JP2010003044A - Document tracking system, user terminal, document management server, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document tracking system or the like which can recognize the operation of document information exchanged between enterprises, and can reduce time and labor necessary for operations. <P>SOLUTION: This document tracking system includes a user terminal 1 and a document management server 2. The user terminal 1 includes: a means for generating the featured value of encrypted document information prepared by encrypting document information; a means for specifying the operator of the user terminal 1, and for acquiring operator information showing validity of the operator; a means for transmitting browsing management information including the featured value and the operator information to the document management server 2; and a means for receiving key information for decryption from a document management server 2 and decrypting it. The document management server 2 includes: a means for receiving the browsing management information; a means for authenticating the operator; a means for acquiring key information for decryption associated with the featured value, and for transmitting it to the user terminal 1; and a means for storing at least the information of the operator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a document tracking system, a user terminal, a document management server, and a program.

In order to manage digitized document information, for example, management of access authority for preventing anyone other than a predetermined person from browsing, management of editions performed on digital documents, and the like are performed. There is a document management system as a system for performing such management. A conventional document management system is premised on operating in a company, and the access authority and edition version described above are centrally managed by a document management server installed in the company.
Japanese Patent Laid-Open No. 8-292916

  In recent years, it has been required to grasp how document information exchanged between companies is handled by other companies due to the development of laws such as the Personal Information Protection Law and changes in social security awareness. Although it is conceivable to apply a document management system as a countermeasure for this, the document management system is premised on a situation where the liquidity of the user terminal and the operator who operates the document terminal is low, such as operation in a company. . For this reason, when a document management system is operated between companies in which both user terminals and operators are fluid, for example, operational problems such as a management burden of operator information and a burden of document ID management are encountered.

  The present invention has been made in view of the above problems, and its purpose is to be able to grasp the operation of document information exchanged between companies and to reduce the labor required for operation. To provide a document tracking system, a user terminal, a document management server, and a program.

  The invention of claim 1 is a document tracking system comprising a user terminal and a document management server, wherein the user terminal acquires encrypted browsing document information obtained by encrypting document information to be browsed. Means for generating a characteristic value of the encrypted browsing document information; means for identifying operator of the user terminal and acquiring operator information indicating the validity of the operator; and the encrypted browsing document information Browsing management information transmitting means for transmitting browsing management information including the feature value and the operator information to the document management server, key receiving means for receiving decryption key information transmitted from the document management server, Means for decrypting the encrypted browsing document information based on decryption key information, wherein the document management server receives the browsing management information from the browsing management information transmitting means. And authentication means for authenticating the operator based on the operator information included in the browsing management information, and when the operator is authenticated, the encrypted browsing document information is stored from the key information storage means. When receiving the decryption key information associated with the feature value and transmitting the decryption key information to the user terminal, and when receiving the browsing management information, at least as management information Management information acquisition means for acquiring information on the operator corresponding to the operator information included in the browsing management information, and management information storage means for storing the management information.

  A second aspect of the present invention is the document tracking system according to the first aspect, wherein the user terminal corresponds to the new document information and means for acquiring new document information that is newly created document information. Means for generating encryption key information and decryption key information, and generating information obtained by encrypting the new document information based on the encryption key information corresponding to the new document information as encrypted new document information Means for generating a feature value of the encrypted new document information, and the key information for accessing the feature value of the encrypted new document information and the decryption key information for the encrypted new document information by communication Means for storing in the storage means.

  A third aspect of the present invention is the document tracking system according to the second aspect, wherein the document management server is configured such that the management information acquisition unit includes decryption key information for the encrypted new document information. In the case of storing the information, at least information indicating the new document information is acquired as management information.

  A fourth aspect of the present invention is the document tracking system according to any one of the first to third aspects, wherein the user terminal edits the edited document information, which is the decrypted document information. Means for detecting that information has been generated; means for generating encryption key information and decryption key information corresponding to the generated edited document information; and an encryption key for the edited document information Means for generating information obtained by encrypting the edited document information based on information as encrypted edited document information, means for generating a feature value of the encrypted edited document information, and the encrypted edited document Means for storing in the key information storage means accessible by communication the decryption key information for the encrypted edited document information, the information indicating the edited document information, and the editing target document information; Edit management information transmitting means for transmitting edit management information including information to the document management server, wherein the document management server receives the edit management information from the edit management information transmitting means. The management information acquisition means, when receiving the editing management information, acquires at least information indicating the edited document information and information indicating the editing target document information as management information, and the browsing When management information is received, at least information indicating the browsed document information and management information corresponding to the operator information included in the browse management information are acquired as management information.

  The invention of claim 5 is a user terminal, means for acquiring encrypted browsing document information obtained by encrypting document information to be browsed, and means for generating a feature value of the encrypted browsing document information; Means for identifying operator of the user terminal and obtaining operator information indicating the legitimacy of the operator, and browsing management information including the feature value of the encrypted browsing document information and the operator information Browsing management information transmitting means for transmitting to the document management server; key receiving means for receiving decryption key information transmitted from the document management server; and the encrypted browsing document information based on the decryption key information. And means for decoding.

  The invention of claim 6 is a document management server, wherein the browsing management information receiving means for receiving browsing management information from the user terminal, and authentication for authenticating the operator based on the operator information included in the browsing management information And when the operator is authenticated, obtains the decryption key information associated with the feature value of the document information from the key information storage means, and transmits the decryption key information to the user terminal. And a management information acquisition means for acquiring the operator information according to the operator information included in the browsing management information at least as management information when receiving the browsing management information, Management information storage means for storing the management information.

  According to a seventh aspect of the present invention, there is provided means for acquiring encrypted browsing document information obtained by encrypting document information to be browsed, means for generating a characteristic value of the encrypted browsing document information, and an operator of the user terminal. Means for acquiring operator information that identifies and indicates the legitimacy of the operator, browsing management information transmission that transmits browsing management information including the characteristic value of the encrypted browsing document information and the operator information to the document management server And a means for receiving the decryption key information transmitted from the document management server, and a means for decrypting the encrypted browsing document information based on the decryption key information. It is a program for.

  The invention of claim 8 is a browsing management information receiving means for receiving browsing management information from a user terminal, an authentication means for authenticating an operator based on operator information included in the browsing management information, and the operator is authenticated. The key response transmission means for obtaining the decryption key information associated with the feature value of the document information from the key information storage means and transmitting the decryption key information to the user terminal, the browsing management When receiving information, management information acquisition means for acquiring at least the operator information corresponding to the operator information included in the browsing management information as management information, and a management information storage for storing the management information A program for causing a computer to function as means.

  According to the first aspect of the present invention, at least the information of the operator who browses the document information can be stored in the document management server based on the feature value of the encrypted browsing document information transmitted from the user terminal and the operator information. .

  According to the invention of claim 2, the feature value of information obtained by encrypting newly created document information and the corresponding decryption key information can be registered from the user terminal.

  According to the invention of claim 3, the document management server can store the fact that a document has been newly created at the user terminal.

  According to the fourth aspect of the present invention, the document management server stores that the editing target document information is edited and the edited document information is generated at the user terminal, and the information obtained by encrypting the edited document information is stored. The feature value and the corresponding decryption key information can be registered from the user terminal.

  According to the fifth and seventh aspects of the present invention, it is possible to send the information of the operator who viewed the document information from the user terminal to the document management server together with the feature value of the encrypted browsed document information.

  According to the sixth and eighth aspects of the invention, the operator information transmitted from the user terminal is authenticated, and the decryption key information associated with the feature value of the encrypted browsing document information is transmitted to the user terminal. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of a configuration and processing outline of a document tracking system according to the present embodiment. As shown in the figure, the document tracking system includes user terminals 1a and 1b (hereinafter referred to as user terminal 1 unless otherwise necessary), a document management server 2, and a network 3. The user terminal 1 is realized by, for example, a personal computer, and the document management server 2 is realized by, for example, a server computer. The network 3 is composed of, for example, the Internet, a LAN (local communication network), and the like, and provides a communication connection between the user terminal 1 and the document management server 2.

  In the present embodiment, the type of processing performed between the user terminal 1 and the document management server 2 is, for example, processing when document information that is a target of inter-company document exchange is newly created (hereinafter referred to as new creation processing). (Corresponding to (1) and (2) in the figure), processing when browsing an encrypted document (hereinafter referred to as browsing processing, corresponding to (4) to (6) in the figure), and editing document information (Hereinafter referred to as editing processing, not shown).

  Before performing the new creation process, the operator of the user terminal (hereinafter referred to as a new operator) prepares in advance in the user terminal 1a document information D to be exchanged with another company. In the new creation process, first, the user terminal 1a generates an encryption key Ke and a decryption key Kd for the document information D. Next, the document information D is encrypted using the encryption key Ke to generate encrypted document information De ((1) in FIG. 1). Next, the user terminal 1a transmits a decryption key Kd and a hash value Hash (De), which is a kind of feature value of the encrypted document information, to the document management server 2 ((2) in the figure). The document management server 2 registers the decryption key Kd in the document management server using the received hash value Hash (De) as a key. The new operator sends the encrypted document information De obtained by the new creation process to the operator of the user terminal 1b (hereinafter referred to as a viewing operator) in another company by means of e-mail transmission or the like (see FIG. (3)).

  The browsing operator causes the user terminal 1b to perform the following browsing process in order to browse the encrypted document information De. First, the user terminal 1b transmits history information including the hash value Hash (De) of the sent encrypted document information De and an electronic certificate that verifies the legitimacy of the browsing operator to the document management server 2 (see FIG. (4)), the document management server records such information. If the legitimacy of the browsing operator is authenticated by the electronic certificate, the document management server obtains the decryption key Kd from the database using the hash value Hash (De) as a key, and returns it to the user terminal 1b ( (5) in FIG. The user terminal 1b obtains the original document information D by decrypting the document information De encrypted with the received decryption key Kd ((6) in the figure). Thereby, the browsing operator browses or edits the decrypted document.

  When the document information D is edited (for example, changed) after performing the above-described new creation process, the edit process is performed. In the editing process, in addition to performing the same process (see (1) and (2) in the figure) as the process for the new creation process such as encryption of the changed document and registration of the decryption key, A process of transmitting history information indicating the relationship between the previous document information and the changed document information to the document management server 2 is performed.

  Details of the document tracking system according to this embodiment will be described below. FIG. 2 is a diagram illustrating an example of the configuration of the user terminal 1 according to the present embodiment. The user terminal 1 includes a CPU 11, a storage unit 12, a communication unit 13, and an input / output unit 14.

  The CPU 11 operates according to a program stored in the storage unit 12. The program may be provided by being stored in an information recording medium such as a CD-ROM or DVD-ROM, or may be provided via a network such as the Internet.

  The storage unit 12 includes a memory element such as a RAM and a ROM, a hard disk drive, and the like. The storage unit 12 stores the program. The storage unit 12 stores information input from each unit and calculation results.

  The communication unit 13 includes communication means for establishing communication connection with other devices. The communication unit 13 inputs information received from another device to the CPU 11 or the storage unit 12 based on the control of the CPU 11 and transmits (outputs) the information to the other device.

  The input / output unit 14 includes a display output unit such as a monitor, a keyboard, and a mouse, an input unit, and the like. The input / output unit 14 displays (outputs) image data or the like on a monitor or the like based on the control of the CPU 11 and acquires information from the operator from a keyboard or a mouse.

  FIG. 3 is a diagram showing an example of the configuration of the document management server 2 according to the present embodiment. The document management server 2 includes a CPU 21, a storage unit 22, a communication unit 23, and an input / output unit 24. In the document management server 2, the CPU 21, the storage unit 22, the communication unit 23, and the input / output unit 24 have the same configurations as the CPU 11, the storage unit 12, the communication unit 13, and the input / output unit 14.

  FIG. 4 is a diagram showing functional blocks of the user terminal 1 according to the present embodiment. The user terminal 1 functionally acquires a new document information acquisition unit 41, a new management information generation / transmission unit 42 and a new key registration unit 43 related to a new creation process, and an encrypted browsing document information acquisition related to a browsing process. Unit 44, browsing management information generation / transmission unit 45, key reception unit 46 and decryption unit 47, editing detection unit 48 related to editing processing, editing management information generation / transmission unit 49 and editing key registration unit 50. And a key generation unit 51 and an encryption unit 52 used. These functions are realized by the CPU 11 executing a program stored in the storage unit 12 and controlling the communication unit 13 and the input / output unit 14. Details of each function will be described for each type of processing together with the functions of the document management server 2 except for the functions used in common.

  The key generation unit 51 is realized centering on the CPU 11 and the storage unit 12. The key generation unit 51 is called from another function and generates key information for encryption and key information for decryption. For example, when using a public key cryptosystem, the generated key has a secret key as key information for encryption and a public key as key information for decryption. Further, the common key encryption method may be used, and the key information for encryption and the key information for decryption may be the same.

  The encryption unit 52 is realized centering on the CPU 11 and the storage unit 12. The encryption unit 52 is called from another function, encrypts the specified document information using the generated key information for encryption, and generates encrypted document information.

  FIG. 5 is a diagram showing functional blocks of the document management server 2 according to the present embodiment. The document management server 2 functionally includes a new management information receiving unit 61 related to the process at the time of new creation, a browsing management information receiving unit 62 and a key response transmission unit 63 related to the process at the time of browsing, and an editing related to the editing process. A management information receiving unit 64, a management information acquisition unit 71, an authentication unit 72, a management information storage unit 73, and a key information storage unit 74 that are used in common are included. These functions are realized by the CPU 21 executing a program stored in the storage unit 22 and controlling the communication unit 23 and the input / output unit 24.

  The management information acquisition unit 71 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. Necessary information is acquired from information transmitted from the user terminal 1 in each of the new creation process, the browse process, and the edit process (hereinafter referred to as new management information, browse management information, and edit management information, respectively). The new management information, the browsing management information, and the editing management information each include history information and electronic certificate information.

  6 and 7 are diagrams showing an example of the data format of the history information. The history ID is information for uniquely identifying each history information. For example, the history ID may be obtained by obtaining a hash value that is a value indicating the characteristics of the contents of the history information excluding the history ID. As a method for calculating the hash value, for example, a method such as SHA-256 that has a sufficiently low probability that the hash values collide with each other may be selected. In the example of this figure, the contents of the history information are expressed in XML format. The value of the user tag represents the name of an operator that is a kind of operator information. The value of the timestamp tag represents the date and time when this history information is created. For this item, in the case of editing processing, the date and time when the document information is edited may be used instead. The value of the method tag represents the type of processing at the time of new creation, processing at the time of browsing, or processing at the time of editing. Here, the types are not limited to the above-described three types, and details of editing processing such as change and copy may be expressed in detail. The value of the body tag stores the feature value of the encrypted document information. The feature value of the encrypted document information needs to be a value that can uniquely identify the document information. For example, the hash value described above may be used. The value of the base tag is a history ID of history information sent immediately before in relation to this document information. This associates with the operation performed immediately before. The value of the filename tag stores the file name of the document information file on the user terminal. Here, the document information and the history ID are linked by the body tag. That is, in the editing process, the history ID also indicates the document information to be edited, and the value of the base tag also indicates the edited document information. Note that items that may be useful when tracking a document, such as a feature value of unencrypted document information and a document file size, may be added to the history information item. Details of the acquisition method of each item will be described later.

  The electronic certificate information is a kind of operator information, and can identify the operator and indicate the legitimacy of the operator. The electronic certificate is issued to each operator, for example, by a third-party certification authority (CA).

  The authentication unit 72 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. The authentication unit 72 authenticates the legitimacy of the operator using the information acquired by the management information acquisition unit 71. The authentication is performed by, for example, a known method using an electronic certificate. Since information necessary for authentication is included in the electronic certificate and information received at the same time, it is not necessary to prepare information for authenticating the operator as a database.

  The management information storage unit 73 is realized centering on the CPU 21 and the storage unit 22. The management information acquisition unit 71 stores the management information acquired for each of the new creation process, browsing process, and editing process.

  The key information storage unit 74 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. Using the communication unit 23, the feature value and the decryption key information of the encrypted document information sent from the user terminal during the new creation process and the edit process are acquired, and decrypted in association with the feature value of the encrypted document information. The key information for storing is stored in the storage unit 22. Also, the decryption key information corresponding to the feature value of the encrypted document information designated from another functional block is acquired from the storage unit 22 and passed to the caller functional block.

  In the following, functional blocks related to the processing flow will be described for each type of processing. Here, FIG. 8 is a diagram showing an example of the processing flow of the user terminal 1 during the new creation processing.

  The new document information acquisition unit 41 is realized centering on the CPU 11, the storage unit 12, and the input / output unit 14. The new document information acquisition unit 41 acquires the document information (hereinafter referred to as “new document information”) prepared by the operator as a document exchange target from the storage unit 12 and the input / output unit 14 (S101).

  The new management information generation / transmission unit 42 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The new management information generation / transmission unit 42 calls the key generation unit 51 to generate key information for encryption and key information for decryption for the acquired new document information (S102). Using the generated encryption key information, the encryption unit 52 is called to encrypt the new document information (S103), and a hash value is generated as a feature value of the information obtained by encrypting the new document information (S104). . Next, electronic certificate information corresponding to the operator stored in advance in the storage unit 12 is acquired (S105). Next, new management information is generated (S106). Specifically, for example, the history information as shown in FIG. 7 is digitally signed with the electronic certificate information, and the new management information is generated by attaching the electronic certificate information. For each item of history information, for example, the user tag contains user name information acquired from the certificate information, the timestamp tag contains the creation date and time of the history information, and the method tag indicates a new creation process However, the body tag stores a feature value of information obtained by encrypting new document information. Then, the generated new management information is transmitted to the document management server 2 (S107).

  The new key registration unit 43 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The decryption key information generated by the key generation unit 51 is transmitted to the key information storage unit 74 of the document management server 2 together with the feature value of the information obtained by encrypting the new document information, and the information is stored in the key information storage unit 74. Is stored (S108).

  FIG. 9 is a diagram illustrating an example of a processing flow of the document management server 2 during the new creation process. The new management information receiving unit 61 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. The new management information receiving unit 61 receives new management information from the new management information generating / transmitting unit 42 of the user terminal 1 through the communication unit 23 (S111).

  During the new creation process, the management information acquisition unit 71 extracts management information that is information to be stored from the received new management information (S112). Examples of management information items include the history ID of the history information shown in FIG. 7, the value of the body tag, the value of the timestamp tag, the value of the filename tag, the value of the user tag, and the operator acquired from the electronic certificate. There is a character string to identify. And the management information storage part 73 memorize | stores the management information which consists of those items (S113). It should be noted that the operator may be authenticated by the authentication unit 72 before storing, and if not valid, that fact may be stored.

  FIG. 10 is a diagram illustrating an example of a processing flow of the user terminal 1 during the browsing process. The encrypted browsing document information acquisition unit 44 is realized centering on the CPU 11, the storage unit 12, and the input / output unit 14. The encrypted browsing document information acquisition unit 44 stores the encrypted document information (hereinafter referred to as “encrypted browsing document information”), which has been created during the above-described new creation process, as the storage unit 12 and the input / output unit 14. (S121). Note that the encrypted browsing document information is acquired in advance from an operator who has performed an operation at the time of new creation processing in a method that is not directly managed by a document tracking system such as an e-mail.

  The browsing management information generation / transmission unit 45 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The browsing management information generation / transmission unit 45 first generates a hash value as a feature value of the encrypted browsing document information (S122), and acquires electronic certificate information corresponding to the operator stored in advance in the storage unit 12. (S123). Next, browsing management information is generated (S124). Specifically, the browsing management information is generated, for example, by digitally signing history information as shown in the browsing column of FIG. 6 with electronic certificate information and attaching the electronic certificate information. For each item of history information, for example, the user tag contains user name information extracted from the certificate information, the timestamp tag contains the creation date and time of the history information, and the method tag contains a character string indicating that it is during browsing processing. The body tag stores the feature value of the encrypted browsing document information. Then, the generated browsing management information is transmitted to the document management server 2 (S125).

FIG. 11 is a diagram illustrating an example of a processing flow of the document management server 2 during the browsing process.
The browsing management information receiving unit 62 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. The browsing management information receiving unit 62 receives browsing management information from the browsing management information generating / transmitting unit 45 of the user terminal 1 (S131).

  During the browsing process, the management information acquisition unit 71 extracts management information that is information to be stored from the browsing management information (S132). The management information items include, for example, the history ID of the history information shown in FIG. 6, the value of the body tag, the value of the timestamp tag, the value of the filename tag, the value of the user tag, and the operator acquired from the electronic certificate. There is a character string to identify. The management information storage unit 73 stores management information including items extracted by the management information acquisition unit 71 (S133).

  The key response transmission unit 63 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. The key response transmission unit 63 authenticates whether the operator is valid using the authentication unit 72 (S134). If it is valid, the decryption key information is acquired from the key information storage unit 74 using the feature value of the encrypted browsing document information included also as the value of the body tag (S135). The decryption key information is transmitted (S136).

  The key receiving unit 46 of the user terminal 1 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The decryption key information transmitted from the key response transmission unit 63 of the document management server 2 is received (S126).

  The decryption unit 47 is realized centering on the CPU 11 and the storage unit 12. Using the received decryption key information, the encrypted browsing document information is decrypted (S127).

  FIG. 12 is a diagram showing an example of the processing flow of the user terminal 1 during the editing process. The edit detection unit 48 is realized centering on the CPU 11, the storage unit 12, and the input / output unit 14. The edit detection unit 48 detects an edit operation on document information (hereinafter referred to as “edit target document information”) performed by the operator (S141). In order to detect an editing operation, for example, a time stamp of a file of document information to be edited is stored in advance, and a known method such as checking whether the time stamp has been changed at some timing is used. Next, the history ID of the history information corresponding to the file before editing the document information to be edited is acquired (S142). FIG. 14 shows an example of information stored in the user terminal 1 in order to acquire the history ID. By storing the file path of the document information to be edited and the history ID corresponding to the previous operation performed on the file as shown in this figure, the document information (hereinafter referred to as “ The history ID corresponding to the document information to be edited, which is a document before editing of “edited document information”, can be acquired. These pieces of information may be generated and updated when the history information is created at the time of new creation processing, browsing processing, and editing processing.

  The edit management information generation / transmission unit 49 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The edit management information generation / transmission unit 49 calls the key generation unit 51 to generate encryption key information and decryption key information for the edited document information (S143). Using the generated encryption key information, the encryption unit 52 is called to encrypt the edited document information (S144), and a hash value is generated as a feature value of the information obtained by encrypting the edited document information (S144). S145). The electronic certificate information corresponding to the operator stored in advance in the storage unit 12 is acquired (S146). Next, edit management information is generated (S147). Specifically, for example, the history information as shown in the editing time column of FIG. 6 is digitally signed with the electronic certificate information, and is generated by attaching the electronic certificate information. For each item of history information, for example, the user tag contains user name information acquired from the certificate information, the timestamp tag contains the creation date and time of the history information, and the method tag indicates a new creation process However, a history ID corresponding to the document information to be edited is stored in the base tag, and a feature value of information obtained by encrypting the edited document information is stored in the body tag. Then, the generated editing management information is transmitted to the document management server 2 (S148).

  The editing key registration unit 50 is realized centering on the CPU 11, the storage unit 12, and the communication unit 13. The decryption key information generated by the key generation unit 51 is transmitted to the key information storage unit 74 of the document management server 2 together with the feature value of the information obtained by encrypting the edited document information. Information is stored (S149).

  FIG. 13 is a diagram illustrating an example of a processing flow of the document management server 2 during the new creation process. The edit management information receiving unit 64 is realized centering on the CPU 21, the storage unit 22, and the communication unit 23. The edit management information receiving unit 64 receives edit management information from the edit management information generating / transmitting unit 49 of the user terminal 1 (S151).

  During the editing process, the management information acquisition unit 71 extracts management information that is information to be stored from the received editing management information (S152). The management information items include, for example, the history ID of the history information shown in FIG. 6, the value of the base tag, the value of the body tag, the value of the timestamp tag, the value of the filename tag, and the operator acquired from the electronic certificate. There is a character string to identify. And the management information storage part 73 memorize | stores the management information which consists of those items (S153). It should be noted that the operator may be authenticated by the authentication unit 72 before storing, and if not valid, that fact may be stored.

  During the editing process, the history ID is stored in the value of the base tag, so that it is possible to correspond to the immediately preceding operation. Further, by taking the correspondence with the immediately preceding operation, it is possible to take correspondence with the document information before editing. For example, the history ID of the history information at the time of browsing in FIG. 6 is stored in the base tag column of the history information at the time of editing. Thus, even if the document information changes due to editing and the value of the body tag changes, the original file can be traced afterwards. FIG. 15 is an example of history information when the operator Alice edits a document, sends information obtained by encrypting edited document information to Bob, and Bob browses the information. In this example, since the information is not stored in the base tag in the processing at the time of browsing, the original document cannot be traced from the history ID. However, since the document information is equal, the value of the body tag is equal, and the original file is postponed. Can be tracked. In order to reliably track the document information, it is preferable to control the user terminal so that only the encrypted document information can be directly accessed by the operator as a file that can be transmitted to others.

  Although the embodiment has been described so far, the present invention is not limited to this embodiment. For example, in this embodiment, the decryption key is also stored in the document management server, but may be separated into another server. This is because storing the key itself is an independently possible operation. Further, when the storage of the decryption key is managed by the document management server, the decryption key information and various management information may be collectively transmitted and received as one piece of information.

  Note that the content of the document information described in the present embodiment is not limited to a simple text document, but also includes graphics, sounds, moving images, and the like. This is because there is no need to separately handle graphics, sounds, moving images, etc., as long as the above-mentioned items can be handled without distinction in an application such as a word processor.

It is a figure which shows an example of the structure of the document tracking system which concerns on this embodiment, and the outline of a process. It is a figure which shows an example of a structure of the user terminal which concerns on this embodiment. It is a figure which shows an example of a structure of the document management server which concerns on this embodiment. It is a figure which shows the functional block of the user terminal which concerns on this embodiment. It is a figure which shows the functional block of the document management server concerning this embodiment. It is a figure which shows an example of the data format of log | history information. It is a figure which shows an example of the data format of log | history information. It is a figure which shows an example of the processing flow of a user terminal at the time of a new creation process. It is a figure which shows an example of the processing flow of the document management server at the time of a new creation process. It is a figure which shows an example of the processing flow of a user terminal at the time of a browsing process. It is a figure which shows an example of the processing flow of the document management server at the time of a browsing process. It is a figure which shows an example of the processing flow of a user terminal at the time of an edit process. It is a figure which shows an example of the processing flow of the document management server at the time of an edit process. It is a figure which shows the example of the information memorize | stored in a user terminal in order to acquire log | history ID. It is a figure which shows the example of the log | history information when another person browses the information which encrypted edited document information.

Explanation of symbols

  1, 1a, 1b User terminal, 2 Document management server, 3 Network, D Document information, De encrypted document information, Kd decryption key, 11, 21 CPU, 12, 22 Storage unit, 13, 23 Communication unit 14, 24 I / O unit, 41 New document information acquisition unit, 42 New management information generation / transmission unit, 43 New key registration unit, 44 Encrypted browsing document information acquisition unit, 45 Browsing management information generation / transmission unit, 46 Key reception unit , 47 Decryption unit, 48 Edit detection unit, 49 Edit management information generation / transmission unit, 50 Edit key registration unit, 51 Key generation unit, 52 Encryption unit, 61 New management information reception unit, 62 Browsing management information reception unit, 63 Key response transmission unit, 64 editing management information receiving unit, 71 management information receiving unit, 72 authentication unit, 73 management information storage unit, 74 key information storage unit.

Claims (8)

A document tracking system comprising a user terminal and a document management server,
The user terminal is
Means for obtaining encrypted browsing document information obtained by encrypting document information to be browsed;
Means for generating a feature value of the encrypted browsing document information;
Means for identifying operator of the user terminal and acquiring operator information indicating the legitimacy of the operator;
Browsing management information transmitting means for transmitting browsing management information including the feature value of the encrypted browsing document information and the operator information to the document management server;
Key receiving means for receiving decryption key information transmitted from the document management server;
Means for decrypting the encrypted browsing document information based on the decryption key information;
Including
The document management server
Browsing management information receiving means for receiving the browsing management information from the browsing management information transmitting means;
Authentication means for authenticating the operator based on the operator information included in the browsing management information;
When the operator is authenticated, the decryption key information associated with the feature value of the encrypted browsing document information is acquired from the key information storage unit, and the decryption key information is transmitted to the user terminal. A key response transmission means for
When receiving the browsing management information, management information acquisition means for acquiring information of the operator according to the operator information included in at least the browsing management information as management information;
Management information storage means for storing the management information;
A document tracking system comprising: The user terminal is
Means for acquiring new document information, which is newly created document information;
Means for generating encryption key information and decryption key information corresponding to the new document information;
Means for generating, as encrypted new document information, information obtained by encrypting the new document information based on encryption key information corresponding to the new document information;
Means for generating a feature value of the encrypted new document information;
Means for storing the characteristic value of the encrypted new document information and the decryption key information for the encrypted new document information in the key information storage means accessible by communication;
The document tracking system according to claim 1, further comprising: The document management server
The management information acquisition unit acquires at least information indicating the new document information as management information when decryption key information for the encrypted new document information is stored in the key information storage unit.
The document tracking system according to claim 2, wherein: The user terminal is
Means for detecting that the editing target document information which is the decrypted document information is edited and the edited document information is generated;
Means for generating encryption key information and decryption key information corresponding to the generated edited document information;
Means for generating, as encrypted edited document information, information obtained by encrypting the edited document information based on encryption key information for the edited document information;
Means for generating a feature value of the encrypted edited document information;
Means for storing the characteristic value of the encrypted edited document information and the decryption key information for the encrypted edited document information in a key information storage means accessible by communication;
Edit management information transmitting means for transmitting edit management information including information indicating the edited document information and information indicating the edit target document information to the document management server;
Further including
The document management server
Editing management information receiving means for receiving the editing management information from the editing management information transmitting means;
Further including
When receiving the editing management information, the management information acquisition unit acquires at least information indicating the edited document information and information indicating the editing target document information as management information, and receives the browsing management information In this case, at least information indicating the browsed document information as management information and the operator information corresponding to the operator information included in the browse management information are acquired.
The document tracking system according to any one of claims 1 to 3, wherein Means for obtaining encrypted browsing document information obtained by encrypting document information to be browsed;
Means for generating a feature value of the encrypted browsing document information;
Means for identifying operator of the user terminal and acquiring operator information indicating the legitimacy of the operator;
Browsing management information transmitting means for transmitting browsing management information including the feature value of the encrypted browsing document information and the operator information to the document management server;
Key receiving means for receiving decryption key information transmitted from the document management server;
Means for decrypting the encrypted browsing document information based on the decryption key information;
The user terminal characterized by including. Browsing management information receiving means for receiving browsing management information from the user terminal;
Authentication means for authenticating the operator based on the operator information included in the browsing management information;
When the operator is authenticated, a key response for acquiring the decryption key information associated with the feature value of the document information from the key information storage means and transmitting the decryption key information to the user terminal A transmission means;
When receiving the browsing management information, management information acquisition means for acquiring information of the operator according to the operator information included in at least the browsing management information as management information;
Management information storage means for storing the management information;
A document management server comprising: Means for obtaining encrypted browsing document information obtained by encrypting document information to be browsed;
Means for generating a feature value of the encrypted browsing document information;
Means for identifying operator of the user terminal and acquiring operator information indicating the legitimacy of the operator;
Browsing management information transmitting means for transmitting browsing management information including the feature value of the encrypted browsing document information and the operator information to the document management server;
Key receiving means for receiving decryption key information transmitted from the document management server; and
Means for decrypting the encrypted browsing document information based on the decryption key information;
As a program to make the computer function. Browsing management information receiving means for receiving browsing management information from a user terminal;
Authentication means for authenticating the operator based on the operator information included in the browsing management information;
When the operator is authenticated, a key response for acquiring the decryption key information associated with the feature value of the document information from the key information storage means and transmitting the decryption key information to the user terminal Transmission means,
When receiving the browsing management information, management information acquisition means for acquiring at least the operator information corresponding to the operator information included in the browsing management information as management information; and
Management information storage means for storing the management information;
As a program to make the computer function.

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