JP2002312222A - Cryptic file managing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cryptic file managing device and method capable of allowing only the user to obtain access to a specified file even if the user who belongs to the process of an application program is different from a user who uses the application program actually in the case where the program cannot be amended. SOLUTION: This device has a temporary file name generating means, which inputs information to specifying a file and generates a temporary file name corresponding to the information specifying the input file, and a file access means, which decodes the file corresponding to the temporary file name using an encryption key only when a file is accessed by the generated temporary file name and outputs as a file having the temporary file name.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling the use of a file and preventing the file from being illegally used, and capable of decrypting and reading the contents of an encrypted file. File management apparatus such as a file server and a file system, and a method and a program.

[0002]

2. Description of the Related Art In order to prevent unauthorized use of a file, when a file is encrypted and only a person having the key decrypts the file, a corresponding key must be provided to obtain the contents of the file. Conventionally, a method of calling a subroutine for decrypting a file is known.

A conventional example of a file management apparatus in which a file is encrypted is an encrypted file system provided in an OS.

[0004]

According to the conventional method of calling the subroutine for decrypting a file, if an application using an encrypted file is provided only with an object program, the program cannot be modified. However, there is a problem that a method of calling a subroutine for decrypting a file cannot be applied.

In other words, there is a problem that an application provided with only an object program without a source program cannot handle an encrypted file.

On the other hand, when an encrypted file system provided in the OS is used to decrypt an encrypted file, even if the application is provided only by an object program as described above, the encryption is performed. File can be handled, but there is a problem that the file can be accessed only within the range of access control to the file in the OS.

For this reason, for example, if a user belonging to a process of an application program such as an application of an Internet server is different from a user who actually uses the application, access to the encrypted file may be controlled for each user. There is a problem that can not be.

The present invention relates to a case where a program cannot be modified, such as a case where an application of an Internet server is provided only by an object program, and a user who belongs to a process of the application program actually executes the application. It is an object of the present invention to provide an encrypted file management device and an encrypted file management method that allow only a user to access a target file even when the user is different.

[0009]

According to the present invention, in an encrypted file management apparatus storing an encrypted file, information for designating a file is input, and the information corresponding to the input information for specifying the file is input. A temporary file name generating means for generating a temporary file name, and only when accessed by the generated temporary file name, decrypts the file corresponding to the temporary file name using an encryption key, And a file access means for outputting the file as a file having the same name.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a diagram showing an encrypted file management apparatus 100 according to a first embodiment of the present invention.

The encrypted file management apparatus 100 is an encrypted file management apparatus that stores an encrypted file, and includes a temporary file name generation unit 10, a file access unit 20, a correspondence table 30, and an access control unit 40. When,
It has an encryption key 50, an encrypted file 60, and an allowable access source table 70.

[0012] Temporary file name generation means 10 inputs information specifying a file, and generates a temporary file name corresponding to the input information specifying the file, that is, information 11 specifying the file and authentication information. 12 and outputs the temporary file name 13.

The file access means 20 is a means for decrypting the file corresponding to the temporary file name using the encryption key and outputting the file as a file with the temporary file name only when accessed with the temporary file name. That is, it is a means for accessing with the temporary file name 13 and outputting the decrypted contents of the file corresponding to the temporary file name 13.

FIG. 2 is a diagram showing the correspondence table 30 in the above embodiment.

The correspondence table 30 includes a temporary file name 13, a file name 31, a file handle 32, a temporary file handle 33, an encryption key 50, an accessible last date and time 34, and a remaining openable number 35. It is a corresponding table.

The contents of the encrypted file are stored as a normal file.

Also, the encryption key 5 of each encrypted file
0 is stored in the form of a file so as to correspond to the file name 31 of the encrypted file by the file of the key correspondence table 30 or the like.

In the above embodiment, since the common key method is used for encryption, the encryption key 50 and the decryption key are the same, and are described as the encryption key 50.

Next, a description will be given of a case where the access source decrypts these encrypted files and attempts to access them.

Temporary file name generating means 1 from access source
The interface to 0 may be a communication interface such as HTTP, or an interface for subroutine calls.

The file access means 20 is called as a file server or by a method such as hooking or replacing a file access routine of the OS.
Called by a normal file access interface such as read / close.

In the following description, the method for replacing the file access routine of the OS will be described. However, the case of operating as a file server is the same as the following description.

First, the access source gives the temporary file name generating means 10 information 11 specifying a file such as a file name 31 and an ID.
give. If the authentication has already been completed before reaching the temporary file name generation means 10, the authentication information 12 is given.

If the authentication has already been completed before reaching the temporary file name generating means 10, the authentication information 12 is unnecessary. 12 are required.

Temporary file name generating means 1 from access source
The interface to 0 may be a communication interface such as HTTP or an interface for subroutine calls.

When the authentication information 12 is given, the temporary file name generating means 10 determines whether the access source is permitted to access based on the information 11 specifying the file and the authentication information 12, and If is not permitted, an error is returned to the access source, and the process ends. If the access is permitted, the following processing is continued.

[0027] The temporary file name generating means 10 generates the information 11 for specifying a file based on the correspondence table 30 in which the information 11 for specifying the file and the file name 31 are described.
, Obtains the file name 31 of the original encrypted file, uses a “random number temporary file name generation unit” as the temporary file name generation unit 10, uses a random number as at least a part of the file name 31, or After the random number is generated, conversion is performed using a function, thereby generating a temporary file name 13 completely unrelated to the original file name 31.

The generated temporary file name 13 is associated with the file name 31 of the original encrypted file,
The temporary file name 13 is temporarily stored as the correspondence table 30 on the memory and returned to the access source.

When setting at least one of the number-of-accesses limit and the access-period limitation in the temporary file name 13, the access control means 40 sets the correspondence table 3
0, the final accessible date and time 3 obtained by adding the time for restricting the access to the base time such as the date and time when the temporary file name 13 was generated in association with the temporary file name 13
4. At least one of the remaining number of open times 35 is added to the temporary file name 13 and stored.

When opening the temporary file thereafter, the access control means 40 obtains the corresponding accessible final date and time 34 and the remaining number of openable files 35 from the correspondence table 30.

The last accessible date and time 34 is compared with the current system date and time.
Check for a first condition that the current system date and time has not passed. In addition, a second condition that the remaining number of open times 35 of the file is 1 or more is checked.
If the remaining number of openable files 35 is 1 or more, the remaining openable number of files 35 is decremented by one. Only when one or both of the first and second conditions are satisfied, it is permitted to continue the open process.

The access control means 40 deletes the corresponding entry in the correspondence table 30 when the continuation of the open processing is not permitted.

Next, the access source uses the temporary file name 13 already returned from the temporary file name generation means 10 and requests the file access means 20 to open the file.

At this time, the file access means 20 obtains from the access control means 40 whether or not the processing should be continued. When the processing is continued, the file name 31 of the encrypted file corresponding to the temporary file name 13 is obtained by using the correspondence table 30, the encrypted file is opened, and the file handle 32 is obtained.

The temporary file name 13 functions as a password known only to the authenticated access source. It is not necessary to use the entire temporary file name 13 for authentication, and only a part of the temporary file name 13 may be used.

Next, the extension will be described.

When the file name 31 of “encrypted file” is obtained based on the temporary file name 13 and the correspondence table 30, the presence or absence of an extension starting from the last period of the temporary file name 13 is determined. The type of the extension can be ignored, and the receiving side of the temporary file name 13 can freely add the extension.

At this time, at least one of a network address permitted as an access source and a user name of the access source is specified in an allowable access source table 70 in advance.
By comparing with and continuing the process only when it is included, the file access source can be restricted.

Further, a temporary file handle 33 corresponding to the temporary file used for access is generated.

Also, based on the file name 31 of the previously obtained encrypted file, a file of the encryption key 50 is obtained from the correspondence table 30, and the encryption key 50 corresponding to the encrypted file is obtained. . The timing at which the encryption key 50 is obtained may be a stage at which the temporary file name 13 is generated.

Further, the file handle 32, the temporary file handle 33, and the encryption key 50 are stored in the correspondence table 30 in a pair with the temporary file name 13, and the temporary file handle 33 is returned to the access source.

Next, the access source uses the temporary file handle 33 to cause the file access means 20 to read the file. The file access means 20
On the basis of the designated temporary file handle 33, the file handle 32 and the encryption key 50 are obtained from the correspondence table 30,
The data encrypted using the file handle 32 is read out, and the data decrypted using the encryption key 50 is read.
When an operation such as seeking of the temporary file handle 33 or acquisition of a file attribute is performed, all the operations are mapped to the corresponding file handle 32 or an operation to the “file” and processed.

When the operation on the file is completed, the access source uses the temporary file handle 33 to request the file access means 20 to close the file. Based on the temporary file handle 33, the file access means 20 reads the file handle 3
2, the file handle 32 is closed, and the entry corresponding to the temporary file handle 33 is deleted from the correspondence table 30.

That is, in the above-described embodiment, the authentication process is performed by creating an external application, obtaining a file to be accessed by an actual user and the authentication information through the external application, and providing the file to the temporary file name generating means. The temporary file name is generated only when the authentication is established, and is notified only to the user via an external application.

[Second Embodiment] FIG. 3 is a block diagram showing an encrypted file management apparatus 200 according to a second embodiment of the present invention.

The encrypted file management device 200 is an encrypted file management device that stores an encrypted file, and has a device A and a device B.

The device A includes a temporary file name generating means 10a
, A file access unit 20a, a correspondence table 30, an access control unit 40, an encryption key 50, and an encrypted file 60.

The temporary file name generating means 10a inputs the information for designating the file and the authentication information for authenticating the accessor, and inputs the information only when it is determined that the access is permitted based on the authentication information. This is a means for generating a temporary file name corresponding to the information for specifying the specified file.

The file access means 20a decrypts the file corresponding to the temporary file name using an encryption key only when the file is accessed using the generated temporary file name, and generates the file having the temporary file name as the file having the temporary file name. Output means.

The device B has a file encryption means 80, a file 81, an encryption key 51, and an encrypted file 61.

In the encrypted file management apparatus 200, the file access means 20a and the file encryption means 80 on another apparatus B connected by a network
The encryption key 51 is generated, the file 81 is encrypted to create an encryption file 61, and the encryption key 51 and the encryption file 61 are transferred to the file access means 20a via the network. To use.

[Third Embodiment] FIG. 4 is a block diagram showing an encrypted file management apparatus 300 according to a third embodiment of the present invention.

The encrypted file management device 300 is a device C
, Device B, and key management means 90.

The device C includes a temporary file name generating means 10
, A file access unit 20, a correspondence table 30, an access control unit 40, a key acquisition unit 52, and an encrypted file 60.

The device B has file encryption means 80, a file 81, an encryption key 51, and an encrypted file 61.

The key management means 90 has an encryption key 91.

The encrypted file management apparatus 300 generates the encryption key 51 in the file access means 20 and the file encryption means 80 on another apparatus B connected to the network in advance, encrypts the file, and encrypts the file. The encrypted file 60 is created, and the encrypted file 60 is transferred to the file access unit 20 via the network.

At the same time, the encryption key 51 is transferred via the network to the key management means 90 connected to the file access means 20 via the network. The key management unit 90 stores the encryption key 91 in a form linked with the file name 31 of the encrypted file.

Here, instead of the step of “obtaining the encryption key 50 corresponding to the encrypted file based on the file name 31 of the encrypted file” during the operation of the encrypted file management apparatus 100, the key acquisition means 52 Is used.

The key acquisition means 52 transfers the file name 31 of the encrypted file to the key management means 90 by communication, and the key management means 90 transmits the encryption key 5 based on the file name 31.
1 and returns the encryption key 51 to the key acquisition means 52 by communication, so that the key acquisition means 52 obtains and processes the encryption key 51.

According to the above embodiment, when the application cannot be modified, such as when the application of the Internet server is provided only by the object program, the user belonging to the process of the application program actually Even if it is different from the user who uses the application, an external application is created, the file to be accessed by the actual user and the authentication information 12 are acquired through the external application, and the temporary file name generation means 10, the temporary file name 13 is generated only when the authentication is successful, and is notified only to the user via the external application. Allow access to It can be a.

The above embodiment can be understood as a program invention. That is, in the above embodiment, a temporary file name generating procedure of inputting information specifying a file and generating a temporary file name corresponding to the input information specifying the file, and accessing with the generated temporary file name This is an example of a program that causes a computer to execute a file access procedure of decrypting the file corresponding to the temporary file name using an encryption key only when the file is accessed and outputting the file as a file with the temporary file name.

In the above embodiment, the information for designating the file and the authentication information for authenticating the accessor are input, and the input is performed only when it is determined that the access is permitted based on the authentication information. A temporary file name generation procedure for generating a temporary file name corresponding to information specifying a file, and decrypting the file corresponding to the temporary file name using an encryption key only when accessed using the temporary file name This is an example of a program for causing a computer to execute a file access procedure for outputting a file having the temporary file name.

[0064]

According to the present invention, when a program cannot be modified, such as when an application of an Internet server is provided only by an object program, a user belonging to a process of the application program can Even when the user is different from the user who actually uses the application, an effect is provided that only the user can be permitted to access the target file.

[Brief description of the drawings]

FIG. 1 is a diagram showing an encrypted file management device 100 according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a correspondence table 30 in the embodiment.

FIG. 3 is a block diagram showing an encrypted file management device 200 according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating an encrypted file management device 300 according to a third embodiment of the present invention.

[Explanation of symbols]

 100, 200, 300: encrypted file management device, A, B, C: device, 10, 10a: temporary file name generation means, 11: information specifying a file, 12: authentication information, 13: temporary file name, 20, 20a: File access means, 30: Correspondence table, 40: Access control means, 50, 51, 91: Encryption key, 52: Key acquisition means, 60, 61: Encrypted file, 70: Permitted access source table, 80: File Encryption means, 81: file, 90: key management means.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04L 9/32 H04L 9/00 673Z (72) Inventor Tadahiro Izumiya 2-3-1 Otemachi, Chiyoda-ku, Tokyo Japan Within Telegraph and Telephone Co., Ltd. (72) Nobuo Mutoh Inventor F-term within Nihon Telegraph and Telephone Co., Ltd. 2-3-1 Otemachi, Chiyoda-ku, Tokyo 5B017 AA07 BA05 BA07 BB10 CA16 5B082 EA12 GA11 5J104 AA01 AA16 EA01 EA04 NA02 NA05 PA07

Claims (13)

[Claims] 1. An encrypted file management apparatus storing an encrypted file, wherein information specifying a file is input, and a temporary file for generating a temporary file name corresponding to the input information specifying the file is provided. Name generation means; only when accessed with the generated temporary file name, decrypts the file corresponding to the temporary file name using an encryption key;
File access means for outputting as a file having the temporary file name. 2. An encrypted file management apparatus storing an encrypted file, wherein information for designating a file and authentication information for authenticating an accessor are input, and access is permitted based on the authentication information. A temporary file name generating means for generating a temporary file name corresponding to the information specifying the input file only when it is determined that the temporary file has been input; and the temporary file only when accessed by the generated temporary file name. File access means for decrypting the file corresponding to the file name using an encryption key and outputting the file as a file having the temporary file name. 3. The file access device according to claim 1, wherein the file access unit is configured to execute the file access when the temporary file name is accessed according to at least one of the number of times the temporary file name can be accessed and the limit of the accessible period. And a means for controlling access. 4. The method according to claim 1, wherein a key is generated for each file, the file is encrypted with the key, and the key and the encrypted file are transmitted via communication. An encrypted file management device, further comprising a file encryption unit for transferring the file to the file access unit in advance, wherein the file encryption unit is a separate device from the file access unit. 5. A key management unit according to claim 1, wherein the key management unit manages a key corresponding to the encrypted file on a device different from the file access unit. A key acquisition unit for acquiring the corresponding key by communication from the key management unit. 6. The apparatus according to claim 5, wherein the key is generated on a device different from the file access means, the file is encrypted with the key, and the encrypted file is transferred to the file via communication. An encrypted file management device, comprising: file encryption means for transferring the generated key to the key management device via communication by transferring the generated key to the access means. 7. The temporary file name generating means according to claim 1, wherein said temporary file name generating means generates a part or all of said temporary file name using random numbers. An encrypted file management device comprising: 8. The file access means according to claim 1, wherein said file access means is means for identifying by using only a part of the temporary file name when accessed by a temporary file name. An encrypted file management device comprising: 9. The file access means according to claim 1, wherein the file access means performs authentication based on an access source network address or an access source user name and a password, and the authentication is established. An encrypted file management device, which extracts the contents of a real file corresponding to the temporary file name only in a case. 10. An encrypted file management method for storing an encrypted file, wherein information specifying a file is input, and a temporary file for generating a temporary file name corresponding to the input information specifying the file is provided. A name generation step; decrypting the file corresponding to the temporary file name using an encryption key only when accessed with the generated temporary file name;
A file access step of outputting as a file having the temporary file name. 11. An encrypted file management method for storing an encrypted file, wherein information for designating a file and authentication information for authenticating an accessor are input, and access is permitted based on the authentication information. A temporary file name generating step of generating a temporary file name corresponding to the information designating the input file only if it is determined that the temporary file has been accessed; Decrypting the file corresponding to the file name using an encryption key and outputting the file as a file having the temporary file name. 12. A temporary file name generating procedure for inputting information for specifying a file and generating a temporary file name corresponding to the input information for specifying the file; and accessing the file with the generated temporary file name. Only when
A file access procedure for decrypting the file corresponding to the temporary file name using an encryption key and outputting the decrypted file as a file with the temporary file name. 13. An encrypted file management method for storing an encrypted file, wherein information for designating a file and authentication information for authenticating an accessor are input, and access is permitted based on the authentication information. A temporary file name generation procedure for generating a temporary file name corresponding to the information specifying the input file only when it is determined that the temporary file has been accessed; and only when the temporary file is accessed using the generated temporary file name, A file access procedure for decrypting the file corresponding to the file name using an encryption key and outputting the file as a file with the temporary file name.