Server, communication system, communication method, and program

Abstract

Provided is a server comprising: a random number / key generation unit that generates a random number or key data that is to be transmitted; a terminal position information acquisition unit that acquires position information about a terminal; a mobile body trajectory information acquisition unit that acquires mobile body trajectory information which is information indicating trajectories of a plurality of mobile bodies; a transmission plan generation unit that, on the basis of the position information of the terminal and the mobile body trajectory information, identifies a transmission-destination mobile body from among the plurality of mobile bodies in order to transmit the random number or key data to the terminal, and generates a transmission plan; and a transmission unit that transmits the transmission plan and the random number or key data to the transmission-destination mobile body on the basis of the transmission plan.

Description

Server, communication system, communication method and program

[0001] The present invention relates to a server, a communication system, a communication method, and a program.

[0002] To improve security in communications, it is becoming increasingly necessary to encrypt various types of information. Encryption requires a key and a random number as its source. In particular, in systems such as symmetric key cryptography, where both the sender and receiver use a secret key, the issue of how to safely deliver the generated key becomes an issue.

[0003] Special Publication No. 2022-515965

[0004] The disclosures of the above prior art documents are incorporated herein by reference. The following analysis has been carried out by the present inventors.

[0005] In the past, keys and random numbers were often delivered via applications or at layers above the IP layer, such as IKE (Internet Key Exchange). The other party in a communication is identified by an IP address, but because IP addresses are logical values, they do not provide accurate location information. Furthermore, using a proxy server or a VPN (Virtual Private Network) can result in keys being delivered to unexpected parties or to areas where they cannot be delivered, posing a problem in terms of reachability.

[0006] Furthermore, if encrypted keys or random numbers are transmitted over the network, there is a risk that communications may be intercepted. Even if encryption is sufficiently strong, there is a risk that illegally obtained keys may be analyzed after the fact using high-performance quantum computers, and plaintext keys may be obtained.

[0007] In this way, when logical IP addresses are used, there are problems with reachability and the risk that encrypted keys and random numbers may be stolen and analyzed.

[0008] Patent Document 1 discloses an invention related to a satellite communication procedure using a non-terrestrial network (NTN) constellation. In particular, with regard to technology for transmitting data from a satellite, it discloses, for example, a packaging technology that divides data into packets or frames using a communication protocol, and that it is possible to transmit data in multiple frequency ranges in an order known only to the transmitting and receiving devices. It also discloses that the satellites that make up the constellation may be low earth orbit (LEO) satellites.

[0009] Patent Literature 1 suggests that by utilizing a communication network based on an NTN constellation, particularly a LEO constellation, it is possible to selectively distribute packaged data to very limited targets. However, it is not clear how to achieve highly reachable and highly secure communication between multiple mobile units and multiple terminals.

[0010] Therefore, an object of the present invention is to provide a server, a communication system, a communication method, and a program that contribute to communication between multiple mobile bodies and multiple terminals with higher reachability and higher security.

[0011] According to a first aspect of the present invention or disclosure, there is provided a server having a random number / key generation unit that generates random numbers or key data to be transmitted, a terminal location information acquisition unit that acquires terminal location information, a mobile object trajectory information acquisition unit that acquires mobile object trajectory information that is information indicating the trajectories of multiple mobile objects, a transmission plan generation unit that identifies a destination mobile object from the multiple mobile objects based on the terminal location information and the mobile object trajectory information and generates a transmission plan in order to transmit the random number or key data to the terminal, and a transmission unit that transmits the random number or key data to the destination mobile object based on the transmission plan.

[0012] According to a second aspect of the present invention or disclosure, there is provided a communication system including a server having a random number / key generation unit that generates random numbers or key data to be transmitted, a terminal location information acquisition unit that acquires location information of a terminal, a mobile body trajectory information acquisition unit that acquires mobile body trajectory information that is information indicating the trajectories of multiple mobile bodies, a transmission plan generation unit that identifies a destination mobile body from multiple mobile bodies based on the location information of the terminal and the mobile body trajectory information and generates a transmission plan to transmit the random number or key data to the destination mobile body, a mobile body having a server communication unit that communicates with the server and receives the random number or key data, and a terminal communication unit that communicates with the terminal based on the transmission plan and transmits the random number or key data to the terminal, and a mobile body communication unit that communicates with the mobile body and receives the random number or key data.

[0013] According to a third aspect of the present invention or disclosure, there is provided a communication method for a communication system having a server, a mobile body traveling on a predetermined trajectory, and a terminal, the communication method including the steps of: the server generating random numbers or key data to be transmitted; the server acquiring location information of the terminal; the server acquiring mobile body trajectory information, which is information indicating the trajectories of multiple mobile bodies; the server identifying a destination mobile body from multiple mobile bodies based on the location information of the terminal and the mobile body trajectory information, and generating a transmission plan to transmit the random number or key data to the terminal; the server transmitting the random number or key data to the destination mobile body based on the transmission plan; the mobile body communicating with the server and receiving the random number or key data; the mobile body communicating with a terminal based on the transmission plan and transmitting the random number or key data to the terminal; and the terminal communicating with the mobile body and receiving the random number or key data.

[0014] According to a fourth aspect of the present invention or disclosure, a program is provided for causing a computer to execute the following processes: generating random numbers or key data to be transmitted; acquiring location information of a terminal; acquiring mobile body trajectory information which is information indicating the trajectories of multiple mobile bodies; identifying a destination mobile body from multiple mobile bodies based on the location information of the terminal and the mobile body trajectory information in order to transmit the random number or key data to the terminal, and generating a transmission plan; and transmitting the random number or key data to the destination mobile body based on the transmission plan.

[0015] According to each aspect of the present invention and disclosure, a server, a communication system, a communication method, and a program are provided that contribute to communication between multiple mobile bodies and multiple terminals with higher reachability and higher security.

[0016] FIG. 1 is a block diagram showing an example of a configuration of a server according to an embodiment. FIG. 2 is a schematic diagram showing an overview of processing of a server according to a first embodiment. FIG. 3 is a block diagram showing an example of a configuration of a server according to the first embodiment. FIG. 4 is a schematic diagram showing an example of encryption processing of a first encryption unit of the server according to the first embodiment. FIG. 5 is a diagram showing an example of a transmission plan generated by the server according to the first embodiment. FIG. 6 is a flowchart showing an example of operation of the server according to the first embodiment. FIG. 7 is a block diagram showing an example of a hardware configuration of a server according to the first embodiment. FIG. 8 is a block diagram showing a configuration of a communication system according to a second embodiment. FIG. 9 is a diagram showing details of processing in a second encryption unit of the communication system according to the second embodiment. FIG. 10 is a diagram showing decryption processing when a terminal receives data from a mobile body (satellite) in the communication system according to the second embodiment. FIG. 11 is a sequence diagram showing an example of a series of operations of the communication system according to the second embodiment.

[0017] [Overview of Processing of One Embodiment] First, an overview of processing of one embodiment will be described. Note that the drawing reference symbols attached to this overview are attached to each element for convenience as an example to facilitate understanding, and the description of this overview is not intended to be limiting in any way. Furthermore, connection lines between blocks in each figure include both bidirectional and unidirectional. Unidirectional arrows are used to schematically indicate the flow of the main signal (data) and do not exclude bidirectionality. Furthermore, although not explicitly shown in the circuit diagrams, block diagrams, internal configuration diagrams, connection diagrams, etc. shown in this disclosure, input ports and output ports exist at the input and output ends of each connection line. The same applies to input / output interfaces.

[0018] [Configuration of an embodiment] Next, the configuration of a server according to an embodiment will be described with reference to the drawings. Fig. 1 is a block diagram showing an example of the configuration of a server according to an embodiment. As shown in this diagram, a server 10 according to an embodiment includes a random number and key generation unit 11, a terminal position information acquisition unit 12, a mobile object trajectory information acquisition unit 13, a transmission plan generation unit 14, and a transmission unit 15.

[0019] The random number / key generation unit 11 generates random numbers or key data to be transmitted. The terminal location information acquisition unit 12 acquires terminal location information. The mobile object trajectory information acquisition unit 13 acquires mobile object trajectory information, which is information indicating the trajectories of multiple mobile objects. The transmission plan generation unit 14 identifies a destination mobile object from the multiple mobile objects based on the terminal location information and the mobile object trajectory information, and generates a transmission plan to transmit the random number or key data to the terminal. The transmission unit 15 transmits the random number or key data to the destination mobile object based on the transmission plan.

[0020] According to one embodiment of the server 10, it is possible to select a mobile object from a plurality of mobile objects to transmit the generated key data or random number to the terminal based on the acquired terminal location information and the trajectory information of the plurality of mobile objects. Since the future position of the mobile object can also be identified based on the trajectory information of the mobile object, even if the mobile object moves out of the communication range, it is possible to continue transmitting the random number or key data by planning to hand over the communication to another mobile object.

[0021] Although there is no limitation here on the size of the communication range of the multiple mobile devices that are the communication destinations of the server 10, as the density of mobile devices increases, the communication range that needs to be covered becomes smaller, and therefore it is possible to make the destinations more limited and selective. In this way, by providing an appropriate random number or key depending on the location information of the terminal, it becomes possible to deliver a random number or key that requires high confidentiality with a high degree of security.

[0022] Specific embodiments will be described in more detail below with reference to the drawings. Note that the same components in each embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0023] [First Embodiment] Fig. 2 is a schematic diagram showing an overview of server processing according to the first embodiment. As shown in this diagram, a server 10 communicates with a satellite, which is a mobile body 20, and transmits a random number or a key. The mobile body 20 communicates with a terminal 30 and transmits a random number or a key. The mobile body 20 travels on a predetermined orbit, and examples thereof include a satellite constellation as shown in the diagram, a high-altitude long-endurance (HAPS), a UAV (unmanned aerial vehicle), and a terrestrial unmanned ground vehicle (UGV), but is not necessarily limited to these.

[0024] As shown in Figure 2, each satellite has its own communication range (cell), within which it is possible to distribute random numbers or keys. The server of this embodiment identifies the satellite that provides or is expected to provide the cell to which the terminal belongs, based on the terminal's location information and the orbit of the satellite, which is a moving object, and then transmits the key to that satellite.

[0025] [Configuration of First Embodiment] Next, the configuration of the server 10 according to the first embodiment will be described with reference to the drawings. Fig. 3 is a block diagram showing an example of the configuration of the server 10 according to the present embodiment. As shown in this diagram, the server 10 according to the first embodiment includes a random number and key generation unit 11, a terminal position information acquisition unit 12, a mobile object trajectory information acquisition unit 13, a transmission plan generation unit 14, a transmission unit 15, and a first encryption unit 16.

[0026] The random number and key generation unit 11 generates random numbers or key data to be transmitted. Conventional generation techniques can be applied to the random numbers or key data. The generated data is sent to the first encryption unit 16 for encryption. The random number and key generation process may be executed or re-executed in response to a request from the terminal.

[0027] The terminal location information acquisition unit 12 acquires location information of the terminal. The "terminal" may be a smartphone or the like, but any device capable of direct communication with a mobile body can be used. However, if the device acquiring location information and the terminal are separated, key delivery may fail, so both must be present in at least the same communication range (cell). As described above, the location information of the terminal can be identified by the GPS (Global Positioning System) possessed by the mobile body. Alternatively, location registration information of the smartphone at a carrier terrestrial base station may be used. The acquired terminal location information may be acquired via the mobile body or via a terrestrial base station.

[0028] The mobile object trajectory information acquisition unit 13 acquires mobile object trajectory information, which is information indicating the trajectories of multiple mobile objects. As mentioned above, "mobile objects" can be various objects, including satellites. Mobile object trajectory information defines the trajectories of these mobile objects. "Trajectory information" includes position (x, y, z) and velocity (v ｘ , v ｙ , v ｚ ) In the case of a mobile object that orbits the Earth, such as a satellite, the orbit information may be orbit information specified by latitude, longitude, and altitude, or orbit information that can be specified by seven elements: "semi-major axis, orbital eccentricity, orbital inclination, longitude of ascending node, argument of periapsis, true anomaly (orbital deviation), eccentric anomaly (orbital deviation), or mean anomaly (orbital deviation)." The orbit information may also be actual information held by the mobile object or information calculated from an operation plan for the mobile object. These are stored in advance in a memory area of ​​the server and are used in the process of specifying the mobile object in the transmission plan generation unit 14, which will be described later.

[0029] The first encryption unit 16 encrypts the random number or key data to generate first encrypted random number or key data. While the encryption of the random number or key data may be performed using existing technology, it is preferable to perform encryption for each terminal, particularly to identify the terminal. This preferably involves performing processing using terminal-specific information, such as an IMEI (International Mobile Equipment Identifier) ​​or a MAC address (Media Access Control address), that is shared in advance between the terminal and the server. Furthermore, the terminal-specific information may be user information related to the terminal. In this case, user or terminal identification information provided by a trusted authentication server such as Active Directory (registered trademark), or official key information issued by a public institution such as a My Number card, may be used. This terminal-specific information may be stored in a hash tree, and is stored, distributed, and utilized in a verifiable state. For example, a hash of the terminal-specific information may be used to encrypt the generated random number and key data in this section, or the hash may be used as an insertion position when inserting dummy data or rearranging data.

[0030] 4 is a schematic diagram illustrating an example of encryption processing by the first encryption unit of the server according to this embodiment. As shown in this diagram, the generated random number and key data are encrypted for each terminal using terminal-specific information. For example, the MAC address of the terminal is converted into some kind of numeric value and used as a PSK (Pre-Shared Key) as the encryption key source, using AES (Advanced Encryption Standard) or the like for encryption processing.

[0031] Next, the encrypted data is divided into transmission block data. Each divided block is assigned to a mobile object (satellite) appropriate for distribution to the terminal according to the time, and then transmitted. As shown in the figure, before transmission, dummy data generated from terminal-specific data previously shared in each block may be inserted, or a block rearrangement procedure may be adopted. In Figure 4, the encrypted data is divided into six blocks for each terminal, two dummy data are inserted, and eight blocks are sent to the mobile satellite S １ ~S８ However, the present invention is not limited to this, and it is also possible to increase or decrease the number of divisions each time a transmission is made.

[0032] The transmission plan generation unit 14 identifies a destination mobile object from the multiple mobile objects based on the terminal's location information and the mobile object orbit information, and generates a transmission plan to transmit random numbers or key data to the terminal. If the mobile object is a satellite, the current or future position of the mobile object can be identified from the orbit information, and the center point on the Earth (latitude, longitude) when projected from that position onto the Earth can be determined. Furthermore, by taking into account the directivity of the mobile object's transmitting antenna, it is possible to identify the mobile object's communication range (cell) at a certain time. In this way, a transmission plan can be created by identifying the mobile object (satellite) within the communication range of the destination terminal's location according to time.

[0033] 5 is a diagram for explaining an example of a transmission plan generated by the server of this embodiment. ｍ The same values ​​as in Figure 4 are used. １ In the case of transmission data d ３ The position coordinates of the acquired terminal are (λ ３ , Φ ３ , h ３ ) so t １ The terminal searches for the closest mobile object (satellite) within its communication range. That is, (λ ３ , Φ ３ , h ３ ) and (λ ｓｉ , Φ ｓｉ , h ｓｉ ) and calculate the distance between them. ４ In addition, (λ ｓｉ , Φ ｓｉ , h ｓｉ ) is calculated from the acquired mobile trajectory information. １ are the (predicted) coordinates of each moving object in ｓｉ is altitude).

[0034] 5, the distance is calculated using the geodetic coordinates of the terminal and the mobile unit, but various calculation methods are possible and are not limited to the above. In this way, the mobile unit to which the terminal is to send random numbers or key data at each time is identified, and a transmission plan is created.

[0035] The transmitter 15 transmits the transmission plan and the random number or key data based on the transmission plan to the destination mobile entity. The transmission plan data may be held by a server and controlled to be transmitted to the mobile entity at the required timing, or each mobile entity may hold all or part of the transmission plan data and control the transmission on the mobile entity side.

[0036] [Explanation of Operation] Fig. 6 is a flowchart for explaining an example of the operation of the server 10 of this embodiment. As shown in this figure, the server 10 first generates a random number or key data (step S101). Next, it acquires the location information of the terminal (step S102). Next, it acquires the moving object trajectory information (step S103). The order of the processes up to this point is not specified, and the processes may be performed one after the other or simultaneously.

[0037] Next, the generated random number or key data is encrypted (step S104). Next, a transmission plan is generated based on the terminal location information and the mobile object trajectory information (step S105). After that, the random number or key data is transmitted based on the generated transmission plan (step S106).

[0038] [Hardware Configuration] The server 10 of this embodiment can be executed by an information processing device (computer) and has the configuration shown in Fig. 7. The server 10 includes a CPU (Central Processing Unit) 301, a memory 302, an input / output interface 303, and a NIC (Network Interface Card) 304 as a communication means, which are interconnected by an internal bus 305.

[0039] However, the configuration shown in Fig. 7 is not intended to limit the hardware configuration of the server. The server 10 may include hardware not shown, and may not include the input / output interface 303 as necessary. Furthermore, the number of CPUs and other components included in these devices is not intended to be limited to the example shown in Fig. 7; for example, the server 10 may include multiple CPUs.

[0040] The memory 302 is a RAM (Random Access Memory), a ROM (Read Only Memory), or an auxiliary storage device (such as a hard disk).

[0041] The input / output interface 303 is a means for interfacing with a display device and an input device (not shown). The display device is, for example, a liquid crystal display. The input device is, for example, a camera or sensor that receives biometric information, and a device that receives user operations such as a keyboard or mouse.

[0042] Although not shown, the server of this embodiment is connected to a device for transmitting random numbers or key data to a mobile object. For example, if the destination mobile object is a satellite, a transmitting antenna is connected. The connection may be made via an input / output interface 303 provided in the server, or may be made to an antenna device on the network via a NIC 304.

[0043] The functions of the server 10 are realized by a group of programs (processing modules) stored in the memory 302, such as a random number / key generation program, a terminal location information acquisition program, a mobile object trajectory information acquisition program, a first encryption program, a transmission plan generation program, and a transmission program, as well as a group of data, such as parameters, used by each program. The processing modules are realized, for example, by the CPU 301 executing each program stored in the memory 302. The programs can be downloaded via a network or updated using a storage medium storing the programs. Furthermore, the processing modules may be realized by semiconductor chips. That is, it is sufficient to have some means for executing the functions performed by the processing modules using hardware and / or software.

[0044] [Hardware Operation] In the server 10, a random number / key generation program is called from the memory 302 and executed by the CPU 301. The program acquires unique information of the terminal and generates a random number or a key using the unique information.

[0045] Next, the terminal location information acquisition program is called from memory 302 and executed by CPU 301. This program communicates with the terminal and receives location information data. The location information data may be location information acquired by a GPS device attached to the terminal, location registration information for a base station of a mobile phone network, or the like.

[0046] Next, the mobile object trajectory information acquisition program is called from memory 302 and is executed by CPU 301. This program reads the mobile object trajectory information data stored in memory 302 so that it can be used for the transmission plan generation program described later. The mobile object trajectory information does not necessarily have to be stored in the server, and may be acquired from another server via NIC 304.

[0047] Next, the first encryption program is called from memory 302 and executed by CPU 301. This program reads the random number or key data generated and stored in memory 302, and executes encryption processing. While conventional techniques can be applied to encryption processing, the server of this embodiment particularly performs processing to divide transmission data into block data. The divided block data is stored in a transmission queue or stack provided in memory 302. When storing, dummy data generated by CPU 301 using terminal-specific information is mixed in. Furthermore, the storage order is changed by rearranging the order of the block data on CPU 301 using the terminal-specific information.

[0048] Next, the transmission plan generation program is called from memory 302 and is put into execution state by CPU 301. This program reads the acquired terminal position information and mobile object trajectory information from memory 302, and when transmitting block data to the terminal at a predetermined time, determines by calculation the mobile object that is within the communication range and closest to the terminal, and associates data such as an ID that identifies that mobile object with each element of the block data stored in a transmission queue or the like on memory 302.

[0049] Next, the transmission program is called from memory 302 and is put into execution state by CPU 301. This program reads block data from a transmission queue or the like provided in memory 302, and transmits the data to the mobile object associated with the data. The timing of data transmission may be acquired and controlled on the server side, or transmission may be performed at a timing selected by the server, with the timing of transmission being controlled by the mobile object at the transmission destination.

[0050] [Explanation of Effects] According to the server 10 of this embodiment, by encrypting the encrypted random number or key data and dividing it into block data, it is possible to deliver the random number or key data more securely than if it were sent to the terminal all at once. It is also possible to generate a transmission plan for transmitting the random number or key data in a time-division manner from multiple mobile objects that arrive within a communication range that includes the terminal's location. This allows the delivery of the random number or key data to be extremely limited to the location of the terminal, significantly reducing the risk of encrypted data stolen by eavesdropping being analyzed later or data being sent to an unexpected area or an area where it cannot be provided, and enabling the delivery of the random number or key with a high degree of security.

[0051] Second Embodiment In this embodiment, the configuration and operation of a communication system including the above-described server, a mobile unit, and a terminal will be described.

[0052] [Configuration of the Second Embodiment] Fig. 8 is a block diagram showing the configuration of a communication system according to the second embodiment. As shown in this diagram, the communication system of this embodiment includes a server 10, a mobile object 20, and a terminal 30. Here, there are multiple mobile objects 20, which cooperate to directly communicate with the terminal 30.

[0053] The mobile object 20 may be a low earth orbit (LEO) satellite traveling in a low orbit (generally at an altitude of 2,000 kilometers or less). The distribution of random numbers or key data via a constellation of LEO satellites allows data distribution to terminals within an extremely limited area from multiple different satellites, since the coverage (communication range) of a single satellite is small and the satellite is not a geostationary satellite. Another advantage is that the low orbit allows direct access by terminals such as smartphones with relatively low wireless output.

[0054] The configuration of the server 10 has been explained above, so a detailed description will be omitted. The mobile unit 20 has a server communication unit 21, a terminal communication unit 22, and a second encryption unit 23. The terminal 30 has a mobile communication unit 31 and a decryption unit 32.

[0055] The server communication unit 21 communicates with the server in the mobile unit 20. Specifically, it receives the first encrypted random number or key data generated and encrypted by the server. It also receives the transmission plan generated by the server as needed.

[0056] The terminal communication unit 22 in the mobile unit 20 communicates with the terminal 30 based on a transmission plan generated by the server. The unit also transmits the transmission strength of data to the terminal 30 and receives the reception strength of the data from the terminal 30. Using this reception strength, encryption (scrambling) is performed by the second encryption unit 23, which will be described later.

[0057] The second encryption unit 23 encrypts data destined for the terminal in the mobile unit 20. Specifically, it further encrypts the first encrypted random number or key data using the transmission strength of the data destined for the terminal 30 and the reception strength of the data to generate the second encrypted random number or key data. More specifically, this unit quantifies the difference between the transmission strength of the data destined for the terminal and the reception strength of the data received from the terminal, converts it into an argument for encryption, and performs encryption.

[0058] Figure 9 is a diagram showing details of the processing in the second encryption unit 23. As shown in this diagram, the mobile device 1. identifies the transmission level of data directed to the terminal. 2. generates and transmits probe packet 1 with transmission level information superimposed. On the terminal side, 3. receives probe packet 1 and acquires the transmission and reception levels. 4. Next, generates probe packet 2 including the transmission and reception levels, and 5. transmits it to the mobile device. 6. On the terminal side, the transmission and reception levels are normalized, etc., and a descrambling code is generated. 7. On the mobile device side, the transmission level of the mobile device itself and the reception level of the terminal are normalized, etc., and a scrambling code is generated.

[0059] In this way, by further encrypting (scrambling) the first encrypted random number or key data to generate and transmit the second encrypted random number or key data, a high level of security can be ensured for communications between the mobile unit and the terminal. More specifically, since the scramble code can be generated at any time and used disposably, communications with the terminal can be limited to each mobile unit and on a time axis, enabling even more secure communications.

[0060] In communication with the terminal in the mobile unit 20, the terminal communication unit 22 is preferably configured not to add header information that can identify the destination and sequence number to the encrypted random number or key data sent to the terminal. By concealing the destination and sequence number in the header, it is possible to reduce the risk of attacks on the sender and unauthorized restoration of data.

[0061] In the terminal 30, the mobile communication unit 31 receives first probe data including transmission strength from the mobile unit 20, acquires the reception strength of the data, transmits the reception strength to the mobile unit 20 as second probe data, and then receives the random number or key data to be transmitted that has been encrypted based on the transmission strength and the reception strength. That is, as explained in Figure 9 above, the transmission level and the reception level at the terminal are acquired by exchanging probe data, and the mobile unit 20 and the terminal 30 respectively generate a scrambling code and a descrambling code to perform second encryption and decryption. The encrypted random number or key data is transmitted from the mobile unit 20 to the terminal 30 after the second encryption, and is received by the mobile communication unit 31.

[0062] In addition, the second probe data transmitted from the terminal 30 to the mobile body 20 is associated with the terminal's unique identification information, and is used to identify the random number or key data that has been subjected to the first encryption and is the target of scrambling in the mobile body 20.

[0063] In addition to the above, when the terminal 30 receives scrambled data from the mobile unit 20, if the terminal 30 does not have a key for decrypting the scrambled data exchanged with the mobile unit 20, the terminal 30 requests the key from the mobile unit 20. The request may include the reception strength from the mobile unit 20.

[0064] The decryption unit 32 decrypts the encrypted data. Specifically, the decryption unit 32 decrypts the encrypted (scrambled) data received from the mobile unit based on the transmission strength and the reception strength (decryption of the second encryption), and then further decrypts the decrypted encrypted data (decryption of the first encryption) using a key previously shared with the server to obtain the random number or key data to be transmitted.

[0065] Figure 10 is a diagram for explaining the decryption process when a terminal receives data from a mobile object (satellite) in the communication system of this embodiment. As shown in this diagram, data is received from each satellite. At this time, the data is scrambled based on the second encryption state, i.e., the transmission and reception strength of the communication. Therefore, the terminal first performs a process to decrypt the second encryption state for each satellite using a descrambling code stored on the terminal side.

[0066] Next, the first encrypted state is decrypted. First, the sorting is restored using the device-specific information shared with the server. Next, the dummy data is removed. Once removal is complete, the block data is combined and the encryption using the device-specific information is decrypted.

[0067] [System Operation] Figure 11 is a sequence diagram showing an example of a series of operations of the communication system of this embodiment. As shown in this diagram, first, random numbers or key data are generated in the server (step S1101). Next, location information is acquired from the terminal (step S1102). Next, mobile object trajectory information is acquired (step S1103). The random numbers or key data are encrypted to become first encrypted random numbers or key data (step S1104). Next, a transmission plan is generated based on the terminal location information and the mobile object trajectory information (step S1105). Part or all of the generated transmission plan may be shared with each mobile object. Next, the first encrypted random numbers or key data is transmitted based on the transmission plan (step S1106). On the mobile object side, a scrambling code and a descrambling code for performing second encryption and decryption with the terminal are generated using the transmission strength and reception strength of the communication, respectively (steps S1107 and S1108). This processing has already been described in Figure 9 above. The generated scramble code is used to generate a second encrypted random number or key data (step S1109), and the second encrypted random number or key data is transmitted to the terminal based on the transmission plan (step S1110). The terminal receives the second encrypted random number or key data and performs a decryption process (step S1111). The decryption process has already been described with reference to FIG. 10.

[0068] [Explanation of Effect] In the communication system of this embodiment, in addition to encryption based on terminal-specific information shared by each terminal, it is possible to perform second encryption that scrambles random numbers or key data for each mobile unit that transmits the data when the random numbers or key data are transmitted from the mobile unit to the terminal. The second encryption is based on the transmission strength and reception strength when the mobile unit and the terminal communicate, and these two-stage encryptions enable communication with sufficient strength even if data is stolen.

[0069] Some or all of the above-described embodiments can also be described as in the following supplementary notes. However, the following supplementary notes are merely examples of the present invention, and the present invention is not limited to such cases. [Supplementary Note 1] As in the server according to the first aspect described above. [Supplementary Note 2] Preferably, the server according to Supplementary Note 1, which has a first encryption unit that encrypts random numbers or key data to generate first encrypted random numbers or key data, and a transmission unit that transmits the first encrypted random numbers or key data encrypted by the first encryption unit to the destination mobile object based on the transmission plan. [Supplementary Note 3] Preferably, the server according to Supplementary Note 2, wherein the first encryption unit encrypts the random numbers or key data using terminal-specific information shared with the terminal in advance, divides the random numbers or key data into block data as transmission data, and performs at least one of inserting dummy block data or rearranging the transmission order to generate the first encrypted random numbers or key data. [Supplementary Note 4] A mobile device having a server communication unit that communicates with a server, a terminal communication unit that communicates with a terminal based on a transmission plan generated by the server, and a second encryption unit that encrypts data destined for the terminal, wherein the server communication unit receives first encrypted random numbers or key data generated and encrypted by the server, the terminal communication unit transmits data including a transmission strength of the data to the terminal and receives a reception strength of the data from the terminal, the second encryption unit further encrypts the first encrypted random numbers or key data using the transmission strength and the reception strength of the data to generate second encrypted random numbers or key data, and the terminal communication unit transmits the second encrypted random numbers or key data to the terminal. [Supplementary Note 5] The mobile device is an aircraft moving in an orbit at an altitude of 2,000 kilometers or less, preferably the mobile device of Supplementary Note 4. [Supplementary Note 6] The second encryption unit quantifies the difference between the transmission strength of the data destined for the terminal and the reception strength of the data received from the terminal, converts it into an argument for encryption, and performs encryption, preferably the mobile device of Supplementary Note 4 or Supplementary Note 5. [Supplementary Note 7] Preferably, the mobile body according to any one of Supplementary Notes 4 to 6, wherein the terminal communication unit does not add header information that can identify the destination and sequence number to the encrypted random number or key data that is transmitted to the terminal.[Supplementary Note 8] A terminal having a mobile communication unit that communicates with a mobile body traveling on a predetermined trajectory, and a decryption unit that decrypts encrypted data, wherein the mobile communication unit receives encrypted data to be transmitted from the mobile body and transmission strength data superimposed on the data, obtains the reception strength of the data, and transmits the reception strength to the mobile body, the decryption unit decrypts the encrypted data received from the mobile body based on the transmission strength and the reception strength, and the decryption unit further decrypts the decrypted encrypted data using a key previously shared with a server to obtain random number or key data to be transmitted. [Supplementary Note 9] As in the communication system according to the second aspect described above. [Supplementary Note 10] As in the communication method according to the third aspect described above. [Supplementary Note 11] As in the program according to the fourth aspect described above.

[0070] The disclosures of the above-cited patent documents and other documents are incorporated herein by reference. Modifications and adjustments of the embodiments are possible within the scope of the entire disclosure of the present invention (including the claims), and further based on the basic technical concepts thereof. Furthermore, various combinations and selections (including partial deletions) of various disclosed elements (including elements of each claim, each embodiment, each element of each embodiment, each element of each drawing, etc.) are possible within the scope of the entire disclosure of the present invention. In other words, the present invention naturally includes various modifications and alterations that would be possible by a person skilled in the art in accordance with the entire disclosure and technical concepts, including the claims. In particular, with regard to the numerical ranges described herein, any numerical value or subrange included within the range should be construed as being specifically described, even if not otherwise specified.

[0071] 10: Server 11: Random number and key generation unit 12: Terminal position information acquisition unit 13: Mobile body trajectory information acquisition unit 14: Transmission plan generation unit 15: Transmission unit 16: First encryption unit 20: Mobile body 21: Server communication unit 22: Terminal communication unit 23: Second encryption unit 30: Terminal 31: Mobile body communication unit 32: Decryption unit 301: CPU 302: Memory 303: Input / output interface 304: NIC (Network Interface Card) 305: Internal bus

Claims

1. a random number / key generation unit that generates random numbers or key data to be transmitted; a terminal location information acquisition unit that acquires location information of the terminal; a mobile object trajectory information acquisition unit that acquires mobile object trajectory information that is information indicating the trajectories of a plurality of mobile objects; a transmission plan generation unit that identifies a destination mobile object from among the plurality of mobile objects based on the location information of the terminal and the mobile object trajectory information to transmit the random number or key data to the terminal, and generates a transmission plan; a transmission unit that transmits the transmission plan to the destination mobile body and transmits the random number or key data based on the transmission plan; A server having:

2. a first encryption unit that encrypts the random number or key data to generate first encrypted random number or key data; the transmitting unit transmits the first encrypted random number or key data encrypted by the first encrypting unit based on the transmission plan to the destination mobile object. The server of claim 1.

3. The server of claim 2, wherein the first encryption unit encrypts the random number or key data using terminal-specific information shared with the terminal in advance, divides it into block data as transmission data, and performs at least one of inserting dummy block data or rearranging the transmission order to obtain the first encrypted random number or key data.

4. a server communication unit that communicates with the server; a terminal communication unit that communicates with a terminal based on the transmission plan generated by the server; a second encryption unit that encrypts data destined for the terminal; and the server communication unit receives a first encrypted random number or key data that is generated and encrypted by the server; the terminal communication unit transmits data including a transmission strength of the data to the terminal and receives a reception strength of the data from the terminal; the second encryption unit further encrypts the first encrypted random number or key data using the transmission strength of the data and the reception strength of the data to generate a second encrypted random number or key data; the terminal communication unit transmits the second encrypted random number or key data to the terminal; Mobile object.

5. 5. The moving body according to claim 4, wherein the moving body is a flying body that moves in an orbit at an altitude of 2,000 kilometers or less.

6. the second encryption unit quantifies the difference between the transmission strength of the data directed to the terminal and the reception strength of the data received from the terminal, converts it into an argument for encryption, and executes encryption; The moving body according to claim 4.

7. 5. The mobile body according to claim 4, wherein said terminal communication unit does not add header information that can identify a destination and a sequence number to said encrypted random number or key data that is transmitted to said terminal.

8. a mobile communication unit that communicates with a mobile object traveling along a predetermined trajectory; a decryption unit that decrypts the encrypted data; and the mobile communication unit receives first probe data including a transmission strength of data from the mobile unit, acquires the reception strength of the data, associates the reception strength with terminal-specific information, and transmits the second probe data to the mobile unit, and then receives, at the mobile unit, random number or key data to be transmitted, encrypted based on the terminal-specific information, the transmission strength, and the reception strength; the decryption unit decrypts encrypted data received from the mobile unit based on the transmission strength and the reception strength; Furthermore, the decryption unit further decrypts the decrypted encrypted data using a key previously shared with the server to obtain the random number or key data to be transmitted. Terminal.

9. a random number / key generation unit that generates random numbers or key data to be transmitted; a terminal location information acquisition unit that acquires location information of the terminal; a mobile object trajectory information acquisition unit that acquires mobile object trajectory information that is information indicating the trajectories of a plurality of mobile objects; a transmission plan generation unit that identifies a destination mobile object from among a plurality of mobile objects based on the location information of the terminal and the mobile object trajectory information to transmit the random number or key data to the terminal, and generates a transmission plan; a transmission unit that transmits the transmission plan to the destination mobile body and transmits the random number or key data based on the transmission plan; a server having a server communication unit that communicates with the server and receives the random number or key data; a terminal communication unit that communicates with the terminal based on the transmission plan and transmits the random number or key data to the terminal; a mobile object having a terminal having a mobile communication unit that communicates with the mobile device and receives the random number or key data, Communication system.

10. A communication method for a communication system having a server, a mobile object traveling on a predetermined trajectory, and a terminal, comprising: generating random numbers or key data to be transmitted by the server; The server acquires location information of the terminal; a step of the server acquiring moving object trajectory information which is information indicating trajectories of a plurality of moving objects; The server identifies a destination mobile object from among a plurality of mobile objects based on the location information of the terminal and the mobile object trajectory information to transmit the random number or key data to the terminal, and generates a transmission plan; a step of the server transmitting the random number or key data to the destination mobile body based on the transmission plan; a step of the mobile device communicating with the server and receiving the random number or key data; a step of the mobile device communicating with the terminal based on the transmission plan and transmitting the random number or key data to the terminal; and a step in which the terminal communicates with the mobile unit and receives the random number or key data.

11. A process of generating random numbers or key data to be transmitted; A process of acquiring location information of the terminal; A process of acquiring moving object trajectory information, which is information indicating the trajectories of a plurality of moving objects; A process of identifying a destination mobile object from among a plurality of mobile objects to transmit the random number or key data to the terminal based on the location information of the terminal and the mobile object trajectory information, and generating a transmission plan; a process of transmitting the random number or key data to the destination mobile body based on the transmission plan; A program that causes a computer to execute the following.