JP2004151163A - System and method for document management, device, method and program for secretization, and device, method and program for browsing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method for document management for easily and properly managing a document according to its secrecy, and to provide a device, a method and a program for secretization, and a device, a method and a program for browsing. <P>SOLUTION: A managing server 1 manages a secrecy policy including designation of a person who is allowed to browse a document, and clients 3 (3-1 to 3-n) which create secret documents obtain the secrecy policy from the managing server 1 and perform secretization of documents including ciphering of the documents, sticking of images, etc., on the basis of the obtained secrecy policy. Then the managing server 1 manages information regarding he secretized documents and controls whether browsing-side clients 4 (4-1 to 4-m) are allowed to browse or print the documents. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a document management system and method, a confidentiality device and method, a program, a browsing device and method, and a program, and in particular, a document management system and method, a confidentiality device and method, and a program for managing a document that requires confidentiality, The present invention relates to a browsing apparatus, method, and program.
[0002]
[Prior art]
In recent years, with the development of computer technology, various documents have been digitized. Recently, with the development of network technology, it has become possible to easily exchange and distribute digitized documents. In particular, since the Internet has been widely used, documents can be exchanged and distributed over a wide range.
[0003]
However, as the distribution amount of digitized documents increases, the opportunity for information leakage from these documents has also increased, and prevention of information leakage is becoming a new issue in companies and the like.
[0004]
Information leakage from documents occurs in various situations such as unauthorized acquisition of documents stored on servers, eavesdropping in the course of transmission during distribution of documents, negligence or intention of the right document acquisition rights Can do. For this reason, techniques for preventing information leakage in various situations have been proposed.
[0005]
As such a technique, there is a technique in which a document is stored and transmitted by performing encryption at a level set according to the confidentiality of the document (for example, see Patent Document 1).
[0006]
In addition, there is a method in which access authority and usage authority control of a document to be distributed is set as a policy and registered in a policy server. The access authority is set in units of users or groups, time units, and networks (domains), and the use authority can be set to enable / disable printing and posting. In addition, the policy server can easily remove or change authority after document distribution.
[0007]
[Patent Document 1]
JP-A-7-295589
[0008]
[Problems to be solved by the invention]
As described above, many conventional techniques perform encryption processing on a document when protecting the document. There are various methods for encrypting documents, such as those using a common key for both encryption and decryption, and those using different keys for encryption and decryption. Management is an important issue.
[0009]
For example, when transmitting a key via a network, it is conceivable that the key is illegally acquired during the transmission. In addition, when the key is managed by a server or the like, it is necessary to consider a mechanism for preventing the loss of the key, a mechanism for dealing with an attack on the server, or the like.
[0010]
In addition, when encrypting a document, it may be necessary to set an authorized person who can view the document, or it may be necessary to perform an encryption process according to the number of authorized persons. It may take a lot of time and effort.
[0011]
Therefore, the present invention provides a document management system and method, a confidentiality device and method, a program, a browsing device and method, and a program capable of easily and appropriately managing a document according to the sensitivity. With the goal.
[0012]
[Means for Solving the Problems]
In order to achieve the above-described object, the invention of claim 1 is a document management system for managing a document that needs to maintain confidentiality, and specifies a person who is permitted to view the document and a certificate that proves the legitimacy of the person who is permitted to view the document. A management device that manages at least one confidential policy including a certificate, and a confidential policy selected from the confidential policy managed by the management device, and an encryption process based on a certificate specified by the acquired confidential policy And a secrecy device that executes a secrecy process for a document including
[0013]
The invention according to claim 2 is the invention according to claim 1, wherein the certificate includes a public encryption key unique to a corresponding authorized person to view, and the security device is a document to be confidentialized with a common encryption key. And encrypting the common encryption key with the public encryption key, attaching the encrypted common encryption key to the encrypted document, and executing the encryption process.
[0014]
According to a third aspect of the present invention, in the second aspect of the present invention, the security policy includes image information to be pasted on a document to be confidentialized, and the security processing is performed on an image based on the security policy. And a process of pasting the document into the document.
[0015]
The invention according to claim 4 further comprises a browsing device for browsing the document subjected to the confidentialization process according to the invention of claim 2, wherein the management device uses the browsing device based on the security policy. Control the browsing of a confidential document, and the browsing device has a secret encryption key corresponding to the public encryption key, and the management device is permitted to browse the confidential document In addition, the classified document is decrypted and displayed.
[0016]
In the invention of claim 5, in the invention of claim 4, the management device permits the browsing device to browse a confidential document within a predetermined period, and the browsing device The classified document is decrypted and displayed without obtaining permission again from the management apparatus on the condition that it is within the period.
[0017]
According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the confidential policy includes a confidential document browsing deadline, and the management device is classified by the browsing device based on the browsing deadline. It is characterized by controlling browsing of a document.
[0018]
The invention according to claim 7 is the invention according to claim 4, wherein the confidential policy includes information on whether or not the confidential document can be printed, and the management device uses the browsing device based on the information on whether or not to print. It is characterized by controlling the printing process of a confidential document.
[0019]
Further, the invention of claim 8 is a security device that performs security processing on a document that needs to maintain confidentiality, and that specifies the designation of a viewing authorized person and the validity of the viewing authorized person for the document. A list acquisition unit that acquires a list of the confidential policies from a management device that manages at least one confidential policy including a document, and a confidential policy that acquires a confidential policy selected from the list of confidential policies acquired by the list acquisition unit An acquisition unit; and a confidentiality processing unit that performs a confidentiality process including an encryption process on a document to be classified based on a certificate specified by the confidential policy acquired by the confidential policy acquisition unit. It is characterized by.
[0020]
The invention according to claim 9 is the invention according to claim 8, wherein the certificate includes a public encryption key unique to a corresponding browsing authorized person, and the security processing means uses a common encryption key to be classified. Encryption processing means for encrypting a document, encrypting the common encryption key with the public encryption key, attaching the encrypted common encryption key to the encrypted document, and executing the encryption processing It is characterized by doing.
[0021]
The invention according to claim 10 is the invention according to claim 8, wherein the security policy includes image information to be pasted on a document to be confidentialized, and the security processing means applies an image based on the security policy to the security policy. Image pasting means for pasting on a document to be processed.
[0022]
The invention of claim 11 is a browsing apparatus that manages a document subjected to confidential processing and displays the document to a person who is permitted to browse the document, and is encrypted with a common encryption key. The encrypted common key is extracted from a confidential document including the encrypted encrypted document and the encrypted common key obtained by encrypting the common encryption key with the public encryption key, and the extracted encrypted common key is extracted from the public encryption key. A decryption processing means is provided for decrypting with a secret encryption key corresponding to the key and decrypting the encrypted document with the decrypted common encryption key.
[0023]
The invention of claim 12 further comprises a browsing permission confirmation means for checking whether or not the confidentialized document can be browsed with respect to a management device that manages information related to the confidentialized document in the invention of claim 11. The decryption processing means decrypts the encrypted document on the condition that browsing permission is confirmed by the browsing permission confirmation means.
[0024]
The invention according to claim 13 is the invention according to claim 12, wherein the decryption processing means, within the validity period, when the browsing permission confirmation means confirms permission of browsing having a predetermined validity period. The encrypted document is decrypted on the condition that it exists.
[0025]
According to a fourteenth aspect of the present invention, in the twelfth aspect of the present invention, in the twelfth aspect of the invention, the management device confirms whether the confidential document can be printed or not, and the print permission confirmation means confirms the permission of printing. And a print processing means for executing a printing process of the document decrypted by the decryption processing means on the condition that the processing has been performed.
[0026]
Further, the invention of claim 15 is a document management method for managing a document that needs to maintain confidentiality, and includes a confidential policy that includes designation of a viewing authorized person for the document and a certificate proving the legitimacy of the viewing authorized person. Is managed by at least one management device, and when performing confidentialization of a document, a desired security policy is acquired from the security policy managed by the management device, and the certificate specified by the acquired security policy A document confidentiality process including an encryption process based on the above is executed.
[0027]
Further, in the invention of claim 16, in the invention of claim 15, the confidentiality policy includes a browsing time limit of the confidential document, and controls the browsing of the confidential document based on the browsing time limit. Features.
[0028]
The invention according to claim 17 is the invention according to claim 15, wherein the confidential policy includes information on whether or not the confidential document is printable, and print processing of the confidential document based on the information on whether or not printing is performed. It is characterized by controlling.
[0029]
Further, the invention of claim 18 is a security method for performing security processing on a document that requires confidentiality, and is a certificate for certifying the designation of a viewing authorized person and the validity of the viewing authorized person for the document. A list of the confidential policies is acquired from a management device that manages at least one confidential policy including, and the confidential policy selected from the acquired confidential policy list is acquired, and the certificate specified by the acquired confidential policy is acquired. A security process including an encryption process is performed on a confidential processing target document based on the document.
[0030]
The invention according to claim 19 is the invention according to claim 18, wherein the certificate includes a public encryption key unique to the corresponding authorized person, and the encryption processing is performed using a common encryption key. And encrypting the common encryption key with the public encryption key, and attaching the encrypted common encryption key to the encrypted document.
[0031]
According to a twentieth aspect of the present invention, in the invention of the eleventh aspect, the security policy includes image information to be pasted on a document to be confidentialized, and the security processing is to make an image based on the security policy confidential. It includes a process of pasting on a document to be processed.
[0032]
The invention of claim 21 is a browsing method for managing a document subjected to confidentialization processing and displaying the document to a person who is permitted to browse the document, wherein the document is encrypted with a common encryption key. The encrypted common key is extracted from a confidential document including the encrypted encrypted document and the encrypted common key obtained by encrypting the common encryption key with the public encryption key, and the extracted encrypted common key is extracted from the public encryption key. Decrypting with a secret encryption key corresponding to the key, decrypting the encrypted document with the decrypted common encryption key, and displaying the document.
[0033]
The invention of claim 22 is the invention of claim 21, wherein the confidential document confirms whether or not the confidential document can be browsed with respect to a management device that manages information related to the confidential document. As a result, decryption is performed on condition that browsing is permitted.
[0034]
The invention of claim 23 is characterized in that, in the invention of claim 22, when the permission has a predetermined valid period, the confidential document is decrypted on the condition that it is within the valid period. To do.
[0035]
In the invention of claim 24, in the invention of claim 22, the confidential document confirms whether or not the confidential document can be printed to the management apparatus, and as a result of the confirmation, printing is permitted. It is printed on the condition.
[0036]
The invention of claim 25 is a security program for performing security processing for a document that needs to be kept confidential, and is a certificate that designates a viewing permitter for the document and proves the legitimacy of the viewing permitter. A list acquisition step of acquiring a list of confidential policies from a management device that manages at least one confidential policy including the security policy, and acquiring a confidential policy selected from the list of confidential policies acquired in the list acquisition step And a security processing step of performing security processing including encryption processing on a document to be processed based on the certificate specified by the security policy acquired in the security policy acquisition step. It is characterized by that.
[0037]
In the invention of claim 26, in the invention of claim 25, the certificate includes a public encryption key unique to a corresponding viewing authorized person, and the security processing step includes a common encryption key to be classified. A document encryption step for encrypting a document, a key encryption step for encrypting the common encryption key with the public encryption key, and a common encryption key encrypted in the key encryption step in the document encryption step. And a synthesizing step of synthesizing with the encrypted document.
[0038]
The invention of claim 27 is the invention of claim 25, wherein the security policy includes image information to be pasted on a document to be confidentialized, and the security processing step includes processing the image based on the security policy as the security information. And an image pasting step to be pasted on the document to be processed.
[0039]
The invention of claim 28 is a browsing program for managing a document subjected to confidential processing and displaying the document to a person who is permitted to view the document, and encrypts the document using a common encryption key. When the encrypted common key is extracted from the confidential document including the encrypted encrypted document and the encrypted common key obtained by encrypting the common encryption key with the public encryption key, the key extraction step and the key extraction step A key decryption step of decrypting the encrypted common key with a secret encryption key corresponding to the public encryption key; and a document decryption step of decrypting the encrypted document with the common encryption key decrypted in the key decryption step. And making the computer execute.
[0040]
The invention according to claim 29 is the invention according to claim 28, further causing the computer to further execute a confirmation step of confirming whether or not the confidentialized document can be browsed with respect to a management device that manages information relating to the confidentialized document. The key extraction step, the key decryption step, and the document decryption step are executed on condition that the browsing permission is confirmed by the confirmation step.
[0041]
Further, in the invention of claim 30, in the invention of claim 29, in the case where confirmation of browsing having a predetermined validity period is confirmed in the confirmation step, the key extraction step is performed on the condition that it is within the validity period. And the key decryption step and the document decryption step.
[0042]
According to a thirty-first aspect of the present invention, in the thirty-ninth aspect of the present invention, a print confirmation step for confirming whether or not the confidential document can be printed is confirmed with respect to the management device, and the permission of printing is confirmed in the print confirmation step On the condition, the computer is further caused to execute a print processing step for executing the print processing of the document decrypted by the document decryption step.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a document management system and method, a security device and method, a program, a browsing device and method, and a program according to the present invention will be described in detail with reference to the accompanying drawings.
[0044]
FIG. 1 is a block diagram showing a basic configuration example of a document management system according to the present invention. As shown in the figure, the document management system is used by a management server 1 for managing various information used for document management, a client 2 used by an administrator of the document management system, and a document creator. A client 3 (3-1 to 3-n) and a client 4 (4-1 to 4-m) used by a document viewer are connected via a network 5.
[0045]
FIG. 2 is a block diagram showing a configuration example when the document management system shown in FIG. 1 is actually used. As shown in the figure, the document management system is used by a management server 1 for managing various information used for document management, a client 2 used by an administrator of the document management system, and a document creator. A client 3 and a client 4 used by a document viewer are connected via the Internet 6. In the configuration shown in the figure, the number of clients 3 and 4 is set to 1 for simplification of explanation, but a plurality of clients 3 and 4 can be used. Further, the number of clients 2 used by the administrator is not necessarily one.
[0046]
In this configuration, the management server 1 manages confidential policies in the document management system, and also manages each user's authentication, document attributes, history, logs, and the like.
[0047]
The client 2 is operated by the administrator of the document management system, and the administrator sets or changes the confidential policy managed by the management server 1 and browses the log. In the client 2, dedicated software for performing these processes may be operated, but these processes may be performed by a general-purpose web browser. When a general-purpose web browser is used on the client 2, the management server 1 operates the web server.
[0048]
The client 3 is operated by a document creator, and performs encryption processing for converting the created document into a confidential document. In the encryption process, a confidential policy managed by the management server 1 is used.
[0049]
The client 4 is operated by a document viewer and performs a decryption process for browsing a confidential document.
[0050]
Note that the client 3 and the client 4 may have both functions described below.
[0051]
Next, details of each unit constituting the document management system shown in FIG. 2 will be described. First, details of the management server 1 will be described.
[0052]
The management server 1 manages confidential policies, and performs authentication processing for each user, management of document attributes, control of whether or not to view a document based on document attributes, management of processing history for a document, management of log information, and the like. Do.
[0053]
The confidential policy is set by an administrator who operates the client 2, and has settings such as an authorized person to view the document, a pasted image on the document, whether or not to allow printing, and a viewing time limit.
[0054]
FIG. 3 and FIG. 4 are diagrams showing a configuration example of the confidential policy. A plurality of confidential policies can be set in the management server 1. For example, the confidential policy 10A shown in FIG. 3, the confidential policy 10B shown in FIG. 4 (a), and the confidential policy 10C shown in FIG. 4 (b) are set. The These confidential policies 10A and the like can be given arbitrary names (in the figure, they are classified as confidential policy A, confidential policy B, and confidential policy C, respectively).
[0055]
The confidential policy has a hierarchical structure, in which an authorized person to view, an image to be attached to a document, whether or not to print, a viewing time limit, and the like are set. For example, in the confidential policy 10A, a role 11A and a role 11B are set as browsing authorized persons. The role is a group of authorized users, and the authorized person 12A is included in the role 11A. Further, the roll 11B further includes a roll 11C, and together with this, a viewing authorized person 12B and a viewing authorized person 12C are included. The role 11C includes a browsing permitted person 12D and a browsing permitted person 12E. Note that an arbitrary name can be assigned to the roll 11A or the like (in the figure, it is referred to as a roll A or the like). In addition, in the permitted viewing person 12A and the like, it is indicated as permitted viewing person A and the like in the figure, but actually, information that can specify the permitted viewing person such as the name and user name of the permitted viewing person is set. Has been.
[0056]
In addition, the viewing-permitted person 12A and the like include a digital certificate of the corresponding viewing-permitted person or information for obtaining the digital certificate. In other words, the confidential policy may be configured to include the digital certificate of the authorized person, or may be configured to include information for acquiring the digital certificate without including the digital certificate itself. This digital certificate may be issued by the management server 1 or may be issued by another certification authority. When the digital certificate is obtained based on the information, the acquisition destination is the management server. 1 or other certification body.
[0057]
Further, in the confidential policy 10A, a pasting image 13A and a pasting image 13B are set as pasting images to a document, a printing permission / non-permission setting 14A is set as printing permission / prohibition control information, and a browsing time limit information 15A is set as document browsing time limit information. . In the pasted image 13A and pasted image 13B, information for generating an image to be pasted on a document or an image to be pasted on a document is set. The image to be pasted on the document is, for example, pasted on a predetermined area 18 of the document shown in FIG. 5A, and includes information including information shown in FIG. 5B or FIG. There is something like the symbol shown in. In the print permission / inhibition setting 14A, information as to whether or not to permit document printing is set. In the browsing time limit information 15A, a time limit for permitting browsing of the document is set. This time limit may be common to all viewing permitters set in the confidential policy 10A, or may be different for each viewing permitting user.
[0058]
Similarly, the confidential policy 10B is set with a roll 11C including a browsing permitted person 12D and a browsing permitted person 12E, and a pasted image 13B and a browsing time limit 15B are set. The confidential policy 10C includes a browsing permitted person 12A. The roll 11A to be included is set. As is clear from the configuration of the confidential policy 10B and the confidential policy 10C, the setting of the pasted image and the setting of the viewing time limit are arbitrary.
[0059]
The authentication process for each user in the management server 1 is performed using a digital certificate. The digital certificate may be issued by the management server 1 or may be issued by another certification authority. This digital certificate is set in the client 2, the client 3, and the client 4. When the management server 1 is accessed from these, the digital certificate is presented and user authentication is performed.
[0060]
Document attributes are managed by receiving the attributes of the document together with identification information for identifying the document from the client 3 when the client 3 makes the document confidential. The attributes managed here are information such as the viewing time limit of the document and whether or not printing is possible.
[0061]
When a document viewer tries to browse a document with the client 4, the document browsing control receives document identification information from the client 4, and browses based on the identification information and managed document attributes. The client 4 is notified of whether or not printing is possible and whether or not printing is possible.
[0062]
The management of processing history for a document is performed by receiving processing information when the document is browsed or printed by the client 4 and accumulating it. This history is presented when there is an inquiry from the document creator or the like.
[0063]
Log information management is performed by accumulating and managing log information generated each time the above-described processes are performed, and presenting this when there is an inquiry from an administrator or the like.
[0064]
Next, details of the client 3 will be described. The client 3 is operated by the document creator, and makes the document confidential. The confidential processing of the document may be performed by operating dedicated software on the client 3, or by operating software provided as a plug-in of general-purpose document processing software such as a word processor on the client 3. Also good.
[0065]
Here, the confidential processing of the document by the client 3 will be described. First, the operation flow of the client 3 by the creator will be described. FIG. 6 is a flowchart showing a flow of operation of the client 3 by the creator.
[0066]
First, the creator creates or edits a document (step 101). When the creation or editing of the document is completed, the creator instructs the confidentiality of the document from a menu or the like (step 102). As a result, the client 3 accesses the management server 1. In this case, since it is necessary to present a digital certificate, this is applicable when a plurality of digital certificates are set in the client 3. A digital certificate is selected (step 103). Then, the client 3 acquires a list of confidential policies from the management server 1 and presents it to the creator. In response, the creator selects a desired confidentiality policy (step 104). When the creator selects the confidential policy, the client 3 performs confidentialization of the document according to the selected confidential policy. Thereafter, the creator distributes the confidential document using e-mail or the like (step 105), and ends the operation.
[0067]
By the way, when selecting the confidential policy, the creator confirms the details of the confidential policy if the content cannot be determined only by the list display. At that time, the details of the confidential policy can be displayed in various formats. One of the display formats is a method for displaying the hierarchical structure of the confidential policy as it is. In this case, for example, when the confidential policy 10A shown in FIG. 3 is displayed, first, as shown in FIG. 7A, the first hierarchy is displayed. Here, when the creator selects the role B, as shown in FIG. 7B, the next hierarchy is displayed. As another display method, there is a method of enumerating and displaying each permitted viewer in parallel without displaying a role. In this case, when the confidential policy 10A is displayed, a display as shown in FIG. Further, when the browsing deadline and the print permission / inhibition are set for each browsing authorized person, the display is as shown in FIG.
[0068]
Next, the flow of processing for document confidentiality by the client 3 will be described. FIG. 8 is a flowchart showing a flow of document confidentialization processing by the client 3.
[0069]
When the client 3 receives an instruction operation for document confidentiality processing by the creator, the client 3 accesses the management server 1 and performs authentication processing (step 151). In this authentication processing, the corresponding digital certificate is managed. Present to server 1. If the authentication is successful, the client 3 acquires a list of confidential policies from the management server 1 and displays it (step 152).
[0070]
Thereafter, when the secret policy is selected by the creator, the selected secret policy is acquired from the management server 1 (step 153). At this time, the client 3 also obtains from the management server 1 or the like a digital certificate of a viewing-permitted person included in the confidential policy or a digital certificate specified from the confidential policy. Then, the pasted image is pasted on the document based on the acquired confidentiality policy (step 154), and attributes such as setting of whether printing is permitted are set on the document (step 155). However, the processing of step 154 and step 155 is not necessarily executed (for example, when a pasted image is not included in the confidential policy).
[0071]
Next, the client 3 generates a common key for encrypting the document (step 156). This common key is arbitrarily generated by the client 3. However, the common key does not necessarily have to be generated at this timing, and a previously generated one may be held and acquired. Then, the document is encrypted with the generated or acquired common key (step 157).
[0072]
Subsequently, the client 3 encrypts the common key obtained by encrypting the document by using the public key included in the digital certificate of the authorized person who has obtained the document (step 158). The encryption of the common key is executed using each public key according to the number of authorized users. Then, the encrypted common key (there may be a plurality of cases) and the encrypted document are synthesized (step 159). Thereafter, document information such as identification information for identifying the document is sent to the management server 1 (step 160). The document confidentialization process ends.
[0073]
Here, the document confidentialization process executed by the client 3 will be described in detail. FIG. 9 is a diagram for explaining the flow of confidential processing of a document.
[0074]
In document confidentiality processing by the client 3, first, a common key 31 for performing encryption processing on the document 30 to be confidentialized is generated or acquired in advance, and this common key is acquired. The document 30 is encrypted at 31 to obtain an encrypted document 32. Next, the common key 31 is encrypted using the public key 34 (34A, 34B, 34C) attached to each of the digital certificates 33 (33A, 33B, 33C) acquired from the management server 1 or the like. This public key 34 is unique to each authorized person who is certified by the digital certificate 33. Next, the client 3 synthesizes the encrypted common key 35 (35A, 35B, 35C) obtained by encrypting the common key 31 with the public key 34 and the encrypted document 32 that has been encrypted previously, to thereby create a confidential document. 36 is obtained, and the confidential processing of the document is completed.
[0075]
As described above, the confidential document 36 is composed of the encrypted document 32 and the encrypted common key 35. In order to obtain the original document 30 from the confidential document 36, the encrypted common key 35 is decrypted. A secret key is required for the user, and this secret key is possessed only by each authorized viewer. If the common key 31 can be obtained by decrypting the encrypted common key 35 with the secret key, the encrypted document 32 can be decrypted, and the original document 30 can be obtained. Details of browsing the confidential document 36 (including decryption processing) will be described later.
[0076]
By applying such confidentialization processing to the document, it is possible to distribute the same confidential document to a plurality of authorized users. On the other hand, for example, when a document is encrypted with a public key corresponding to each authorized person, an encrypted document corresponding to the number of authorized persons is generated. It becomes complicated.
[0077]
Next, details of the client 4 will be described. The client 4 is operated by a document viewer and releases the confidentiality of the document. This declassification processing of the document may be performed by operating dedicated software on the client 4, and software provided as a plug-in of general-purpose document processing software such as a word processor is operated on the client 4. You may go.
[0078]
Here, the process of declassifying the document by the client 4 will be described. First, the flow of operations of the client 4 by the viewer will be described. FIG. 10 is a flowchart showing the flow of operation of the client 4 by the viewer.
[0079]
First, the viewer selects a document to browse (step 201). If the selected document is a confidential document, the client 4 accesses the management server 1. At this time, since a digital certificate must be presented, a plurality of digital certificates are set in the client 4. If so, the corresponding digital certificate is selected (step 202). When the client 4 receives the browsing permission notification from the management server 1, the client 4 releases the confidentiality of the document and displays it, and the viewer browses the document (step 203) and ends the operation. At this time, the client 4 expands the confidential document on the memory, but does not store it on a disk or the like. Then, document storage in a state where confidentiality is released is prohibited.
[0080]
Next, the flow of processing for declassifying a document by the client 4 will be described. FIG. 11 is a flowchart showing the flow of the declassification process of the document by the client 4.
[0081]
When the client 4 receives a document browsing instruction operation by the viewer, the client 4 accesses the management server 1 and performs an authentication process (step 251). In this authentication process, the client 4 sends the corresponding digital certificate to the management server 1. Present. If the authentication is successful, the client 4 transmits document identification information to the management server 1 and confirms that browsing of the document is permitted (step 252). As a result of the confirmation, if browsing is not permitted, the processing is immediately terminated. If browsing is permitted, information on whether printing is possible is also acquired.
[0082]
As a result of the confirmation, if browsing of the document is permitted, the encryption common key is extracted from the confidential document (step 253), and the extracted encryption common key is decrypted with the secret key (step 254). Then, the encrypted document is decrypted with the decrypted common key, and the decrypted document is displayed to allow the viewer to browse (step 255). Then, processing information for notifying that the confidentiality of the document has been released is sent to the management server 1 (step 256). Thereafter, when the viewer does not print the document, the client 4 ends the document declassification process.
[0083]
When the viewer instructs printing of the document, the client 4 executes printing processing on the condition that printing is permitted (step 257), and notifies that the document has been printed. The processing information is sent to the management server 1 (step 258), and the confidentiality release processing for the document is terminated.
[0084]
Here, the declassification processing of the document that is executed by the client 4 will be described in detail. FIG. 12 is a diagram for explaining the flow of the declassification process of a document.
[0085]
In the declassification processing of the document by the client 4, first, a corresponding one of the encryption common keys 35 included in the confidential document 36, for example, encryption, is used by using the private key of the viewer himself / herself that the client 4 has. The common key 35B is decrypted to obtain the common key 31. Then, the encrypted document 32 is decrypted using the common key 31 to obtain the original document 30. At this time, the client 4 only expands the document 30 on the memory, does not store it on a disk or the like, and does not store it as the document 30. Of course, since the confidential document 36 is stored on the disc or the like, the confidential document 36 can be declassified again and browsed as necessary. However, the confidentiality of the confidential document 36 can be canceled within a period during which browsing is permitted.
[0086]
Next, information exchanged between the management server 1, the client 3, and the client 4 in the above-described document confidentiality processing and confidentiality cancellation processing will be described. FIG. 13 is a diagram illustrating a flow of information exchanged between the management server 1, the client 3, and the client 4.
[0087]
When a document is classified, first, a digital certificate is presented as authentication information from the client 3 to the management server 1 (step 301). The management server 1 authenticates the client 3 based on this authentication information, and when the authentication is successful, a response to that effect is returned to the client 3.
[0088]
Subsequently, the client 3 requests acquisition of the confidential policy list information set in the management server 1 (step 302), and in response thereto, the management server 1 transmits the confidential policy list information to the client 3. (Step 303).
[0089]
Next, the client 3 transmits an acquisition request for the confidential policy selected by the creator to the management server 1 (step 304), and the management server 1 transmits the selected confidential policy to the client 3 in response thereto (step 304). 305).
[0090]
Thereafter, when the confidentiality of the document is executed by the client 3, document information including identification information of the document is transmitted from the client 3 to the management server 1 (step 306), and the confidential document is transmitted from the client 3. It is transmitted to the client 4 (step 307).
[0091]
Thereafter, when the declassification processing of the document is performed by the client 4, a digital certificate is presented as authentication information from the client 4 to the management server 1 (step 308). The management server 1 authenticates the client 4 based on this authentication information, and when the authentication is successful, a response to that effect is returned to the client 4.
[0092]
Subsequently, the client 4 transmits document information including identification information of the document to be declassified to the management server 1 (step 309). The management server 1 confirms whether or not the document can be browsed based on the received document information, and if browsing is possible, transmits permission information permitting browsing to the client 4 (step 310). When the client 4 permitted to view the document releases the confidentiality of the document, processing information indicating that is transmitted from the client 4 to the management server 1.
[0093]
By the way, it is conceivable that the client 4 may not be able to connect to the management server 1, that is, when it is desired to browse a confidential document in an offline state. As a method of coping with such a request, by providing a certain effective period for the browsing permission notified from the management server 1 to the client 4, once the client 4 receives the browsing permission, the certain level of validity is set. It is possible to browse confidential documents offline for a period of time. Processing of the client 4 in this case will be described.
[0094]
FIG. 14 is a flowchart showing the flow of the document declassification processing by the client 4 in the offline state.
[0095]
When the client 4 accepts a document browsing instruction operation by the viewer, the client 4 confirms whether the management server 1 can be accessed. If access to the management server 1 is possible (YES in step 401), the above-described processing is performed to release the confidentiality of the document.
[0096]
On the other hand, if the access to the management server 1 from the client 4 is impossible (NO in step 401), the client 4 confirms the browsing permission information when the confidentialization of the document is first canceled (step 401). 402). As a result of the confirmation, if the current browsing is permitted, that is, if the previously received browsing permission is within the valid period (YES in step 403), the encrypted common key is extracted from the confidential document (step 405). ) Decrypt the extracted encrypted common key with the secret key (step 406). Then, the encrypted document is decrypted with the decrypted common key, and the decrypted document is displayed to allow the viewer to browse (step 407). Then, processing information for notifying that the confidentiality of the document has been released is accumulated (step 408), and the confidentiality releasing processing of the document is terminated. The accumulated processing information is transmitted to the management server 1 when access to the management server 1 becomes possible later. If the browsing permission received first is invalid (NO in step 404), the client 4 naturally terminates the process because browsing of the document is not permitted.
[0097]
As described above, even when the client 4 releases the confidentiality of the document in an offline state with the management server 1, the release of the confidentiality requires the secret key of the viewer who is permitted to view the document. The declassification by a third party is impossible. In other words, it can be said that the processing when the client 4 is online with the management server 1 has double security.
[0098]
【The invention's effect】
As described above, according to the present invention, the confidentiality policy including the designation of the person who is permitted to view the document is managed by the management server, and the client on the creation side that creates the confidential document acquires the confidentiality policy from the management server. Execute confidential document processing including encryption of documents and pasting of images based on the confidential policy, manage information on confidential documents on the management server, and whether the management server can view or print Therefore, the creator of the confidential document can make the document confidential by simply selecting a desired confidential policy from the confidential policies managed by the management server.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration example of a document management system according to the present invention.
FIG. 2 is a block diagram showing a configuration example when the document management system shown in FIG. 1 is actually used.
FIG. 3 is a diagram (1) illustrating a configuration example of a confidential policy.
FIG. 4 is a diagram (2) illustrating a configuration example of a confidential policy.
FIG. 5 is a diagram for explaining a pasting image.
FIG. 6 is a flowchart showing a flow of operation of the client 3 by the creator.
FIG. 7 is a diagram showing a display example of a confidential policy to a creator.
FIG. 8 is a flowchart showing a flow of document confidentialization processing by the client 3;
FIG. 9 is a diagram for explaining the flow of a confidentialization process of a document.
FIG. 10 is a flowchart showing a flow of operations of the client 4 by a viewer.
FIG. 11 is a flowchart illustrating a flow of a document declassification process performed by a client.
FIG. 12 is a diagram for explaining the flow of a declassification process of a document.
13 is a diagram showing a flow of information exchanged between the management server 1, the client 3, and the client 4. FIG.
FIG. 14 is a flowchart showing a flow of a document declassification process by the client 4 in an offline state.
[Explanation of symbols]
1 management server
2 clients
3, 3-1 to 3-n client
4, 4-1 to 4-m client
5 network
6 Internet
10A, 10B, 10C Confidential policy
11A, 11B, 11C roll
12A, 12B, 12C, 12D, 12E
13A, 13B pasted image
14A Print availability setting
15A, 15B Viewing deadline information
18 areas
30 documents
31 Common key
32 Encrypted documents
33A, 33B, 33C Digital certificate
34A, 34B, 34C Public key
35A, 35B, 35C Encryption common key
36 Confidential documents
37 private key

Claims (31)

A document management system for managing documents that require confidentiality,
A management device that manages at least one confidentiality policy that includes designation of a person authorized to view the document and a certificate proving the legitimacy of the person permitted to view;
A security device that acquires a security policy selected from the security policy managed by the management device, and executes a security process for the document including an encryption process based on a certificate specified by the acquired security policy. A document management system characterized by: The certificate is
Including the public encryption key unique to the corresponding viewing author,
The security device is
The document to be classified is encrypted with a common encryption key, the common encryption key is encrypted with the public encryption key, and the encrypted common encryption key is attached to the encrypted document to perform the encryption process. The document management system according to claim 1, wherein the document management system is executed. The confidential policy is:
Contains image information to be pasted into confidential documents,
The confidentialization process is:
The document management system according to claim 2, further comprising a process of pasting an image based on the confidentiality policy on a confidentiality target document. Further comprising a browsing device for browsing the confidentialized document;
The management device
Controlling browsing of confidential documents by the browsing device based on the confidentiality policy;
The browsing device is
Decrypting and displaying the confidential document on the condition that the management apparatus has a secret encryption key corresponding to the public encryption key and permission to view the confidential document is permitted by the management apparatus. The document management system according to claim 2, wherein: The management device
Permits browsing of confidential documents within a predetermined period for the browsing device,
The browsing device is
5. The document management system according to claim 4, wherein the confidential document is decrypted and displayed without obtaining permission again from the management apparatus on condition that the period is within the predetermined period. The confidential policy is:
Including the deadline for viewing confidential documents,
The management device
5. The document management system according to claim 4, wherein browsing of the classified document by the browsing device is controlled based on the browsing time limit. The confidential policy is:
Contains printability information for confidential documents,
The management device
5. The document management system according to claim 4, wherein a printing process of a confidential document by the browsing device is controlled based on the information on whether to print. A security device that performs security processing on a document that requires confidentiality,
A list acquisition means for acquiring a list of confidential policies from a management device that manages at least one confidential policy including designation of a permitted person for viewing the document and a certificate proving the legitimacy of the permitted person;
A confidential policy acquisition means for acquiring a confidential policy selected from a list of confidential policies acquired by the list acquisition means;
Security processing means for performing security processing including encryption processing on a document to be processed on the basis of a certificate specified by the security policy acquired by the security policy acquisition device. Confidential device. The certificate is
Including the public encryption key unique to the corresponding viewing author,
The security processing means includes
The document to be classified is encrypted with a common encryption key, the common encryption key is encrypted with the public encryption key, and the encrypted common encryption key is attached to the encrypted document to perform the encryption process. 9. The security apparatus according to claim 8, further comprising encryption processing means to be executed. The confidential policy is:
Contains image information to be pasted into confidential documents,
The security processing means includes
9. The security device according to claim 8, further comprising image pasting means for pasting an image based on the security policy to the document to be classified. A browsing device that manages a document subjected to confidentialization processing and displays the document to a person who is permitted to browse the document,
Extracting the encrypted common key from a confidential document including an encrypted document encrypted with the common encryption key and an encrypted common key obtained by encrypting the common encryption key with a public encryption key, and the extracted encryption A browsing apparatus comprising decryption processing means for decrypting a common key with a secret encryption key corresponding to the public encryption key and decrypting the encrypted document with the decrypted common encryption key. A browsing permission / non-permission confirmation means for confirming whether or not the confidentialized document can be browsed with respect to a management device that manages information related to the classified document;
The decryption processing means includes:
12. The browsing apparatus according to claim 11, wherein the encrypted document is decrypted on condition that browsing permission is confirmed by the browsing permission confirmation unit. The decryption processing means includes:
13. The browsing according to claim 12, wherein when the browsing permission confirmation unit confirms permission of browsing having a predetermined valid period, the encrypted document is decrypted on the condition that it is within the valid period. apparatus. A print permission confirmation means for confirming whether the confidential document can be printed with respect to the management apparatus;
The print processing means for executing a print process of the document decrypted by the decryption processing means on condition that the print permission is confirmed by the print permission confirmation means. Browsing device. A document management method for managing documents that require confidentiality,
Managing at least one confidentiality policy including a designation of a viewing permitter for a document and a certificate proving the legitimacy of the viewing permitter with a management device;
When performing confidentialization of a document, a desired confidentiality policy is acquired from the confidentiality policy managed by the management apparatus, and the confidentiality of the document including encryption processing based on a certificate specified by the acquired confidentiality policy is acquired. Document management method, characterized by executing a conversion process. The document management method according to claim 15, wherein the confidentiality policy includes a browsing period of classified documents, and browsing of the classified documents is controlled based on the browsing period. 16. The document management method according to claim 15, wherein the confidential policy includes information on whether or not to print a confidential document, and print processing for the confidential document is controlled based on the information on whether or not to print. A confidentiality method for performing confidentiality processing on a document that requires confidentiality,
A list of confidential policies is acquired from a management apparatus that manages at least one confidential policy including designation of a permitted person to view a document and a certificate that proves the legitimacy of the permitted person. A confidentiality method comprising: acquiring a confidentiality policy selected from the above, and performing a confidentiality process including an encryption process on a document to be confidentialized based on a certificate specified by the acquired confidentiality policy . The certificate includes a public encryption key that is unique to the corresponding authorized viewer,
The encryption process encrypts a document to be confidentialized with a common encryption key, encrypts the common encryption key with the public encryption key, and attaches the encrypted common encryption key to the encrypted document. 19. The security method according to claim 18, which is a process. The confidential policy includes image information to be pasted on a confidential document.
19. The security method according to claim 18, wherein the security process includes a process of pasting an image based on the security policy on the security processing target document. A browsing method for managing a confidentialized document and displaying the document to a person who is permitted to browse the document,
Extracting the encrypted common key from a confidential document including an encrypted document encrypted with the common encryption key and an encrypted common key obtained by encrypting the common encryption key with a public encryption key, and the extracted encryption A browsing method, comprising: decrypting a common key with a secret encryption key corresponding to the public encryption key, decrypting the encrypted document with the decrypted common encryption key, and displaying the document. The confidential document is:
The management apparatus that manages information related to the classified document confirms whether or not the confidential document can be browsed, and is decrypted on the condition that browsing is permitted as a result of the confirmation. 21. The browsing method according to 21. 23. The browsing method according to claim 22, wherein when the permission has a predetermined effective period, the confidential document is decrypted on condition that the permission is within the effective period. The confidential document is:
23. The browsing method according to claim 22, wherein the management apparatus confirms whether or not the confidentialized document can be printed, and printing is performed on the condition that printing is permitted as a result of the confirmation. A security program that performs security processing on documents that require confidentiality,
A list acquisition step of acquiring a list of confidential policies from a management device that manages at least one confidential policy including designation of a permitted person to view the document and a certificate proving the validity of the permitted person;
A confidential policy acquisition step of acquiring a confidential policy selected from the list of confidential policies acquired in the list acquisition step;
A security processing step of causing a computer to execute a security processing step including performing a security processing including an encryption processing on a confidentiality processing target document based on a certificate specified by the security policy acquired in the security policy acquisition step. Confidentiality program. The certificate is
Including the public encryption key unique to the corresponding viewing author,
The security processing step includes
A document encryption step for encrypting a document to be classified with a common encryption key;
A key encryption step of encrypting the common encryption key with the public encryption key;
26. The security program according to claim 25, further comprising a combining step of combining the common encryption key encrypted in the key encryption step with the document encrypted in the document encryption step. The confidential policy is:
Contains image information to be pasted into confidential documents,
The security processing step includes
26. The security program according to claim 25, further comprising an image pasting step of pasting an image based on the security policy onto the document to be classified. A browsing program for managing a document that has been classified and displaying the document to a person who is permitted to view the document,
Extracting the encrypted common key from a confidential document including an encrypted document encrypted with the common encryption key and an encrypted common key obtained by encrypting the common encryption key with a public encryption key; and a key extraction step;
A key decryption step of decrypting the encrypted common key extracted in the key extraction step with a secret encryption key corresponding to the public encryption key;
A browsing program that causes a computer to execute a document decrypting step of decrypting the encrypted document with the common encryption key decrypted in the key decrypting step. Further causing the computer to execute a confirmation step of confirming whether or not the confidentialized document can be browsed with respect to a management device that manages information related to the confidentialized document;
29. The browsing program according to claim 28, wherein the key extraction step, the key decryption step, and the document decryption step are executed on the condition that browsing permission is confirmed by the confirmation step. When it is confirmed in the checking step that browsing has a predetermined valid period, the key extracting step, the key decrypting step, and the document decrypting step are executed on the condition that they are within the valid period. 30. The browsing program according to claim 29. A print confirmation step of confirming whether or not the confidentialized document can be printed to the management apparatus;
30. A print processing step of executing a printing process of a document decrypted by the document decryption step on the condition that the permission of printing is confirmed in the print confirmation step is further executed by a computer. The listed viewing program.

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