JP2008197746A - File sharing system, file sharing method, server, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a file sharing method reducing the loads of a transmitter and a recipient, for example, and reducing the possibility of information leakage. <P>SOLUTION: A server creates an access program required for accessing a specified file. A transmitting computer transfers the access program to a receiving computer. A receiving computer transmits an access request with unique identification information of its own to the server. The server creates a password for authentication from the received identification information. When the access request is the first request, the server holds the created password and permits the access. When the access request is not the first request, the server compares the held password with the created password. When the passwords do not coincide with each other, the server rejects the access to the file from the receiving computer. When the passwords coincide with each other, the server permits the access to the file from the receiving computer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a file sharing technique for sharing a file between a plurality of computers via a server.

  E-mail is a tool conventionally used as a means of sharing information within a company or between companies. E-mail is a convenient tool that allows you to share information by attaching a file to an e-mail and sending it to the mail address of the person you want to share. However, there are a number of problems with information sharing via email transmission and reception. Security issues include the possibility of eavesdropping by a third party at the time of transmission, and the possibility of leakage to a third party by a file recipient. Further, when sending a file to a plurality of users, there is a problem of a mail server load due to making a copy of the file by the number of destinations on the mail server. Furthermore, there is a problem of loss of information integrity due to a file being transmitted to another user in a state where the transmitted file has been modified by the recipient or the information remains old.

The service of Non-Patent Document 1 realizes secure file exchange between a sender and a recipient by encrypting a mail transmission / reception route and data itself. The invention described in Patent Document 1 sends only label information for accessing a file by e-mail without providing the file body to the user, and allows only an authenticated user to view the file using a viewing tool. That's it.
NRI Secure Technologies, Inc. “Crypt service” <URL http: // www. nri-secure. co. jp / service / crypto / index. html> JP 2005-267379 A

  According to the technology of Non-Patent Document 1, the possibility that an email is intercepted by encrypted communication and leaked to a third party can be avoided. However, if a file decrypted by the receiver is transmitted to a third party not intended by the sender, information is leaked. Further, the invention described in Patent Document 1 can prevent leakage by a non-malicious user. However, if a malicious user transfers a file browsing program to a third party and gives a password, information is leaked.

  In addition, the file sharing technique disclosed in Non-Patent Document 1 and Patent Document 1 involves operations such as changing a mail system by a sender, setting a password of a transmission partner, and distributing it. In addition, the recipient is required to perform very troublesome operations such as storing a password, installing a browsing program, and entering a password. Therefore, both the sender and the receiver have a heavy work load.

  Therefore, an object of the present invention is to solve at least one of these problems and other problems. For example, an object of the present invention is to provide a file sharing method that reduces the load on the sender and the receiver and reduces the possibility of information leakage. Other problems and purposes will be understood from the entire specification and drawings.

  In order to achieve the above object, the present invention can be realized, for example, as a file sharing system, a file sharing method, a server, and a computer that share a file among a plurality of computers via a server.

For example, a file sharing system
A specification means for specifying a file to be shared;
Program generation means for generating an access program necessary for accessing the specified file;
Transfer means for transferring the generated access program to a receiving computer that will share the file;
A means realized by starting the access program in the receiving computer, an acquisition means for acquiring unique identification information given to the receiving computer, and an access request with the acquired identification information as a server An access request transmitting means for transmitting to the file receiving means for receiving the file transmitted from the server when the access request is a legitimate access request;
Means provided in the server, the password generating means for generating an authentication password from the identification information transmitted from the receiving computer, and the access request by the access program is an initial access request to the file Determining means for determining whether the access request is an initial access request, holding means for holding the generated password as a password for accessing the file through the access program, and the generation An authentication unit that executes an authentication process according to whether the stored password matches the password held in the holding unit, and the generated password and the password held in the holding unit If not, the receiving computer for the file Denies et access, characterized in that it comprises a permitting means the the generated password and the password stored in the holding means to allow access from the receiving computer to said file if they match.

The file sharing system
The identification information includes at least one of a MAC address of the receiving computer, a domain name, a build number of an OS running on the receiving computer, a license number of the OS, and a user ID of a user logged on to the receiving computer. It may be configured to include one.

The file sharing system
When the password is generated, it may further include an erasing unit that erases the identification information received from the receiving computer.

The file sharing system
4. The file sharing system according to claim 1, wherein the transfer unit includes an e-mail transmission unit that transmits the access program attached to an e-mail.

The file sharing system
The program generation means includes a management table that assigns an access program ID for distinguishing the access program from other access programs, and manages the access program ID and the file in association with each other,
The access request transmitting means extracts the access program ID from the access program and transmits the access program ID to the server together with the access request;
The holding unit specifies the file corresponding to the access program ID by searching the management table based on the access program ID received together with the access request, and includes the password together with the file ID of the specified file. May be configured to hold.

The file sharing system
The access request transmitting means
A flag for recognizing whether or not the file is included in the access program for the first time is transmitted together with the access request,
The server is
Instructing means for instructing the receiving computer executing the access program to rewrite the flag when the determining means determines that the access request is the first access request based on the flag received together with the access request. Further including
The receiving computer is
When instructed to rewrite the flag, it may be configured to include a rewriting means for rewriting the content of the flag to indicate that it is not the first access.

  According to the present invention, for example, it is possible to realize a file sharing method or the like in which the load on the sender and the receiver is small and the possibility of information leakage is reduced. That is, there is an advantage that the sender only needs to transmit the access program to the receiver. Further, since the receiver can access the file designated by the sender by executing the access program, the work load is reduced as compared with the conventional technique. In addition, since the file is not directly transmitted from the sender to the receiver, the possibility of leakage is reduced.

  Further, according to the present invention, the password is created from the unique information given to the recipient's computer. Therefore, even if the access program is transferred to a third party, the password created by the access request by the third party is different from the legitimate password, and information leakage is suppressed. Further, since the password is created and held in the server, the password itself never leaks.

  Furthermore, according to the present invention, since the identification information used for creating the password is deleted from the server after the password is created, the possibility that this identification information leaks from the server is reduced.

  Further, according to the present invention, widely used electronic mail can be used to transfer the access program, so that the burden on the sender and the receiver is reduced.

  Further, according to the present invention, it is possible to share a single file with a plurality of recipients at the same time by assigning an access program ID for distinction to the access program provided to each recipient.

  Further, according to the present invention, by introducing a flag for managing whether or not the access to the file is the first time, there is an advantage that the password generated for the recipient who made the first access can be held as a valid password. is there. This means that in general, the first recipient of a file is a legitimate recipient, and it is extremely rare for an unauthorized third party to access it before the legitimate recipient. It is in accordance with the facts.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an outline of a file sharing system according to an embodiment. The server 101 is a computer (information processing apparatus) for sharing files among a plurality of computers (transmission computer 102 and reception computer 103). Here, an access program is created for a file designated by the sending computer 102 among the files under the management of the server 101. The access program is transmitted to the reception computer 103 via the transmission computer 102. Then, the receiving computer 103 accesses the file according to the activated access program. Therefore, the undesired computer 104 that does not have an access program cannot access the file.

  FIG. 2 is a sequence diagram for file sharing according to the embodiment. In step S201, the sending computer designates a file to be shared. At this time, the file disclosure deadline may be notified from the transmission computer 102 to the server 101. In step S <b> 202, the server 101 generates an access program necessary for accessing the specified file, and transmits the access program to the transmission computer 102.

  In step S203, the transmission computer 102 transfers the access program received from the server 101 to the reception computer 103 that will share the file. In step S204, the reception computer 103 activates the access program received from the transmission computer 102.

  In step S205, the receiving computer 103 acquires unique identification information given to itself. The identification information is, for example, the MAC address of the receiving computer, the domain name, the build number of the OS running on the receiving computer, the OS license number, the user ID of the user logged on to the receiving computer, and the like. Then, the receiving computer 103 transmits an access request with the acquired identification information to the server 101.

  In step S <b> 206, the server 101 generates an authentication password from the identification information transmitted from the receiving computer 103. If the access from the receiving computer 103 is the first access, the password created at this time is held in the server 101 as a password for subsequent access. If it is not the first access, the authentication process is executed by comparing the password generated by the current access with the password generated by the first access.

  If the authentication is successful, the server 101 permits the receiving computer 103 to access the sharing target file in step S207. In step S208, the receiving computer 103 accesses the file, receives the file, and displays the contents of the file. Note that the act of saving the file in the receiving computer 103 is prohibited by the access program. That is, the file is temporarily stored in a cache or the like, and is deleted when the access program ends.

  By the way, even if the access program is transferred to the undesired computer 104, access to the file is denied. In step S213, the receiving computer 103 transfers the access program to the undesired computer 104. In step S214, the undesired computer 104 activates the access program. In step S215, the undesired computer 104 transmits an access request with identification information of the undesired computer 104 to the server 101 in accordance with the access program.

  In step S <b> 216, the server 101 generates a password from the identification information of the undesired computer 104 and compares it with a password held in advance. Here, since both passwords do not match, the server 101 refuses access to the file from the undesired computer 104 in step S217. In step S218, the undesired computer 104 outputs an error message according to the access program.

  FIG. 3 is a block diagram showing a file sharing system according to an embodiment of the present invention. Each unit can be realized by hardware such as a CPU, RAM, and ASIC, and software such as a computer program.

  The transmission computer 102 includes a designation unit 300 that designates a file to be shared and a transfer unit 301 that transfers an access program to the reception computer 103.

  The server 101 includes a file storage unit 302 that stores files, a file information database 303 that stores file information, an access program generation unit 305, and a password generation unit 306. Further, the server 101 includes an authentication control unit 307 and a file information management unit 304 that returns file information corresponding to a request for file information. Further, the server 101 includes an access control unit 308 that permits file access from the receiving computer 103 based on the result of the authentication control unit 307.

  The receiving computer 103 holds an access program 311 received from the sending computer 102 by e-mail. The access program includes a program module for realizing various means on the receiving computer 103. Examples of realized means include an ID acquisition unit 312, a file browsing unit 313, and an access storage unit 314. The ID acquisition unit 312 acquires the ID of the receiving computer 103. The file browsing unit 313 accesses the file and displays the file contents. The access storage unit 314 stores the fact that the recipient has performed the first access in the flag. The access program is a computer program for displaying a file, and it is preferable that the access program only displays the file and does not have a storage function (overwrite storage, alias storage, etc.). This is to prevent a file copy from leaking.

  When sharing a file, the transmission computer 102 designates one or more files to be shared among the files stored in the file storage unit 302. For example, when the transmission computer 102 accesses the server 101, the server 101 provides a menu dialog (eg, a web page). From the menu dialog, file upload (storage processing), sharing target file specification, etc. can be selected. When the designation of the file to be shared is selected, the server 101 provides a file selection screen to the transmission computer 102, and the transmission computer 102 designates the file to be shared according to information input from a pointing device or the like.

  The file information management unit 304 acquires the file ID of the designated file from the file information database 303. Further, the file information management unit 304 sends an access program generation request with the acquired file ID to the access program generation unit 305.

  FIG. 4 is a diagram illustrating an example of an access program generation request according to the embodiment. The access program generation request 401 includes, for example, a file ID.

  When receiving the access program generation request, the access program generation unit 305 issues an access program ID. The access program generation unit 305 generates an access program that includes an access program ID. Note that the access program generation unit 305 may inquire the disclosure computer 102 about the disclosure deadline. The transmission computer 102 transmits the disclosure deadline data input from the keyboard by the sender to the access program generation unit 305. The disclosure deadline is registered in the file information management table by the access program generation unit 305, as will be described later.

  FIG. 5 is a diagram illustrating an example of information installed in the access program according to the embodiment. It includes an access program ID and an access management flag for distinguishing the access program generated this time from other access programs. The access management flag is information indicating whether the receiving computer 103 has already accessed the server 101 using the access program. If access has not yet been made from the receiving computer, the value of the flag is FALSE. This indicates that the password has not been registered in the server 101 yet. If the receiving computer 103 has already accessed the file to be shared, the flag value is TRUE. That is, the access program 311 rewrites the content of the flag from FALSE to TRUE so as to indicate that it is not the first access at the first access. Note that TRUE indicates that the password has already been registered in the server 101. Of course, the access program immediately after being generated by the access program generating unit 305 has the access management flag value set to FALSE.

  When the transmission computer 102 designates a plurality of files, the access program generation unit 305 generates access programs for the designated number of files. It may be desirable for the icon of the access program to contain the same name and picture as that of the file body. This is to make it easier to visually grasp the type of file to be shared.

  FIG. 6 is a diagram illustrating an example of a file information management table according to the embodiment. The access program generation unit 305 records the generated access program information in the file information management table of the file information management unit 304. As shown in FIG. 6, the file information management table includes a file ID, a file address (path name), an access program ID, a disclosure deadline, and a password. The file address is also obtained from the file information database 303. Since no password is set when the access program is generated, the password field is blank. Instead of leaving the password field blank, specific information indicating that the password has not been set may be stored.

  The transfer unit 301 of the sending computer 102 receives the generated access program from the server 101, attaches it to an e-mail, and sends it to the user who wants to share the file. The sender operates the keyboard or pointing device to input the recipient's email address. The protocol for transmitting the access program from the server 101 to the transmission computer 102 may be any protocol that can transfer the access program, such as HTTP, FTP, and others.

  When the receiving computer 103 activates the received access program 311, the ID acquisition unit 312 automatically acquires unique identification information (hereinafter, computer ID) of the receiving computer 103. The computer ID is, for example, at least one of a MAC address, a domain name, an operating OS build number, an OS license number, and a user ID of a user logged on to the receiving computer. When these computer IDs are acquired, the file browsing unit 313 issues an access request to the server 101.

  FIG. 7 is a diagram illustrating an example of an access request according to the embodiment. As shown in FIG. 7, the access request includes an access program ID, a computer ID (logon user ID, domain name, MAC address), and an access management flag. In order to increase the uniqueness of the computer ID, it is preferable to combine a plurality of identification information. For example, if only the MAC address is a computer ID, all users who can log on to the receiving computer 103 can access the file to be shared through the access program 311. Therefore, in order to strictly manage the receiver, not only the MAC address but also a logon ID or the like will be required as the computer ID.

  When receiving the access request, the access control unit 308 of the server 101 transfers the computer ID included in the access request to the password generation unit 306. The password generation unit 306 generates an authentication password using the computer ID. The password generation unit 306 deletes the computer ID included in the access request at the time of generation. This is a design consideration not to hold personal information on the server. It is also preferable from the viewpoint of preventing information leakage.

  When the password is generated, the password generation unit 306 acquires the access request date from a timer (not shown) of the server 101. The access request date is the date when the access request is generated (received). Further, the password generation unit 306 sends an authentication request including the generated password and access request date data to the authentication control unit 307.

  FIG. 8 is a diagram illustrating an example of an authentication request according to the embodiment. As shown in FIG. 8, the authentication request includes an access date, an access program ID, a password, and an access management flag. The authentication control unit 307 refers to the file information management table 601 of the file information management unit 304 and executes an authentication process for determining whether there is an access right. The authentication control unit 307 sends an access control request with an authentication result to the access control unit 308.

  The authentication process is executed as follows, for example. First, the authentication control unit 307 extracts the disclosure deadline corresponding to the access program ID from the file information management table 601, and compares the extracted disclosure deadline with the access date included in the authentication request, thereby obtaining the access date. Determine whether the date is within the disclosure deadline. If it is outside the disclosure deadline, access is not permitted. If it is within the disclosure deadline, the authentication control unit 307 executes either password registration or password verification according to the access management flag.

  That is, when the access management flag is FALSE, the authentication control unit 307 registers the password included in the authentication request in the file information management table 601 in association with the access program ID. Further, since the access management flag indicates that the access is the first time, the authentication control unit 307 determines that access is permitted.

  On the other hand, when the access management flag is TRUE, the authentication control unit 307 extracts a password registered in association with the access program ID included in the authentication request from the file information management table 601. The authentication control unit 307 compares the extracted password with the password included in the authentication request. If the password included in the authentication request matches one of the registered passwords, the authentication control unit 307 determines that access is permitted. On the other hand, the authentication control unit 307 determines that access is not permitted if there is no matching password.

  When determining that access is permitted, the authentication control unit 307 returns TRUE as an access determination value (authentication result), acquires the file address of the target file from the file information management table 601, and sends it to the access control unit 308. On the other hand, when it is determined that access is not permitted, the authentication control unit 307 returns FALSE to the access control unit 308 as an access determination value. These pieces of information are sent from the authentication control unit 307 to the access control unit 308 as an access control request.

  FIG. 9 is a diagram illustrating an example of an access control request according to the embodiment. As shown in FIG. 9, the access control request includes, for example, an access determination value, a file address, and a new password registration flag.

  The access control unit 308 that has received the access control request transmits the access result to the file browsing unit 313 of the receiving computer 103 when the access determination value is TRUE. Further, the access control unit 308 permits the file browsing unit 313 to access the sharing target file stored in the file storage unit 302 according to the file address. Finally, the access control unit 308 starts communication between the receiving computer 103 and the file storage unit 302. In this way, the receiving computer 103 can receive the file transmitted from the server 101 and display it on a display or the like.

  FIG. 10 is a diagram illustrating an example of an access result according to the embodiment. As shown in FIG. 10, the access result includes an access determination value and a new password registration flag. If the value of the access determination is not TRUE, the file browsing unit 313 displays an error message indicating “access not possible”. When the value of the new password registration flag is TRUE, the file browsing unit 313 transmits a rewrite request for rewriting the access management flag to the access storage unit 314. The access control unit 308 functions as an instruction unit that instructs the receiving computer 103 executing the access program to rewrite the flag. That is, setting the value of the new password registration flag to TRUE and transmitting it corresponds to instructing rewriting of the access management flag. When receiving the rewrite request, the access storage unit 314 rewrites the value of the access management flag of the access program 311 to TRUE.

  FIG. 11 is an exemplary block diagram of a server, a transmission computer, and a reception computer according to the embodiment. Here, a hardware unit for realizing the functional blocks shown in FIG. 3 will be described. For simplification of explanation, the internal configurations of the server 101, the transmission computer 102, and the reception computer 103 are assumed to be the same, but some of them may actually be different.

  The CPU 1101 is a control unit that comprehensively controls each unit of the computer based on a computer program. The ROM 1102 is a nonvolatile storage unit that stores control programs such as firmware and OS. The RAM 1103 is a volatile storage unit that functions as a work area. A hard disk drive (HDD) 1104 is a large-capacity storage unit. For example, the hard disk drive (HDD) 1104 of the server 101 stores files to be shared, a file information database 303, a file information management table 601, and the like. The input device 1105 is an input unit such as a pointing device or a keyboard. For example, the input device 1105 of the sending computer 102 is used for designating a file to be shared and inputting a recipient's mail address. The display device 1106 is a display unit for displaying various information to the user. For example, the display device 1106 of the receiving computer 103 displays the sharing target file permitted to be accessed. The communication device 1107 is a communication unit such as a network communication card (NIC). For example, the communication device 1107 is used for transmission / reception of electronic mail, transmission / reception of various requests and responses thereto.

  FIG. 12 is a flowchart illustrating a procedure for generating an access program according to the embodiment. The server 101 can generate an access program according to this flowchart.

  In step S <b> 1201, the CPU 1101 of the server 101 receives designation of a file desired to be shared from the transmission computer 102 through the communication device 1107. At this stage, a plurality of files may be designated, or the number of recipients may be designated by the sending computer 102. In step S1202, the CPU 1101 searches the file information database 303 based on the name of the designated file and extracts a corresponding file ID. At this time, the file address may also be extracted.

  In step S <b> 1203, the CPU 1101 acquires file disclosure deadline data from the transmission computer 102 through the communication device 1107. In step S1204, the CPU 1101 issues an access program ID. The access program ID is identification information that differs for each access program, and usually differs for each set of file and recipient (FIG. 6). For example, even if the file is the same, the access program ID is different if the recipient is different. Even if the recipient is the same, the access program ID is different if the file is different.

  In step S1205, the CPU 1101 generates an access management flag set in the issued access program ID and FALSE. It is assumed that the access program template is stored in advance in the HDD 1104 or the like. In this way, it is only necessary to mount the access program ID and the access management flag in the template, so that the processing load on the CPU 1101 can be reduced.

  In step S1206, the CPU 1101 registers the file ID, file address, access program ID, disclosure deadline, and password (blank or specific information) in the file management table stored in the HDD 1104. In step S <b> 1207, the CPU 1101 transmits the generated access program to the transmission computer 102 through the communication device 1107.

  As described above, the CPU 1101 of the transmission computer 102 transfers the received access program to the recipient using e-mail or the like. The e-mail address is input from the input device 1105 of the sending computer 102. Of course, an e-mail address may be selected from an address book stored in the HDD 1104 or the like in accordance with a selection instruction input from the input device 1105.

  The recipient receives the email using any computer. The recipient executes the access program attached to the e-mail using an arbitrary computer. Note that the computer that receives the e-mail and the computer that executes the access program do not have to be the same, but the computer that performed the initial access operates as the receiving computer 103. This is because the computer ID of the computer that performed the first access is reflected in the password.

  FIG. 13 is a flowchart illustrating a procedure of processing in which a receiving computer according to the embodiment accesses a file. The receiving computer 103 can access the file by starting the access program according to this flowchart.

  In step S1301, the CPU 1101 of the receiving computer 103 receives and activates the access program 311 transmitted from the transmitting computer 102. In step S1302, the CPU 1101 acquires the computer ID of the receiving computer 103 in accordance with the activated access program.

  In step S <b> 1303, the CPU 1101 transmits an access request with the acquired computer ID to the server 101 through the communication device 1107. In step S1304, the CPU 1101 receives an access result from the server 101 as a response to the access request.

  In step S1305, the CPU 1101 determines whether or not access is permitted depending on whether or not the access determination value included in the access result is TRUE. If it is not TRUE (FALSE), the process proceeds to step S1307. In step S <b> 1307, the CPU 1101 displays a message meaning “access not possible” on the display device 1106. Thereafter, the process proceeds to step S1310.

  On the other hand, if the access determination value is TRUE, the process proceeds to step S1306. In step S1306, the CPU 1101 accesses the file through the server 101, and displays the content of the file on the display device 1106. In step S1308, the CPU 1101 determines whether to rewrite the access management flag of the access program according to whether the value of the new password registration flag included in the access result is TRUE. If the value of the new password registration flag is TRUE, the process advances to step S1309, and the CPU 1101 rewrites the value of the access management flag from FALSE to TRUE. If the value of the new password registration flag is FALSE, it is the second and subsequent accesses, and the process advances to step S1310 without rewriting the access management flag.

  In step S <b> 1310, when an instruction to end file browsing (end of access program) is input from input device 1105, CPU 1101 ends the access program.

  FIG. 14 is a flowchart illustrating an access request processing procedure according to the embodiment. The server 101 can process the access request from the receiving computer 103 according to this flowchart.

  In step S <b> 1401, the CPU 1101 of the server 101 receives an access request from the receiving computer 103 through the communication device 1107. In step S1402, the CPU 1101 generates a password using the computer ID included in the access request. In step S1403, the CPU 1101 deletes the computer ID.

  In step S <b> 1404, the CPU 1101 acquires information on the date on which the access request has occurred from a timer inside the CPU 1101. In step S1405, the CPU 1101 obtains information on the disclosure deadline corresponding to the access program ID included in the access request from the file information management table 601, and determines whether the date when the access request occurred is within the disclosure deadline. judge. If it is not within the disclosure deadline, the process advances to step S1406, and the CPU 1101 transmits an access result indicating access denied (denied) to the receiving computer 103.

  On the other hand, if it is within the disclosure deadline, the process advances to step S1407, and the CPU 1101 determines whether or not the access is the first time depending on whether or not the value of the access management flag included in the access request is FALSE.

  If it is the first access, the process advances to step S1408, and the CPU 1101 registers a password in the file information management table 601 in association with the access program ID. In step S1409, the CPU 1101 permits access to the file from the receiving computer 103. In step S1410, the CPU 1101 transmits an access determination (TRUE) and a new password registration flag (TRUE) as an access result to the receiving computer 103.

  On the other hand, if it is the second or subsequent access, the process advances to step S1411, and the CPU 1101 executes an authentication process. That is, the CPU 1101 extracts the password registered in the file information management table 601 in association with the access program ID included in the access request. Further, the CPU 1101 compares the extracted password with the generated password. In step S1412, the CPU 1101 determines whether or not both passwords match. If the passwords do not match, authentication has failed, and the process advances to step S1406.

  On the other hand, if the passwords match, the process advances to step S1413, and the CPU 1101 permits access to the file. In step S <b> 1414, the CPU 1101 transmits an access determination (TRUE) as an access result to the receiving computer 103.

  As described above, according to the present embodiment, it is possible to realize a file sharing system or the like in which the load on the sender and the receiver is small and the possibility of information leakage is reduced. That is, there is an advantage that the sender only needs to transmit the access program to the receiver. Further, since the receiver can access the file designated by the sender by executing the access program, the work load is reduced as compared with the conventional technique. In addition, since the file is not directly transmitted from the sender to the receiver, the possibility of leakage is reduced.

  Further, according to the present embodiment, a password is created from a unique computer ID assigned to the recipient's computer. Therefore, even if the access program is transferred to a third party, the password created by the access request by the third party is different from the legitimate password, and information leakage is suppressed. In addition, since the password is created and held in the server, it is unlikely that the password itself will be leaked.

  Furthermore, according to this embodiment, since the identification information used for creating the password is deleted from the server after the password is created, the possibility that this identification information leaks from the server is reduced. This may be preferable from the viewpoint of protecting personal information.

  Further, according to the present embodiment, widely used electronic mail can be used to transfer the access program, so that the burden on the sender and the receiver is reduced. The ability to use familiar tools may also be desirable in terms of providing a user-friendly interface.

  In addition, according to the present embodiment, it is possible to share a single file with a plurality of recipients at the same time by assigning an access program ID for distinction to the access program provided to each recipient. .

  In addition, according to the present embodiment, by introducing a flag for managing whether or not access to a file is the first time, it is possible to hold a password generated for a recipient who made the first access as a valid password There is. This means that in general, the first recipient of a file is a legitimate recipient, and it is extremely rare for an unauthorized third party to access it before the legitimate recipient. It is in accordance with the facts.

  Further, since the access program is generated for each file, it can be managed in the same way as a normal file. Therefore, authentication can be performed by the same operation as opening a normal file, and a desired file can be accessed.

  Furthermore, the file body is stored in the file server. For this reason, when a file is shared with a plurality of users, it is not necessary to copy the file with a mail server as in the prior art, so the load is reduced. In addition, the problem of loss of information integrity caused by the file being transmitted to another user in a state where the transmitted file has been altered by the recipient or the information remains old will also be solved.

[Other Embodiments]
FIG. 15 is a diagram illustrating a modification of the file sharing system according to the embodiment. You may arrange | position the server 101 in the embodiment mentioned above or a partial function of the server 101 in the transmission computer 102. FIG. For example, the file information management unit 304, the access program generation unit 305, the password generation unit 306, the authentication control unit 307, and the access control unit 308 of the server 101 may be arranged in the transmission computer. According to FIG. 15, the file server 1501 includes a file information database 303 and a file storage unit 302.

  Further, the transmission computer 102 may be an information processing apparatus other than the computer. For example, a scanner device 1502 having a network function or a network facsimile device may be used. FIG. 15 shows a configuration example when the scanner device 1502 includes a part of the functions of the server 101 and the processing of the transmission computer 102. In this case, an image file is generated by the image scanning unit 1503 of the scanner device 1502. This image file is stored in the file storage unit 302. Further, the access program generation unit 305 generates an access program for this image file. The mail transmitting unit 1504 transmits an e-mail with an access program attached. As a result, only the recipient of the e-mail attached with the access program can access the image file.

1 is a diagram showing an outline of a file sharing system according to an embodiment. It is a sequence diagram about file sharing according to the embodiment. 1 is a block diagram showing a file sharing system according to an embodiment of the present invention. It is a figure which shows an example of the access program production | generation request | requirement which concerns on embodiment. It is a figure which shows an example of the information mounted in the access program which concerns on embodiment. It is a figure which shows an example of the file information management table which concerns on embodiment. It is a figure which shows an example of the access request which concerns on embodiment. It is a figure which shows an example of the authentication request | requirement which concerns on embodiment. It is a figure which shows an example of the access control request | requirement which concerns on embodiment. It is a figure which shows an example of the access result which concerns on embodiment. It is an exemplary block diagram about a server, a transmitting computer, and a receiving computer concerning an embodiment. It is a flowchart which shows the production | generation procedure of the access program which concerns on embodiment. It is a flowchart which shows the procedure of the process in which the receiving computer which concerns on embodiment accesses a file. It is a flowchart which shows the process sequence of the access request which concerns on embodiment. It is a figure which shows the modification of the file sharing system which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Server 102 ... Transmission computer 103 ... Reception computer 300 ... File designation part 301 ... File transfer part 302 ... File storage part 303 ... File information database 304 ... File information management part 305 ... Access program generation part 306 ... Password generation part 307 ... Authentication control unit 308 ... access control unit 311 ... access program 312 ... ID acquisition unit 313 ... file browsing unit 314 ... access storage unit

Claims (9)

A file sharing system for sharing files between a plurality of computers via a server,
A specification means for specifying a file to be shared;
Program generation means for generating an access program necessary for accessing the specified file;
Transfer means for transferring the generated access program to a receiving computer that will share the file;
A means realized by starting the access program in the receiving computer, an acquisition means for acquiring unique identification information given to the receiving computer, and an access request with the acquired identification information as a server An access request transmitting means for transmitting to the file receiving means for receiving the file transmitted from the server when the access request is a legitimate access request;
Means provided in the server, the password generating means for generating an authentication password from the identification information transmitted from the receiving computer, and the access request by the access program is an initial access request to the file Determining means for determining whether the access request is an initial access request, holding means for holding the generated password as a password for accessing the file through the access program, and the generation An authentication unit that executes an authentication process according to whether the stored password matches the password held in the holding unit, and the generated password and the password held in the holding unit If not, the receiving computer for the file And a permitting means for permitting access from the receiving computer to the file if the generated password matches the password held in the holding means. Shared system.   The identification information includes at least one of a MAC address of the receiving computer, a domain name, a build number of an OS running on the receiving computer, a license number of the OS, and a user ID of a user logged on to the receiving computer. The file sharing system according to claim 1, comprising one.   3. The file sharing system according to claim 1, further comprising an erasing unit that erases the identification information received from the receiving computer when the password is generated. 4.   The file sharing system according to any one of claims 1 to 3, wherein the transfer unit includes an e-mail transmission unit that transmits the access program attached to an e-mail. The program generation means includes
Issuing means for issuing an access program ID for distinguishing the access program from other access programs, and a management table for managing the access program ID and the file in association with each other,
The access request transmission means extracts the access program ID from the access program and transmits it to the server together with the access request.
The holding unit specifies the file corresponding to the access program ID by searching the management table based on the access program ID received together with the access request, and includes the password together with the file ID of the specified file. The file sharing system according to any one of claims 1 to 4, wherein the file sharing system is held. The access request transmission means includes
A flag for determining whether or not it is the first access to the file included in the access program is transmitted together with the access request,
The server
Instructing means for instructing the receiving computer executing the access program to rewrite the flag when the determining means determines that the access request is the first access request based on the flag received together with the access request. Further including
The receiving computer is
6. The file sharing system according to claim 1, further comprising a rewriting unit that rewrites the flag to indicate that the flag is not an initial access when instructed to rewrite the flag. . A file sharing method for sharing a file between a plurality of computers via a server,
A designation process in which the first computer designates a file to be shared;
A program generation step in which the server generates an access program necessary for the second computer to access the designated file;
A transfer step in which the first computer transfers the generated access program to the second computer that will share the file;
A starting step in which the second computer starts the access program;
An acquisition step in which the second computer acquires unique identification information given to the second computer;
An access request transmitting step in which the second computer transmits an access request with the acquired identification information to the server;
The server generates a password for authentication from the identification information transmitted from the second computer;
A determination step of determining whether or not the access request by the access program is an initial access request to the file;
If the access request is an initial access request, the server holds the generated password as a password when accessing the file through the access program; and
An authentication step in which the server executes an authentication process according to whether the generated password matches the password held by the holding step;
If the generated password and the password held in the holding step do not match, the server rejects access from the second computer to the file, and is held by the generated password and the holding step. And a permission step of permitting access to the file from the second computer if the password matches. A server for sharing files among multiple computers,
Program generation means for generating an access program necessary for accessing a file to be shared;
Transfer means for transferring the generated access program to a receiving computer that will share the file via a first computer that specifies the file to be shared;
When the access program is executed in the receiving computer, an access request receiving means for receiving an access request with unique identification information given to the receiving computer;
Password generating means for generating a password for authentication from the identification information transmitted from the receiving computer;
Determining means for determining whether the access request by the access program is an initial access request to the file;
If the access request is an initial access request, holding means for holding the generated password as a password for accessing the file through the access program;
An authentication unit that performs an authentication process according to whether the generated password matches the password held in the holding unit;
If the generated password and the password held in the holding unit do not match, the access from the receiving computer to the file is denied, and the generated password and the password held in the holding unit are And a permitting means for permitting access from the receiving computer to the file if they match. A computer program executed on a server for sharing a file between a plurality of computers,
Program generation means for generating an access program necessary for accessing a file to be shared;
Transfer means for transferring the generated access program to a receiving computer that will share the file via a first computer that specifies the file to be shared;
When the access program is executed in the receiving computer, an access request receiving means for receiving an access request with unique identification information given to the receiving computer;
Password generating means for generating a password for authentication from the identification information transmitted from the receiving computer;
Determining means for determining whether the access request by the access program is an initial access request to the file;
If the access request is an initial access request, holding means for holding the generated password as a password for accessing the file through the access program;
An authentication unit that performs an authentication process according to whether the generated password matches the password held in the holding unit;
If the generated password and the password held in the holding unit do not match, the access from the receiving computer to the file is denied, and the generated password and the password held in the holding unit are A computer program causing the server to function permission means for permitting access from the receiving computer to the file if they match.

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