JP2023142647A - Data management device, data management program, and data management method - Google Patents

Abstract

To provide a new technique for achieving safe data usage based on the status of a device that uses data.SOLUTION: A data management device stores encrypted data and decrypts it only under predetermined conditions. The data management device includes: communication means for receiving shared information on the encrypted data, including condition information indicating decryption conditions for decrypting the encrypted data, together with the encrypted data; storage means for associating and storing the received encrypted data and shared information; surrounding information acquisition means for acquiring surrounding information indicating a surrounding situation of the data management device; and decryption means for decrypting the encrypted data based on the condition information and the surrounding information. The decryption means decrypts the encrypted data when the surrounding information satisfies the decryption conditions indicated by the condition information associated with the encrypted data.SELECTED DRAWING: Figure 1

Description

The present invention relates to a data management device, a data management program, and a data management method.

Various methods have been known for transmitting and sharing data. Data has been shared in a variety of ways so far, such as sending by email or sharing in a group using shared storage in a so-called cloud service.

By the way, in such data sharing, it has been required to ensure its safety from the viewpoint of unauthorized use. From this point of view, Patent Document 1 discloses a technique in which a file to be shared is stored on a server and the use of the file is permitted only when sessions with all participating members have been established.

JP2009-237662A

However, in the technique described in Patent Document 1, since files are stored on the server, there is a risk that the files may be leaked from the server. Additionally, if a session is established between the server and the participating members, the files can be used no matter where each member is, so for example, if the participating members use the files in a location that is not highly confidential. There was a risk of leakage.

In view of these problems, it is an object of the present invention to provide a new technique that realizes safe data usage based on the status of the device that uses the data.

In order to solve the above problems, the present invention provides a data management device that stores encrypted data and decrypts it only under predetermined conditions, the device decrypts the encrypted data as well as the encrypted data. a communication means for receiving shared information of the encrypted data including condition information indicating decryption conditions for decryption; a storage means for storing the received encrypted data and shared information in association with each other; peripheral information acquisition means for acquiring peripheral information indicating a surrounding situation; and decryption means for decrypting the encrypted data based on the condition information and the peripheral information, and the decryption means is configured to , the encrypted data is decrypted when the decryption condition indicated by the condition information associated with the encrypted data is satisfied.

With such a configuration, encrypted data can be decrypted based on the surrounding situation of the data management device. This makes it possible, for example, to allow decryption only in a specific location, or to allow decryption based on conditions such as the presence of nearby devices, allowing data to be used only in situations that meet pre-specified conditions. be able to.

In a preferred embodiment of the present invention, the decoding condition includes a neighborhood condition regarding a nearby device existing in the vicinity of the data management device, and the peripheral information acquisition means uses nearby device information that specifies the nearby device as the peripheral information. and the decryption means decrypts the encrypted data when it is determined that the proximity condition indicated by the condition information associated with the encrypted data is satisfied based on the neighboring device information.

With such a configuration, for example, encrypted data can be decrypted only when members using a specific device gather nearby or when they approach a device installed at a fixed location.

In a preferred embodiment of the present invention, the shared information includes shared device information that identifies a plurality of shared devices that share the encrypted data, and the neighborhood condition specifies a minimum number of the shared devices included in the nearby devices. and the decryption means determines that the neighborhood condition is satisfied and decrypts the encrypted data when the neighborhood devices include the minimum number or more of the shared devices.

With such a configuration, encrypted data can be decrypted only when a predetermined number or more of predetermined shared devices gather nearby. This allows, for example, to set a minimum number of nearby devices for data that involves many members, and check the content with only the number of people below the set minimum number to prevent acts such as unauthorized use of the data. becomes possible.

In a preferred embodiment of the present invention, the neighborhood condition includes a condition that the nearby devices include a specified designated device, and the decoding means includes a condition that all of the one or more designated devices are included in the nearby devices. If it is included, it is determined that the neighborhood condition is satisfied and the encrypted data is decrypted.

With such a configuration, it is possible to limit the use of data when a particularly important designated device among the devices designated as shared devices does not exist nearby. Thereby, for example, it is possible to prevent data from being used illegally in a situation where there is no administrator or person in charge.

In a preferred embodiment of the present invention, the shared information includes transmitting device information that identifies a transmitting device that has transmitted the encrypted data, and the neighborhood condition includes a condition that the transmitting device is included in the nearby devices.

With such a configuration, it is possible to limit the use of data when there is no transmitting device nearby.

In a preferred embodiment of the present invention, the decoding condition includes a location condition regarding the location of the data management device, and the peripheral information acquisition means acquires location information indicating the location of the data management device as the peripheral information, and The decryption means decrypts the encrypted data when the location information satisfies the location condition indicated by the condition information associated with the encrypted data.

With such a configuration, it is possible to permit the use of data only when the data management device is located at a position that satisfies pre-specified conditions. This makes it possible, for example, to allow the use of data only in specific highly secure locations, or to permit the use of encrypted data as a bonus on the condition of visiting a specific venue. .

In a preferred embodiment of the present invention, the communication means receives the encrypted data and shared information through direct communication between terminals using short-range communication.

With this configuration, data is directly transmitted and received between the terminals without going through an external server, so the risk of information leakage to the outside during transmission and reception and subsequent data storage can be further reduced.

In order to solve the above problems, the present invention provides a data management program that causes a computer to function as a data management device that stores encrypted data and decrypts the encrypted data only under predetermined conditions. Also, a communication means for receiving shared information of the encrypted data, including condition information indicating decryption conditions for decrypting the encrypted data, and a memory for storing the received encrypted data and shared information in association with each other. a peripheral information acquisition means for acquiring peripheral information indicating a peripheral situation of the data management device; and a decryption means for decrypting the encrypted data based on the condition information and the peripheral information. and the decryption means decrypts the encrypted data when the peripheral information satisfies a decryption condition indicated by the condition information associated with the encrypted data.

In order to solve the above problems, the present invention provides a data management method for storing encrypted data and decrypting it only under predetermined conditions, the method including decrypting the encrypted data together with the encrypted data. a communication step of receiving shared information of the encrypted data including condition information indicating decryption conditions for the decryption, a storage step of storing the received encrypted data and shared information in association with each other, and peripherals of the data management device. A computer executes a peripheral information acquisition step of acquiring peripheral information indicating the situation, and a decryption step of decrypting the encrypted data based on the condition information and the peripheral information, and in the decryption step, the peripheral information The encrypted data is decrypted when the information satisfies the decryption condition indicated by the condition information associated with the encrypted data.

According to the present invention, it is possible to provide a novel technique that realizes safe data usage based on the status of a device that uses data.

FIG. 1 is a configuration diagram of a data sharing system using a plurality of data management devices according to an embodiment of the present invention. 1 is a diagram showing a functional configuration of a data management device in an embodiment of the present invention. It is a sequence diagram which shows the procedure of the connection between apparatuses by the data management apparatus in embodiment of this invention. FIG. 3 is a diagram showing an example of information stored by a data management device according to an embodiment of the present invention. 5 is a flowchart showing encrypted data transmission processing by the data management device according to the embodiment of the present invention. It is a flowchart which shows the decryption process of encrypted data by the data management apparatus in embodiment of this invention. It is an example of a screen display by the data management apparatus in embodiment of this invention. It is an example of a screen display by the data management apparatus in embodiment of this invention. It is an example of a screen display by the data management apparatus in embodiment of this invention.

Hereinafter, a data sharing system using a data management device of the present invention will be explained using the drawings. Note that the embodiment shown below is an example of the present invention, and the present invention is not limited to the following embodiment, and various configurations can be adopted.

For example, in this embodiment, the configuration, operation, etc. of a data management device will be described, but methods, computer programs, etc. with similar configurations can also produce similar effects. Further, the program may be stored in a recording medium. Using this recording medium, for example, a program can be installed on a computer. Here, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

<Definition>
In the present invention, encrypted data refers to any data that has been encrypted. The encryption method is not limited, and any known encryption technique can be used. Furthermore, the format of the data to be shared can be arbitrarily determined, and in this embodiment, data such as documents, images, videos, and audio are assumed.

Further, in the present invention, the data management device acquires peripheral information indicating the surrounding situation of the data management device. The surrounding situation includes, for example, the geographical location of the data management device, the number and number of devices existing around the data management device, the size of the space, the number of people around the data management device, etc. It's okay to stay. Surrounding information is information indicating such surrounding conditions, and includes position information indicating geographic coordinates, nearby device information regarding devices existing around the data management device, and the like.

Hereinafter, in this specification, devices existing around the data management device will be referred to as nearby devices. Note that in this embodiment, a device existing within a range where direct communication between the data management device and a terminal via short-range communication is possible is treated as a nearby device. However, the present invention is not limited thereto, and is particularly applicable to devices existing within a predetermined distance range or devices existing within a range where direct communication between terminals is possible through short-range communication with a data management device. A device with which communication between terminals has been established may be treated as a nearby device. Here, the nearby device information is information regarding nearby devices, and includes information regarding any other nearby devices, such as a device ID that uniquely identifies the device, the name of the device, communication status, and the like. In this embodiment, the device information described below regarding nearby devices is treated as nearby device information.

Further, in this embodiment, encrypted data can be shared among a specific group made up of a plurality of data management devices. In this embodiment, the above group is called a "room", and the devices (room members) that share encrypted data are called "shared devices." The number of shared devices in one room is not particularly limited, but in this embodiment, it is preferable that the number of shared devices be used by about 8 to 10 people. Note that in the case of one-to-one data transmission between devices, the two devices on the sending side and the receiving side become shared devices.

<Configuration>
Next, the configuration of the data management device and data management system of this embodiment will be explained using FIGS. 1 to 4. FIG. 1 is a configuration diagram of a data sharing system using a plurality of data management devices P. In this embodiment, a plurality of data management devices P communicate directly with each other, so-called P2P communication, and transmit and receive data. In the example of FIG. 1, a case is shown in which four data management devices P share data as shared devices. In this way, each shared device establishes one-to-one direct communication with each shared device participating in the same room.

In this embodiment, it is assumed that one of the shared devices becomes the owner device, particularly as the device of the owner who is the representative of the room. In this case, hereinafter, data management devices P other than the owner device will be referred to as "participant devices" for distinction. In this embodiment, the data management device P that first created the room becomes the owner device.

As the data management device P, any computer device such as a smartphone can be used, which is equipped with various input/output devices including an arithmetic device, a storage device, and a means for connecting to the network NW. In addition, a PC (Personal Computer) or a tablet terminal may be used as the data management device P. A dedicated application for executing each process described below, a browser application for accessing a dedicated web page, etc. are stored in the storage device of the data management device P, and the arithmetic unit executes various processes. Any computer device functions as each means in the data management device P of the present invention.

FIG. 2 is a diagram showing the functional configuration of the data management device P of this embodiment. In this way, the data management device P of this embodiment is connected to another data management device P that is a shared device, and includes the connection means 1, the communication means 2, the peripheral information acquisition means 3, the decoding means 4, and the storage device P. means 5.

The connection means 1 executes a connection process for establishing communication with another data management device P. Connection processing between devices will be explained with reference to FIG. 3. Here, we will exemplify a case where a connection is made between the owner device and another participant device, but the same procedure is executed when a new shared device is added to an already created room. Note that in this embodiment, each shared device can add a new shared device to the room, but it is also possible to set a restriction on the addition of new shared devices by the owner device. If the owner device imposes a restriction, no new shared device will be added to the room until the restriction is lifted.

The connection means 1 of the data management device P that attempts to perform a connection process with another device first detects devices existing within the connectable range, acquires device information, and displays the data management device P in step S11. Display device information in the section. Then, in step S12, the user selects a device to be connected from among the detected devices, and in step S13, a connection request is sent to the target device. The connection request includes device information of the device that sent the request. Here, the device information is information such as device ID, model, device name, user name, etc., and includes information that can identify the device.

The connection means 1 of the data management device P that has received the connection request displays the fact that the connection request has been made together with the device information, and receives an input from the user to permit or deny the connection (step S14). The connection means 1 of the data management device P that received the connection request transmits a response to the connection request in step S15, and if the response is to permit connection, the connection means 1 of both data management devices P sends a response to the connection request in step S16. 1 establishes a connection between devices.

Here, if a plurality of devices are selected in step S12, that is, if a request is made to create a room including three or more shared devices, the data management device P serving as the owner device and each selected device are The processes of steps S13 to S16 are performed with each of the devices, thereby establishing a direct terminal-to-terminal communication connection between the owner device and all participant devices. Furthermore, although not shown, the processes of steps S13 to S16 are automatically executed between all the participant devices, and as a result, as shown in FIG. A one-to-one connection is established.

The communication means 2 sends and receives encrypted data to and from another data management device P connected through the above procedure. The communication means 2 of the data management device P on the sending side (hereinafter referred to as the sending device) accepts the selection of data, encrypts the target data, and sends the encryption to each of the shared devices with which the connection means 1 has established communication. Send converted data. The communication means 2 also transmits the encrypted data as well as shared information regarding sharing of the encrypted data. Further, the communication means 2 of the data management device P on the receiving side (hereinafter referred to as receiving device) receives the encrypted data and the shared information, stores them in the storage means 5 in association with each other.

The shared information is information regarding sharing of encrypted data, and includes condition information indicating conditions for decrypting encrypted data. The shared information includes information that specifies the encrypted data, information that specifies the transmitting device that transmitted the encrypted data, information that specifies the room in which the encrypted data is shared, condition information, and the like. Here, the condition information may be set for each room, or the corresponding condition information may be specified from information specifying the room.

FIG. 4 is a diagram showing an example of information stored in the storage means 5 in this embodiment. The file information, room information, and room member information of this embodiment are all included in the shared information of the present invention. The storage means of this embodiment stores file information for each encrypted data. The file information includes a data ID specifying the encrypted data, a data name, information indicating the transmitting device (transmitting device information), and a room ID indicating the shared room. Furthermore, the encrypted data may include an expiration date for use of the encrypted data, and the encrypted data for which the expiration date has been set is automatically deleted when the expiration date has passed.

Furthermore, in this embodiment, the room ID, room name, owner device, and condition information are stored for each room as room information. Thereby, room information is specified from the room ID in the file information, and condition information corresponding to the encrypted data is specified. Then, in the room member information, the room information and the shared devices are associated with each other, thereby identifying the shared devices that are members of each room. That is, in this embodiment, room member information functions as shared device information. For example, in the example of FIG. 4, it can be seen that in the room with room ID 1111, three data management devices P, peer1, peer2, and peer3, are shared devices.

Here, the condition information includes neighborhood condition information indicating neighborhood conditions regarding nearby devices and location condition information indicating location conditions regarding the location of data management device P. Each includes information indicating the required connected device indicating the required designated device and the minimum number of shared devices (number of connected devices) included in the neighboring devices. Note that none of these conditions are essential, and no conditions can be specified.

For example, for the encrypted data shared in the room with room ID 1111 in FIG. decryption is allowed if the Note that although condition information is stored for each room in this embodiment, different condition information is stored for each encrypted data, and even if encrypted data is shared within the same room (same shared device), different condition information may be stored. It may also be possible to set decryption conditions.

The surrounding information acquisition means 3 obtains surrounding information indicating the surrounding situation of the data management device P. In this embodiment, device information regarding a connected nearby device is received from the connecting means 1 as nearby device information, and position information of the data management device P is also acquired. As the position information, for example, GPS information indicating the coordinates of the data management device P, information regarding the distance from a specific device, etc. are assumed, but the format of the information is not limited. The peripheral information acquisition means 3 then transmits this peripheral information to the decoding means 4.

The decoding means 4 determines whether or not the decoding condition is satisfied based on the condition information registered in the storage means 5 and the peripheral information acquired by the peripheral information acquisition means 3, and the peripheral information satisfies the decoding condition. decrypt the encrypted data. For example, it is possible to receive a selection of target encrypted data from the user, refer to the corresponding condition information each time, and determine whether the conditions are appropriate before decrypting, or it is possible to determine the conditions for all encrypted data. Then, only the encrypted data that satisfies the conditions may be decrypted and displayed on the display unit.

<Data transmission processing>
Next, the encrypted data transmission process will be described using FIG. 5. FIG. 5 is a flowchart showing a procedure for transmitting encrypted data by the transmitting device. When the communication means 2 receives a data transmission request from the user, it encrypts the data and starts the process shown in FIG. First, in step S21, specifications of the data to be transmitted as well as the destination and decoding conditions are accepted.

Specifically, it accepts an instruction to select an already created room or create a new room. In this embodiment, since condition information is specified for each room, the decoding conditions are automatically specified by specifying the room, but the decoding conditions may be specified for each data. In addition, when specifying a created room as a destination, basically all data management devices P other than the transmitting device associated with the room are specified as receiving devices, but some of the members of the room It may also be possible to individually designate only devices as shared devices. Note that if a time limit is set for the encrypted data, the designation of the time limit is also accepted in step S21.

Next, in step S22, the connection with the device designated as the destination is confirmed. Specifically, it is checked whether direct communication has been established with the data management device P designated as the destination. Specifically, a request to send encrypted data is sent to each receiving device and a response is obtained. If the transmission request is approved, the process advances to step S23.

If no response is obtained in step S22, or if a response indicating refusal of reception is received from the receiving device, the process advances to step S24, where error processing is performed and the process is terminated. As the error processing, it is assumed that, for example, information indicating that communication has failed or information indicating that reception has been refused is displayed together with information on the target data management device P, and displayed on the display unit.

In step S23, encrypted data is created by encrypting the data to be transmitted using a preset method, shared information is generated according to the decryption conditions specified in step S21, and the encrypted data and shared information are generated. Send. The transmission here is performed using direct communication between terminals established by the connection means 1.

Then, the communication means 2 repeats these processes until the transmission to all the designated receiving devices is completed (step S25), so that the encrypted data is transmitted to other shared devices and stored in the storage device 5 of the receiving device. Encrypted data and shared information are stored in association with each other. Although not shown, encrypted data and shared information are similarly stored in the storage means 5 of the transmitting device according to the designation in step S21.

<Encrypted data decryption process>
Next, the decryption process of the encrypted data stored in the storage means 5 will be explained using FIG. 6. First, in step S31, the decryption means 4 refers to the condition information corresponding to the encrypted data and identifies peripheral information related to the condition. For example, if neighborhood condition information is specified in the condition information, it is determined that nearby device information is necessary, and if location condition information is specified, it is determined that location information is necessary.

In step S32, the decoding means 4 requests the peripheral information acquisition means 3 for the peripheral information determined to be necessary in step S31. The peripheral information acquisition means 3 acquires nearby device information and position information regarding the device connected by the connection means 1, that is, the nearby device, and passes it to the decoding means 4. Note that all obtainable peripheral information may always be requested regardless of the conditions. In that case, the order of execution of step S31 and step S32 can be changed arbitrarily.

Next, in step S33, the decoding means 4 checks whether all essential conditions are satisfied based on the peripheral information and condition information. If all the conditions specified in the condition information corresponding to the target encrypted data are satisfied, the process advances to step S34 and the encrypted data is decrypted. On the other hand, if the decryption conditions for the encrypted data are not satisfied, error processing is executed in step S35. As the error processing, it is assumed that a process of displaying on the display unit that the decryption conditions for the encrypted data are not satisfied, or a control such that the encrypted data that does not satisfy the decryption conditions is simply not displayed.

Then, in step S36, the decoding conditions are checked at regular intervals, and as long as the decoding conditions are satisfied, the process waits until the use of the data is finished. If the decoding conditions are no longer satisfied, or if an operation to leave the room or an operation to end the use of the decrypted data is accepted, the process proceeds to step S37, where the decrypted data is erased and the process ends. If the encrypted data is to be used again, the decryption process starts again from step S31.

In this way, by controlling the decrypted data to be temporarily stored only while the data is being used and deleted when the use is finished, it is possible to prevent the data from being stored in an unprotected state. In this embodiment, continuation of the condition is checked at regular intervals in step S36, but the decrypted data may be configured to have a short usage time limit and delete the decrypted data after the time limit has passed. In this case, if a certain period of time has passed since decoding, the decoding process will be performed again, so it is necessary to check the decoding conditions again.

<Display example>
Examples of screen displays of the data management device P in this embodiment will be described below with reference to FIGS. 7 to 9. FIG. 7 is a display example of the home screen. On the home screen, other data management devices P detected by the connection means 1 and existing within the communication range are displayed as "connectable friends." Furthermore, data management devices P that have been connected to in the past are displayed as "friends you know," and a display indicating whether or not they are within the communication range is displayed. Here, being within the communication range means being in a position where direct communication is possible and running a dedicated application on the terminal used as the data management device P of this embodiment. .

Furthermore, when the "Room" tab is selected in the menu at the bottom of the screen, the room screen shown in FIG. 8 is displayed. On the room screen, a list of rooms in which the user is registered as a shared device is displayed based on the room information and room member information stored in the storage means 5. When a room is selected, the user is moved to a room details screen where more detailed information about the selected room is displayed.

FIG. 9(a) is a display example of the room details screen. At the top of the screen, icons are displayed for each shared device in the room. Here, the device itself is displayed at the left end, and a mark is displayed for the owner device so that it can be identified. For example, it is preferable to indicate the icon of the owner device using a colored mark or the like. Here, an operation section for restricting the addition of a new shared device to the room is displayed on the owner device. By operating the operating unit via the owner device, a request to stop adding a member is sent to the shared device, and the addition of new members by the connection means 1 of each shared device can be stopped.

On the room details screen, encrypted data shared in the room is displayed. Specifically, based on the file information in the storage means 5, encrypted data associated with the target room ID is displayed as a "shared file." In this embodiment, an upward arrow is displayed for a file for which the sending terminal itself is the file (the file on the left side of the screen in FIG. 9(a)), and a downward arrow is displayed for a file sent from another data management device P. An arrow will appear.

Here, the encrypted data can only be used if the decryption conditions are met, so here you can display only metadata such as file name and format, or display thumbnails of only the encrypted data that meet the decryption conditions. It is assumed that

When the menu at the top right of the screen is selected, the screen shown in FIG. 9(b) is displayed, and room settings can be made. In this embodiment, room settings are performed via this screen, and decoding conditions are specified for each room as described above. The "number of decryptable members" is the number of connected devices (minimum number of shared devices included in the neighboring devices) among the neighborhood conditions.

In addition, the items “Setting of essential members for decryption” and “Decryption possible even if the sender is away” are items for specifying an essential connection device among the proximity conditions. The device specified in "Setting essential members for decryption" becomes the designated device, and if "Decryption possible even if sender leaves" is turned off, the transmitting device becomes the designated device. This is a setting that allows decryption when all designated devices are included in the nearby devices (if the device itself is the designated device, all designated devices other than itself are included in the nearby devices).

In "Setting decoding location", location conditions can be set. Examples of location conditions include specifying the range in which decoding is permitted using coordinates, specifying a range within a predetermined distance from specific coordinates as a position where decoding is possible, and specifying a range within a predetermined distance from a specific facility or device. It is assumed that a range is specified as a decodable position.

“File decryption expiration date” is an item for setting a usage expiration date for shared encrypted data. When the period specified here has elapsed since the encrypted data was received, the encrypted data is automatically deleted from the storage means 5 of each shared device. Note that the room settings may be changeable only by the owner device, or may be changeable by each device individually. In the case where each device can change the decryption condition individually, it is preferable to store condition information specified by the transmitting device without applying the decryption condition to the received encrypted data.

As described above, according to the data management device P of the present embodiment, encrypted data can be directly transmitted and received between devices to be shared, and the data can be used only when the data management device P is in a predetermined situation. It becomes possible to control the permission of This enables highly secure data management and prevents unintended use or misuse of data. For example, by gathering in a conference room for a specific project and sharing data, and then restricting the use of the data unless the members gather again, it is possible to reliably prevent sensitive data from being taken away. In other applications, by distributing encrypted data in advance and allowing decryption of the encrypted data only when you go to a specific location, you can invite people to an on-site event or visit a store. It can be used for promotions such as store visits.

Note that the above-described embodiment is merely an example, and any design changes can be made without departing from the spirit of the present invention.

1: Connection means 2: Communication means 3: Surrounding information acquisition means 4: Decoding means 5: Storage means 1111: Room ID
NW: Network P: Data management device

Claims (9)

A data management device that stores encrypted data and decrypts it only under predetermined conditions,
Communication means for receiving shared information of the encrypted data, including condition information indicating decryption conditions for decrypting the encrypted data, together with the encrypted data;
storage means for storing the received encrypted data and shared information in association with each other;
peripheral information acquisition means for acquiring peripheral information indicating a peripheral situation of the data management device;
a decryption means for decrypting the encrypted data based on the condition information and the peripheral information,
The decryption means is a data management device that decrypts the encrypted data when the peripheral information satisfies a decryption condition indicated by the condition information associated with the encrypted data. The decoding condition includes a neighborhood condition regarding a nearby device existing in the vicinity of the data management device,
The peripheral information acquisition means acquires nearby device information that specifies the nearby device as the peripheral information,
The decryption unit decrypts the encrypted data when it is determined that the neighborhood condition indicated by the condition information associated with the encrypted data is satisfied based on the neighborhood device information. Data management device as described. The shared information includes shared device information that identifies a plurality of shared devices that share the encrypted data,
The neighborhood condition includes a condition that defines a minimum number of the shared devices included in the neighborhood device,
3. The data management device according to claim 2, wherein the decryption means determines that the neighborhood condition is satisfied and decrypts the encrypted data when the neighboring devices include the minimum number or more of the shared devices. Device. The neighborhood condition includes a condition that the nearby device includes a specified designated device,
According to claim 2 or 3, the decryption means determines that the neighborhood condition is satisfied and decrypts the encrypted data when all of the one or more designated devices are included in the neighborhood devices. Data management device as described. The shared information includes transmitting device information that identifies a transmitting device that transmitted the encrypted data,
5. The data management device according to claim 2, wherein the neighborhood condition includes a condition that the transmitting device is included in the neighborhood devices. The decoding condition includes a position condition regarding the position of the data management device,
The peripheral information acquisition means acquires position information indicating the position of the data management device as the peripheral information,
Any one of claims 1 to 5, wherein the decryption means decrypts the encrypted data when the location information satisfies the location condition indicated by the condition information associated with the encrypted data. The data management device described in . 7. The data management device according to claim 1, wherein the communication means receives the encrypted data and shared information through direct communication between terminals using short-range communication. A data management program that causes a computer to function as a data management device that stores encrypted data and decrypts it only under predetermined conditions,
Communication means for receiving shared information of the encrypted data, including condition information indicating decryption conditions for decrypting the encrypted data, together with the encrypted data;
storage means for storing the received encrypted data and shared information in association with each other;
peripheral information acquisition means for acquiring peripheral information indicating a peripheral situation of the data management device;
causing the computer to function as a decryption means for decrypting the encrypted data based on the condition information and the peripheral information;
The decryption means is a data management program that decrypts the encrypted data when the peripheral information satisfies a decryption condition indicated by the condition information associated with the encrypted data. A data management method using a data management device that stores encrypted data and decrypts it only under predetermined conditions,
a communication step of receiving shared information of the encrypted data, including condition information indicating decryption conditions for decrypting the encrypted data, together with the encrypted data;
a storage step of storing the received encrypted data and shared information in association with each other;
a peripheral information acquisition step of acquiring peripheral information indicating a peripheral situation of the data management device;
A computer executes a decryption step of decrypting the encrypted data based on the condition information and the peripheral information,
In the decrypting step, the encrypted data is decrypted when the peripheral information satisfies a decryption condition indicated by the condition information associated with the encrypted data.