JP7143088B2 - File encryption system and file encryption program - Google Patents

Description

The present invention relates to a file encryption system comprising a server and a plurality of terminals, and a file encryption program for the system.

A conventional example of such a file encryption system is described in Japanese Unexamined Patent Application Publication No. 2018-007088 (Patent Document 1). In the file encryption system of Patent Literature 1, a first terminal executes encryption processing to encrypt a data file, generates an encrypted file, and stores the encrypted file in an external device. Then, the decryption process is executed in the second terminal to decrypt the encrypted file stored in the external device to generate the data file. Here, the first terminal embeds connection environment information that uniquely indicates the external device in the encrypted file when executing the encryption process. When the second terminal decrypts the encrypted file, the second terminal compares the connection environment information of the external device connected to the second terminal with the connection environment information embedded in the encrypted file, and confirms that they match. The encrypted file is decrypted to the data file when the two match, and the encrypted file is not decrypted to the data file when they do not match.

JP 2018-007088 A

In the file encryption system described above, the encrypted file cannot be decrypted unless the encrypted file and the external device in which the encrypted file is first stored are available. Therefore, it is possible to prevent the encrypted file from being illegally copied and spread. However, in this file encryption system, if a malicious person obtains an external device in which the encrypted file is initially stored together with the encrypted file due to the theft of the external device, etc., the encrypted file will be decrypted and the contents will be revealed. It may be read.

Therefore, it is desired to implement a file encryption system that can restrict decryption of an encrypted file by an outsider.

In view of the above, a first characteristic configuration of a file encryption system includes a server and a plurality of terminals, the server generates organization information that is information indicating an organization to which the server belongs, and a plurality of the Among the terminals, the terminal that executes encryption processing is defined as a first terminal, the terminal that executes decryption processing is defined as a second terminal, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs . and the encryption process encrypts the data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal. The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal, and the first terminal an identification information generation process for generating identification information unique to the data file to be encrypted; and an encryption key generation process for generating the encryption key based on the identification information and the organization information of the first terminal. and a combining process of encrypting the identification information based on the organization information of the first terminal to generate encrypted identification information, and combining the encrypted identification information with the encrypted file; an identification information decryption process of decrypting the encrypted identification information combined with the encrypted file into the identification information based on the organization information of the second terminal; and a decryption key generation process for generating the decryption key based on the organization information, wherein in the decryption process, the organization information of the second terminal used for the decryption key is used for the encryption key. when the identification information used for the decryption key matches the identification information used for the encryption key , the decryption key is stored in the encrypted file It is effective against
In view of the above, a second characteristic configuration of a file encryption system includes a server and a plurality of terminals, the server generates organization information that is information indicating an organization to which the server belongs, and a plurality of the Among the terminals, the terminal that executes encryption processing is defined as a first terminal, the terminal that executes decryption processing is defined as a second terminal, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs. and the encryption process encrypts the data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal. The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal, wherein the decryption process includes: When the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is valid for the encrypted file. , the first terminal performs a date and time combination process for combining date and time information indicating a date and time when the organization information of the first terminal was generated with the encrypted file, and combines the date and time information with the encrypted file in the decryption process. If the date and time indicated by the date and time information stored in the second terminal is later than the date and time when the organization information of the second terminal was generated, the encrypted file is not decrypted into the data file.
In view of the above, a third characteristic configuration of a file encryption system includes a server and a plurality of terminals, the server generates organization information that is information indicating an organization to which the server belongs, and a plurality of the Among the terminals, the terminal that executes encryption processing is defined as a first terminal, the terminal that executes decryption processing is defined as a second terminal, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs. and the encryption process encrypts the data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal. The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal, wherein the decryption process includes: When the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is valid for the encrypted file. , the first organization to which the first terminal belongs and the second organization to which the second terminal belongs are different organizations, and the servers include the first server belonging to the first organization and the second organization and the first server is configured to be able to input second server information, which is information indicating the second server, and based on the input second server information, the executing a retrieval preparation process of encrypting the first organization information, which is the organization information indicating the first organization, to generate encrypted first organization information, wherein the second server has self information, which is information indicating itself; , the second terminal configured to be able to input the encrypted first organization information, and executing an introduction process of decrypting the input encrypted first organization information into the first organization information based on the self information; is that the first organization information decrypted by the introduction process is used in addition to the organization information possessed by the second terminal as the organization information used for the decryption key.

According to these configurations, when the first terminal and the second terminal belong to the same organization, the decryption key is valid for the encrypted file, and the encrypted file can be decrypted into the data file. On the other hand, if the first terminal and the second terminal belong to different organizations, the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key. Since the decryption key is not valid for the encrypted file, the encrypted file cannot be decrypted to a data file. That is, an encrypted file encrypted at the first terminal cannot be decrypted at a terminal belonging to an organization different from that of the first terminal. Therefore, according to this file encryption system, the encrypted file can be restricted from being decrypted by an outsider.
Also, according to the first characteristic configuration described above, in addition to the organization information, the identification information is used to generate the encryption key and the decryption key. Therefore, encryption and decryption keys can be made more complicated. In addition, since the encryption identification information is combined with the encrypted file, the structure of the encrypted file itself can be complicated. Therefore, the encryption strength of the encrypted file can be increased.
Further, if the date and time when the organization information of the second terminal was generated is older than the date and time when the organization information of the first terminal was generated, there is a possibility that the organization information of the second terminal has not been updated to the new organization information. There is According to the second characteristic configuration, since the decryption process is not performed in such a case, it is possible to prevent a situation where the encrypted file cannot be decrypted into the data file due to the decryption process being performed based on the old organizational information. can.
Further, according to the above third characteristic configuration, the organization information of the first organization to which the first server belongs can be introduced to the second server belonging to the second organization. At this time, the first organization information indicating the first organization is encrypted and transferred between the first server and the second server, and cannot be decrypted without the information of the second server. Therefore, it is possible to reduce the possibility that the first organization information is leaked to the outside, and to introduce the first organization information to the second server with high safety. This makes it possible for the second terminal belonging to the same organization as the second server to generate the decryption key based on the first organization information. Therefore, according to the third characteristic configuration, only when the organization information of the first organization is introduced to the second server belonging to the second organization, the encrypted file encrypted by the first terminal belonging to the first organization can be decoded by a second terminal belonging to a second organization different from the first organization.

Here, the server encrypts the organization information indicating the organization to which the server and the plurality of terminals managed by the server belong with a private key, and transfers the encrypted organization information to the plurality of terminals managed by the server. It is preferable that a distribution process for distributing information is executed, and a public key paired with the private key is disclosed to the plurality of terminals managed by the server.

In this file encryption system, organization information is important information used for encryption keys. According to this configuration, the organization information encrypted with the private key is transferred between the server and the terminals managed by the server. The encrypted organizational information cannot be decrypted unless a public key that is open to multiple terminals managed by the server is obtained. Therefore, it is possible to reduce the possibility that the organization information is leaked to the outside.

Preferably, the encrypted file is deleted when the decryption key is not valid for the encrypted file and the encrypted file cannot be decrypted into the data file .

According to this configuration, it is possible to prevent multiple executions of the decryption process using the decryption key that is not valid for the encrypted file. Therefore, it is possible to further reduce the possibility that the encrypted file will be decrypted by an outsider.

Further, the first terminal and the second terminal are configured so that a password can be input, and in the encryption key generation process, the identification information, the organization information of the first terminal, and the password input to the first terminal. the encryption key is generated based on the password obtained, and in the decryption key generation process, the decryption is performed based on the identification information, the organization information of the second terminal, and the password input to the second terminal; Preferably, the decryption key is valid for the encrypted file when a key is generated and the password matches the organizational information and the identification information.

According to this configuration, if the password input to the first terminal for encryption does not match the password input to the second terminal for decryption, the decryption key is valid for the encrypted file. not. Thus, according to this configuration, the encrypted file cannot be decrypted unless the password in addition to the organization information and the identification information match. can be further restricted. Also, in addition to organizational information and identification information, passwords will be used to generate encryption and decryption keys. Therefore, the encryption key and the decryption key can be made more complicated, and the encryption strength of the encrypted file can be further increased.

In addition, the first terminal is configured to be able to set an expiration date, and executes an expiration date combining process for combining expiration information, which is information indicating the set expiration date, with the encrypted file, and in the decryption process, the It is preferable that the encrypted file is not decrypted into the data file when the expiration date indicated by the expiration information linked to the encrypted file is earlier than the date and time of execution of the decryption process.

According to this configuration, the time limit for decrypting the encrypted file is limited within the use time limit set at the time of encryption. Therefore, even if the encrypted file leaks unintentionally, the possibility of decryption of the encrypted file can be reduced. Therefore, the encrypted file can be less likely to be decrypted by an outsider.

The file encryption system according to the present invention having the above configurations can also be applied to file encryption programs, and therefore, the present invention can also target such programs.

A first characteristic configuration of the file encryption program in that case is provided with a server and a plurality of terminals, the server generates organization information that is information indicating an organization to which the server belongs, and Each is a program for a computer system having the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs; Using the terminal as a first terminal and the terminal executing the decryption process as a second terminal, encrypting a data file into an encrypted file using an encryption key generated based on the organization information possessed by the first terminal. and a function of executing the decryption process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information possessed by the second terminal. and the function of executing the encryption process includes, in the first terminal, an identification information generation process of generating identification information unique to the data file to be encrypted; and an encryption key generation process for generating the encryption key based on the organization information of the first terminal, and encrypting the identification information based on the organization information of the first terminal to generate encrypted identification information. , and a combining process of combining the encrypted identification information with the encrypted file, and the function of executing the decryption process includes, in the second terminal, the encrypted identification information combined with the encrypted file. an identification information decryption process of decrypting information into the identification information based on the organizational information of the second terminal; and decryption of generating the decryption key based on the decrypted identification information and the organizational information of the second terminal. and a key generation process, wherein in the decryption process, the organization information of the second terminal used for the decryption key is combined with the organization information of the first terminal used for the encryption key. If there is a match and the identity used in the decryption key matches the identity used in the encryption key, then the decryption key is valid for the encrypted file. is further realized in the computer system.
A second characteristic configuration of the file encryption program comprises a server and a plurality of terminals, wherein the server generates organization information, which is information indicating an organization to which the server belongs, and each of the plurality of terminals is a program for a computer system having the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs, wherein, among the plurality of terminals, the terminal that executes encryption processing is a first terminal, and the terminal that executes the decryption process is a second terminal, and a data file is encrypted into an encrypted file using an encryption key generated based on the organization information possessed by the first terminal a function of executing the encryption process; a function of executing the decryption process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information possessed by the second terminal; In the decryption process, if the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is used for the encrypted file and a function to enable the computer system to implement the encryption process, and the function to execute the encryption process is provided to the first terminal by the date and time when the organizational information of the first terminal was generated. with the encrypted file, wherein in the decryption process, the date and time indicated by the date and time information associated with the encrypted file is the organizational information of the second terminal The computer system further implements a function of not decrypting the encrypted file into the data file if it is later than the date and time when the encrypted file was generated.
A third characteristic configuration of the file encryption program comprises a server and a plurality of terminals, wherein the server generates organization information, which is information indicating an organization to which the server belongs, and stores information on each of the terminals. is a program for a computer system having the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs, wherein, among the plurality of terminals, the terminal that executes encryption processing is a first terminal, and the terminal that executes the decryption process is a second terminal, the first organization to which the first terminal belongs and the second organization to which the second terminal belongs are different organizations, and the server There are a first server belonging to the first organization and a second server belonging to the second organization, and the first server can input second server information that is information indicating the second server. The second server has self information that indicates itself, is configured to be able to input encrypted first organizational information, and is a cipher generated based on the organizational information possessed by the first terminal a function of executing the encryption process of encrypting a data file into an encrypted file using an encryption key; a function of executing the decryption process for decrypting the data file; enabling the decryption key to be valid for the encrypted file if it matches organization information; and indicating to the first server the first organization based on the input second server information. a function of encrypting the first organization information, which is the organization information, to execute retrieval preparation processing for generating the encrypted first organization information; a function of causing the computer system to implement an introduction process for decrypting the first organization information based on the The point is that the first organizational information decrypted by the introduction process is used as the organizational information in addition to the organizational information possessed by the second terminal.

Of course, this file encryption program can also obtain the effects associated with the file encryption system described above, and can incorporate some additional techniques given as examples of its preferred configuration.

Schematic diagram showing the schematic configuration of a file encryption system Diagram showing information held by the server Diagram showing information held by the client terminal Diagram showing processing in server and client terminal Flowchart of processing performed by the server Diagram showing processing in the first terminal Flowchart of processing executed by the first terminal Diagram showing file selection image before data file is selected Diagram showing file selection image after data file is selected Diagram showing encryption setting image Diagram showing processing in the second terminal Flowchart of processing executed by the second terminal A diagram showing a decoded image A diagram showing processing in the server, the first terminal, and the second terminal

1. Embodiment 1-1. Overall Configuration of System An embodiment of a file encryption system will be described with reference to the drawings.
As shown in FIG. 1, a file encryption system 1 (hereinafter simply referred to as system 1) comprises a server 2, a management terminal 3, a client terminal 4, and a database 5. FIG.

As shown in FIG. 1, the system 1 is deployed in multiple organizations G. As shown in FIG. That is, when the system 1 is composed of a first organization G1 and a second organization G2 as a plurality of organizations G, the system 1 includes a server 2, a management terminal 3, a client terminal 4, and It comprises a database 5, a server 2 belonging to a second organization G2, a management terminal 3, a client terminal 4, and a database 5. A server 2 , a management terminal 3 , a client terminal 4 and a database 5 belonging to the same organization G are connected via a communication network 6 . The server 2 manages the client terminals 4 belonging to the same organization G, but does not manage the client terminals 4 belonging to different organizations G. The server 2 also does not manage external terminals 7 that do not belong to any of the multiple organizations G in which the system 1 is arranged. In this embodiment, the system 1 includes one server 2, one management terminal 3, a plurality of client terminals 4, and one database 5 for both the first organization G1 and the second organization G2. .

As shown in FIG. 2, the server 2 is installed with an organizational information generation tool 11, an organizational information bring-out tool 12, an organizational information introduction tool 13, and an authentication library 18. FIG. Further, the server 2 stores a private key 16, a public key 17 paired with the private key 16, and serial information 19. FIG. The authentication library 18 is a collection of programs, for example, a program that encrypts the organization information 26 (see FIG. 4) indicating the organization G with the private key 16 to generate encrypted organization information 26X, or a program that generates encrypted organization information 26X. 26X with the public key 17 to generate the organization information 26. The serial information 19 corresponds to self information that is information indicating itself, and in this embodiment, is information of the serial number of the server 2 .

The organizational information generation tool 11 is a tool (program) for generating the organizational information 26 and the encrypted organizational information 26X obtained by encrypting the organizational information 26. FIG. As shown in FIGS. 4 and 5, the server 2 activates the organization information generation tool 11 to generate unique organization information 26 indicating the organization G to which the server 2 belongs; A cryptographic organization information generating process S12 is executed to generate cryptographic organization information 26X by encrypting the organization information 26 generated by the information generating process S11 by combining the secret key 16 and the unique process of the authentication library 18. In this way, the server 2 encrypts the organization information 26 indicating the organization G to which the server 2 and the plurality of client terminals 4 managed by the server 2 belong, with the secret key 16 .

The server 2 transmits the generated cryptographic organization information 26X to the database 5 and registers the cryptographic organization information 26X in the database 5 . The server 2 also manages the date and time when the organization information 26 was created as the date and time information 27 . The server 2 executes distribution processing S13 for distributing the policy 28 to a plurality of client terminals 4 managed by the server 2 . Here, the policy 28 defines rules, restrictions, etc. in this system 1 . In this embodiment, the policy 28 includes encryption organization information 26 X (encrypted organization information 26 ), date/time information 27 and public key 17 . Thus, the server 2 distributes the encrypted organization information 26X (encrypted organization information 26) to the plurality of client terminals 4 managed by the server 2 by distributing the policy 28 in the distribution process S13. Here, the delivery process S13 is transmitted to the client terminal 4 by a push notification from the server 2 side. Note that the distribution process S13 may be performed in response to a request from the client terminal 4. FIG.

As shown in FIG. 3, the client terminal 4 has an organization information acquisition tool 21, a file encryption tool 22, a file decryption tool 23, and an authentication library 18 installed. The client terminal 4 also stores encryption organization information 26X, date/time information 27, and public key 17. FIG. These were included in the policy 28 sent from the server 2 to the client terminal 4 as described above.

The client terminal 4 activates the organization information acquisition tool 21 and executes the organization information decoding process. The organizational information decryption process is a process of generating the organizational information 26 by decrypting the encrypted organizational information 26X by combining the public key 17 and the unique processing of the authentication library 18 . As the client terminal 4 executes this organizational information decoding process, the client terminal 4 acquires the organizational information 26 and stores the organizational information 26 in the client terminal 4 as shown in FIG. Thus, the client terminal 4 has the organization information 26, which is information indicating the organization G to which the client terminal 4 belongs.

The communication network 6 is constructed using communication technologies such as the Internet, WAN (Wide Area Network), and LAN (Local Area Network). For example, the communication network 6 is constructed as a network for communication within a limited facility such as a company or school. In this case, part of the communication network 6 can be constructed using an external network such as the Internet. At least part of the communication network 6 may be constructed using wireless communication technology.

As shown in FIG. 1, each of the management terminal 3, the client terminal 4, and the external terminal 7 is a terminal device including a main body 41, a display device 42, and an input device 43. FIG. FIG. 1 illustrates a desktop-side personal computer in which a main body 41, a display device 42, and an input device 43 are separate units.

The main body 41 includes an arithmetic processing unit such as a CPU (Central Processing Unit) as a core member, and a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory) that can be directly referenced by the arithmetic processing unit. ing. In this embodiment, an organizational information acquisition tool 21, a file encryption tool 22, and a file decryption tool 23 are installed in the body 41 of the client terminal 4, and the body 41 of the client terminal 4 activates these tools. process. The input device 43 is a keyboard or a mouse, and the client terminal 4 accepts operations for encrypting or decrypting the data file 31 or accepts input of a password, which will be described later, by operating the input device 43. is configured as

The main body 41 is also provided with terminals (not shown) for connecting the external device 8 . The external device 8 is a device capable of recording information, such as a USB memory, an external hard disk, or a memory card. Therefore, for example, by connecting the external device 8 to the main body 41 of the client terminal 4 , information stored in the client terminal 4 can be written to the external device 8 and stored in the external device 8 . The information stored in the client terminal 4 can be written to the storage device of the client terminal 4 and stored in the client terminal 4 .

The management terminal 3 is a terminal for operating the server 2. In addition to being able to input execution commands for various processes in the server 2, the management terminal 3 can set the system 1 centering on the server 2, and the like. In this embodiment, as one of the settings of the system 1, it is configured to set whether or not to use a password when the client terminal 4 executes encryption processing. Such setting information of the system 1 is distributed from the server 2 to each client terminal 4 while being included in the policy 28 .

1-2. Encryption of Data File Next, a process for encrypting the data file 31 in the client terminal 4 and storing it in the external device 8 will be described. When encrypting the data file 31 in the client terminal 4, the client terminal 4 executes encryption processing. Hereinafter, the client terminal 4 that executes the encryption process will be referred to as the first terminal 4A.

The user connects the external device 8 to the main body 41 of the first terminal 4A. When the first terminal 4A recognizes that the external device 8 is connected to the main body 41, it displays a file selection image E1 as shown in FIG. This file selection image E1 includes a file display area E2, a first operation area E3, and a second operation area E4.

Then, the user performs an operation (drag and drop) to move the data file 31 to the file display area E2 on the first terminal 4A. The first terminal 4A recognizes the data file 31 moved to the file display area E2 as the data file 31 to be encrypted, and displays the information of the data file 31 to be encrypted in the file display area E2 as shown in FIG. display. The user confirms the data file 31 to be encrypted displayed in the file display area E2, and selects the first operation area E3 when writing the encrypted file 31X, which is the encrypted data file 31, to the external device 8. I do. When writing the encrypted encrypted file 31X to the storage device in the first terminal 4A, an operation to select the second operation area E4 is performed.

When an operation to select the first operation area E3 is performed, the first terminal 4A displays an encryption setting image E5 as shown in FIG. The encryption setting image E5 includes a first storage destination selection area E6, a first password input area E7, an expiration date setting area E8, and an encryption command area E9. The user selects a folder or the like in the external device 8 as the storage destination of the encrypted file 31X in the first storage destination selection area E6. Also, the user enters a password in the first password entry area E7. Furthermore, the user performs an operation to set the expiration date of the password and the number of times the password can be entered unsuccessfully (permissible number of erroneous entries) in the expiration date setting area E8. The information of the expiration date of the password set here becomes the expiration information 32, which will be described later, and the information of the allowable number of erroneous inputs becomes the input count information 34, which will be described later. By unchecking the check box, it is possible not to set the expiration date of the password and the allowable number of erroneous password entries. After that, when the user performs an operation to select the encryption command area E9, the first terminal 4A activates the file encryption tool 22 described later, and as shown in FIG. , an encryption key generation process S22, an encryption execution process S23, and a combination process S24 are executed. As a result, the first terminal 4</b>A writes the encrypted file 31</b>X in which the encrypted organization information 26</b>X, the date/time information 27 and the deadline information 32 are combined to the designated storage destination of the external device 8 . Thus, the encrypted file 31X is stored in the external device 8. FIG.

Note that the above description of the encryption setting image E5 is an example in which the use of a password is selected as the setting of the system 1. FIG. If no password is selected as the setting of the system 1, the first password input area E7 and the expiration date setting area E8 are not displayed in the encryption setting image E5, or the first password input area E7 and Part of the expiration date setting area E8 is displayed in a grayed out state. Thereby, the user can recognize that the input of the password and the information related to the password (expiration date and allowed number of erroneous inputs) is not required.

1-3. File Encryption Tool Specific processing for encrypting the data file 31 by the file encryption tool 22 in the first terminal 4A will be described with reference to FIGS. 6 and 7. FIG. When encrypting the data file 31, the first terminal 4A activates the file encryption tool 22 to perform identification information generation processing S21, encryption key generation processing S22, encryption execution processing S23, and connection processing S24. and The identification information generation process S21 is a process of generating unique identification information 29 . Here, the identification information 29 is identification information unique to the data file 31 to be encrypted. In this example, the identification information 29 is a GUID (Globally Unique Identifier) randomly generated by the file encryption tool 22 .

The encryption key generation process S22 is a process of generating the encryption key 30 based on the identification information 29 generated in the identification information generation process S21 and the organization information 26 acquired by the organization information acquisition tool 21. FIG. The first terminal 4A refers to the setting information of the system 1 included in the policy 28, and if the use of a password is selected, the identification information 29 and the organization In addition to the information 26, the encryption key 30 is generated based on the password information PW indicating the password input to the first terminal 4A.

The encryption execution process S23 is a process of encrypting the data file 31 into the encrypted file 31X using the encryption key 30 generated by the encryption key generation process S22. Such encryption key generation processing S22 and encryption execution processing S23 are performed according to a unique algorithm of the file encryption tool 22. FIG.

The combining process S24 is a process of encrypting the identification information 29 based on the organization information 26 to generate encrypted identification information 29X, and combining the encrypted identification information 29X with the encrypted file 31X. Here, the encrypted identification information 29X is obtained by encrypting the identification information 29 with the encryption key 30 generated according to the unique algorithm of the file encryption tool 22 based on the organization information 26. FIG. Also, in the combining process S24, a process of combining the date/time information 27 with the encrypted file 31X (date/time combining process) is executed. As described above, the date and time information 27 is information indicating the date and time when the organization information 26 was created. Furthermore, in the combining process S24, when the expiration date of the password is set in the first terminal 4A, a process (expiration combining process) of combining the expiration information 32 indicating the expiration date with the encrypted file 31X is executed. In addition, in the connection processing S24, if the number of times the password can be entered unsuccessfully (permissible number of erroneous inputs) is set in the first terminal 4A, the input count information 34 indicating the permissible number of erroneous inputs is stored in the encryption file 31X. Executes the process of combining (input count combining process). In this way, by executing the combining process S24, the encryption identification information 29X, the date/time information 27, the deadline information 32, and the number of times of input information 34 are combined into the encrypted file 31X.

In short, in this embodiment, the first terminal 4A generates the unique identification information 29 (identification information generation processing S21). Then, the first terminal 4A generates the encryption key 30 based on the organization information 26, the identification information 29, and the password information PW (encryption key generation processing S22), and uses the encryption key 30 to encrypt the data file. 31 is encrypted into the encrypted file 31X (encryption execution processing S23). Then, the cipher identification information 29X, the date and time information 27, the time limit information 32, and the number of times of input information 34 are combined with this encrypted file 31X (combining process S24).

1-4. Decryption of Encrypted File Next, processing for decrypting the encrypted file 31X stored in the external device 8 in the client terminal 4 will be described. When the client terminal 4 decrypts the encrypted file 31X, the client terminal 4 executes decryption processing. Hereinafter, the client terminal 4 that executes the decryption process will be referred to as a second terminal 4B.

The user connects the external device 8 to the main body 41 of the second terminal 4B and performs an operation to activate the file decryption tool 23 on the second terminal 4B. When an operation to activate the file decryption tool 23 is performed, the second terminal 4B displays a decrypted image E11 as shown in FIG. The decrypted image E11 includes a second password input area E12, a second save destination selection area E13, and a decryption command area E14.

Then, the user selects a folder or the like as a storage destination of the data file 31 in the second terminal 4B in the second storage destination selection area E13. Also, the user enters a password in the second password entry area E12. The password entered here is required to be the same password that was set during the encryption process. Thereafter, when the user performs an operation to select the decryption command area E14, the second terminal 4B activates the file decryption tool 23, which will be described later, and as shown in FIG. A key generation process S32 and a decryption execution process S33 are executed. As a result, the second terminal 4B writes the data file 31 obtained by decrypting the encrypted file 31X to the designated storage destination of the second terminal 4B. Thus, the data file 31 is stored in the second terminal 4B.

1-5. File Decryption Tool Next, specific processing for decrypting the encrypted file 31X by the file decryption tool 23 in the second terminal 4B will be described with reference to FIGS. 11 and 12. FIG. When decrypting the encrypted file 31X, the second terminal 4B activates the file decryption tool 23 and executes identification information decryption processing S31, decryption key generation processing S32, and decryption execution processing S33. The identification information decryption process S31 is a process of decrypting the encrypted identification information 29X combined with the encrypted file 31X into the identification information 29 based on the organization information 26 of the second terminal 4B. Here, the identification information 29 is obtained by decrypting the encrypted identification information 29X with the decryption key 33 generated according to the unique algorithm of the file decryption tool 23 based on the organization information 26. FIG.

The decryption key generation processing S32 generates a decryption key based on the identification information 29 decrypted in the identification information decryption processing S31, the organization information 26 of the second terminal 4B, and the password information PW if a password is set. 33 is generated. The decryption execution process S33 is a process of decrypting the encrypted file 31X into the data file 31 using the decryption key 33 generated by the decryption key generation process S32. Such decryption key generation processing S32 and decryption execution processing S33 are performed according to the unique algorithm of the file decryption tool 23. FIG.

In the decryption process, all of the organization information 26, identification information 29, and password information PW used for the decryption key 33 match the organization information 26, identification information 29, and password information PW used for the encryption key 30. , the decryption key 33 is valid for the encrypted file 31X, and decrypts the encrypted file 31X into the data file 31. FIG.

In other words, since the first terminal 4A and the second terminal 4B belong to different organizations G, the organization information 26 of the second terminal 4B used for the decryption key 33 and the first terminal 4A used for the encryption key 30 , the decryption key 33 is not valid for the encrypted file 31X, and the encrypted file 31X is not decrypted into the data file 31. That is, a terminal belonging to an organization G different from the organization G to which the first terminal 4A in which the encrypted file 31X is generated cannot decrypt the encrypted file 31X. Therefore, according to this system 1, the encryption file 31X can be restricted from being decrypted by an outsider of a different organization G.

Furthermore, in this embodiment, in the decryption process, if the organization information 26 of the second terminal 4B used for the decryption key 33 and the organization information 26 of the first terminal 4A used for the encryption key 30 do not match, the second The terminal 4B executes an erasing process for erasing the encrypted file 31X. In this example, in the erasing process, a message indicating that the encrypted file 31X is to be erased is displayed on the display device 42 of the second terminal 4B, and the decrypted encrypted file 31X is erased from the external device 8.

Further, when the password information PW used for the decryption key 33 and the password information PW used for the encryption key 30 do not match, that is, when the password entered in the second terminal 4B and the password entered in the first terminal 4A If the password does not match, the decryption key 33 is not valid for the encrypted file 31X, and the encrypted file 31X is not decrypted into the data file 31. FIG. In this case, the second terminal 4B displays a message indicating that the password is invalid on the display device 42 and requests the user to re-enter the password. Also, as described above, when the number of times the password can be entered unsuccessfully (permissible number of erroneous inputs) is set during the encryption process, the number-of-inputs information 34 is combined with the encrypted file 31X. In this case, the second terminal 4B acquires the input count information 34 combined with the encrypted file 31X. Then, when the number of invalid password inputs reaches the permissible number of erroneous inputs indicated by the number-of-inputs information 34, the second terminal 4B performs an erasing process of erasing the encrypted file 31X.

If the identification information 29 used for the decryption key 33 and the identification information 29 used for the encryption key 30 do not match, the decryption key 33 is not valid for the encrypted file 31X, and the encrypted file 31X is not decoded into the data file 31. As described above, the identification information 29 used for the decryption key 33 is obtained by decrypting the encrypted identification information 29X combined with the encrypted file 31X in the identification information decryption process S31. Therefore, the reason why the identification information 29 does not match during the decryption process is that the organization information 26 of the second terminal 4B used for the decryption key 33 and the organization information 26 of the first terminal 4A used for the encryption key 30 are different. This is due to inconsistency. Therefore, also in this case, the second terminal 4B executes the erasing process of erasing the encrypted file 31X.

Further, as described above, the date and time information 27 indicating the date and time when the organization information 26 was created is combined with the encrypted file 31X according to the present embodiment. Therefore, in the present embodiment, in the decryption process, it is further checked whether the date and time indicated by the date and time information 27 linked to the encrypted file 31X is later than the date and time when the organization information 26 of the second terminal 4B was generated. Perform judgment processing. If the date and time indicated by the date and time information 27 combined with the encrypted file 31X is later than the date and time when the organization information 26 of the second terminal 4B was generated, the encrypted file 31X is not decrypted into the data file 31. In this case, the second terminal 4B assumes that the second terminal 4B has not acquired the new policy 28 even though the server 2 has published the new policy 28, and displays a message to that effect. Display on device 42 . In this case, the second terminal 4B does not perform the erasing process of erasing the encrypted file 31X.

Further, as described above, the expiration information 32 indicating the expiration date of the password is combined with the encrypted file 31X according to the present embodiment. Therefore, in the present embodiment, in the decryption process, a process of determining whether or not the date and time indicated by the expiration information 32 combined with the encrypted file 31X is before the date and time when the decryption process is executed is further performed. If the date and time indicated by the expiration information 32 linked to the encrypted file 31X is before the date and time when the decryption process is executed, the encrypted file 31X is not decrypted into the data file 31. FIG. In this case, the second terminal 4B displays a message indicating that the password has expired on the display device 42, and executes an erasing process for erasing the encrypted file 31X.

Also, if the terminal to which the external device 8 storing the encrypted file 31X is connected is the external terminal 7 that does not have the file decryption tool 23, the encrypted file 31X will not be decrypted. In this case, let's store the self-extinguishing program in the external device 8 in which the encrypted file 31X is stored, and open the encrypted file 31X in the external terminal 7 that does not have the file decryption tool 23. It is also preferable to be configured to execute an erasing process of erasing the encrypted file 31X when the operation is performed.

In short, in the present embodiment, in the decryption process, the second terminal 4B uses the organization information 26, the identification information 29, and the password information PW used for the decryption key 33, the organization information 26 used for the encryption key 30, If at least one of the identification information 29 and the password information PW is different, the decryption key 33 is not valid for the encrypted file 31X, and the encrypted file 31X is not decrypted into the data file 31. FIG. In this way, when the decryption key 33 is not valid for the encrypted file 31X, the organization information 26 used for the decryption key 33 and the organization information 26 used for the encryption key 30 do not match, or When the password information PW does not match and the number of times of failure in entering the password reaches the preset permissible number of erroneous inputs, the identification information 29 used for the decryption key 33 and the If it does not match the identification information 29 obtained, deletion processing is performed, and the encrypted file 31X to be decrypted is deleted from the external device 8 .

1-6. Bring-out Process and Introduction Process In addition, in the system 1 according to the present embodiment, even if the organization G to which the first terminal 4A belongs is different from the organization G to which the second terminal 4B belongs, a predetermined organization information introduction procedure is performed. Thus, the encrypted file 31X encrypted by the first terminal 4A can be decrypted by the second terminal 4B. Next, based on FIG. 14, the procedure for enabling the second terminal 4B to decrypt the encrypted file 31X encrypted by the first terminal 4A will be described. Hereinafter, the first terminal 4A belongs to the first organization G1, the second terminal 4B belongs to the second organization G2, and the server 2 belonging to the first organization G1 is referred to as the first server 2A. The server 2 to which it belongs will be referred to as a second server 2B.

In this organization information introduction procedure, first, the user operates the management terminal 3 belonging to the first organization G1 to transfer the second serial information 19B, which is the information (serial information 19) indicating the second server 2B, to the first server. Enter 2A. In this embodiment, the second serial information 19B corresponds to the second server information, and information indicating the serial number of the second server 2B is used. The user obtains the second serial information 19B from the system administrator or the like of the second organization G2. In other words, the users who perform this organization information introduction procedure are limited to persons concerned with both the first organization G1 and the second organization G2. When the second serial information 19B is input, the first server 2A activates the organization information bring-out tool 12 (see FIG. 2) to execute extraction preparation processing S41 and generate encrypted first organization information 26AX. This extraction preparation process S41 encrypts the organization information 26 (first organization information 26A) indicating the first organization G1 based on the second serial information 19B input to the first server 2A to generate encrypted first organization information 26AX. This is the process to generate. Here, the encrypted first organizational information 26AX is obtained by encrypting the first organizational information 26A with the encryption key 30 generated according to the unique algorithm of the organizational information bring-out tool 12 based on the second serial information 19B. The first server 2A obtains the first organization information 26A by decoding the encrypted first organization information 26AX by combining the public key 17 and the unique processing of the authentication library 18. FIG.

Next, the user inputs the encrypted first organization information 26AX generated by the first server 2A to the second server 2B. This input is performed, for example, as follows. That is, the user connects the external device 8 to the management terminal 3 belonging to the first organization G1, and writes the encrypted first organization information 26AX stored in the first server 2A to the external device 8. FIG. Then, the external device 8 in which the encrypted first organization information 26AX is written is connected to the management terminal 3 belonging to the second organization G2, and the encrypted first organization information 26AX of the external device 8 is input to the second server 2B. Thus, the encrypted first organization information 26AX is input to the second server 2B.

When the encrypted first organization information 26AX is input, the second server 2B activates the organization information introduction tool 13 and executes the introduction process S42. The introduction process S42 is a process of decrypting the encrypted first organization information 26AX input to the second server 2B into the first organization information 26A based on the second serial information 19B (self information). The second server 2B also executes the same process as the above-described encrypted organization information generation process S12, encrypts the first organization information 26A based on the private key 16, and generates encrypted first organization information 26AX. The second server 2B encrypts the generated encrypted first organization information 26AX and the encrypted second organization information generated by encrypting the organization information 26 (second organization information 26B) indicating the second organization G2 based on the secret key 16. As with 26BX, it is registered in the database 5 belonging to the second organization G2. The encrypted first organization information 26AX registered in the database 5 of the second organization G2 is distributed from the second server 2B to the second terminal 4B together with the encrypted second organization information 26BX while being included in the policy 28. FIG. As a result, the second terminal 4B stores the encrypted first organization information 26AX together with the encrypted second organization information 26BX.

The second terminal 4B executes the same processing as the above-described organization information decryption processing (see FIG. 4), and combines the public key 17 and the unique processing of the authentication library 18 to decrypt the encrypted first organization information 26AX. Generate the first organization information 26A. Then, the second terminal 4B uses, as the organization information 26 used for the decryption key 33, the first organization information 26A decrypted by the introduction processing S42 in addition to the second organization information 26B possessed by the second terminal 4B. That is, in the present embodiment, the second terminal 4B generates the normal decryption key 33 based on the identification information 29, the organization information 26 (second organization information 26B), and the password information PW, and the identification information 29, the first A second decryption key 37 is generated as the second decryption key 33 based on the organization information 26A and the password information PW. The second organization information 26B is obtained by decrypting the encrypted second organization information 26BX in the second terminal 4B by combining the public key 17 of the second server 2B and the unique processing of the authentication library 18 of the second terminal 4B. generated.

As a result, the second terminal 4B uses the ordinary decryption key 33 based on the organization information 26 (second organization information 26B) of the second organization G2 to decrypt the encrypted file 31X encrypted by the client terminal 4 of the second organization G2. Decryption In addition to normal decryption processing, encrypted file 31X encrypted at client terminal 4 of first organization G1 with second decryption key 37 based on organization information 26 (first organization information 26A) of first organization G1 It is also possible to perform a different tissue decoding process for decoding . This different organization decryption process is basically the same process as the normal decryption process described above, but as the organization information 26, the organization of the organization (second organization G2) to which the client terminal 4 performing the decryption belongs to The difference is that the organization information 26 (first organization information 26A) of a different organization (first organization G1) is used instead of the information 26 (second organization information 26B).

That is, in this different organization decryption process, the second terminal 4B first identifies the encryption identification information 29X combined with the encrypted file 31X based on the organization information 26 (first organization information 26A) of the first organization G1. An identification information decoding process S31 for decoding into information 29 is executed. Next, the second terminal 4B obtains the identification information 29 decrypted in the identification information decryption process S31, the first organization information 26A possessed by the second terminal 4B, password information PW if a password is set, , a decryption key generation process S32 for generating the second decryption key 37 is executed. After that, the second terminal 4B uses the second decryption key 37 generated by the decryption key generation process S32 to execute the decryption execution process S33 for decrypting the encrypted file 31X into the data file 31. FIG. The organization information 26, identification information 29, and password information PW used for the second decryption key 37 all match the organization information 26, identification information 29, and password information PW used for the encryption key 30. , the decryption key 33 is valid for the encrypted file 31X, and decrypts the encrypted file 31X into the data file 31. FIG. In this way, by performing the predetermined organization information introduction procedure, the encrypted file 31X encrypted by the first terminal 4A belonging to the first organization G1 can be transferred to the second organization G2 belonging to the second organization G2 different from the first organization G1. 2 can be decoded by the terminal 4B.

As described above, the file encryption system has a function of executing encryption processing, a function of executing decryption processing, and in the decryption processing, the organization information of the second terminal used as the decryption key is used as the encryption key. Each function such as a function that the decryption key is valid for the encrypted file is realized when the decryption key matches the organization information of the first terminal. A file encryption program for realizing each function of this file encryption system is stored in the storage device of each terminal such as the server 2, the management terminal 3, and the client terminal 4. FIG.

2. Other Embodiments Next, other embodiments of the file encryption system will be described.

(1) In the above-described embodiment, the configuration for generating the encryption key 30 and the decryption key 33 based on the identification information 29, the organization information 26, and the password information PW has been described as an example. However, the configuration is not limited to this, and for example, a configuration in which the encryption key 30 and the decryption key 33 are generated based on the organization information 26 without using the identification information 29 and the password information PW is also suitable. Alternatively, for example, the encryption key 30 and the decryption key 33 may be generated based on one of the organization information 26, the identification information 29, and the password information PW without using the other of the identification information 29 and the password information PW. preferred.

(2) In the above embodiment, the server 2 executes the distribution processing S13 to distribute the encrypted organization information 26X obtained by encrypting the organization information 26 to the plurality of client terminals 4 managed by the server 2. . However, the configuration is not limited to this, and for example, the organization information 26 may be stored in the client terminal 4 in advance. Although the security level is lowered, the organization information 26 may be distributed from the server 2 to the client terminal 4 without being encrypted.

(3) In the above embodiment, the configuration in which the file decryption tool 23 is pre-installed in the second terminal 4B has been described as an example. However, the present invention is not limited to this. , the file decoding tool 23 stored in the external device 8 may be activated.

(4) In the above embodiment, when the decryption key 33 is not valid for the encrypted file 31X and the reason is a predetermined specific reason, the erasing process for erasing the encrypted file 31X is performed. , the configuration has been described as an example in which the erasing process of erasing the encrypted file 31X is not performed for reasons other than the specific reason. However, the present invention is not limited to this, and for example, if the decryption key 33 is not valid for the encrypted file 31X, the deletion process for deleting the encrypted file 31X may be performed regardless of the reason. Alternatively, conversely, if the decryption key 33 is not valid for the encrypted file 31X, the deletion process for deleting the encrypted file 31X may not be performed regardless of the reason.

(5) In the above-described embodiment, the configuration in which the date/time information 27 indicating the date and time when the organization information 26 was generated and the expiration date information 32 indicating the expiration date of the password are combined with the encrypted file 31X has been described as an example. However, the present invention is not limited to this. For example, either one of the date/time information 27 and the expiration information 32 may be combined with the encrypted file 31X, or both of them may not be combined with the encrypted file 31X. In this case, in the decryption process, it is preferable to use the determination of the information combined with the encrypted file 31X as a condition for whether or not to decrypt the encrypted file 31X.

(6) It should be noted that the configurations disclosed in the respective embodiments described above can also be applied in combination with configurations disclosed in other embodiments, as long as there is no contradiction. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate without departing from the scope of the present disclosure.

The technology according to the present disclosure can be used in file encryption systems and file encryption programs that include a server and multiple terminals.

1: File encryption system 2: Server 2A: First server 2B: Second server 4: Client terminal (terminal)
4A: First terminal 4B: Second terminal 16: Private key 17: Public key 19: Serial information (self information)
19B: Second serial information (second server information)
26: Organization information 26A: First organization information 26X: Encryption organization information 27: Date and time information 29: Identification information 29X: Encryption identification information 30: Encryption key 31: Data file 31X: Encryption file 32: Expiration information 33: Decryption key G : Organization G1: First organization G2: Second organization PW: Password information S13: Distribution processing S21: Identification information generation processing S22: Encryption key generation processing S24: Connection processing S31: Identification information decryption processing S32: Decryption key generation processing S41 : Extraction preparation process S42: Introduction process

Claims (8)

A file encryption system comprising a server and a plurality of terminals,
The server generates organization information, which is information indicating an organization to which the server belongs,
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
each of the plurality of terminals has the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs;
The encryption process is a process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information held by the first terminal,
The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal,
The first terminal performs identification information generation processing for generating identification information unique to the data file to be encrypted, and encryption for generating the encryption key based on the identification information and the organization information of the first terminal. performing encryption key generation processing and combining processing for generating encrypted identification information by encrypting the identification information based on the organization information of the first terminal, and combining the encrypted identification information with the encrypted file;
The second terminal performs identification information decryption processing for decrypting the encrypted identification information combined with the encrypted file into the identification information based on the organization information of the second terminal, and decrypting the decrypted identification information and the a decryption key generation process for generating the decryption key based on the organization information of the second terminal;
In the decryption process, the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, and the organization information used for the decryption key A file encryption system wherein the decryption key is valid for the encrypted file if the identification information matches the identification information used for the encryption key. A file encryption system comprising a server and a plurality of terminals,
The server generates organization information, which is information indicating an organization to which the server belongs,
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
each of the plurality of terminals has the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs;
The encryption process is a process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information held by the first terminal,
The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal,
In the decryption process, if the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is used for the encrypted file is valid for
The first terminal executes date and time combining processing for combining date and time information indicating a date and time when the organization information of the first terminal was generated with the encrypted file,
In the decryption process, if the date and time indicated by the date and time information linked to the encrypted file is later than the date and time when the organization information of the second terminal was generated, the encrypted file is decrypted into the data file. No file encryption system. A file encryption system comprising a server and a plurality of terminals,
The server generates organization information, which is information indicating an organization to which the server belongs,
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
each of the plurality of terminals has the organization information generated by the server belonging to the same organization as the organization to which the terminal belongs;
The encryption process is a process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information held by the first terminal,
The decryption process is a process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information held by the second terminal,
In the decryption process, if the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is used for the encrypted file is valid for
a first organization to which the first terminal belongs and a second organization to which the second terminal belongs are different organizations;
The servers include a first server belonging to the first organization and a second server belonging to the second organization,
The first server is configured to be able to input second server information, which is information indicating the second server, and is the organization information indicating the first organization based on the input second server information. executing retrieval preparation processing for encrypting the first organization information to generate encrypted first organization information;
The second server has self information that indicates itself, is configured to be able to input the encrypted first organization information, and converts the input encrypted first organization information to the Execute the introduction process to decrypt to the first organization information,
A file encryption system in which the second terminal uses the first organization information decrypted by the introduction process in addition to the organization information possessed by the second terminal as the organization information used for the decryption key . The server encrypts the organization information indicating the organization to which the server and the plurality of terminals managed by the server belong with a private key, and distributes the encrypted organization information to the plurality of terminals managed by the server. 4. The file encryption system according to any one of claims 1 to 3 , wherein a distribution process is executed, and the public key paired with the private key is made public to the plurality of terminals managed by the server. File encryption according to any one of claims 1 to 4, wherein the encrypted file is deleted if the decryption key is not valid for the encrypted file and the encrypted file is not decrypted to the data file. system. A server and a plurality of terminals are provided, the server generates organization information that is information indicating an organization to which the server belongs, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs. A file encryption program for a computer system having said organizational information generated by said server, comprising:
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
a function of executing the encryption process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal;
causing the computer system to implement the decryption process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information possessed by the second terminal;
The function for executing the encryption processing includes, in the first terminal, identification information generation processing for generating identification information unique to the data file to be encrypted, and the identification information and the organization information of the first terminal. and encrypting the identification information based on the organization information of the first terminal to generate encrypted identification information, and transmitting the encrypted identification information to the encrypted file and a function to execute the
The function for executing the decryption process is an identification information decryption process for decrypting the encrypted identification information combined with the encrypted file into the identification information based on the organization information of the second terminal. and a decryption key generation process for generating the decryption key based on the decrypted identification information and the organization information of the second terminal,
In the decryption process, the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, and the organization information used for the decryption key File encryption that further enables the computer system to enable the decryption key to be valid for the encrypted file if the identification information matches the identification information used for the encryption key. program. A server and a plurality of terminals are provided, the server generates organization information that is information indicating an organization to which the server belongs, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs. A file encryption program for a computer system having said organizational information generated by said server, comprising:
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
a function of executing the encryption process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal;
a function of executing the decryption process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information possessed by the second terminal;
In the decryption process, if the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is used for the encrypted file enabling the computer system to implement a function that is effective for
The function of executing the encryption processing includes a function of causing the first terminal to execute date and time combining processing of combining date and time information indicating a date and time when the organization information of the first terminal was generated with the encrypted file. ,
In the decryption process, if the date and time indicated by the date and time information linked to the encrypted file is later than the date and time when the organization information of the second terminal was generated, the encrypted file is decrypted into the data file. A file encryption program that further implements the function of encrypting files to the computer system . A server and a plurality of terminals are provided, the server generates organization information that is information indicating an organization to which the server belongs, and each of the plurality of terminals belongs to the same organization as the organization to which the terminal belongs. A file encryption program for a computer system having said organizational information generated by said server, comprising:
Among the plurality of terminals, the terminal that executes the encryption process is defined as a first terminal, and the terminal that executes the decryption process is defined as a second terminal,
a first organization to which the first terminal belongs and a second organization to which the second terminal belongs are different organizations;
The servers include a first server belonging to the first organization and a second server belonging to the second organization,
The first server is configured to be able to input second server information that is information indicating the second server,
The second server has self information that indicates itself, and is configured to be able to input encrypted first organization information,
a function of executing the encryption process of encrypting a data file into an encrypted file using an encryption key generated based on the organizational information possessed by the first terminal;
a function of executing the decryption process of decrypting the encrypted file into the data file using a decryption key generated based on the organizational information possessed by the second terminal;
In the decryption process, if the organization information of the second terminal used for the decryption key matches the organization information of the first terminal used for the encryption key, the decryption key is used for the encrypted file a function that is enabled for
The first server executes a retrieval preparation process of encrypting the first organization information, which is the organization information indicating the first organization, to generate the encrypted first organization information based on the input second server information. and
causing the second server to execute an introduction process of decrypting the input encrypted first organization information into the first organization information based on the self information ;
The function for executing the decryption process provides the second terminal with the first decrypted decrypted by the introduction process in addition to the organizational information possessed by the second terminal as the organizational information used for the decryption key. A file encryption program that includes features that also allow organizational information to be used .

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