Apparatus and method for controlling data access using encrypted link position information

An access restriction apparatus, an access restriction method, a computer readable program storage medium having a recorded access restriction program, and the access restriction program, all capable of making a terminal refer only to management information existing at a position designated by link position information. An access restriction apparatus for limiting the access of terminals desiring access to managed management information is provided with a supply section for supplying the terminals with partially or totally encrypted link position information indicating a linking destination of the management information, and an access management section for managing the access of the terminals to the management information based on the link position information decoded by the terminals.

TECHNICAL FIELD

The present invention relates to an access restriction apparatus, an access restriction method, a computer readable program storage medium in which an access restriction program is recorded, and an access restriction program.

BACKGROUND ART

Recently, image data such as, for example, an image photographed with a digital camera or an image read with an optical character reader (OCR) is being exchanged through a network, such as the Internet. A cellular telephone equipped with a digital camera is available, and it is now possible to exchange image data between cellular telephones. Conventionally, an aggregate of binary data, such as image data, is managed as a file including information relating to the image, for example, information relating to image resolution.

For example, as shown inFIG. 24, conventionally first image data161and the information157relating to the image data161have been managed as one file; second image data162and the information158relating to the image data162have been managed as one file; third image data163and the information159relating to the image data163have been managed as one file; and fourth image data164and the information160relating to the image data164have been managed as one file.

If a plurality of binary data is to be copied or deleted, it has been necessary to process each binary data file individually, except for performing a process on the folder or on the directory. So, if a plurality of binary data is processed by batch processing, the batch processing may not always be completed due to an omission in the processing of a part of the binary data. Because binary data, such as image data, cannot include character information, the file name associated with the binary data is keys to retrieving such binary data, their creation dates and their update dates. Therefore, it is difficult for the user to handle such binary data.

Further, owing to the recent advancement of the information industry, data communications of document information including the binary data described above are frequently performed though networks, such as the Internet. For example, on the Internet, browser software is configured to read data described by means of a mark up language called Hyper Text Markup Language (HTML) for displaying the description of the data.

The markup language can describe a site that is desired to be linked to and the markup language is adapted to make it possible for the browser software to access link position information, such as a Uniform Resource Locator (URL), as the link destination. In the following description, “URLs” will be exemplified. In the conventional file linking by means of the HTML markup language, the linking functions to change a display corresponding to a change of URLs by changing one URL to another URL designating a position of a document. This is described in Japanese Patent Laid-open Publication Hei 11-96098 at page 5, section 0012.

Since the URL is described, however, by means of text data which is easily understood visually, the URL may easily be altered. Consequently, files other than the file designated by an original URL may easily be accessed.

More specifically, suppose a URL such as “http://www.aaa.ne.3p/20010101.html” was originally designated, the above-mentioned problem occurs at the time of amending the URL to another estimated URL such as “http://www.aaa.ne.jp/20010102.html,” which is intended to refer to the next file.

That is, there is a problem in that a person having an evil intention can access the file (“http://www.aaa.ne.jp/20010102.html”) other than the original file (“http://www.aaa.ne.jp/20010101.html”).

Conventionally, it was impossible to prohibit tracing a URL other than the originally designated URL. If the prohibition was attempted, it was necessary to perform complicated processing, such as alteration of the file designated by the URL, in advance.

Moreover, if a URL to be kept secret is transferred by electronic mail, there is a problem in that anyone who receives the URL can easily access a file at a URL other than the transferred URL.

Accordingly, the present invention aims to provide an access restriction apparatus, an access restriction method, a computer readable program storage medium having a recorded access restriction program, and the access restriction program, capable of solving the problems described above and of allowing a terminal to refer only to management information that exists at a position designated by link position information.

SUMMARY OF THE INVENTION

According to the present invention, there are provided an access restriction apparatus, an access restriction method, a computer readable program storage medium having a recorded access restriction program, and the access restriction program, capable of allowing a terminal to refer only to management information that exists at a position designated by link position information.

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

Since the embodiments to be described in the following are a suitable concrete examples, various technically preferable limitations can be added to it. The scope of the present invention, however, is not limited to the forms of the limitations as long as a description indicating that the present invention is especially limited to the forms is not made.

First Embodiment

FIG. 1is a system block diagram showing a configuration of a data management system1to which a data management apparatus as a preferable embodiment of the present invention is applied.

The data management system1is provided with a document management server computer25, client computers23A,23B,23C and23D as terminals, a network8and a mail server computer27. In the following descriptions, persons operating the client computers23A,23B,23C and23D will be called, “Mr. A”, “Mr. B”, “Mr. C” and “Mr. D”, respectively. Collectively, they will be referred to as “accessing persons”.

The management server25is provided with an authority information management table16, an access management section14and a document management section18.

The authority information management table16is a table for managing the access authority of the client computers23A–23Ds which the accessing persons operate. The authority information management table16manages the access authority to the access persons, for example, as shown inFIG. 2. As shown inFIG. 2, Mr. A has the access authority of “3”, Mr. B has the access authority of “2”, and Mr. C has the access authority of “1”.

The document management section18manages documents to be stored as shown inFIG. 3as a document group19. The document group19is managed under a classification in which the document group19is classified into documents19A,19B and19C as management information. It is assumed in this example that the document group19has a document group name “AAA”, and that the document19B has a document name “bbb”.

Moreover, the document19B has documents composed of pages, for example, from a first page PI to a sixth page P6comprising a plurality of pieces of unit information, as shown inFIG. 4, and authority information37is attached to them. The authority information37is the access authority set in the authority information management table16shown inFIG. 2, and the authority information37is, for example, “2”.

The access management section14ofFIG. 1acquires the access authority from the authority information management table16to every accessed client, such as client23A and so on. The access management section14is configured to supply the client23A and others with a document composed of set pages such as the document19A ofFIG. 3and so on when the access management section14judges that the client23A and others have the access authority.

On the other hand, the client23D inFIG. 1includes a notification content setting section35and mail software33. The notification content setting section35has the function of setting link position information39shown inFIG. 5including the information indicating a linking destination such as the document19A and so on as the contents intended to be notified to the client23A. More specifically, in the link position information39, “a” as a server name, “AAA” as a document group, “bbb” as a document name, “pages 2–5” as page specification, and “ON” as an attribute are set, as shown inFIG. 5. The link position information39may be adapted to encrypt not only the information indicating the linking destination, but also any one of or a combination of some of the page specification, access authority, and the attribute.

The mail software33shown inFIG. 1is software having the function of exchanging electronic mail with the other clients23A–23D by utilizing mail boxes21A–21C of the mail server27. The mail software33can receive the documents19A–19C composed of the pages corresponding to access authority from the management server25as will be described later. It is needless to say that the means of data communication is not limited to mail software, but other means may be used as well.

The client23A includes a document acquisition section31and mail software33. Since the mail software33has functions similar to those of the above-mentioned mail software33of the client23D, the description thereof is omitted. The document acquisition section31can acquire the documents19A–19C composed of predetermined pages received by the mail software33to display the documents19A–19C. Since the clients23B and23C have configurations and functions similar to those of the client23A, the descriptions thereof are omitted here.

The management server25has the configuration described above. Next,FIGS. 1–4are referred to while an example of the data management method of the management server25is described.

FIG. 5is a view showing the data management method of the management server25conceptually.FIG. 6is a flow chart showing of the data management method of the management server25. In the following descriptions, the client23A is called as “Mr. A”; the client23B is called as “Mr. B”; the client23C is called as “Mr. C”; and the client23D is called as “Mr. D”.

As shown inFIG. 5, it is assumed that the document19B composed of six pages from the first page P1to the sixth page P6shown inFIG. 4is prepared in the document group19as “document group AAA” shown inFIG. 3together with the access authority “2” on the management server25having the name “a” as in Step ST1ofFIG. 6.

Moreover, it is assumed that the pieces of access authority “3”, “2” and “1” are given to Messrs. A, B and C, respectively, as the access authority, as shown inFIG. 2and comprising Step ST2ofFIG. 6.

Now, Mr. D is going to notify Messrs. A, B and C of the locations of the data of the pages of the document19B having the document name “bbb” from the second page P2to the fifth page P5which are public pages shown inFIG. 4for showing the pages to Messrs. A, B and C.

Mr. D inputs pieces of position information for example from the server name to the document name concerning the location of the document19B by means of the notification content setting section35as shown inFIG. 5. Thereby, Mr. D performs page setting as described above, and sets the attribute “ON”. Hereupon, the attribute indicates that only receivers, such as Mr. A and the like having the access authority, for example, smaller than a certain number of access authority can browse the document19B after the confirmation of the existence of the authority of the receivers at the time of setting “ON”. Thus, the receivers can browse the document19B regardless of their access authority without the confirmation of the existence of the authority at the time of setting “OFF”.

At the time of the performance of these settings, it is preferable that Mr. D has the authority for referring to at least the document19B having the document name “bbb”. As the setting methods of the authority, for example, direct inputting by hand may be adopted, or designation in conformity with the gist of copying and pasting at the time of editing may be adopted.

After the completion of the setting of the link position information39as such notification information, Mr. D encrypts the page specification and the attribute in the link position information39, as shown inFIG. 5by means of the notification content setting section35. Then, the encrypted link position information39ais distributed by being transmitted by electronic mail to the mail boxes21A–21C of the mail server27by means of the mail software33to be notified to Mr. A and so on comprising Step ST3ofFIG. 6.

Mr. A and Mr. D operate the client23A–23D respectively, to refer to the electronic mail pertaining to the link position information39a, and initiate access to the management server25comprising Step ST4ofFIG. 6. Accessing the management server25first initiates the checking of the attribute comprising Step ST5ofFIG. 6. As described above, the authority is set so that Mr. A has the access authority “3”, Mr. B has the access authority “2”, and Mr. C has the access authority “1” for example.

Although the link position information39ais automatically encrypted in the memories of the client A and so on, the access authority of Mr. A and so on is “3”, which is larger than the above-mentioned “2”. Consequently, Mr. A and Mr. D so on do not have the access authority, and cannot browse the encrypted link position information39.

Hereupon, since the attribute is “ON” in the link position information, the clients23A and so on severally confirm the access authority necessary for referring to the document19B having the document name “bbb” in the management server25, and know that, in this example, access authority “2” is necessary.

Since Messrs. A and B have the authority number larger than the authority “2”, Messrs. A and B do not have the access authority to the pages from the second page P2to the fifth page P5of the document19B. On the contrary, since Mr. C has the authority number “1”, it is known that Mr. C has the access authority for referring to the pages comprising Step ST6ofFIG. 6. As described above, when the attribute of the link position information39is “OFF”, the confirmation of the access authority to the management server25is not performed, and Messrs A and B having no proper access authority also can refer to the pages of the document19B having the document name “bbb” from the second page P2to the fifth page P5.

The transmission of the link position information30aconcerning the document19B having the document name “bbb” from Mr. D to Mr. C is notified to Mr. C comprising Step ST7ofFIG. 6. When Mr. C accesses the management server25by means of the contents of the link position information39aas a key, Mr. C can browse only the pages of the document19B from the second page P2to the fifth page P5. That is, the management server25is configured so that Mr. C cannot browse the pages other than the browsable pages such as the first page P1and the sixth page P6. Consequently, the management server25is configured to be able to make the document19B intended to be browsed secret or browsable at every page.

In this case, it is preferable that the actual page numbers indicating the first page P1and the sixth page P6severally cannot be browsed. This makes it impossible for Mr. A and so on, who browsed the browsable pages, to recognize the existence of the non-browsable pages, such as the first page P1.

In this situation, Messrs. A and B cannot refer to the document name “bbb” as long as their access authority is made to be “2” or more, or as long as the link position information39ain which the attribute “OFF” is encrypted is transmitted to them. Consequently, it is possible to make the respective clients23A and23B of Messrs. A and B, which have no access authority, impossible to browse the document19B of the management server25. Hence, secrets can be kept.

According to the first embodiment of the present invention, it is possible that the client23C can access only the partial pages of the document19B which the client23C is allowed to access. Moreover, even if the access authority to the document19B is not changed, it is possible to make a specific person refer to the information of the document19B by setting the attribute of the link position information39to “OFF”. Moreover, in the embodiment described above, the input and the output of the file of the pages of the document19B, for example, from the second page P2to the fifth page P5are limited to be fixed.

Moreover, since the link position information39ais encrypted, it is difficult to alter the link position information39aincluding the linking destination. If the alteration of the link position information39ais performed, the decoding of the information39abecomes impossible, thus making it impossible to use the data. Moreover, if the document19B at the linking destination is transferred without previous notice, the terminal having no access authority to which the document19B has been transferred cannot browse the document19B, since the access authority is individually set for every client.

Second Embodiment

FIG. 7is a data management system1aincluding a server computer SV to which an access restriction apparatus is applied according to a second embodiment of the present invention.

The data management system1aincludes the server computer SV, a network11and client computers CL, and is a computer system employing the so-called client server system.

The server computer SV is capable of processing predetermined processes at a high speed in response to a demand of a client computer CL. For example, predetermined basic software is operated on the server computer SV. The client computers CL, for example, demand predetermined processes from the sever computer SV. Predetermined basic software is operated on the client computers CL. The basic software is also called an operating system (OS) which has the function of data communication by use of a protocol, such as Transmission Control Protocol/Internet Protocol (TCP/IP) or the like, on the network11and can carry out an access restriction program that will be described later. The access restriction program may have a function substantially same as the basic software, so that the program performs without the basic software.

The data management system1ais characterized in that management information corresponding to the document19A of the first embodiment and the like is managed in the following way instead of performing functions of the data management system1of the first embodiment. That is, the data management system1aperforms management processing on a data aggregate that is integrated by combining a plurality of data while having delimiter information between those plurality of data. The plurality of data constitute management information, and related information in the aggregate that is integrated by combining a plurality of related information, each of which respectively relates to the plurality of data.

The network11includes a router5and cables3. The network11has the function of data communication between the server computer SV and the client computers CL through network cards or the like provided at the server computer SV and the client computers CL. The cables3are for the 10-BASE-T or for 100-BASE-T protocols, for example. The router5has the function of performing data exchange while controlling the data passing through the cables3.

FIG. 8is a block diagram showing a simple configuration of the server computer SV ofFIG. 7. The server computer SV includes an operation section15, a central processing unit13, a memory9, and a hard disk7.

The operation section15is a user operation unit such as a keyboard or a mouse. The hard disk7is a large capacity information recording medium capable of recording various kinds of data and programs.

The memory9is a volatile information recording medium capable of temporarily storing various kinds of data, basic software, and a program. The CPU13can recognize operations of the operation section15and can execute a predetermined process, also the CPU13can read an access restriction program17stored in the hard disk7, and write into a work area of the memory9for executing the access restriction program17. Descriptions of the operation of the client computers CL are omitted because the server computer SV has the substantially the same configuration as the client computers CL except that the processing of the CPU13operates at a higher speed than the client computers CL.

FIG. 9is a diagram of a directory structure for the management of data by the access restriction program17ofFIG. 8.FIG. 10is a diagram showing the structure of data stored in a first document directory25ofFIG. 9.

The access restriction program17ofFIG. 8manages a plurality of data stored in the hard disk7in a way shown inFIG. 9by using the memory9as the work area. Specifically, the access restriction program17has a document group directory20as a root directory, and has the function of managing a plurality of image data read with, for example, a scanning apparatus such as an optical character reader.

A group version directory21, a DOC directory23, an STG directory29, a BIN directory36and a TMP directory40are formed at a lower layer of the document group directory20. The group version directory21is a directory for storing the version information of created document group directory20. In the DOC directory23, the information concerning a plurality of image data is stored for each document. Further, in the DOC directory23, document text data, tag data, index data and thumbnail image data are stored in addition to the image data.

A first document STG directory32and a second document STG directory34are formed at a lower layer of the STG directory29. The first document STG directory32stores attached files which are managed in a one-to-one correspondence basis to the information, such as image data, to be stored in the first document STG directory31. Further, in practice, the attachment file is stored not for each page over the one-to-one basis but for each document if the attachment file for a certain document is to be managed in the one-to-one basis. The above-described attachment file includes, for example, tables, graphs and the like relating to results of analysis of information, such as image data of the first document directory26. Here, the attachment file is an attribute data that exists not for each page but for each document, for example. The first document directory26stores, for example, electronic documents that are originals of image data or attribute data for voice or moving picture images, for example.

The BIN directory36is for retaining indices to perform a search over the entire image data. The TMP directory40is for storing data temporarily. The TMP directory40is a temporary directory to be used inside programs for editing, for example. In other words, the TMP directory40has the function of storing data being edited.

The first document directory26and a second document directory28are formed at a lower layer of the DOC directory23. In the first document directory26as shown inFIG. 10, an index file41forming a related information aggregate and an actual file43forming a data aggregate are stored. Preferably, a thumbnail file45, a tag file47, a page summary file51and an attached file list file53are also stored therein.

The access restriction program17manages a plurality of image data as the index file41and the actual file43. Preferably, the thumbnail file45, the tag file47, the page summary file51and the attached file list file53are also managed.

The actual file43includes a plurality of image data, andt details of the actual file43will be described later. The index file41indicates the information related to the actual file43. For example, if the actual file43includes a plurality of image data, the index file41includes the information pertaining to the resolution or the like of the image data. The details of the index file41will be described later.

The thumbnail file45stores reduced image data of the actual file43. The tag file47is for handling the index of each of the image data and is thus. index information. Here, the index information means a list of data consisting of heading positions (1–4), index titles and pages. The page summary file51is text data indicating the summary information of the actual file43. The page summary files51are text data, for example, extracted from image data by the optical character reader or the like, or, included in image data and registered by another device. The attached file list file53is a figure indicating lists of the attached files stored in the first document STG directory32ofFIG. 9.

FIG. 11Ais a diagram showing a data configuration of the actual file43ofFIG. 10, andFIG. 11Bis a diagram showing a data configuration of the index file41ofFIG. 10.

The access restriction program17manages a plurality of data as a single integrated structure, as shown inFIG. 11A. For example, four image data from first image data61to fourth image data64are combined with tags66(69),67(69),68(69) inserted between the image data as delimiter information.

More specifically, the tag66(69) is provided between the first image data61and the second image data62; the tag67(69) is provided between the second image data62and the third image data63; the tag68(690is provided between the third image data63and the fourth image data64. Consequently, the first image data61and so forth can easily be separated by the use of the tag66(69) and so forth because the first image data61and so forth are delimited by the tag66(69) and so forth, respectively.

As shown inFIG. 11B, the index file41includes a header55, a first body57, a second body58, a third body59, and a fourth body60. The header55is information for identifying each index file41from the other index files, which not shown inFIG. 11B. The first body57and so forth are data indicating information regarding the first image data61and so forth of the actual file43. For example, the first body57includes the related information such as resolution and the like, concerning the first image data61.

FIG. 12shows an example of the data format of the index file41ofFIG. 11B. The second body58and so forth except the first body57in the index file41shown inFIG. 11Bare omitted inFIG. 12for the simplification of description.

The index file41chiefly includes an “INDEX” tag, an “IDXJHEAD” tag and an “IDX_BODY” tag. “IDX_HEAD {IDX_BODY}” following the “INDEX” tag indicates that there are one or more of the “IDX_HEAD” tag and the “IDX_BODY” tag.

InFIG. 12, “DTAG_OFF” indicates the offset from the tag66(69) and so forth. “DTAG_COUNT” indicates the number of the tag66(69) and so forth shown inFIG. 11A. By referring to “DTAG_COUNT”, it is possible to learn the number of the first image data61and so forth. These various tag informations make it possible to access desired image data with a higher speed than heretofore possible.

InFIG. 12, “DABS_OFF” indicates the offset from the head of the page summary file51ofFIG. 10, and “DABS_LEN” indicates the number of bytes of the page summary file51ofFIG. 10. The number of bytes in this place is assumed not to include the header in the page summary file51ofFIG. 10.

The “DEG” tag indicates rotation angles of image data and the like. The “ACT_WIDTH” tag and the “ACT_HEIGHT” tag indicate the offsets from the head of the page summary file51ofFIG. 10. The “ACT_DPI” tag indicates the resolutions of image data of actual images and the “ACT_CMP” tag indicates an example of the compression method of image data. The “ACT_OFF” tag indicates the offset from the head of the actual file43. The “ACT_LEN” tag indicates the numbers of bytes of image data.

The “THUMB_WIDTH” tag and the “THUMB_HEIGHT” tag indicate the dot size of the thumbnail file45. The “THUMB_CMP” tag indicates the compression rate of the thumbnail file45. The “THUMB_OFF” tag indicates the offset from the head of the thumbnail file45. The “THUMB_LEN” tag indicates the number of the bytes of the thumbnail file45.

The “TAG_OFF” tag indicates the offsets from the head of the tag66and so forth shown inFIG. 11A. The “TAG_NUM” tag indicates the numbers of the tag66and so forth.

The “ANN_NUM” tag indicates the number of annotations. The “ABS_OFF” tag indicates the offset from the head of the page summary file51. The “ABS_LEN” tag indicates the number of bytes of the page summary file51. The “ABS_REGD” tag indicates whether the summary file51has been registered or not. These tags may be used by an OCR or the like.

The data management system1ahas the configuration described above. With reference toFIGS. 7–12, an operation example of the data management system1ais described. In the following description, as an example of the operation of the data management system1a, an operation of data communication from the server computer SV as a transmission terminal shown inFIG. 7to a client computer CL as a receiving terminal is exemplified.

<Creation Processing of Image Data>

The data to be objects are read with an optical character reader or the like provided in the client computer CL, and the information such as an rotation angle, a resolution, a compression method and the like of an image is newly generated to be recorded in the index file41shown inFIG. 11B. In addition, the thumbnail file45is generated. Such data may be created in other words, reading images with a scanner, by reading images with a printing processing of a virtual printer driver, or by reading images via data exchange of image data with another program.

<Generation Processing of Actual File by Combining Image Data Mutually>

Then, the read image is made to be the actual file43, as it will be described later. The sizes of the actual file43and the thumbnail file45, both shown inFIG. 10, are registered in “ACT_LEN” and “THUMB_LEN” of the index file41shown inFIG. 12, respectively. In a full-text keyword retrieval index retention directory38as shown inFIG. 9, keywords for the full-text keyword retrieval with respect to the actual file43are stored. These keywords are data in text format and the index in this section indicates an index file that is separately managed for the full-text retrieval.

For the mutual combination of the image data, the information of the tag66and so forth in the actual file43shown inFIG. 11Ais changed. More specifically, the data of “DTAG_COUNT” in the index file41shown inFIG. 12is increased by the data of “DTAG_COUNT” of the image data to be inserted. On the other hand, in the actual file43, as shown inFIG. 1A, both of the tag68(69) to be inserted and the fourth image data64are made to be a set, and are combined after the third image data63.

The server computer SV has the function of managing a plurality of data as described above. The server computer SV manages, for example, the data of four sheets of images as the actual file43in which the image data are combined with the tag66(69) and so forth as the delimiter information for each of the image data from the first image data61to the fourth image data64shown inFIG. 11A. Because the first image data61to the fourth image data64can be managed integrally by managing the first image data61and so forth in such a combined state, the burden of the management for the prevention of the separation of these image data can be eliminated.

As another combination method in place of the above-mentioned combination method, in the case where the first image data61includes a first unit of image data and a second unit of image data, the second image data62may be combined with the first unit of image data, and the second unit of image data may be combined after that to form the combination of the first unit of image data+the second image data62+the second unit of image data.

The server computer SV manages the index file41as the information regarding the actual file43in addition to the actual file43itself. The index file41includes the first body57to the fourth body60corresponding to the first image data61to the fourth image data64, respectively, and the header55. That is, the first body57to the fourth body60indicate the information concerning the resolution and the like corresponding to the first image data61to the fourth image data64, respectively. By such a configuration, the first body57to the fourth body60can also be managed integrally.

FIG. 13toFIG. 15are diagrams showing an example of the processing of adding image data and in each diagram, dotted lines indicate a mutual link.

FIG. 16Ais a diagram showing a configuration of the index file41before addition processing, andFIG. 16Bis a diagram showing the index file41after the addition processing.

The actual file43before adding image data includes image data A1, the tag69, image data A2, the tag69, image data A3and an end-of-file word EOF, for example, as shown inFIG. 13A. The index file41before adding image data stores the information concerning an order for example “1”, “2” and “3”) as the first body57to the third body59as shown inFIG. 13.B.

In the following description, the addition of image data B1shown inFIG. 14between the image data A2and the image data A3of the actual file43shown inFIG. 13Ais explained.

First, the image data B1ofFIG. 14is added to the actual file43with the tag69put between them as shown inFIG. 15A, and the end-of-file word EOF is attached at the end. That is, in the actual file43, the image data B1is not added by separating the image data A3from the image data A2. Consequently, because only the image data B1is added in the actual file43, the addition of the image data B1can be processed at a high speed.

In the index file41, the length thereof is elongated by the length of the added image data B1. The position of a page or the like to which the image data B1is inserted is set to a fourth body60as “3”, as shown inFIG. 15B. In addition to the setting, the third body59is set as “4” indicating the position of the image data A3.

If the modification of the index file41is shown concretely, the setting shown inFIG. 16Ais modified to the setting shown inFIG. 16B. Following the procedure described above, the addition processing or insertion processing is completed.

FIG. 17andFIG. 18are diagrams showing the deletion processing of image data in which in each figure, dotted lines indicate a mutual link.

FIG. 19Ais a diagram showing a configuration of the index file41before the deletion processing, andFIG. 19Bis a diagrams showing a configuration of the index file41after the deletion processing.

The actual file43before deleting image data includes the image data A1, the tag69, the image data A2, the tag69, the image data A3, the tag69, the image data B1and the end-of-file EOF, as shown inFIG. 17A. The index file41before deleting the image data stores the information concerning an order for example, “1”, “2”, “3” and “4” as the first body57to the fourth body60, as shown inFIG. 17B.

In the following description, the deletion of the image data B1from the actual file43shown inFIG. 17Ais explained The deletion of the image data B1is not actually performed in the actual file43, however, in the index file41, a mark “x” indicating to be voided is set to the fourth body60corresponding to the image data B1to be deleted.

If the modification of the index file41is specified in a more concrete way, the setting shown inFIG. 19Abecomes the setting shown inFIG. 19B, thus, the deletion processing is completed.

FIG.20A–FIG. 22Bare diagrams showing an example of the division processing of the image data. In each figure, the dotted lines indicate a mutual link.

FIGS. 23A and 23Bare diagrams showing configuration of the index file41.

InFIG. 20A, the actual file43before dividing the image data includes the image data A1, the tag69, the image data A2, the tag69, the image data A3, the tag69, the image data B1and the end-of-file word EOF, as shown inFIG. 20A. The index file41before dividing the image data stores the information concerning an order, for example “1”, “2”, “3” and “4”, as the first body57to the fourth body60, as shown inFIG. 20B.

In the following description, the division of the image data B1from the actual file43shown inFIG. 20Ais explained.

The division of the image data B1is not actually performed in the actual file43, however, in the index file41, a mark “x” indicating to be voided is set to the fourth body60corresponding to the image data B1to be divided.

The image data B1of the actual file43is copied as shown inFIG. 22A, and made to be an actual file43having the end-of-file word EOF at the end thereof. An index file41relating to the actual file43shown inFIG. 22Ais generated, as shown inFIG. 22B.

If the modification of the index file41is explained more specifically, the setting as shown inFIG. 23Abecomes the setting shown inFIG. 23B. In the manner described above, the division processing is completed.

The actual file43and the index file41, both being managed by the server computer SV, are transmitted to the client computers CL by data communication in accordance with, a File Transfer Protocol (FTP) through the network11ofFIG. 7. The data management system1aperforms the data communication of the image data from the first image data61to the fourth image data64, as unified data. By the employment of such a method, the data management system1acan perform the data communication as unified data accurately without partially communicating and without any data going missing.

In the data management system1a, the image data from the first image data61to the fourth image data64may be transmitted by, data communication respectively. By the employment of such a process, the data management system1acan communicate each of the data at a higher speed than communicating integrally. When each of the image data from the first image data61to the fourth image data64is cut out, they are separated by the use of the tag66as references.

According to the second embodiment of the present invention, the image data from the first image data61to the fourth image data64as the plurality of data can be handled easily as unified data. That is, in the data management system1a, the actual file43is made by combining a plurality of image data having different image formats, and it is managed as one file. Consequently, in the case where a plurality of image data is processed as a batch, it prevents leaving off processing some part of the image data. Moreover, according to the second embodiment of the present invention, because the number of times of accessing each file storing image data or the like decreases, file inputs and outputs in reading and writing can be decreased. Moreover, according to the second embodiment of the present invention, the number of files of image data to be managed can be decreased. Thus, if the number of files to be managed is, only one, the program processing can be performed as a batch.

When use each of a plurality of images to resemble a page and turning them over at a high speed, as shown inFIG. 11A, each image can be accessed at a high speed and further corresponding data can be transmitted for each page, because each of the image data from the first image data61to the fourth image data64is only divided with the tag66and so forth within the same data. If the pages of the images are turned over at a high speed, the images having a plurality of image formats can be displayed without any delay that migh cause a sense of discomfort to the user.

In the data management system1a, the first image data61to the fourth image data64can be managed by being combined with the tag66and so forth to be unified data. Consequently, if each of the image data from the first image data61to the fourth image data64is a literary work, the alteration thereof can be prevented to keep the continuity thereof. Further, it is possible to realize a system that may easily be used by a user for creating various forms of files from a single document as described above and utilizing them in accordance with their specific objectives. For example, an overview of image data may be viewed by using the thumbnail files, or a high speed search can be performed by utilizing the text data.

The present invention is not limited to the above-mentioned embodiments.

In the first embodiment, encrypted link information39aregarding only the specified pages and the attribution of the link information39shown inFIG. 5is distributed. It is not limited thereto, however, and any other document group names or document names may be encrypted and distributed.

Further, the link information39amay be used in a similar way as a short-cut file that allows automatic access to the management server25when the link information39ais clicked and for viewing of the pages specified in the document19B if it is authorized. If the file is created as a short-cut file and such a short cut is directly triggered, actual processing such as decryption, checking of the authorization status and the like may be performed by associated applications.

Further, the above described link information39amay be encrypted by employing various encryption codes.

A program storage medium to be used for installing an access restriction program executing the above-mentioned series of processing steps into a computer to make it possible to execute the program by the computer, may be not only a package medium such as a flexible disk, for example, a floppy (a registered trade mark), a compact disc read only memory (CD-ROM), a digital versatile disc (DVD) and the like, but also a semiconductor memory, a magnetic disk and the like, in which a program is stored temporarily or permanently.

As a means for storing a program in such program storage media, a wired or a radio communication medium such as a local area network, the Internet, digital satellite broadcasting and the like may be used, and the program may be stored in such media by interposing various communication interfaces such as a router, a modem and the like.

The above-described management server25, clients23A–23D may be respectively provided with a drive apparatus capable of reading out data, such as programs and the like, of the program storage media described above.

Further, the access restriction program having an access restriction function for performing the above-described functions may not be limited to a form which is stored in the above described program storage media and may be in a form that is data-communicated via various communication means, such as the internet.

The server computer SV and the client computer CL may be equipped with a drive apparatus capable of reading the data such as a program in the program storage media at least.

Although, the second embodiment of the present invention is described in relation to the case where the invention is applied only to the server computer SV managing a plurality of data mainly in the embodiment thereof, it is not limited to the sever computer SV. The invention may be applied to the whole of the data management system1aso as to have a configuration to manage a plurality of data as a whole.

A part of each configuration of the embodiment may be omitted, or each of the configurations may be combined with each other in a different way from that described above, arbitrarily.

As described above, with the access restriction apparatus, the access restriction method, the computer readable program storage medium having a recorded access restriction program, and the access restriction program, it is possible to restrict access to data and prevent information alteration.