JP2005198336A - Information management system and information management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information management system which ensures security of a file locally stored in a mobile information terminal. <P>SOLUTION: A key distribution server 100 comprises: an authentication information storage section 108 for storing identification information; an authentication section 110; a key distribution section 112 for distributing an encryption key that is unique for a user ID, to a mobile information terminal 10 on the condition that the authentication section 110 authenticates the identification information when a distribution request of the encryption key for encrypting a file stored in the mobile information terminal 10 is received together with the identification information; and a server side key storage section 120 for storing a decryption key for decrypting the file encrypted by the encryption key correspondingly to the user ID. The key distribution section 112 reads the decryption key using the user ID as a search key and distributes the decryption key to the mobile information terminal 10 on the condition that the authentication section 110 authenticates the identification information when a distribution request of the decryption key is received from the mobile information terminal 10 together with the identification information. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information management system, a key distribution server, an information management method, and a program for managing security of information stored in portable information terminals connected via a network.

  Conventionally, the security of information stored in an information processing terminal has been protected by, for example, the following method. That is, a method such as access restriction using a password, an IC card, biometric authentication, or the like (see, for example, Non-Patent Document 1) and encryption using a program installed in the terminal.

Novell, press release, “announces security product with identity authentication centralized by directory”, [online], October 25, 2001, Novell, Inc. [searched July 22, 2003], Internet, <URL: http: // www. novell. co. jp / pressrel / 200110251. html>

  However, in the above conventional technique, authentication information and decryption algorithm necessary for accessing protected information are often stored in the terminal itself. For example, when a terminal is stolen or lost, a malicious third party May break security. Therefore, there has been a problem that it is difficult to ensure sufficient security of files stored locally.

  In order to solve the above-described problem, according to the first aspect of the present invention, an information management for managing security of information stored in a portable information terminal, comprising a key distribution server and a portable information terminal connected via a network In the system, the mobile information terminal responds to the distribution request with an encryption key request unit that transmits an encryption key distribution request unique to the user ID to the key distribution server together with the personal authentication information including the user ID, and a file to be stored. The encryption part that encrypts with the encryption key distributed from the key distribution server, the terminal file storage part that stores the encrypted file, and the distribution request for the decryption key that decrypts the file encrypted with the encryption key A decryption key requesting unit that transmits to the key distribution server together with the personal authentication information, and decrypts the decryption key distributed from the key distribution server in response to the distribution request. A terminal side key storage unit for storing until decrypted file by chromatography is closed, the encrypted file, read from the terminal file storage, and a decoder for decoding the decoding key.

  The key distribution server includes an authentication information storage unit that stores user authentication information registered in advance as a user of the information management system, and the user authentication information stored in the authentication information storage unit. When the authentication unit authenticates by collating with and the distribution request of the encryption key is received from the portable information terminal together with the personal authentication information, the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. An encryption key distribution unit that distributes an encryption key unique to the user ID included in the mobile information terminal to the portable information terminal, a server-side key storage unit that stores a decryption key corresponding to the encryption key in association with the user ID, and a decryption key When the distribution request is received from the portable information terminal together with the personal authentication information, the user included in the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. Reads the decryption key ID as a search key, and a decryption key distributing unit that distributes to the portable information terminal.

  The terminal-side key storage unit may store the decryption key until the portable information terminal logs off from the connection with the key distribution server, instead of storing the decryption key until the file decrypted with the decryption key is closed. Good.

  According to the second aspect of the present invention, in the information management system comprising the key distribution server and the portable information terminal connected via a network and managing the security of the information stored in the portable information terminal, the portable information terminal includes: Encryption key request for sending a distribution request for a file index unique to the file in the information management system and an encryption key unique to the file index to the key distribution server together with the identity authentication information including the user ID when creating a new file , A file index and an encryption key unique to the file index received from the key distribution server and stored in association with each other, and a file index corresponding to the file to be saved is encrypted as a search key. Read the key and encrypt the file with the encryption key. A file index associated with the file, a terminal file storage unit storing the encrypted file in association with the file index, and a decryption key distribution request for decrypting the encrypted file And the decryption key request part that is transmitted to the key distribution server together with the user authentication information, and the decryption key distributed from the key distribution server in response to the distribution request is associated with the file index, and the file decrypted with the decryption key is closed. And a decryption unit for reading a decryption key using a file index associated with the encrypted file as a search key and decrypting the file with the decryption key.

  The key distribution server includes an authentication information storage unit that stores user authentication information registered in advance as a user of the information management system, and the user authentication information stored in the authentication information storage unit. An authentication unit that authenticates by collating with, an index issuing unit that issues a unique file index in the information management system, and a file index and encryption key distribution request received from the portable information terminal together with the personal authentication information In addition, on the condition that the authentication unit has authenticated the personal authentication information, a new file index is acquired from the index issuing unit, and an encryption key unique to the file index is distributed to the portable information terminal, and A server that stores the decryption key corresponding to the encryption key in association with the file index. When the side key storage unit and the decryption key distribution request are received from the portable information terminal together with the file index and the personal authentication information, the file index is used as a search key on the condition that the personal authentication information is authenticated by the authentication unit. You may have a decoding key distribution part which reads a decoding key and distributes to a portable information terminal with the said file index.

  The terminal side decryption key storage unit stores the decryption key until the portable information terminal logs off from the connection with the key distribution server, instead of storing the decryption key until the file decrypted with the decryption key is closed. Also good.

  According to the third aspect of the present invention, in an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of information stored in the portable information terminal is as follows: In the portable information terminal, the encryption key requesting unit transmits a request for distributing the encryption key unique to the user ID to the key distribution server together with the personal authentication information including the user ID, and the encryption unit stores the file to be stored. The step of encrypting with the encryption key distributed from the key distribution server in response to the distribution request, the step of storing the encrypted file in the terminal file storage unit, and the step of decrypting the key request unit encrypted with the encryption key Transmitting a decryption key distribution request for decrypting the received file to the key distribution server together with the personal authentication information, and a terminal-side key storage unit Storing the decryption key distributed from the key distribution server in response to the distribution request until the file decrypted with the decryption key is closed, and the decryption unit stores the encrypted file from the terminal file storage unit. Reading and decrypting with a decryption key.

  Further, in the key distribution server, the authentication information storage unit stores the user authentication information of the user registered in advance as the user of the information management system, and the authentication unit stores the input user authentication information as the authentication information. Authenticating by comparing with the personal authentication information stored in the unit, and when the cryptographic key distribution unit receives the cryptographic key distribution request from the portable information terminal together with the personal authentication information, On the condition that the authentication unit has authenticated, the step of distributing the encryption key unique to the user ID included in the personal authentication information to the portable information terminal, and the server-side key storage unit, the decryption key corresponding to the encryption key, When the step of storing in association with the user ID and the decryption key distribution unit receive the decryption key distribution request from the portable information terminal together with the personal authentication information On condition that the authentication information authentication unit authenticates the read decryption key the user ID included in the authentication information as a search key, and a step of distributing to the portable information terminal.

  According to the fourth aspect of the present invention, in an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of information stored in the portable information terminal is as follows: In the portable information terminal, when a new file is created, the encryption key request unit authenticates the distribution request for the file index unique to the file in the information management system and the encryption key unique to the file index, including the user ID. Transmitting to the key distribution server together with the information, a step in which the terminal side encryption key storage unit receives the file index and the encryption key unique to the file index from the key distribution server, and stores them in association with each other; , Using the file index corresponding to the file to be saved as the search key The key is read, the file is encrypted with the encryption key, the terminal file storage unit that stores the encrypted file in association with the file index, and the decryption key request unit decrypts the encrypted file And a step of transmitting a decryption key distribution request to the key distribution server together with a file index and personal authentication information associated with the file, and the terminal-side decryption key storage unit responds to the distribution request with the key distribution server. Storing the decryption key distributed from the file index in association with the file index, storing the file decrypted with the decryption key until the file is closed, and storing the decryption unit in association with the encrypted file. The decryption key is read using the specified file index as a search key, and the file is read with the decryption key. Gosuru and a step.

  Further, in the key distribution server, the authentication information storage unit stores the user authentication information of a user registered in advance as a user of the information management system, and the authentication unit stores the input user authentication information. A step of authenticating by verifying with the personal authentication information stored in the information storage unit, a step of issuing an index file issuing unit unique file index in the information management system, and an encryption key distributing unit When a key distribution request is received from the portable information terminal together with the personal authentication information, a new file index is acquired from the index issuing unit on the condition that the authentication unit has authenticated the personal authentication information, and the file index is stored in the file index. Distributing the unique encryption key to the portable information terminal, and the server side key The unit stores the decryption key corresponding to the encryption key in association with the file index, and the decryption key distribution unit receives the decryption key distribution request from the portable information terminal together with the file index and the personal authentication information. And a step of reading out the decryption key using the file index as a search key and delivering it to the portable information terminal together with the file index on condition that the authentication unit has authenticated the personal authentication information.

  In the step of storing the decryption key on the terminal side, instead of storing the decryption key until the file decrypted with the decryption key is closed, until the portable information terminal logs off from the connection with the key distribution server It may be stored.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 shows an example of a system configuration of an information management system 200 according to an embodiment of the present invention. The information management system 200 includes a portable information terminal 10 in which a user creates a file related to customer personal information, and a key distribution server 100 that manages security of personal information stored in the portable information terminal 10. The information management system 200 is intended to protect personal information stored in the portable information terminal 10 using an encryption key and a decryption key distributed by the key distribution server 100. In the information management system 200 of this embodiment, the encryption key and the decryption key may be the same or different.

  The portable information terminal 10 encrypts personal information with the encryption key distributed from the key distribution server 100, and locally stores the encrypted information. Then, a copy of the encrypted file is transmitted to the key distribution server 100. The key distribution server 100 stores a copy received from the portable information terminal 10 in association with the user ID. The information manager of the information management system accesses the key distribution server 100 using, for example, the manager terminal 50, acquires the decryption key for copying, and decrypts the copy according to the authority for each manager. It can be used after being converted. Thereby, the information manager can share the customer's personal information, which is a company resource, with the user in charge.

  FIG. 2 shows an example of a functional configuration of the portable information terminal 10. The portable information terminal 10 includes an authentication information reception unit 12 that receives input of personal authentication information, a key request unit 14 that transmits an encryption key distribution request and a decryption key distribution request to the key distribution server 100 together with the personal authentication information, a key A terminal-side key storage unit 18 that stores an encryption key and a decryption key distributed from the distribution server 100; an encryption unit 20 that encrypts a file to be stored; and a terminal file storage unit 26 that stores the encrypted file; A decryption unit 22 for decrypting the encrypted file, and an application execution unit 24 for creating a file to be encrypted and developing the decrypted file. The key request unit 14 is an example of an encryption key request unit and a decryption key request unit according to the present invention. The terminal side key storage unit 18 is an example of a terminal side key storage unit, a terminal side encryption key storage unit, and a terminal side decryption key storage unit according to the present invention.

  According to the above configuration, the portable information terminal 10 encrypts and decrypts the locally stored file using the encryption key and decryption key specific to the user or file distributed from the key distribution server 100. Here, the terminal side key storage unit 18 stores the decryption key only for a certain period. That is, the decryption key is deleted after a certain period. Alternatively, the terminal-side key storage unit 18 may set an expiration date when storing the decryption key. In this case, the decryption unit 22 can use only the decryption key within the expiration date. As a result, at least a part of the information necessary for decrypting the file stored in the portable information terminal 10 is deleted from the portable information terminal 10 after a certain period of time. Further, the user authentication by the key distribution server 100 is sufficiently reliable using conventional techniques. Therefore, the portable information terminal 10 can sufficiently secure the security of the file stored locally.

  The portable information terminal 10 further includes a current position detection unit 16 that detects the current position of the portable information terminal 10 and a terminal-side specific file history storage unit that stores a predetermined specific file usage history in association with a user ID. 30 and a backup file transfer unit 28 that transmits a copy of the file to the key distribution server 100 each time a file is stored in the terminal file storage unit 26. Details of the current position detection unit 16, the terminal-side specific file history storage unit 30, and the backup file transfer unit 28 will be described later.

  The recording medium 60a includes the authentication information reception unit 12, the key request unit 14, the current position detection unit 16, the terminal side key storage unit 18, the encryption unit 20, the decryption unit 22, the application execution unit 24, the terminal file storage unit 26, The program which makes the portable information terminal 10 implement | achieve the function of the backup file transfer part 28 and the terminal side specific file log | history storage part 30 is stored. The recording medium 60a may acquire such a program via a network.

  FIG. 3 shows an example of a functional configuration of the key distribution server 100. The key distribution server 100 includes an authentication information storage unit 108 for storing user authentication information registered in advance, an authentication unit 110 for authenticating the input user authentication information, and an encryption key distribution request or a decryption key distribution request. A key distribution unit 112 that distributes an encryption key or a decryption key specific to a user or a file to the portable information terminal on the condition that the authentication unit authenticates the personal authentication information, and the encryption key and the encryption key. And a server-side key storage unit 120 that stores a decryption key corresponding to. Here, the encryption key and decryption key generation algorithm by the key distribution unit 112 is managed so that it cannot be read from the portable information terminal 10. The key distribution unit 112 is an example of an encryption key distribution unit and a decryption key distribution unit according to the present invention.

  With the above configuration, the key distribution server 100 can distribute the encryption key and the decryption key specific to the user or the file to the portable information terminal 10 on the condition that the user authentication is successful.

  The key distribution server 100 further manages the index issuing unit 118 that issues a unique file index in the information management system, and the right to use the encryption key and the decryption key possessed by the information manager of the information management system. The administrator information storage unit 106, the file user storage unit 104 storing the user ID of the file creator and the shared user in association with the file index, and the usage history of the specific file determined in advance as the user And a server-side specific file history storage unit 102 that stores the information in association with the ID.

  Therefore, the key distribution unit 112 can manage the copy received from the portable information terminal 10 in file index units. In addition, an encryption key and a decryption key unique to a file can be created using the file index. Furthermore, it is possible to determine whether to distribute the decryption key to the information manager according to the authority of the information manager. Further, it is possible to read the user ID of the shared user who should supply the decryption key using the file index as a search key. Furthermore, it is possible to read the usage history of the specific file by the user and determine whether or not to distribute the decryption key depending on whether or not the read usage history satisfies a predetermined standard.

  The key distribution server 100 further stores a backup file storage unit 116 that stores a copy received from the portable information terminal 10, a copy received from the portable information terminal in the backup file storage unit 116, and a user ID as a file of the copy It is stored in the file user storage unit 104 in association with the index, and when the copy download request is received, the user authentication is successful and the user ID is stored in association with the file index. And a backup management unit 114 that reads out the copy and transmits it to the portable information terminal.

  Thus, even if the portable information terminal 10 is lost or stolen, the user uses another terminal, or the file stored in the terminal is damaged, the backup file storage unit By downloading and decoding a copy of the file from 116, the file can be easily restored. Further, by referring to the file user storage unit 104, a copy of the file can be transmitted only to a user who has the authority to share the file. Therefore, the key distribution server 100 can appropriately maintain the file created by the portable information terminal 10.

  Furthermore, when a command for invalidating a decryption key of a specific user is input, the key distribution server 100 reads a copy and a decryption key that can be used by the user, and combines the copy with the decryption key that has been read. The reissuing processing unit 122 invalidates the decryption key. The reissuing processing unit 122 is further configured so that when a command for reissuing an encryption key and a decryption key that can be used by a specific user is input, a new decryption key for the user is invalidated. An encryption key and a decryption key are generated, and the decrypted copy is encrypted with the new encryption key and stored in the backup file storage unit 116. When the user newly obtains the portable information terminal 10, the portable information terminal 10 downloads a copy decrypted with the new encryption key in response to the user's request. Further, a new decryption key for decrypting the copy is acquired from the key distribution server 100.

  Therefore, when there is a possibility that the user authentication information has been leaked, such as when the portable information terminal 10 is lost or stolen, the reissue processor 122 invalidates the conventional decryption key. Even if the third party tries to obtain the decryption key, the conventional decryption key for decrypting the file stored in the portable information terminal 10 cannot be obtained. Therefore, even when lost or stolen, the file stored in the portable information terminal 10 is not decrypted.

  Furthermore, since the reissue processing unit 122 encrypts the copy stored in the backup file storage unit 116 with a new encryption key, even if the conventional decryption key leaks, Simply obtaining a copy encrypted with the key from the key distribution server 100 will not cause the copy to be decrypted. Accordingly, the security of the copy stored in the backup file storage unit 116 can be ensured.

  The key distribution server 100 stores authentication information when a command for invalidating an encryption key or a decryption key assigned to a specific user is input, or when an input for notifying the loss of the portable information terminal 10 is received. The personal authentication information of the specific user stored in the unit 108 is invalidated. Thereafter, new personal authentication information related to the specific user is registered. Thereby, even if the personal authentication information is leaked due to loss of the portable information terminal 10 or the like, unauthorized access can be reliably prevented. The key distribution server 100 further accesses the lost or stolen portable information terminal 10 via the network and requests the portable information terminal 10 to delete the contents of the terminal file storage unit 26. When the portable information terminal 10 receives the request from the key distribution server 100, the portable information terminal 10 deletes the contents of the terminal file storage unit 26.

  The recording medium 60b includes the aforementioned server-side specific file history storage unit 102, file user storage unit 104, administrator information storage unit 106, authentication information storage unit 108, authentication unit 110, key distribution unit 112, backup management unit 114, backup A program for causing the key distribution server 100 to realize the functions of the file storage unit 116, the index issuing unit 118, the server side key storage unit 120, and the reissue processing unit 122 is stored. The recording medium 60b may acquire such a program via a network.

  FIG. 4 shows a first example of the data format of the server side key storage unit 120. The server-side key storage unit 120 is associated with the user ID of the user who has requested the issuance of the encryption key, the encryption key generated by the key distribution unit 112, the decryption key for decrypting the file encrypted with the encryption key, Is stored. According to the server side key storage unit 120 of this example, the key distribution unit 112 and the reissue processing unit 122 can read the encryption key and the decryption key specific to the user ID using the user ID as a search key.

  FIG. 5 shows an example of the data format of the file user storage unit 104. The file user storage unit 104 stores a file user list that manages user IDs of a main user and a shared user who are creators of the file, in association with the file index unique to the file. The key distribution unit 112, the backup management unit 114, and the reissue processing unit 122 can read out the user IDs of the main user and the shared user who can use the file by using the file index as a search key. Further, it is possible to read out the user ID of a shared user who shares a file with the user by using the user ID of an arbitrary user as a search key, and further read out the file index of a file available to the shared user.

  FIG. 6 shows an example of the data format of the administrator information storage unit 106. The administrator information storage unit 106 determines whether or not the information manager of the information management system 200 has the authority to use a file that can be used by each responsible user for each manager ID of the information manager. It is managed in association with the user ID of the user. Here, the authority of the information manager to use the file that can be used by the responsible user is, for example, the authority of the information manager to obtain a decryption key unique to the responsible user. Alternatively, the information manager has the authority to obtain a decryption key unique to the file index of a file that can be used by the user in charge.

  FIG. 7 shows an example of the data format of the server side specific file history storage unit 102. The server-side specific file history storage unit 102 in this example stores a print history that is an example of a predetermined specific file usage history in association with the user ID of the user who specified printing. Further, a display history acquired from the mobile information terminal 10 when online may be further stored. Here, the specific file is a file to be printed or displayed in advance before saving or opening a file related to personal information in the portable information terminal 10, and based on the business flow for each use of the portable information terminal 10, It is determined in advance. For example, when the portable information terminal 10 is used for the purpose of selling insurance products, “important” related to insurance products, which should be explained to customers before storing customer contract data as personal information, Explanation 1. doc ”.

  The key distribution unit 112 can read a print history or a print history of a specific file, for example, “important description item 1.doc”, using the user ID as a search key. Further, by managing the usage history of the specific file by the key distribution server 100, the usage history of the specific file is keyed even when the user uses a plurality of portable information terminals 10 connected to the key distribution server 100. The distribution server 100 can perform unified management.

  FIG. 8 shows an example of the data format of the terminal side specific file history storage unit 30. The terminal-side specific file history storage unit 30 in this example stores the display date and time and the display time in association with the user ID as an example of the usage history of the specific file. A print history may be further stored as the usage history of the specific file. The key request unit 14 can read the usage history of the specific file using the user ID as a search key. The usage history of the specific file includes the print history, display date and time, and display time of the specific file. The key request unit 14 can transmit the usage history of the specific file to the key distribution server 100 together with the transmission request for the encryption key and the decryption key.

  FIG. 9 shows a second example of the data format of the server side key storage unit 120. In the present embodiment, the server-side key storage unit 120 stores an encryption key unique to a file index and a decryption key for decrypting a file encrypted with the encryption key in association with the file index. According to the server-side key storage unit 120 of this example, the key distribution unit 112 and the reissue processing unit 122 can read the encryption key and the decryption key using the file index as a search key.

  FIG. 10 shows a second example of the data format of the authentication information storage unit 108. The authentication information storage unit 108 stores the user authentication information registered in advance as a user of the information management system and the geographical range in which the user is permitted to use the portable information terminal in association with the user ID. To do. In the key distribution server 100, the authentication unit 110 authenticates the user on the further condition that the current position received from the portable information terminal 10 is included in the geographical range in which the user ID is read as a search key. As a result, if the third party takes the portable information terminal 10 out of the geographical range when the portable information terminal 10 is lost or stolen, the personal authentication using the portable information terminal 10 is definitely rejected. can do. When using the portable information terminal 10 in an area that exceeds the geographical range stored in the authentication information storage unit 108, the user must make an application to change the contents of the authentication information storage unit 108 in advance. .

  FIG. 11 shows an example of a procedure in which the information management system 200 encrypts and decrypts a file stored locally in the portable information terminal 10. First, in the portable information terminal 10, the authentication information receiving unit 12 receives input of personal authentication information including a user ID and executes user login (S10). Next, the current position detection unit 16 detects the current position of the portable information terminal 10 (S16). Then, in response to a user request, the application execution unit 24 reads the specific file from the terminal file storage unit 26 and displays or prints it (S18). The specific file is a file that can be disclosed to a third party, such as important explanation items, and is stored in the terminal file storage unit 26 without being encrypted.

  When displaying or printing the specific file, the portable information terminal 10 transmits the display or printing history to the key distribution server 100 in association with the user ID if it is online with the key distribution server 100 (S20). . The application execution unit 24 stores the display history and print history of the specific file in the terminal-side specific file history storage unit 30 (S22). On the other hand, in the key distribution server 100, the server-side specific file history storage unit 102 receives the print history and display history of the specific file from the portable information terminal 10 and stores them in the server-side specific file history storage unit 102 (S24).

  Next, the key request unit 14 receives a request for an encryption key and a decryption key from the application execution unit 24 (S26). The timing for transmitting the encryption key or decryption key distribution request may be when the portable information terminal 10 is activated, when a specific application for creating a file including personal information is activated, or at a timing instructed by the user. Good. The key request unit 14 sends a request for distributing an encryption key unique to the user ID, a request for distributing a decryption key for decrypting a file encrypted with the encryption key, personal authentication information including the user ID, Along with the current position of the information terminal 10 and the specific file display history after the user login, the information is transmitted to the key distribution server 100 (S28).

  In the key distribution server 100, the authentication unit 110 matches the personal authentication information and the geographical range in which the personal authentication information and the current position received from the portable information terminal 10 are read from the authentication information storage unit 108 using the user ID as a search key, or Authenticate users on the condition that they are included. Then, the key distribution unit 112 acquires the specific file usage history based on the user ID, reads the print date and time, the display time, and the display time of the specific file. The delivery request for the encryption key and the decryption key is authenticated on the condition that printing or display has been performed for a certain period of time (S30). If any of the user authentication, the current position, and the specific file usage history does not satisfy the above condition in step 30, the key distribution unit 112 sends a message rejecting the encryption key and decryption key distribution request to the portable information terminal 10. (S30: No).

  On the other hand, if the identity authentication, current position, and specific file display history all satisfy the above conditions in step 30, the key distribution unit 112 determines that the encryption key and decryption key corresponding to the user ID are the server side key storage unit. Whether it is stored in 120 is determined (S32). If it is determined that the encryption key and the decryption key are not stored in the server-side key storage unit 120 (S32: No), the key distribution unit 112 generates an encryption key and a decryption key unique to the user ID and corresponds to the user ID. Then, it is stored in the server side key storage unit 120 (S34). If it is determined in step 32 that the encryption key and the decryption key are stored in the server-side key storage unit 120, step 34 is skipped. Next, the key distribution unit 112 distributes the read or generated encryption key and decryption key to the portable information terminal 10 (S36).

  In the portable information terminal 10, the terminal-side key storage unit 18 stores the encryption key and the decryption key received from the key distribution server 100 in association with the user ID. Among these, the decryption key is stored for a certain period, for example, until the user logs off or for one hour (S38). Next, the application execution unit 24 determines whether a request for saving a file including personal information is input (S40). If it is determined that a request to save the file has not been input (S40: No), the process proceeds to step 50.

  On the other hand, if it is determined that a request to save a file including personal information has been input (S40: Yes), the encryption unit 20 reads the encryption key from the terminal-side key storage unit 18, and whether the encryption key is within the expiration date. It is determined whether or not (S42). If it is determined in step 42 that the encryption key is not within the expiration date (S42: No), the process returns to step 26. On the other hand, if it is determined that the encryption key is within the expiration date (S42: Yes), the encryption unit 20 encrypts the file created by the application execution unit 24 using the encryption key and stores it in the terminal file storage unit 26. (S44).

  When the backup file transfer unit 28 detects that the file is stored in the terminal file storage unit 26, the backup file transfer unit 28 transmits a copy of the file (hereinafter referred to as a backup file) to the key distribution server 100 together with the user ID ( S46). In the key distribution server 100, the backup management unit 114 receives the backup file from the portable information terminal 10 together with the user ID, and determines whether a file index is already associated with the backup file. If the file index is not associated, a new file index is acquired from the index issuing unit 118. Then, the backup file is stored in the backup management unit 114 in association with the file index (S48). Further, the user ID is stored in the file user storage unit 104 in association with the file index.

  On the other hand, in the portable information terminal 10, the key request unit 14 determines whether a request to open a personal file including personal information is input to the application execution unit 24 (S50). If it is determined that a request to open a personal file has not been input, the process returns to step 40. On the other hand, when it is determined that a request to open a personal file has been input, the decryption unit 22 reads the decryption key stored in the terminal-side key storage unit 18 and determines whether or not the decryption key is within the expiration date. Is determined (S52). If it is determined that the decryption key is not within the expiration date (S52: No), the process returns to step 26, and a decryption key distribution request is transmitted again. If it is determined that the decryption key is within the expiration date (S52: Yes), the decryption unit 22 decrypts the file read from the terminal file storage unit 26 using the decryption key and outputs the decrypted file to the application execution unit 24. The application execution unit 24 expands the file acquired from the decryption unit 22 (S54). This flow is completed.

  The encryption unit 20 generates a unique encryption key and a unique decryption key unique to the user by converting the encryption key and the decryption key distributed from the key distribution server 100 using a user key input by the user, You may store in the terminal side key storage part 18. FIG. In this case, the file to be stored in the terminal file storage unit 26 is encrypted with the unique encryption key. Here, the conversion using a user key is a conversion in which a 12-digit unique decryption key is generated by adding a 2-digit user key to a 10-digit decryption key distributed from the server. Alternatively, the conversion may be such that the decryption key distributed from the server is encrypted with the user key so that the pre-conversion cannot be inferred.

  The decrypting unit 22 decrypts the file encrypted with the unique encryption key with the unique decryption key. The backup file transferred to the key distribution server 100 cannot be decrypted with the decryption key stored in the server side key storage unit 120. As a result, the security level of the stored file can be further increased. The user key is preferably a password that can be stored by the user. And the terminal side key storage part 18 may preserve | save a user key on condition that the said specific decoding key will be deleted after the generation | occurrence | production of a specific decoding key after a fixed period of time elapses.

  Hereinafter, the operation of the information management system 200 when the encryption key and the decryption key are unique for each file index will be described. The operations not described below are the same as the operations described in FIG. First, when the application execution unit 24 creates a new file, the key request unit 14 sends a distribution request for a file index unique to the new file and an encryption key unique to the file index together with the personal authentication information to the key distribution server 100. Send to. In the key distribution server 100, the key distribution unit 112 acquires a new file index from the index issuing unit 118 on the condition that the authentication unit 110 authenticates the personal authentication information, and obtains an encryption key unique to the file index. Generate and distribute to the portable information terminal 10.

  The application execution unit 24 associates the file index received from the key distribution server 100 with the new file. As described with reference to FIG. 9, the server-side key storage unit 120 stores the encryption key and the decryption key in association with the file index. On the other hand, the terminal-side key storage unit 18 stores the encryption key and the decryption key received from the key distribution server 100 in association with the file index. Among these, the decryption key is stored for a certain period, for example, until the file is closed or only for one hour.

  When the file storage is requested, the encryption unit 20 reads the encryption key using the file index of the file as a search key, and encrypts the file with the encryption key. The terminal file storage unit 26 stores the encrypted file in association with the file index. The key request unit 14 transmits a decryption key distribution request for decrypting the encrypted file to the key distribution server 100 together with the file index and the personal authentication information associated with the file.

  On the other hand, in the key distribution server 100, when the key distribution unit 112 receives a decryption key distribution request from the portable information terminal together with the file index and the personal authentication information, the authentication unit 110 authenticates the personal authentication information. As a condition, the decryption key is read using the file index as a search key, and distributed to the portable information terminal 10 together with the file index. In the portable information terminal 10, the decryption unit 22 reads the decryption key using the file index associated with the encrypted file as a search key, and decrypts the file using the decryption key.

  According to the above procedure, the information management system 200 can store the file used in the portable information terminal 10 with high security by using the encryption key and the decryption key issued / managed by the key distribution server 100.

  FIG. 12 shows a procedure in which the key distribution server 100 reissues the encryption key and the decryption key. First, the reissue processing unit 122 receives a command for invalidating an encryption key and a decryption key that can be used by a specific user, together with the personal authentication information (S100). Next, it is determined whether or not the personal authentication information by the authentication unit 110 is successful (S102). In step 102, if the authentication fails, the reissue processing unit 122 displays that fact to the user (S104), and this flow ends.

  On the other hand, when the personal authentication is successful (S102: Yes), the reissue processing unit 122 reads the file index that associates the user ID as the main user ID from the file user storage unit 104, and corresponds to the read file index. The backup file to be read is read from the backup file storage unit 116 (S106). Next, the encryption key and the decryption key are read from the server side key storage unit 120 shown in FIG. 4 using the user ID as a search key (S108).

  Next, after the backup file read in step 106 is decrypted with the decryption key read in step 108 (S110), the encryption key and the decryption key are invalidated (S112). Invalidation is, for example, deletion. Next, a command for reissuing an encryption key and a decryption key that can be used by the user is received together with the personal authentication information (S114).

  The reissue processing unit 122 is unique to the user ID on the condition that the authentication information is authenticated by the authentication unit 110 and that the encryption key and the decryption key corresponding to the user ID are recorded as invalid. Then, a new encryption key and decryption key are generated and stored in the server-side key storage unit 120 in association with the user ID (S116). Then, the backup file decrypted in step 110 is encrypted using the encryption key newly generated in step 116 and stored in the backup file storage unit 116 (S118). This flow is completed.

  In step 106, the reissue processing unit 122 may further read a file index that associates the user ID of the user as a shared user ID from the file user storage unit 104. In this case, the backup file associated with the further read file index is further read from the backup file storage unit 116, and the main user ID is further read from the file user storage unit 104. In step 108, the encryption key and the decryption key associated with the further read main user ID are further read from the server side key storage unit 120.

  Then, after decrypting the shared backup file with the decryption key corresponding to the main user ID, the encryption key and decryption key corresponding to the main user ID are invalidated. An example of the server-side key storage unit 120 status at this time will be described later with reference to FIG.

  According to the above flow, when the portable information terminal 10 is lost or stolen, the decryption key usable for the user who has used the portable information terminal 10 is invalidated. It is possible to prevent the file stored in the file from being decrypted. Furthermore, the backup file stored in the key distribution server 100 is decrypted with the conventional decryption key and then encrypted with the newly created encryption key. Therefore, it is possible to prevent the backup file stored in the key distribution server 100 from being decrypted by a third party who has obtained the old decryption key. Therefore, the information management system 200 can both ensure data restoration by the backup file and ensure security by updating the encryption key / decryption key.

  FIG. 13 is a diagram illustrating a first example of the status of the server-side key storage unit 120 when the USER A key is invalidated. This example is based on the status of the file user storage unit 104 shown in FIG. When it is requested to invalidate the encryption / decryption key used by USER A, the file index associated with USER A is read in the file user storage unit 104 and the file is shared with USER A. USER C is further read. Then, in the first example of the server side key storage unit 120, the encryption key and the decryption key associated with USER A or USER C are invalidated.

  FIG. 14 is a diagram illustrating a second example of the status of the server-side key storage unit 120 when the USER A key is invalidated. Similarly, this example is based on the status of the file user storage unit 104 shown in FIG. When a request is made to invalidate the encryption / decryption key used by USER A, the file user storage unit 104 reads the file indexes associated with USER A, that is, “File0001” and “File0003”. In the second example of the server-side key storage unit 120, the encryption key and the decryption key associated with “File0001” or “File0003” are invalidated.

  As is clear from the above description, according to the information management system 200 of the present embodiment, it is possible to sufficiently ensure the security of the file stored locally in the portable information terminal 10.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

2 is a diagram illustrating an example of a system configuration of an information management system 200. FIG. 3 is a block diagram illustrating an example of a functional configuration of a portable information terminal 10. FIG. 3 is a block diagram illustrating an example of a functional configuration of a key distribution server 100. FIG. The 1st example of the data format of the server side key storage part 120 is shown. An example of the data format of the file user storage unit 104 is shown. An example of the data format of the administrator information storage part 106 is shown. An example of the data format of the server side specific file history storage part 102 is shown. An example of the data format of the terminal side specific file history storage part 30 is shown. The 2nd example of the data format of the server side key storage part 120 is shown. The 2nd example of the data format of the authentication information storage part 108 is shown. 4 is a flowchart illustrating an example of a procedure for the information management system 200 to encrypt and decrypt a file stored in the portable information terminal 10. It is a flowchart which shows an example of the procedure in which the key distribution server 100 reissues an encryption key and a decryption key. It is a figure which shows the 1st example of the status of the server side key storage part 120 in the case of invalidating the key of USER A. It is a figure which shows the 2nd example of the status of the server side key storage part 120 in the case of invalidating the key of USER A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Portable information terminal, 12 Authentication information reception part, 14 Key request part, 16 Current position detection part, 18 Terminal side key storage part, 20 Encryption part, 22 Decryption part, 24 Application execution part, 26 Terminal file storage part, 28 Backup File transfer unit, 30 Terminal side specific file history storage unit, 50 Administrator terminal, 60 Recording medium, 100 Key distribution server, 102 Server side specific file history storage unit, 104 File user storage unit, 106 Administrator information storage unit, 108 Authentication information storage unit, 110 Authentication unit, 112 Key distribution unit, 114 Backup management unit, 116 Backup file storage unit, 118 Index issuing unit, 120 Server side key storage unit, 122 Reissue processing unit, 200 Information management system

Claims (8)

An information management system comprising a key distribution server and a portable information terminal connected via a network, and managing security of a file stored in the portable information terminal,
The portable information terminal
An encryption key requesting unit that transmits an encryption key distribution request unique to a user ID to the key distribution server together with personal authentication information including the user ID;
An encryption unit that encrypts a file to be stored with the encryption key distributed from the key distribution server in response to the distribution request;
A terminal file storage for storing the encrypted file;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting a file encrypted with the encryption key to the key distribution server together with the personal authentication information;
A terminal-side key storage unit that stores the decryption key distributed from the key distribution server in response to the distribution request only for a certain period of time until the file decrypted with the decryption key is closed;
A decryption unit that reads the encrypted file from the terminal file storage unit and decrypts the file with the decryption key;
The key distribution server is
An authentication information storage unit for storing user authentication information registered in advance as a user of the information management system;
An authentication unit that authenticates the entered user authentication information by comparing with the user authentication information stored in the authentication information storage unit;
When the distribution request for the encryption key is received from the portable information terminal together with the personal authentication information, the user ID included in the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. An encryption key distribution unit that distributes the encryption key unique to the mobile information terminal;
A server-side key storage unit that stores the decryption key corresponding to the encryption key in association with the user ID;
When the delivery request for the decryption key is received from the portable information terminal together with the personal authentication information, the user ID included in the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. An information management system comprising: a decryption key distribution unit that reads out the decryption key as a search key and distributes it to the portable information terminal. An information management system comprising a key distribution server and a portable information terminal connected via a network, and managing security of a file stored in the portable information terminal,
The portable information terminal
An encryption for transmitting a distribution request for a file index unique to a file in the information management system and an encryption key unique to the file index to the key distribution server together with the personal authentication information including the user ID when creating a new file. A key request section;
A terminal-side encryption key storage unit that receives the file index and the encryption key unique to the file index from the key distribution server and stores them in association with each other;
An encryption unit that reads the encryption key using the file index corresponding to the file to be stored as a search key, and encrypts the file with the encryption key;
A terminal file storage unit for storing the encrypted file in association with the file index;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting the encrypted file to the key distribution server together with the file index and the personal authentication information associated with the file;
A terminal-side decryption key storage unit that stores the decryption key distributed from the key distribution server in response to the distribution request in association with the file index until the file decrypted with the decryption key is closed; ,
A decryption unit that reads the decryption key using the file index associated with the encrypted file as a search key, and decrypts the file with the decryption key;
The key distribution server is
An authentication information storage unit for storing user authentication information registered in advance as a user of the information management system;
An authentication unit that authenticates the entered user authentication information by comparing with the user authentication information stored in the authentication information storage unit;
An index issuing unit for issuing a unique file index in the information management system;
When the distribution request for the file index and the encryption key is received from the portable information terminal together with the personal authentication information, a new request is issued from the index issuing unit on the condition that the authentication unit has authenticated the personal authentication information. An encryption key distribution unit that obtains the file index and distributes the encryption key unique to the file index to the portable information terminal;
A server-side key storage unit that stores the decryption key corresponding to the encryption key in association with the file index;
When the delivery request for the decryption key is received from the portable information terminal together with the file index and the personal authentication information, the file index is searched as a condition that the authentication unit has authenticated the personal authentication information. And a decryption key distribution unit that reads the decryption key and distributes the decryption key to the portable information terminal together with the file index. An information management system comprising a key distribution server and a portable information terminal connected via a network, and managing security of a file stored in the portable information terminal,
The portable information terminal
An encryption key requesting unit that transmits an encryption key distribution request unique to a user ID to the key distribution server together with personal authentication information including the user ID;
An encryption unit that encrypts a file to be stored with the encryption key distributed from the key distribution server in response to the distribution request;
A terminal file storage for storing the encrypted file;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting a file encrypted with the encryption key to the key distribution server together with the personal authentication information;
A terminal-side key storage unit that stores the decryption key distributed from the key distribution server in response to the distribution request only when the portable information terminal stores until the mobile information terminal logs off from the connection with the key distribution server;
A decryption unit that reads the encrypted file from the terminal file storage unit and decrypts the file with the decryption key;
The key distribution server is
An authentication information storage unit for storing user authentication information registered in advance as a user of the information management system;
An authentication unit that authenticates the entered user authentication information by comparing with the user authentication information stored in the authentication information storage unit;
When the distribution request for the encryption key is received from the portable information terminal together with the personal authentication information, the user ID included in the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. An encryption key distribution unit that distributes the encryption key unique to the mobile information terminal;
A server-side key storage unit that stores the decryption key corresponding to the encryption key in association with the user ID;
When the delivery request for the decryption key is received from the portable information terminal together with the personal authentication information, the user ID included in the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. An information management system comprising: a decryption key distribution unit that reads out the decryption key as a search key and distributes it to the portable information terminal. An information management system comprising a key distribution server and a portable information terminal connected via a network, and managing security of a file stored in the portable information terminal,
The portable information terminal
An encryption for transmitting a distribution request for a file index unique to a file in the information management system and an encryption key unique to the file index to the key distribution server together with the personal authentication information including the user ID when creating a new file. A key request section;
A terminal-side encryption key storage unit that receives the file index and the encryption key unique to the file index from the key distribution server and stores them in association with each other;
An encryption unit that reads the encryption key using the file index corresponding to the file to be stored as a search key, and encrypts the file with the encryption key;
A terminal file storage unit for storing the encrypted file in association with the file index;
A decryption key request unit for transmitting a decryption key distribution request for decrypting the encrypted file to the key distribution server together with the file index and the personal authentication information associated with the file;
A terminal-side decryption key storage that stores the decryption key distributed from the key distribution server in response to the distribution request until the portable information terminal logs off from the connection with the key distribution server in association with the file index. And
A decryption unit that reads the decryption key using the file index associated with the encrypted file as a search key, and decrypts the file with the decryption key;
The key distribution server is
An authentication information storage unit for storing user authentication information registered in advance as a user of the information management system;
An authentication unit that authenticates the entered user authentication information by comparing with the user authentication information stored in the authentication information storage unit;
An index issuing unit for issuing a unique file index in the information management system;
When the distribution request for the file index and the encryption key is received from the portable information terminal together with the personal authentication information, a new request is issued from the index issuing unit on the condition that the authentication unit has authenticated the personal authentication information. An encryption key distribution unit that obtains the file index and distributes the encryption key unique to the file index to the portable information terminal;
A server-side key storage unit that stores the decryption key corresponding to the encryption key in association with the file index;
When the delivery request for the decryption key is received from the portable information terminal together with the file index and the personal authentication information, the file index is searched as a condition that the authentication unit has authenticated the personal authentication information. And a decryption key distribution unit that reads the decryption key and distributes the decryption key to the portable information terminal together with the file index. In an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of a file stored in the portable information terminal,
In the portable information terminal,
An encryption key requesting unit transmitting an encryption key distribution request unique to a user ID to the key distribution server together with personal authentication information including the user ID;
An encryption unit encrypting a file to be stored with the encryption key distributed from the key distribution server in response to the distribution request;
A terminal file storage unit storing the encrypted file;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting a file encrypted with the encryption key to the key distribution server together with the personal authentication information;
A terminal-side key storage unit storing the decryption key distributed from the key distribution server in response to the distribution request until the file decrypted with the decryption key is closed;
A decrypting unit reading the encrypted file from the terminal file storage unit and decrypting with the decryption key;
In the key distribution server,
An authentication information storage unit storing user authentication information registered in advance as a user of the information management system;
An authenticating unit authenticating the input personal authentication information by comparing with the personal authentication information stored in the authentication information storing unit;
When the encryption key distribution unit receives the distribution request for the encryption key from the portable information terminal together with the personal authentication information, the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. Delivering the encryption key unique to the user ID included in the mobile information terminal;
A server-side key storage unit storing the decryption key corresponding to the encryption key in association with the user ID;
When the decryption key distribution unit receives the distribution request for the decryption key from the portable information terminal together with the personal authentication information, the personal authentication information is provided on the condition that the authentication unit authenticates the personal authentication information. An information management method comprising: reading out the decryption key using the user ID included in the search key as a search key and distributing it to the portable information terminal. In an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of a file stored in the portable information terminal,
In the portable information terminal,
When a new file is created, the encryption key requesting unit sends a distribution request for a file index unique to the file in the information management system and an encryption key unique to the file index together with the user authentication information including the user ID. Sending to the delivery server;
A terminal-side encryption key storage unit receiving the file index and the encryption key unique to the file index from the key distribution server, and storing them in association with each other;
An encryption unit reads the encryption key using the file index corresponding to the file to be stored as a search key, and encrypts the file with the encryption key;
A terminal file storage unit for storing the encrypted file in association with the file index;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting the encrypted file to the key distribution server together with the file index and the personal authentication information associated with the file; ,
The terminal-side decryption key storage unit associates the decryption key distributed from the key distribution server in response to the distribution request with the file index and stores the file decrypted with the decryption key until the file is closed And storing step,
A decrypting unit reads the decryption key using the file index associated with the encrypted file as a search key, and decrypts the file with the decryption key;
In the key distribution server,
An authentication information storage unit storing user authentication information registered in advance as a user of the information management system;
An authenticating unit authenticating the input personal authentication information by comparing with the personal authentication information stored in the authentication information storing unit;
An index issuing unit issuing a unique file index in the information management system;
When the encryption key distribution unit receives the file index and the distribution request for the encryption key from the portable information terminal together with the personal authentication information, on the condition that the authentication unit has authenticated the personal authentication information. Obtaining the new file index from the index issuing unit, and delivering the encryption key unique to the file index to the portable information terminal;
A server-side key storage unit stores the decryption key corresponding to the encryption key in association with the file index; and
When the decryption key distribution unit receives the distribution request for the decryption key from the portable information terminal together with the file index and the personal authentication information, on the condition that the authentication unit has authenticated the personal authentication information. An information management method comprising: reading the decryption key using the file index as a search key and distributing the decryption key together with the file index to the portable information terminal. In an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of a file stored in the portable information terminal,
In the portable information terminal,
An encryption key requesting unit transmitting an encryption key distribution request unique to a user ID to the key distribution server together with personal authentication information including the user ID;
An encryption unit encrypting a file to be stored with the encryption key distributed from the key distribution server in response to the distribution request;
A terminal file storage unit storing the encrypted file;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting a file encrypted with the encryption key to the key distribution server together with the personal authentication information;
A terminal-side key storage unit storing the decryption key distributed from the key distribution server in response to the distribution request until the portable information terminal logs off from connection with the key distribution server;
A decrypting unit reading the encrypted file from the terminal file storage unit and decrypting with the decryption key;
In the key distribution server,
An authentication information storage unit storing user authentication information registered in advance as a user of the information management system;
An authenticating unit authenticating the input personal authentication information by comparing with the personal authentication information stored in the authentication information storing unit;
When the encryption key distribution unit receives the distribution request for the encryption key from the portable information terminal together with the personal authentication information, the personal authentication information is provided on the condition that the authentication unit has authenticated the personal authentication information. Delivering the encryption key unique to the user ID included in the mobile information terminal;
A server-side key storage unit storing the decryption key corresponding to the encryption key in association with the user ID;
When the decryption key distribution unit receives the distribution request for the decryption key from the portable information terminal together with the personal authentication information, the personal authentication information is provided on the condition that the authentication unit authenticates the personal authentication information. An information management method comprising: reading out the decryption key using the user ID included in the search key as a search key and distributing it to the portable information terminal. In an information management system comprising a key distribution server and a portable information terminal connected via a network, an information management method for managing security of a file stored in the portable information terminal,
In the portable information terminal,
When a new file is created, the encryption key requesting unit sends a distribution request for a file index unique to the file in the information management system and an encryption key unique to the file index together with the user authentication information including the user ID. Sending to the delivery server;
A terminal-side encryption key storage unit receiving the file index and the encryption key unique to the file index from the key distribution server, and storing them in association with each other;
An encryption unit reads the encryption key using the file index corresponding to the file to be stored as a search key, and encrypts the file with the encryption key;
A terminal file storage unit for storing the encrypted file in association with the file index;
A decryption key requesting unit for transmitting a decryption key distribution request for decrypting the encrypted file to the key distribution server together with the file index and the personal authentication information associated with the file; ,
The terminal-side decryption key storage unit associates the decryption key distributed from the key distribution server in response to the distribution request with the file index, and the portable information terminal logs off from the connection with the key distribution server. Storing up to,
A decrypting unit reads the decryption key using the file index associated with the encrypted file as a search key, and decrypts the file with the decryption key;
In the key distribution server,
An authentication information storage unit storing user authentication information registered in advance as a user of the information management system;
An authenticating unit authenticating the input personal authentication information by comparing with the personal authentication information stored in the authentication information storing unit;
An index issuing unit issuing a unique file index in the information management system;
When the encryption key distribution unit receives the file index and the distribution request for the encryption key from the portable information terminal together with the personal authentication information, on the condition that the authentication unit has authenticated the personal authentication information. Obtaining the new file index from the index issuing unit, and delivering the encryption key unique to the file index to the portable information terminal;
A server-side key storage unit stores the decryption key corresponding to the encryption key in association with the file index; and
When the decryption key distribution unit receives the distribution request for the decryption key from the portable information terminal together with the file index and the personal authentication information, on the condition that the authentication unit has authenticated the personal authentication information. An information management method comprising: reading the decryption key using the file index as a search key and distributing the decryption key together with the file index to the portable information terminal.

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