronic document acquisition unit 102, a signature generation unit 104, a time stamp acquisition unit 106, a falsification detection unit 108, a notification unit 110, an electronic document storage unit 114, a hash value storage unit 116, and a setting storage unit 118. Including.

  Each component of the electronic document management apparatus 100 shown in FIG. 1 is not a hardware unit configuration but a functional unit block. Each component of the electronic document management apparatus 100 includes an arbitrary computer CPU, memory, a program for realizing the components shown in the figure loaded in the memory, a storage unit such as a hard disk for storing the program, and a network connection interface. It is realized by any combination of hardware and software. It will be understood by those skilled in the art that there are various modifications to the implementation method and apparatus.

  The electronic document management apparatus 100 is connected to a PC (Personal Computer) 204 and a TSA (Time-Stamping Authority) 202 via a network 200 such as the Internet or a LAN.

  The electronic document acquisition unit 102 acquires an electronic document to be given a time stamp. The electronic document acquisition unit 102 may have, for example, a scanner function, and can read a paper medium document and generate an electronic document. The electronic document acquisition unit 102 can also acquire an electronic document from another terminal via a network or the like, or can acquire an electronic document stored in an electronic medium or the like. In the present embodiment, the electronic document can be image data.

  The signature generation unit 104 generates an electronic signature of the electronic document acquired by the electronic document acquisition unit 102. The signature generation unit 104 can calculate a hash value of the electronic document acquired by the electronic document acquisition unit 102, and can generate an electronic signature by encrypting the hash value with a predetermined encryption key. The electronic document storage unit 114 stores the electronic document acquired by the electronic document acquisition unit 102 in association with the electronic signature generated by the signature generation unit 104.

  The time stamp acquisition unit 106 acquires a time stamp from the TSA 202 via the network 200. The user of the electronic document management apparatus 100 performs user registration with the TSA 202 in advance and acquires an account. At the time of time stamp acquisition, the time stamp acquisition unit 106 requests the TSA 202 to issue a time stamp after login authentication using a previously acquired account.

  In the present embodiment, the time stamp acquisition unit 106 acquires a time stamp as follows. First, the time stamp acquisition unit 106 calculates a hash value of the electronic signature generated by the signature generation unit 104. The hash value generated by the time stamp acquisition unit 106 is temporarily stored in the hash value storage unit 116. The time stamp acquisition unit 106 performs the above-described login authentication to the TSA 202 and transmits a hash value to request issue of a time stamp. Here, the TSA 202 can issue a time stamp by a simple protocol (RFC3161) method, for example. The TSA 202 adds accurate time information to the hash value transmitted from the electronic document management apparatus 100 to generate a time stamp. The TSA 202 transmits the generated time stamp to the electronic document management apparatus 100. The time stamp acquisition unit 106 acquires the time stamp transmitted from the TSA 202 and stores it in the electronic document storage unit 114 in association with the corresponding electronic document.

  For the electronic document to which the time stamp is given as described above, the hash value of the electronic document stored in the electronic document storage unit 114 is calculated, and the electronic signature associated with the electronic document is decrypted and compared. By doing so, the presence or absence of tampering can be detected.

  When the time stamp acquisition unit 106 calculates the hash value of the electronic signature to acquire the time stamp and fails to acquire the time stamp, the time stamp acquisition unit 106 uses the hash value stored in the hash value storage unit 116 to Acquisition can be retried. The time stamp acquisition unit 106 can also calculate the hash value again based on the electronic signature stored in the electronic document storage unit 114 when retrying. The processing performed by the time stamp acquisition unit 106 can be set in the setting storage unit 118 in advance.

  The tampering detection unit 108 detects whether the electronic document or electronic signature stored in the electronic document storage unit 114 has been tampered with when the time stamp acquisition unit 106 tries to acquire the time stamp again. The falsification detection process can be performed as follows.

FIG. 2 is a diagram schematically illustrating processing in which the tampering detection unit 108 detects tampering of the electronic document 300.
The electronic document storage unit 114 stores an electronic signature 300 generated by encrypting the electronic document 300 and the hash value 302 of the electronic document 300. The hash value storage unit 116 stores a hash value 306 of the electronic signature 304. The electronic document 300, the electronic signature 304, and the hash value 306 of the electronic signature are stored in association with each other.

  As an example, the falsification detection unit 108 can cause the signature generation unit 104 to generate the hash value 310 of the electronic document 300 stored in the electronic document storage unit 114. Further, the tampering detection unit 108 can obtain the hash value 320 of the electronic document by decrypting the electronic signature 304 stored in the electronic document storage unit 114. The tampering detection unit 108 can detect the presence or absence of tampering by comparing the hash value 310 of the electronic document with the hash value 320 of the electronic document.

  As another example, the tampering detection unit 108 can cause the time stamp acquisition unit 106 to generate the hash value 330 of the electronic signature 304 stored in the electronic document storage unit 114. The tampering detection unit 108 can detect the presence or absence of tampering by comparing the hash value 330 of the electronic signature with the hash value 306 of the electronic signature stored in the hash value storage unit 116. In this case, the presence or absence of falsification of the electronic document 300 itself is not directly detected, but the electronic document 300 and the hash value 306 of the electronic signature are not falsified, for example, based on the fact that the electronic document 300 It can be inferred that there is a high probability of not being tampered with.

  As another example, the falsification detection unit 108 causes the signature generation unit 104 to generate the hash value 310 of the electronic document 300 stored in the electronic document storage unit 114, and further generates the electronic signature by encrypting the hash value 310. Then, the time stamp acquisition unit 106 can generate a hash value (not shown) of the electronic signature. The tampering detection unit 108 can detect the presence or absence of tampering by comparing the hash value with the hash value 330 of the electronic signature and the hash value 306 of the electronic signature. As a result, when one of the electronic document 300 and electronic signature 304 stored in the electronic document storage unit 114 and the hash value 306 of the electronic signature stored in the hash value storage unit 116 has been altered, it is detected. can do.

  Although the falsification detection processing by the falsification detection unit 108 has been described above, it is possible to set in advance in the setting storage unit 118 what kind of procedure the falsification detection is performed. Accordingly, the user can perform a falsification detection at a desired level in consideration of the time required for falsification detection and the accuracy of verification of whether or not falsification has occurred.

  Returning to FIG. 1, when the falsification detection unit 108 detects falsification, the notification unit 110 notifies the falsification. For example, the notification unit 110 can transmit an email notifying that a predetermined email address has been tampered with. A mail address of a transmission destination can be set in the setting storage unit 118. Although not shown, the electronic document management apparatus 100 includes a reception unit that receives an instruction from the user, and receives an instruction to acquire a time stamp to be added to the electronic document from the user via the reception unit.

FIG. 3 is a flowchart showing a processing procedure of the electronic document management apparatus 100 in the present embodiment.
When the electronic document acquisition unit 102 acquires an electronic document to be time stamped (S100), the signature generation unit 104 calculates a hash value of the electronic document. Next, the signature generation unit 104 generates an electronic signature by encrypting the calculated hash value (S102). The signature generation unit 104 stores the electronic signature in the electronic document storage unit 114 in association with the electronic document. Subsequently, the time stamp acquisition unit 106 calculates the hash value of the electronic signature generated by the signature generation unit 104 and temporarily stores it in the hash value storage unit 116 (S104). Further, the time stamp acquisition unit 106 requests the time stamp by transmitting the calculated hash value to the TSA 202 (S106).

  When the time stamp acquisition unit 106 acquires the time stamp from the TSA 202 (YES in S108), the time stamp acquisition unit 106 stores the time stamp in association with the corresponding electronic document in the electronic document storage unit 114 (S126). On the other hand, until the time stamp is acquired in step S108 (NO in S108), the time stamp acquisition unit 106 determines whether or not a predetermined time has elapsed since the time stamp request was made (S110). When the predetermined time has elapsed (YES in S110), the time stamp acquisition unit 106 determines whether to retry the time stamp request (S112). For example, when an error that cannot be retried occurs, it is determined not to retry (NO in S112). In this case, the notification unit 110 performs error notification (S124).

  When retrying (YES in S112), the tampering detection unit 108 performs tampering detection processing (S114). When tampering is detected (YES in S116), the notification unit 110 notifies that tampering has occurred (S118).

  If tampering is not detected in step S116 (NO in S116), the time stamp acquisition unit 106 refers to the setting storage unit 118 and determines whether or not to recalculate the hash value (S122). When the hash value is not recalculated (NO in S122), the time stamp acquisition unit 106 reads the hash value stored in the hash value storage unit 116 (S120), returns to step S106, and repeats the same processing. On the other hand, when the hash value is recalculated in step S122 (YES in S122), the process returns to step S104 and the same processing is repeated. In step S122, for example, even if the setting storage unit 118 is not set to perform recalculation of the hash value, it takes time to acquire the time stamp, and the processing from step S110 to step S116 is repeated a predetermined number of times. When it is repeated, the hash value can be recalculated. Such settings can also be stored in the setting storage unit 118.

  If the time stamp cannot be acquired again after retrying the time stamp acquisition, the determination in step S110 is made based on whether or not a predetermined time has elapsed since the tampering detection in the previous step S114. Can do.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  The present invention can also be used for processing for obtaining a time stamp in a long-term signature format. When acquiring a time stamp in the long-term signature format, it is necessary to acquire certification path information, revocation verification data, a certificate, and a revocation list thereof after obtaining the time stamp first. In this case, it may take time until the final time stamp acquisition process is completed. Even in such a case, if the electronic document is tampered with before the time stamp is given, even if the process for giving the time stamp is performed, accurate verification cannot be performed later. By applying the configuration of the present invention, it is possible to ensure the reliability of the electronic document before giving the time stamp.

It is a block diagram which shows the structure of the electronic document management apparatus in embodiment of this invention. It is a figure which shows typically the process which the alteration detection part detects the alteration of an electronic document. It is a flowchart which shows the process sequence of the electronic document management apparatus in embodiment of this invention.

Explanation of symbols

100 electronic document management apparatus 102 electronic document acquisition unit 104 signature generation unit 106 time stamp acquisition unit 108 falsification detection unit 110 notification unit 114 electronic document storage unit 116 hash value storage unit 118 setting storage unit 200 network 202 TSA
204 PC

Claims (6)

An electronic document storage unit for storing electronic documents;
A tamper detection unit that detects the presence or absence of tampering with the electronic document stored in the electronic document storage unit;
A reception unit for receiving an instruction to acquire a time stamp to be given to the electronic document;
After obtaining a time stamp to be given to the electronic document and after a predetermined time elapses from when the accepting unit accepts the time stamp obtaining instruction until the time stamp obtaining is completed, the tampering detecting unit A time stamp acquisition unit that continues the time stamp acquisition process on the condition that the electronic document has not been tampered with;
An electronic document management device. The electronic document management apparatus according to claim 1.
A signature generation unit that generates an electronic signature for the electronic document;
The electronic document storage unit stores the electronic signature in association with the electronic document;
The tampering detection unit is an electronic document management device that detects whether or not the electronic document has been tampered with based on the electronic signature generated by the signature generation unit. The electronic document management apparatus according to claim 2.
The tampering detection unit stores an electronic signature generated for the electronic document stored in the electronic document storage unit after the predetermined time has elapsed, and is stored in association with the electronic document in the electronic document storage unit An electronic document management apparatus that detects whether or not the electronic document has been tampered with by comparing the electronic signature. The electronic document management apparatus according to claim 2 or 3,
The time stamp acquisition unit generates a hash value of the electronic signature associated with the electronic document, acquires a time stamp generated based on the hash value,
The electronic document management device further includes a hash value storage unit that temporarily stores the hash value,
The tampering detection unit stores a hash value calculated based on the electronic signature stored in association with the electronic document in the electronic document storage unit after the predetermined time has elapsed, and is stored in the hash value storage unit An electronic document management device that detects whether or not the electronic document has been tampered with by comparing the hash value of the electronic signature. The electronic document management apparatus according to any one of claims 2 to 4,
The time stamp acquisition unit generates a hash value of the electronic signature associated with the electronic document, acquires a time stamp generated based on the hash value,
The electronic document management device further includes a hash value storage unit that temporarily stores the hash value,
When the time stamp acquisition unit detects that the electronic document has not been tampered with by the tampering detection unit after the predetermined time has elapsed, the time stamp acquisition unit uses the hash value stored in the hash value storage unit, An electronic document management apparatus that acquires a time stamp. Computer
Electronic document storage means for storing electronic documents;
Falsification detection means for detecting the presence or absence of falsification of the electronic document stored in the electronic document storage means;
Receiving means for receiving a time stamp acquisition instruction to be given to the electronic document;
After obtaining a time stamp to be given to the electronic document and after a predetermined time elapses from when the accepting unit accepts the time stamp obtaining instruction until the completion of obtaining the time stamp, the falsification detecting unit Time stamp acquisition means for continuing the time stamp acquisition process on the condition that the electronic document has not been tampered with;
Electronic document management program to function as

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