JPH11212850A - Encrypted shared file transmission / reception system - Google Patents

Abstract

(57) [Summary] A shared file system in which an encryption key and a decryption key are generated by a key generation server information processing apparatus and a file is transmitted / received in an encrypted state, wherein a user generates the key generation server Provided is a shared file transmission / reception system in which once a user logs in to an information processing apparatus, it is not necessary to perform a login process every time a request for generating an encryption key and a decryption key is made. A key generation server access program for relaying data transmission / reception between each application in the client device and the key generation server information processing apparatus;
While the user is logged in to the key generation server information processing apparatus, the connection with the key generation server information processing apparatus is maintained by the key generation server access program 125e.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a shared file system for providing a shared file shared by a plurality of persons in an encrypted state, and more particularly, to generating a key for encryption and decryption. The present invention relates to a shared file transmission / reception system performed using a key generation device installed on a network.

[0002]

2. Description of the Related Art With the spread of a global network called the Internet, the number of cases where the Internet is connected to a company network and information is transmitted and received via the Internet is increasing. When connecting a corporate network to the Internet, it is required to prevent leakage of confidential information from the corporate network due to unauthorized access from the Internet. For this reason, it is common to control the transmission and reception of information between the Internet and a corporate network using a technique called a firewall. For information on firewalls, see "Software Des
ign "(Technical Review Company, 1996.11) pp. 39-
48 and the like.

[0003] When confidential information is transmitted and received via the Internet, there is also a problem that information is intercepted when the information is transferred on the Internet. For this reason, when transferring information, it is common to encrypt and transfer the information. Such a protocol for encrypting and transferring information is, for example, SSL (SecureSocket).
ticket Layer). These technologies are described in “OPEN DESIGN” (CQ Publishing Co., Ltd., 1996.) 100-117.

However, as described above, in the case of encrypting and transferring information at the time of transferring, there is a problem that the access speed becomes slow because the encrypting process is performed immediately before transmitting the information.

[0005] For the purpose of enhancing security, a key used for encryption and decryption is changed every time. Therefore, even when common information is transferred to a plurality of users, encryption processing is performed for each user. Therefore, there is a problem that the access speed is further reduced as a whole.

As a method for solving these problems, Japanese Patent Application Laid-Open No. 9-251426 discloses a method in which even if a plurality of users access a shared file, only one encrypted file is required, and a secure, encrypted file is used. A file receiving system and a control method thereof have been proposed. In this technique, a list describing conditions of a user who is permitted to decrypt (hereinafter, this list is referred to as a disclosure destination list) is transmitted to an IC card installed in a client device, and the disclosure destination list and the IC An encryption key and a decryption key are generated based on information called a master key recorded on the card.

[0007]

However, from the viewpoint of reducing the cost and labor for installing an IC card reader / writer, in an environment where an in-house network has already been prepared, an encryption key and a decryption key are provided on the network. It is desired to provide a key generation server information processing apparatus for generating a key generation server and generate an encryption key and a decryption key on the key generation server information processing apparatus.

In the technique described in Japanese Patent Application Laid-Open No. 9-251426, when the encryption key and the decryption key are generated using the key generation server information processing apparatus, the key generation server information processing is performed. The device is used by multiple users simultaneously from various applications. For this reason, there is a problem in that the user needs to log in to the key generation server information processing apparatus every time a request is made to generate an encryption key and a decryption key.

In the technique described in Japanese Patent Application Laid-Open No. 9-251426, when the encryption key and the decryption key are generated by using the key generation server information processing apparatus, the client apparatus and the server When the connection with the information processing device is disconnected due to a network failure, there is a problem that generation of an encryption key and a decryption key may fail.

In the technique described in Japanese Patent Application Laid-Open No. 9-251426, when the encryption key and the decryption key are generated by using the key generation server information processing apparatus, the key generation server information processing is performed. The key generated by the device is
The data is transferred to the client device as plain text. For this reason,
There is a problem that the key may be obtained illegally by eavesdropping or the like.

According to the technique described in Japanese Patent Application Laid-Open No. 9-251426, when an encryption key and a decryption key are generated using the key generation server information processing apparatus, a password is stored in the key generation server. The information is transferred to the information processing device, and the user of the client device is specified. For this reason, there is a problem that the password may be obtained illegally by eavesdropping.

In the technique described in Japanese Patent Application Laid-Open No. 9-251426, when a master key serving as a seed for generating an encryption key and a decryption key is changed, the shared file already encrypted is changed. Decryption becomes impossible. Therefore, there is a problem that it is difficult to change the master key.

A first object of the present invention is to provide an encryption key and a decryption key such that once a user logs in to the key generation server information processing apparatus, a user authentication process becomes unnecessary for key generation. An object of the present invention is to propose a secure encrypted file receiving system and a control method therefor, in which even when a plurality of users access a shared file, the generation is performed in the key generation server information processing apparatus, and only one encrypted file is required.

[0014] A second object of the present invention is to transfer an encryption key or a decryption key created in the key generation server information processing apparatus to a client apparatus and to illegally encrypt the encryption key even if eavesdropping is performed. The key generation server information processing apparatus generates an encryption key and a decryption key such that a key or a decryption key cannot be obtained. Even when a plurality of users access a shared file, only one encryption file is required. And to provide a secure encrypted file receiving system and a control method therefor.

[0015] A third object of the present invention is to generate an encryption key and a decryption key such that when a user logs in to the key generation server information processing apparatus, a password cannot be illegally obtained by eavesdropping. In the key generation server information processing apparatus, even if a plurality of users access a shared file, only one encrypted file is required, and a secure encrypted file receiving system and a control method thereof are proposed.

A fourth object of the present invention is to generate an encryption key and a decryption key in the key generation server information processing apparatus so that the master key can be changed. An object of the present invention is to propose a secure encrypted file receiving system and a control method therefor, in which only one encrypted file is required for access.

[0017]

According to a first aspect of the present invention, first, second, and third information that can communicate with each other via a communication medium are provided. A processing device, wherein the first information processing device includes a storage device for storing a shared file, the third information processing device includes an encryption key for encrypting the file, and Key generating means for generating a key for generating a decryption key for decrypting the encrypted file, wherein the second information processing apparatus receives a file from the first information processing apparatus; A browsing unit for browsing the contents of a given file; a file encryption unit for acquiring an encryption key from the third information processing device to encrypt the file; Obtain the decryption key from the information processing device The browsing means decrypts a file received from the first information processing apparatus, and maintains a connection between the file decoding means for providing the decrypted file to the browsing means and the third information processing apparatus; and And an access maintaining means for relaying data transmitted and received between the third information processing apparatus and the file encryption means. A file transmission / reception system is provided.

According to a second aspect of the present invention, a first type of program having at least a communication control function and a file input / output control function, and first information having a storage device for storing the file A processing device, a first program having at least a communication control function, and a second type of program for receiving the file from the storage device on the first information processing device via the first type of program. A shared file transmission / reception system in which a second information processing device having a program is connected via a communication line, wherein the third information is connected to the second information processing device through a communication line. A key used for encryption and decryption is generated by the processing device, and the key is provided to the file encryption unit and the file encryption unit via the data relay unit provided in the second information processing device. Encrypted shared file transmission and reception system, characterized in that it is transmitted to the Le decoding means.

According to a third aspect of the present invention, there is provided a file sharing system for providing a shared file to a client information processing apparatus, comprising: a file server information processing apparatus for storing an encrypted shared file; And an encryption key server information processing apparatus for generating an encryption key used for decryption of the shared file, wherein each shared file stored in the file server information processing apparatus is permitted to view the shared file. The encryption key server information processing apparatus includes disclosure destination information indicating a person who has performed the disclosure, and the encryption key server information processing apparatus converts the disclosure destination information included in the shared file requested to be browsed from the connected information processing apparatus to the file server information processing apparatus. Disclosure destination information acquisition means for acquiring from data transferred to the information processing apparatus from the information processing apparatus, User information acquiring means for acquiring information of a user who has requested viewing of the shared file, and determining whether or not the acquired user information satisfies a condition indicated by the acquired disclosure destination information. When the determination means and the determination means are determined to be satisfied,
Key generation means for generating a decryption key for decrypting the shared file, and file transfer means for transferring the requested shared file and the generated decryption key to the connected information processing apparatus The client information processing apparatus holds information for establishing a connection with the encryption key server information processing apparatus, and when requesting the encryption key server information processing apparatus to generate a key, A file sharing system for connecting to the third information processing device by using the held information for establishing the connection when the connection with the server information processing device is disconnected; Is provided.

According to the fourth aspect of the present invention, in a storage medium storing an encryption key and a key generation server access program for relaying the generation request, authentication relating to a user who has issued an encryption key generation request. In the above authentication, if the user is legitimately logged in, relay an encryption key generation request for generating an encryption key to an encryption key generation server information processing apparatus for generating an encryption key, An encryption key generated in response to the encryption key generation request is received from the encryption key server information processing apparatus, and provided to the authenticated user.
Only when the user is logged in to the information processing device on which the key generation server access program is being executed, relays the request for generating the encryption key, and the connection with the key generation server information processing device is established. When disconnected, a storage medium storing a key generation server access program is provided, which is connected to the key generation server information processing apparatus using user information obtained by performing authentication on the user. .

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

First, an outline of the configuration of a file sharing system applied to an encrypted WWW (World-Wide Web) system to which the present invention is applied will be described with reference to FIG.

In FIG. 1, a file sharing system 10 according to the present embodiment includes a server information processing apparatus 11 having a WWW server function, a client information processing apparatus 12 having a WWW client function, and a server information processing apparatus 11 having the WWW client function. And a key generation server information processing apparatus 14 for generating an encryption key / decryption key used for encryption / decryption of a shared file transmitted / received by the client information processing apparatus 12, connected to the network 1. ing.

As the network 1, for example, a local area network (LAN) such as an in-company network is applied.
They are connected to each other via a cable 15.

Here, FIG. 1 shows a case where one client information processing device 12 is connected to the network 1, but the number of connected client information processing devices 12 is not limited to this, and a plurality of client information processing devices 12 are connected. The client information processing device 12 may be connected to the LAN cable 15.

FIG. 1 shows a case in which one server information processing apparatus 11 is connected to the network 1. However, the number of connected server information processing apparatuses is not limited to this. The processing device 11 may be connected to the LAN cable 15.

Similarly, a plurality of key generation server information processing apparatuses 14 may be connected to the LAN cable 15.

Each of the information processing devices may be connected to the network 1 via a telephone line instead of the LAN cable 15. For example, if the client information processing device 12 and the server information processing device 11 are located at locations separated from each other, the LAN cable 15
Alternatively, both may be connected using a public line such as a telephone line. Also, according to the data transfer traffic between the processing devices, specific processing devices can be connected to each other via a transmission path having a larger transfer capacity and speed.

The server information processing apparatus 11 includes a central processing unit (hereinafter referred to as a CPU) 111 and a memory 112.
, A LAN controller 113, a disk controller 114, and a magnetic disk 115.

The server information processing apparatus 11 loads an operating system (hereinafter referred to as OS) 115a and a WWW server program 115b stored in a magnetic disk 115 into a memory 112 via a disk controller 114 at the time of startup. . And the CPU 11
1 functions as a WWW server by executing the WWW server program 115b.

That is, the server information processing apparatus 11 stores the HTML file 200 and the image file on the magnetic disk 115, and transmits the HTML file 200 requested by the client information processing apparatus 12 or the HTML file 200 in addition to the HTML file 200. An image file, a moving image file, an audio file, and the like (hereinafter also referred to as a referred file) linked (reference specified) to the file 200 are transferred to the client information processing apparatus 12.

As the WWW server program 115b, an existing program used in the WWW system can be used without any change.

The client information processing device 12
PU 121, memory 122, LAN controller 1
23, a disk controller 124, and a magnetic disk 125.

When the client information processing apparatus 12 starts up, the OS 125a stored in the magnetic disk 125 and the W
The WW decryption program 125b is loaded into the memory 122 via the disk controller 124.

The WWW decryption program 125b is for decrypting the data received from the server information processing apparatus 11 when the data is encrypted, and passing the decrypted data to the browser program 125c.

The client information processing device 12
According to the user's instructions, the browser program 125c
Is loaded from the magnetic disk 125 to the memory 122 via the disk controller 124. And CP
The U121 functions as a WWW client by executing the browser program 125c.

That is, the transfer of the HTML file 200 requested by the user or, in addition to this, the referenced file such as an image file is performed by the server information processing apparatus 11.
And displays the HTML file 200 and the referenced file transferred from the server information processing apparatus 11.

It should be noted that the browser program 125c uses the function of setting a proxy server so that when transmitting / receiving data to / from the server information processing apparatus 11, the browser program 125c must be set via the WWW decryption program 125b. Have been.

As the browser program 125c, any program that can use a proxy server can be used, and an existing program used in the WWW system can be used without any change.

The client information processing device 12
According to the user's instructions, the file encryption program 12
5d is loaded from the magnetic disk 125 to the memory 122 via the disk controller 124.

The file encryption program 125d is for encrypting the HTML file 200 created by the user.

The client information processing device 12
According to the user's instruction, the key generation server access program 125e is
The data is loaded from the magnetic disk 125 to the memory 122.

Key generation server access program 125e
Is for relaying a key generation request and an encryption key and a decryption key to and from the key generation server information processing apparatus 14.

The key generation request is sent to the WWW decryption program 125b or the file encryption program 125d.
Is transmitted to the key generation server information processing apparatus 14 from the server.
Then, the encryption key and the decryption key are sent from the key generation server information processing apparatus 14 to the WWW decryption program 125.
b and the file encryption program 125d.

The key generation server information processing device 14 has a CPU
141, memory 142, LAN controller 143
, Disk controller 144, magnetic disk 14
5 is provided.

When the key generation server information processing apparatus 14 starts up, the OS 145a stored on the magnetic disk 145,
The key generation program 145b is loaded into the memory 142 via the disk controller 144.

Note that the key generation server information processing apparatus 14
The password management file 145c and the user ID information file 145d are stored on the magnetic disk 145.

The key generation program 145b manages user password information by using a password management file 145c. The password information is loaded into the memory 142 according to an instruction of the key generation program 145b, and is used to identify a user.

The key generation program 145b manages the user's personal information by the user ID information file 145d. The user ID information is loaded into the memory 142 according to an instruction of the key generation program 145b, and is used to determine whether a user of the client device 12 has a right to decrypt.

Hereinafter, the above-described file sharing system 10
Will be described in more detail.

First, a case where a user who provides information (hereinafter, referred to as an information provider) encrypts the HTML file 200 will be described.

First, the information provider creates an HTML file 200 using a text editor, an HTML editor, or the like. FIG. 3 shows the H created by the user.
It is an example of a TML file 200.

Next, the information provider activates the key generation server access program 125e (see FIG. 1) and logs in to the key generation program 145b (see FIG. 1).

Next, the key generation access program 125e will be described with reference to FIGS.

First, the module configuration of the key generation server access program will be described with reference to FIG.

In FIG. 6, the key generation server access program 125e includes a login processing routine 4100,
Logout processing routine and key generation / generation request routine 4
300.

Next, an operation flow of the key generation server access program 125e (see FIG. 6) will be described with reference to FIG.

In the processing of the key generation server access program, first, in step 4001, the user
Acquire the user ID and password.

Next, using the obtained user ID and password, the key generation program 145b (FIG. 1)
(See step 4002). Then, it is determined whether or not the login is successful (step 40).
03).

If login fails, step 4
In step S009, control is performed such that the processing in steps 4001 to 4003 is repeated until three consecutive failures occur. On the other hand, if the login is successful, an event waiting state is set in step 4004.

When an event arrives while waiting for an event in step 4004, it is checked whether or not the event is a logout request (step 4005).

If the request is a logout request, logout processing is performed in step 4006, and the processing ends.
On the other hand, if the event is not a logout request, step 400 for checking whether the event is a key generation request.
7).

If it is a key generation request, step 4
At 008, a key generation request process is performed. If the event is not a key generation request, the flow shifts to step 4004 to return to the event waiting state.

In step 4007, control is performed so that step 4008 is executed only when the partner that has transmitted the key generation request is operating on the same client device 12. By performing such control, it is possible to prevent a user using another client device 12 from impersonating the user by illegally using the key generation server access program 125e.

The user ID and password obtained from the user in step 4001 are held by the key generation server access program 125e, and the connection with the key generation program 145b is disconnected due to a network failure or the like. In some cases, it is used to restore the connection.

Next, the key generation program 145b (see FIG. 1) will be described with reference to FIGS.

First, the module configuration of the key generation program 145b will be described with reference to FIG.

In FIG. 8, the key generation program 145b
Is configured to include a login processing routine 3100, a key generation routine 3200, and a logout processing routine 3300.

Next, an operation flow of the key generation program 145b (see FIG. 8) will be described with reference to FIG.

In the processing of the key generation program, first, in step 3001, the access from the key generation server access program 125e (see FIG. 6) is awaited. Upon receiving the access request, a login process is performed (step 3002), and it is checked in step 3003 whether the login process has been successful.

If login fails, step 3
Return to 001.

On the other hand, if the login is successful, the process goes to a step 3004 to wait for a request from the key generation server access program 125e (see FIG. 6). Upon receiving the request from the key generation server access program 125e, it is checked in step 3005 whether the request is a key generation request. In the case of a key generation request, key generation processing is performed (3008), and the process returns to step 3004.

If it is determined in step 3005 that the request is not a key generation request, it is determined in step 3006 whether the request is a logout request. In the case of a logout request, the connection with the key generation server access program 125e is disconnected, and the process returns to step 3001. If the request is not a logout request, the process returns to step 3004.

Referring to FIG. 17, an operation flow of the login processing routine 3100 (see FIG. 8) will be described. The login processing routine 3100 is for specifying a user who performs access.

First, in step 3101, a user ID is obtained from the client application. next,
The user's password information is read from the password information file (step 3102), and a user login process, that is, a user authentication process is performed (step 3).
103). At step 3104, it is checked whether or not the user authentication process has succeeded (step 3104). If the process has succeeded, the user ID information of the corresponding user is read (step 3105). On the other hand, if the user authentication process has failed, the process ends.

Referring to FIG. 10, transmission and reception of data between client information processing device 12 (see FIG. 1) and key generation information processing device 14 (see FIG. 1) will be described. Here, the key generation server access program 125e (see FIG. 6) in the client information processing device 12 is different from the key generation program 1 in the key generation information processing device 14.
The following description focuses on the timing of data transmitted and received between these programs when performing a login process at 45b (see FIG. 8).

First, the key generation server access program 125e executes the user ID acquired from the user.
Is transmitted to the key generation program. Next, the key generation program 145b generates a random number (hereinafter, the random number is referred to as challenge data).

Next, the challenge data is encrypted using a key (hereinafter, referred to as a user key) corresponding to the user ID, which is registered in advance, as an encryption key.

Next, the key generation program 145b
The encrypted challenge data is transmitted to the key generation server access program 125e. The key generation server access program 125e decrypts the encrypted challenge data using the password as a decryption key.

Next, the key generation server access program 125e creates data obtained by calculating the exclusive OR of the challenge data and 1 (hereinafter referred to as response data), and uses the password as an encryption key. hand,
The response data is encrypted, and the key generation program 1 is encrypted.
45b. The key generation program 145b includes:
The received data is decrypted using the user key, and the response data is extracted. Next, the key generation program 145b compares the extracted response data with data obtained by calculating an exclusive OR of the challenge data and 1 or not. If these data do not match, the key generation server access program is notified that the login has failed.
On the other hand, if these data match, the key generation server access program 125e is notified that the login has been successful.

In the present embodiment, the key generation program 145b and the key generation server access program 125
No password is exchanged with e. For this reason,
Passwords cannot be obtained by eavesdropping on data.

Further, only the encrypted data is transmitted and received between the key generation program 145b and the key generation server access program 125e. For this reason,
It is also difficult to collect a pair of a plaintext and an encryption key and estimate an encryption key, that is, a password.

Next, the information provider activates the file encryption program 125d and sets the HTML file 2
00 is encrypted.

Referring to FIG. 13, HTML file 20
A description will be given of data transmitted and received between the programs of the present embodiment when the encryption process is performed on 0.

First, the information provider uses the file encryption program 125d to create an HTML file 20.
Create the disclosure destination list for 0. Next, the file encryption program 125d stores the created disclosure destination list in the key generation server access program 125e.
Via the key generation program 145b.

The key generation program 145b generates an encryption key based on the received disclosure list and transmits the encryption key to the file encryption program 125d via the key generation server access program 125e. . At this time, the key generation program 145b combines the master key identifier corresponding to the master key used to generate the encryption key and the disclosure destination list with the file encryption program. 125d.

The file encryption program 125
d, using the received encryption key, the HTML file 2
00 is encrypted and the master key identifier and the disclosure destination list are encrypted (hereinafter, referred to as an encrypted disclosure destination list) and added to the HTML file 200. In the present embodiment, the disclosure destination list is encrypted and added. For this reason,
Users who do not have decryption rights will see the HTM
It is difficult to estimate the contents of the L file 200. Therefore, information requiring confidentiality can be stored more safely.

The disclosure destination list includes a condition of a user who is permitted to decrypt an encrypted file, a condition of a user who is permitted to decrypt (hereinafter referred to as an additional condition), or a condition of a user who is refused decryption (hereinafter referred to as additional condition). (Hereinafter referred to as an exclusion condition). The term is described following a delimiter indicating whether the term indicates an additional condition or an exclusion condition. If a plurality of terms are included, they are arranged by being separated by the delimiter. A comma (,) is used as a delimiter indicating the additional condition, and a minus (-) is used as a delimiter indicating the exclusion condition. However, if a term indicating the additional condition appears at the top of the list of disclosure destinations, the delimiter (,)
Is omitted.

The term includes at least one conditional expression in which a user condition is described by a relational operator. The conditional expression describes the condition of the user in the user ID information file 145d.
This is for designating an attribute in (see FIG. 2) or a group name indicating another group. When a common term includes a plurality of conditional expressions, the conditional expressions are connected by a logical operator (＾). This logical operator (＾) has the meaning of logical product.

In each conditional expression, “category number”, “data / code identifier”, “relational operator”, and “condition data” are described in association with each other.

The "category number" is for indicating a category of data used for designating a condition.

The "data / code identifier" is for identifying the type of data in the category indicated by the category number. As the data / code identifier, D (Data) indicating that the type of data used to specify the condition uses data information in the user ID information file 145d and code information in the user ID information file 145d are used. And C (Code) indicating

The "condition data" is used to specify a condition together with a relational operator, and corresponds to the "condition data" corresponding to the information specified by the "category number" and "data / code identifier". ", Any of data and code is used. The relational operators are equal (=), not equal (≠), large (>),
Small (<) can be used. If the “condition data” is a character string other than a numerical value, the relation specified by the relational operator can be defined using the numerical value of the character code.

Here, the operation of the relational operator is performed prior to the operation of the logical operator and the separator.
Further, the operation of the logical operator is performed prior to the operation of the delimiter. The calculation of the delimiter is performed in order from left to right.

For example, when the definition of the user ID information 145d shown in FIG. 2 is used, the disclosure destination list for the disclosure destination of “the chief of the fourth part of the system research institute and Taro Crypt” is “5C = 676 / 6C = 04 / 8C> =
5,2D = Kitaro). That is, this disclosure destination list is described by two items indicating additional conditions, and the first item is described by a logical product of three conditional expressions.

Further, the disclosure destination list for the disclosure destination of “except for the business at the head office and other than the safety section of the system laboratory and excluding the name codes 6781901001 and 678951010” is “5C = 001 ＾ 6C ≠ 2
1,5C = 676 ＾ 7C ≠ 402-4C = 6781901001-
4C = 678951010 ". In other words, this disclosure destination list is described by two terms indicating an additional condition and two terms indicating an exclusion condition. Of these, the first and second terms are each described by a logical expression of two conditional expressions. ing.

In FIG. 13, the key generation server access program 125e and the key generation program 145
The data transmitted / received with b is transmitted / received after being encrypted. For this reason, it is possible to prevent leakage of confidential information due to eavesdropping.

Referring to FIG. 23, the format of data transmitted and received between the key generation server access program 125e (see FIG. 10) and the key generation program 145b (see FIG. 10) will be described.

In FIG. 23, the key generation server access program 125e and the key generation program 145
b includes an area 301 for describing the encryption key and an area 3 for describing the length of the data.
02, an area 303 for describing data, and an area 304 for describing a checksum.

The area 301 is an area for describing a key used for encrypting data to be transmitted next time, and describes an encryption key used for encrypting data to be transmitted next time. Thus, the encryption key can be changed for each transmission without using a special key exchange procedure.

The length of the data described in the area 302 is the length of the data described in the area 203. The contents of data transmitted and received between the key generation server access program 125e and the key generation program 145b are described in the area 303.

The checksum described in the area 304 is used to check whether or not the received data described in the 303 has an error. By comparing the data in the area 303 with the checksum described in the area 204, it is possible to confirm that the data has not been tampered with during transmission.

Since the key to be initially transmitted and received between the key generation server access program 125e and the key generation program 145b does not exchange a key for encryption, the data is encrypted using the password. Perform the conversion.

Referring to FIG. 5, the operation flow of file encryption program 125d (see FIG. 1) will be described.

In FIG. 5, in the processing of the file encryption program, first, in step 1201, a temporary file for temporarily outputting the result is created. Next, step 1
At 202, the disclosure destination list is created. Next, the created disclosure destination list is transmitted to the key generation program 145b (step 1203), and the encrypted disclosure destination list and H
An encryption key for encrypting the TML file 200 is received (step 1204). In step 1205,
The access control header portion including the encrypted disclosure destination list is written in a temporary file. Next, step 1206
The data of the HTML file 200 (hereinafter, referred to as input file) to be encrypted is read into the buffer, and it is checked in step 1207 whether all the data has been read from the input file. This means that if the size of the read data is 0, it is determined that all data has been read from the input file.

If all data has not been read from the input file, the read data is encrypted with the encryption key (step 1208), and the encrypted data is written to a temporary file (step 1209).
It returns to step 1206.

On the other hand, if all the data of the input file has been read, the footer is written in the temporary file (step 1210), the input file is closed (step 1211), and the temporary file is also closed (step 1212). . Next, in step 1213, it is checked whether or not the file name of the encrypted HTML file 500 (hereinafter, referred to as an output file) matches the file name of the input file. If the file names do not match, the file name of the temporary file is changed to the output name (step 1215), and the process ends.

On the other hand, if the file names match, after deleting the input file in step 1214, the file name of the temporary file is changed to the output file name, and the process is terminated.

[0109] The encrypted HTML file 500 that has been subjected to the encryption processing as described above is provided by the information provider.
It is stored on the magnetic disk 115 of the server information processing device 11.

With reference to FIG. 12, a processing flow in the key generation processing request routine 4300 (see FIG. 6) of the key generation server access program 125e (see FIG. 6) will be described.

The key generation server access program 12
In the processing of the key generation processing request routine 4300 of 5e, first, in step 4301, the key generation program 145 is executed.
b (see FIG. 8) is checked to see if the connection has been broken. If the connection is not broken, step 4
Execute step 304 and below.

On the other hand, if the connection has been disconnected, login processing is performed using the user ID and password held by the key generation server access program 125e (step 4302). It is determined whether or not it is (Step 4303).

If the login processing has failed, the WWW decryption program 125 that has transmitted the key generation request
b (see FIG. 7) or the file encryption program 125d (see FIG. 1) (hereinafter these programs are collectively referred to as client applications) to notify the key generation failure (step 4306), and To end.

On the other hand, if the login process is successful,
Proceeding to a step 4304, the key generation program 14
The key generation request received from the client application is transferred to 5b (step 4304). Next, a response to the key generation request is received from the key generation program 145b and transferred to the client application (Step 4305).

The key generation request and the response to the key generation request are encrypted at the time of transmission using the session key exchanged at the time of the login process, and are decrypted at the time of reception using the session key.

Referring to FIG. 15, a description will be given of a procedure in which the key generation program 145b (see FIG. 1) generates an encryption key from the disclosure destination list received from the file encryption program 125d (see FIG. 1). . Here, a procedure for calculating the hash value of the disclosure destination list and generating the encryption key will be described. However, the type of the encryption key and the procedure for generating the key are not limited thereto.

In FIG. 15, first, when the data length of the disclosure destination list is not the number of bytes of an integral multiple of 8 (8 m), a random number is added so as to have a length of an integral multiple of 8. If the data length of the disclosure destination list is an integral multiple of 8, an 8-byte random number is simply added. By adding a random number in this way, even when a plurality of encryption keys are generated for a disclosure destination list having a common disclosure destination content, different encryption keys can be used.

Next, a value of a hash function having the disclosure destination list shaped as described above as an argument is obtained, and the value is used as an encryption key.

That is, from the top of the disclosure destination list,
Encrypt by block encryption every 8 bytes. At the time of these encryptions, in the encryption of the first block, an exclusive OR of a predetermined initial value and a generated block cipher is calculated, and then used as an initial value of the block cipher. Hereinafter, the same processing is repeated until the last block, and the exclusive OR of the encryption output in the last block encryption and the predetermined initial value is used as the encryption key.

In the block cipher, input data is encrypted using an 8-byte master 125f and an 8-byte initial value.

Next, an operation flow of the key generation routine 3200 of the key generation program 145b will be described with reference to FIG.

First, in step 3201, the disclosure destination information is received from the client application, and it is checked whether or not the disclosure destination information is encrypted (step 320).
2). If it is encrypted, it is decrypted (step 3203), and if it is not encrypted, it proceeds to step 3204.

Next, the disclosure destination list is extracted from the disclosure destination information, and it is checked whether or not the logged-in user satisfies the conditions of the disclosure destination list (step 3205).
If the user satisfies the condition, an encryption key is generated from the disclosure destination list (step 3206), and the disclosure destination list and the master key identifier are encrypted to create encrypted disclosure destination information (step 3207). ). Next, the generated encryption key and the encryption disclosure destination list are transmitted to the client application (step 3208), and the process ends.

On the other hand, if the user does not satisfy the condition in step 3205, the client application is notified of "no decryption right" (step 3209).
The process ends.

Referring to FIG. 4, the encrypted HTML file will be described. This HTML file is obtained by encrypting an HTML file 200 (see FIG. 3) described in plain text by the file encryption program 125d (see FIG. 1).

In FIG. 4A, an encrypted HTML file 500 includes a header for access control (hereinafter referred to as a header).
Access control header portion 501) and the plaintext H
A body part 502 obtained by encrypting the TML file 200;
It is configured to include the footer portion 503.

With reference to FIG. 4B, details of each part of the HTML file will be described.

In FIG. 4B, the encrypted HTML file 500 includes an area 510 for storing the access control header part 501, an area 520 for storing the main body part 502, and the footer part 503. And a portion 530 for storing

The area 510 includes an area 511 for writing a character string indicating an access control header,
An area 512 that describes the identifier of the user who encrypted the HTML file, an area 513 that describes the date when the HTML file was encrypted, an area 514 that describes the encryption disclosure destination list, An area 51 for describing a file name of a message to be displayed when there is no right to access the HTML file.
5 and an area 516 for describing the host name of a key generation server information processing apparatus 14 (see FIG. 1) capable of generating a decryption key for decrypting the main part of the HTML file. Is done.

In the area 510 for storing the access control header part 501, the file name indicating the message file storing the message to be displayed when there is no right to access, which is recorded in the area 515, is URL ( UniformResource Loc
attors) format. The message file is stored in the server information processing device 11 (FIG. 1).
(See FIG. 1).

The body part 50 stored in the area 520
2 is the plaintext HTML file 200 encrypted using the encryption key.

Note that, as shown in FIG.
Since the TML file 500 is described using a grammar that describes an HTML comment, the encrypted HTML
Even when the L file 500 is directly displayed by the browser program, it is possible to prevent the screen from being disturbed.

Lastly, the information provider instructs the key generation server access program 125e to log out of the key generation program 145b.

Referring to FIG. 11, logout processing routine 42 of key generation server access program 125e.
00 will be described.

First, in step 4201, the key generation server access program 125e checks whether or not the connection with the key generation program 145b has been disconnected. If the connection is broken, step 4
Step 203 is performed. On the other hand, if the connection has not been disconnected, a logout request is transmitted to the key generation program 145b to request the key generation program 145b to disconnect the connection (step 4202). next,
In step 4203, the stored user ID and password are discarded, and the process ends.

Next, a case where the user browses the encrypted HTML file 500 will be described.

First, the user activates the key generation server access program 125e and logs in to the key generation program 145b.

[0138] For login, the HTML file 2
Since it is the same as the case of encrypting 00, detailed description is omitted here.

Next, the user starts the browser program 125c and browses the encrypted HTML file 500.

Referring to FIG. 14, when transmitting / receiving encrypted HTML file 500 between server information processing apparatus 11 and client information processing apparatus 12, it is transmitted / received between programs of this embodiment. The data will be described.

First, when the user requests the encrypted HTML file 500 from the browser program 125c, the browser program 125c sends the encrypted HTML file 500 to the WWW server program 115b via the WWW decryption program 125b.
Send a transfer request. The WWW server program 1
15b transmits the encrypted HTML file 500 requested by the browser program 125c to the WWW decryption program 125b. The WWW decryption program 125 that has received the encrypted HTML file 500
b, the encrypted disclosure destination list extracted from the encrypted HTML file 500 is stored in the key generation program 145b through the key generation server access program 125d.
Transfer to The key generation program 145b decrypts the encrypted disclosure destination list, checks whether the ID information of the user matches the decrypted disclosure destination list, and notifies the result to the key generation server access program 125e. At this time, if it is determined that “the user has the right to decrypt the encrypted HTML file 500”, a key for decryption is generated, and the WWW decryption program 125 is generated via the key generation server access program 125d.
b. The WWW decryption program 125b includes:
If the key generation program 145b determines that “the user has the right to decrypt the encrypted HTML file 500”, the key generation program 145b receives the decryption key and
The L file 200 is decrypted using the decryption key and transferred to the browser program 125c. On the other hand, the key generation program 145b indicates that “the user does not have the right to decrypt the HTML file 200”.
If it is determined, the file name of the error message file is extracted from the HTML file 200, and an error message file is requested to the WWW server program 115b. Then, the error message file received from the WWW server program 115b is transferred to the browser program 125c. The browser program 125c displays the file received from the 135b on the screen of the client information processing device 12.

[0142] The contact information of the setter of the disclosure destination list may be added to the contents of the error message file.
As a result, it becomes possible for a person who has not been able to decrypt the content to request a right to decrypt the content or to inquire why the decryption is not permitted. Therefore, for example, a person who has not been permitted to decrypt by mistake can be given an opportunity to obtain the right to decrypt.

Even if the user does not have the right to decrypt, only the unencrypted information may be displayed without displaying the error message. This allows for a user-transparent interface, allowing users to
It is possible to continue browsing without being aware of the existence of hidden information (information that is not allowed to be decrypted).

The module configuration of the WWW decoding program 125b will be described with reference to FIG.

The WWW decryption program 135b comprises a data relay processing routine 2200 and a decryption right confirmation routine 2300.

The data relay processing routine 2200 is for relaying data transmission / reception performed between the WWW server program 115b and the browser program 125c.

Referring to FIG. 19, the processing flow of data relay processing routine 2200 will be described.

First, in step 2201, a request from the browser program 125c is awaited. When the request comes, in step 2202, the request is transferred to the WWW server program 115b. Next, the HTML file 200 is received from the WWW server program 115b. In step 2207, it is determined whether or not the HTML file 200 is the encrypted HTML file 500. If the HTML file 200 is not the encrypted HTML file 500, the HTML file 200 is transmitted to the browser program 125c in step 2218. On the other hand, if the file is an encrypted HTML file 500, step 2
The process proceeds to 205, where the user
It is checked whether the user has already logged in to 5b. If the user has been logged in, the steps from step 2208 on are executed. If the user has not been logged in, the key generation server access program 125e is activated to perform a login process (step 2206). Next, step 220
It is checked whether or not the login process of Step 6 has succeeded. If the login has failed, an error message is transferred to the browser program 125c, and the process returns to Step 2201. On the other hand, if the login is successful, step 22
At 08, the decryption right confirmation routine 2300 is called to check whether the user has the decryption right for the encrypted HTML file 500. If the user has the decryption right, the key generation server access program 125
e, the decryption key is received from the key generation program 145b, and the encrypted HTML file 500 is decrypted. In step 2212, when the decrypted data is transmitted to the browser program 125c,
Return to 01. On the other hand, if the user does not have the decryption right, the URL of the error message file is extracted from the encrypted HTML file 500 (step 2213), and the WWW server program 115b is requested to transfer the error message file (step 2214). next,
In step 2215, the WWW server program 11
5b, and transfers the error message file to the browser program 125c (step 2216). Upon completion of the file transfer, the process returns to step 2201.

Referring to FIG. 20 and FIG. 21, the relationship between the presence or absence of the access right and the displayed screen will be described.

Referring to FIG. 20, it is displayed when a user who has a right to access the encrypted HTML file 500 (see FIG. 4) requests transfer of the encrypted HTML file of FIG. The screen will be described.

Next, referring to FIG. 21, the encrypted HT
A user who does not have the right to access the ML file 500 (see FIG. 4) can use the encrypted HTML of FIG.
The screen displayed when the transfer of the file 500 (see FIG. 4) is requested will be described. In this example, the server information processing apparatus 11 stores the file shown in FIG. 22 as an error message file.

Finally, the user instructs the key generation server access program 125e to log out of the key generation program 145b, and ends browsing the encrypted HTML file 500 (see FIG. 4). The logout process is the same as the logout process for encrypting the HTML file 200 (see FIG. 3) described above, and thus a detailed description is omitted here.

[0153]

As described above, according to the present invention,
Since a key generation server access program for maintaining the connection with the key generation server information processing apparatus is provided on the client apparatus, once a user logs in to the key generation server information processing apparatus, a key is generated. Each time a request is made, there is an effect that it is not necessary to perform a user authentication process.

Further, according to the present invention, when the encryption key and the decryption key created in the key generation server information processing device are transferred to the client device, they are encrypted and transferred.
Even if eavesdropping is performed, there is an effect that the encryption key or the decryption key cannot be obtained illegally.

Further, according to the present invention, when a user logs in to the key generation server information processing apparatus, user authentication is performed by encrypting and decrypting random numbers using a password as a key. There is an effect that it is not possible to obtain a password illegally by eavesdropping on.

Further, according to the present invention, a plurality of master keys are used to transmit a disclosure destination list and a master key identifier when requesting key generation to the key generation server information processing apparatus. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is an encrypted WWW to which an embodiment of the present invention is applied.
FIG. 1 is a schematic configuration diagram of a system.

FIG. 2 is a diagram showing an example of the contents of a user ID information file 145d.

FIG. 3 is a diagram showing an example of an HTML file 200.

FIG. 4 is a diagram showing an example of an encrypted HTML file 500.

FIG. 5 is a diagram showing an operation flow of a file encryption program 125d.

FIG. 6 is a diagram showing a module configuration of a key generation server access program 125e.

FIG. 7 is a diagram showing a module configuration of a WWW decryption program 125b.

FIG. 8 is a diagram showing a module configuration of a key generation program 145b.

FIG. 9 is a diagram showing an operation flow of a key generation server access program 125e.

FIG. 10 is a diagram showing a timing chart of a login process.

FIG. 11 is a diagram showing an operation flow of a logout processing routine 4200 of the key generation server access program 125e.

FIG. 12 is a diagram showing an operation flow of a key generation request processing routine 4300 of the key generation server access program 125e.

FIG. 13 is a diagram showing data transmitted and received between programs when an HTML file 200 is encrypted.

FIG. 14 is a diagram showing data transmitted and received between programs when an encrypted HTML file 500 is transmitted and received.

FIG. 15 is a diagram showing a flow when the key generation program 145b generates an encryption key.

FIG. 16 is a diagram showing an operation flow of the key generation program 145b.

FIG. 17 is a diagram illustrating an operation flow of a login processing routine 3100 of the key generation program 145b.

FIG. 18 is a diagram showing an operation flow of a key generation routine 3200 of the key generation program 145b.

FIG. 19 is a diagram showing a processing flow of a data relay processing routine of the WWW decryption program 125b.

FIG. 20 is an example of a screen displayed when a decryption right user browses an encrypted HTML file 500.

FIG. 21: A user who does not have decryption right can use the
It is an example of a screen displayed when browsing the ML file 500.

FIG. 22: A user who does not have the decryption right can use the encryption HT
7 is an example of an error message file displayed when browsing the ML file 500.

FIG. 23 shows the key generation server access program 125.
FIG. 14 is a diagram showing a format of data transmitted and received between e and the key generation program 145b.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Network, 11 ... Server information processing apparatus, 12 ...
Client information processing device, 14 ... Key generation server information processing device, 111 ... CPU, 112 ... Memory, 113 ... L
AN controller 114 disk controller 1
15 ... magnetic disk, 115a ... OS, 115b ... WW
W server program, 121: CPU (central processing unit), 122: memory, 123: LAN controller,
124 ... disk controller, 125 ... magnetic disk, 125a ... OS (operating system), 1
25c: Browser program, 125d: File encryption program, 131: CPU, 132: Memory, 13
3 LAN controller, 134 disk controller, 135 magnetic disk, 135a OS (operating system), 135b WWW decoding program, 141 CPU (central processing unit), 142 memory, 143 LAN controller, 144 Disk controller, 145 ... magnetic disk, 145a ... OS
(Operating system) 145b Key generation program 145c Password information 145d User ID information 145f Master key 200 HTML file 500 Encrypted HTML file

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04L 9/32 H04L 9/00 675A

Claims (10)

[Claims] An information processing apparatus includes: a first information processing apparatus that can communicate with each other via a communication medium, wherein the first information processing apparatus stores a shared file; The third information processing apparatus generates an encryption key for encrypting a file and a key for generating a decryption key for decrypting the encrypted file. The second information processing device receives a file from the first information processing device, and browses the content of a given file; and File encryption means for obtaining an encryption key from an information processing device of the first type and encrypting a file; obtaining a decryption key from the third information processing device; Decrypt received files A file decrypting unit that provides a decrypted file to the browsing unit, and maintains a connection with the third information processing apparatus, and one of the file encrypting unit and the file decrypting unit; An encrypted shared file transmission / reception system, comprising: access maintaining means for relaying data transmitted / received between the third information processing apparatuses. 2. The encrypted shared file transmission / reception system according to claim 1, wherein the access maintaining means holds information for establishing a connection with the third information processing apparatus, and wherein the third information processing is performed. When the connection to the third information processing device is disconnected when requesting the device to generate a key, the information for establishing the connection is used for the third information processing device.
An encrypted shared file transmission / reception system, wherein the system is connected to an information processing device. 3. The encrypted shared file transmission / reception system according to claim 1, wherein the third information processing device transmits the data to the second information processing device immediately before transferring the data to the second information processing device. The information processing apparatus further includes data encryption means for encrypting and transmitting the data, wherein the second information processing apparatus decrypts data received from the third information processing apparatus and transfers the data to the access maintaining means. An encrypted shared file transmission / reception system, further comprising a data decryption unit. 4. The encrypted shared file transmission / reception system according to claim 3, wherein the second information processing device further includes a random number generation unit for generating a random number; When a connection with the third information processing device is established, a random number generated by the random number generation means transmitted from the second information processing device to the third information processing device is transmitted to the data encryption device. An encrypted shared file transmission / reception system, wherein the encrypting means uses the key as a key for performing encryption. 5. The encrypted shared file transmission / reception system according to claim 4, wherein the second information processing device sends a password of a user of the second information processing device to the third information processing device using an encryption key. The third information processing device transmits the encrypted random number received from the second information processing device to a pre-registered secret information of the user. An encrypted shared file transmission / reception system, characterized in that the decrypted data is used as a key of the data encryption means. 6. The encrypted shared file transmission / reception system according to claim 1, wherein the third information processing device includes: a random number generation unit configured to generate a random number; Data obtained by transmitting a random number obtained by encrypting the secret information of the user of the second information processing apparatus as an encryption key to the client apparatus, and decrypting data returned from the client apparatus using the secret information as a decryption key. And a user verification unit that determines that the user is a valid user when the data obtained by performing the predetermined process matches the random number, and that determines that the user is not a valid user when the data does not match. The second information processing apparatus decrypts data received from the key generation server information processing apparatus using a password input by a user as a decryption key. And a user certification unit for returning data obtained by performing the predetermined processing and encrypting the data using the password as an encryption key to the key generation server information processing apparatus. File transfer system. 7. The encrypted shared file transmission / reception system according to claim 1, wherein the third information processing device has a storage device, and stores first key information and the second key information. The attribute information of the user of the information processing device is stored in the storage device in advance, and the second information processing device sets the attribute information of the user who permits decryption of the file when requesting key generation. The key generation unit transmits the list described in combination with the first key identifier, and only when the attribute information of the user satisfies the condition of the list, the list and the identifier An encrypted shared file transmission / reception system, wherein a second key for encrypting and decrypting the file is generated from the corresponding first key information. 8. A first information processing apparatus having at least a first type of program having a communication control function and a file input / output control function, and a storage device for storing the file, and at least a communication control function. A second program including a first program having the first program and a second program for receiving the file from the storage device on the first information processing device via the first program.
Is a shared file transmission / reception system in which the third information processing device is connected to the second information processing device via a communication line. Generating a key used for decryption, wherein the key is transmitted to a file encryption unit and a file decryption unit via a data relay unit provided in the second information processing apparatus. An encrypted shared file transmission / reception system. 9. A file sharing system for providing a shared file to a client information processing apparatus, wherein the file server information processing apparatus stores an encrypted shared file, and is used for decrypting the shared file. An encryption key server information processing device for generating an encryption key, wherein each shared file stored in the file server information processing device includes disclosure destination information indicating a person who is permitted to view the shared file. The encryption key server information processing device includes: a device for transmitting disclosure destination information included in a shared file requested to be browsed by a connected information processing device from the file server information processing device to the information processing device; And a disclosure destination information acquisition unit for acquiring the shared file in the connected information processing apparatus. User information acquisition means for acquiring the information of the requested user; and determination means for determining whether the acquired information of the user satisfies the condition indicated by the acquired disclosure destination information, A key generation unit for generating a decryption key for decrypting the shared file when the determination unit determines that the shared file is satisfied; and the connected information processing of the requested shared file and the generated decryption key. A file transfer unit for transferring to the device, wherein the client information processing device holds information for establishing a connection with the encryption key server information processing device, and stores a key in the encryption key server information processing device. When requesting the generation, if the connection with the encryption key server information processing apparatus is disconnected, using the information for establishing the held connection, File sharing system, characterized in that connected to the serial third information processing apparatus. 10. A storage medium that stores an encryption key and a key generation server access program for relaying a generation request for the encryption key, authenticates a user who has issued an encryption key generation request. Relays the encryption key generation request for generating the encryption key to the encryption key generation server information processing apparatus for generating the encryption key, and responds to the encryption key generation request. The generated encryption key is received from the encryption key server information processing apparatus, and provided to the authenticated user. In the authentication, the user sends the generated encryption key to the information processing apparatus on which the key generation server access program is executed. Only when the user is logged in, the relay of the above-described encryption key generation request is executed, and the connection with the key generation server information processing apparatus is disconnected. If it is, by using the user information obtained by performing an authentication related to the user, a storage medium which stores a key generation server access program, characterized in that connected to the key generating server information processing apparatus.