Control device, quantum cryptography communication system, information processing device, key management device, control method, information processing method, key management method, and program

Abstract

To more appropriately determine resources to be allocated to a plurality of key distillation units.SOLUTION: A control device includes a processing unit and an output unit. The processing unit acquires information indicating a state of quantum communication from a plurality of reception devices that receive photons via a quantum communication path, and determines resources to be allocated to a plurality of key distillation units of a server device based on information indicating a state of the quantum communication. The output unit outputs resource information indicating resources allocated to the plurality of key distillation units to the server device.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a control device, a quantum cryptography communication system, an information processing device, a key management device, a control method, an information processing method, a key management method, and a program. [Background technology]

[0002] Quantum Key Distribution (QKD) is a technology that securely shares encryption keys between a QKD device that continuously transmits single photons and a QKD device that receives single photons, both connected via an optical fiber link. Based on the principles of quantum mechanics, the encryption key shared by QKD is guaranteed to be resistant to eavesdropping. Information theory guarantees that data encrypted using a shared encryption key and a cryptographic method known as a one-time pad cannot be decrypted by an eavesdropper with any knowledge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4784202 [Patent Document 2] U.S. Patent Application Publication No. 2020 / 0099520

[0004] [Non-Patent Document 1] Quantum key distribution with realistic states: photon-number statistics in the photon-number splitting attack, Norbert Lutkenhaus and Mika Jahma,New J.Phys.4(July 2002) 44 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional techniques, it has been difficult to more appropriately determine resources to be allocated to multiple key distillation units. [Means for solving the problem]

[0006] According to an embodiment, the control device includes a processing unit and an output unit. The processing unit acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of a server device based on the information indicating the state of quantum communication. The output unit outputs resource information indicating the resources to be allocated to the plurality of key distillation units to the server device. [Brief explanation of the drawings]

[0007] [Figure 1] A diagram showing an example of the configuration of a QKD system. [Figure 2] FIG. 1 is a diagram showing an example of the configuration of a QKD system using multiple QKD devices. [Figure 3] FIG. 1 is a diagram showing an example of the configuration of a QKD system using multiple QKD devices. [Figure 4] FIG. 1 is a diagram showing an example of the device configuration of a quantum cryptography communication system according to a first embodiment. [Figure 5] 4 is a flowchart showing an example of a control method according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of the device configuration of a quantum cryptography communication system according to a second embodiment. [Figure 7] FIG. 10 is a diagram showing an example of the device configuration of a quantum cryptography communication system according to a third embodiment. [Figure 8] FIG. 10 is a diagram showing an example of the device configuration of a quantum cryptography communication system according to a fourth embodiment. [Figure 9] FIG. 10 is a diagram showing an example of the configuration of a key management device according to a fourth embodiment. [Figure 10] FIG. 2 is a diagram showing an example of the hardware configuration of a transmission server device, a reception server device, and a control device according to the first to fourth embodiments, and an information processing device and a key management device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of a control device, a quantum cryptography communication system, an information processing device, a key management device, a control method, an information processing method, a key management method, and a program will be described in detail with reference to the accompanying drawings.

[0009] Hereinafter, an encryption key exchange device that uses QKD (Quantum Key Distribution) technology will be referred to as a QKD device. Also, an encryption key exchange system configured with multiple QKD devices will be referred to as a QKD system. First, an example of a QKD system will be described.

[0010] 1 is a diagram showing an example of the configuration of a QKD system 1. The QKD system 100 comprises a transmitter 1, a receiver 2, and two optical fiber links 101 and 102.

[0011] The transmitting device 1 is a QKD device on the transmitting side. The transmitting device 1 includes a transmitting unit 11 and a key distillation unit 12. The transmitting unit 11 generates photons, encodes key information indicating bit information of 0 or 1 into the photons, and transmits the photons with the encoded key information to the receiving device 2. The key distillation unit 12 performs key distillation processing to generate a final encryption key from the transmitted key information.

[0012] The receiving device 2 is a QKD device on the receiving side. The receiving device 2 includes a receiving unit 21 and a key distillation unit 22. The receiving unit 21 receives photons sent from the transmitting unit 11 of the transmitting device and decodes the key information. The key distillation unit 22 performs a key distillation process to generate a final encryption key from the received key information.

[0013] The optical fiber link 101 is used as a quantum communication path for transmitting photons (quantum signals) in which key information is encoded.

[0014] The optical fiber link 102 is used as a classical communication channel for transmitting a classical signal including control information for QKD. For example, the classical communication channel is used for transmitting an optical signal such as a synchronization signal between a photon transmitter used in the transmitting device 1 and a photon receiver 2 used in the receiving device 2, or for transmitting data.

[0015] Since the quantum signal in the quantum communication channel is extremely weak (at the level of one photon per pulse) compared to the optical signal in the classical communication channel, physically separate optical fiber links 101 and 102 are usually used for the quantum communication channel and the classical communication channel. Furthermore, in order to transmit signals dedicated to the QKD device, the optical fiber link 101 for the quantum communication channel and the optical fiber link 102 for the classical communication channel must be dark fiber.

[0016] An example of encryption key generation processing by the QKD system 100 will now be described.

[0017] 1. Photon transmission First, the transmitter 11 selects a basis to be used when encoding the key information. Then, the transmitter 11 encodes the key information into a single photon by modulating the polarization state and phase state of the single photon based on the selected basis, and then transmits the single photon to the receiver 21 via a quantum communication channel.

[0018] 2. Photon reception The receiver 21 selects a basis to be used for decoding the single photon sent from the transmitter 11, modulates the single photon based on the selected basis, and then detects the single photon.

[0019] 3. Key Distillation The key distillation process consists of the following three steps:

[0020] 3.1. Sifting The key distillation units 12 and 22 exchange the selected base information between the sending and receiving sides via the optical fiber link 102 (classical communication channel). The key distillation units 12 and 22 retain the key information whose base information matches between sending and receiving, and discard the key information other than the key information that matches between sending and receiving. Hereinafter, the key information remaining after the sieving process is referred to as the sieved key.

[0021] 3.2 Error Correction Processing (EC (Error Correction) Processing) The key distillation units 12 and 22 transmit and receive control data via the optical fiber link 102 (classical communication channel), and by exchanging the control data, correct bit errors contained in the sieve key so that the sender and receiver have the same key information. The key information corrected in this way is called a correction key.

[0022] 3.3 Privacy Amplification (PA) Processing The key distillation units 12 and 22 transmit and receive control data via the optical fiber link 102 (classical communication channel), and by exchanging the control data, perform bit string compression conversion on the correction key to cancel out the amount of information that may have been stolen by an eavesdropper. The key thus compressed becomes the final encryption key.

[0023] 2 is a diagram showing an example of the configuration of a QKD system 100-2 using multiple QKD devices. The QKD system 100-2 includes transmitting devices 1a to 1c, receiving devices 2a to 2c, and six optical fiber links 101a to 101c and 102a to 102c. In order to improve the transmission speed of the encryption key shared by the QKD devices, the number of QKD devices used in the QKD system 100-2 is increased, thereby improving the transmission speed of the encryption key throughout the entire QKD system 100-2.

[0024] Hereinafter, when there is no need to distinguish between the transmitting devices 1a to 1c, they will simply be referred to as the transmitting device 1. Similarly, when there is no need to distinguish between the receiving devices 2a to 2c and the six optical fiber links 101a to 101c and 102a to 102c, they will be referred to as the receiving device 2, the optical fiber link 101, and the optical fiber link 102, respectively.

[0025] As shown in Figure 2, when three QKD devices are used, the encryption key transmission speed is three times faster than when one QKD device is used. However, in this case, the number of transmitters 1, receivers 2, and optical fiber links 101 and 102 required increases.

[0026] One way to reduce the number of devices that perform the processing of key distillation units 12a to 12c and 22a to 22c is to implement multiple key distillation units 12 on the same device. Key distillation unit 12 is sometimes implemented as software on a server device, making it easy to implement it on the same device.

[0027] Figure 3 is a diagram showing an example configuration of QKD system 100-3 using multiple QKD devices. The example in Figure 3 shows a case where, on the transmitting side, three key distillation units 12a to 12c are implemented in a single transmitting server device 3, and, on the receiving side, three key distillation units 22a to 22c are implemented in a single receiving server device 4. For example, by operating transmitting server device 3 and receiving server device 4 as shown in Figure 3, the number of devices required for QKD system 100-3 as a whole can be reduced, leading to cost savings.

[0028] As described above, when the key distillation unit 12 is implemented in a single transmitting server device 3 and the key distillation unit 22 is implemented in a single receiving server device 4, an issue arises in that the processing loads of the key distillation processes differ, and it is necessary to adjust the resource allocation for each. The processing loads of the EC processing and PA processing included in the key distillation process described above vary depending on the communication state of the quantum communication channel (quantum communication state). For example, the greater the number of photons detected by the receiving device 21 (number of detected photons), the more key information that needs to be processed, and the greater the processing load. Furthermore, the higher the QBER (Quantum Bit Error Rate), which indicates the quantum error rate, the more key information that needs to be error corrected, and the greater the processing load.

[0029] The state of quantum communication can change dynamically. For example, bending or vibration of the optical fiber link 101 between the transmitter and receiver causes the number of detected photons and the QBER to change dynamically. Furthermore, for example, the number of detected photons and the QBER vary depending on individual differences in the hardware performance of the transmitter 11 and the receiver 21. Because the number of detected photons and the QBER change dynamically, the processing load of the key distillation process also changes dynamically, and the resources required for the key distillation units 12 and 22 also change dynamically. Simply allocating resources equally and fixedly to each key distillation unit 12 and 22 can result in a shortage of resources or surplus resource allocation, making resource allocation inefficient.

[0030] (First embodiment) Therefore, in the following first embodiment, a configuration will be described in which efficient resource allocation is achieved by dynamically changing the resource allocation to the key distillation units 12 and 22 depending on the state of quantum communication.

[0031] [Example of equipment configuration] 4 is a diagram showing an example of the device configuration of a quantum cryptography communication system 200 according to the first embodiment. The quantum cryptography communication system 200 according to the first embodiment includes a control device 5 in addition to a plurality of transmitting devices 11, a plurality of receiving devices 21, a transmitting server device 3, a receiving server device 4, and a plurality of optical fiber links 101 (quantum communication paths) and 102 (classical communication paths).

[0032] 4, a single transmission server device 3 is connected to multiple transmission devices 11, and multiple (n: n is an integer equal to or greater than 2) key distillation units 12 are operating within the transmission server device 3. Each transmission device 11 and each key distillation unit 12 are connected one-to-one, and key distillation processing is performed in the key distillation unit 12 based on key information from the transmission device 11.

[0033] Similarly, a single receiving server device 4 is connected to multiple receiving devices 21, and multiple (n: n is an integer equal to or greater than 2) key distillation units 22 are operating within the receiving server device 4. Each receiving device 21 and each key distillation unit 22 are connected one-to-one, and key distillation processing is performed in the key distillation unit 22 based on the key information from the receiving device 21.

[0034] Each transmitter 11 and each receiver 21 are connected by two optical fiber links 101 and 102 .

[0035] The control device 5 includes a processing unit 51, an acquisition unit 52, and an output unit 53.

[0036] The processing unit 10 is realized by at least one processing device and executes the processing of the control device 5. This processing device is realized by, for example, an analog or digital circuit. The processing device may be a central processing unit (CPU), a general-purpose processor, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof.

[0037] The processing unit 51 includes a collection unit 511 and a control unit 512 .

[0038] The collecting unit 511 acquires the state of quantum communication in the optical fiber link 101 obtained by each receiving device 21 and provides it to the control unit 512 .

[0039] The state of quantum communication may include any parameter in addition to the number of detected photons, QBER, etc. For example, the number of detected photons and QBER are used in the key length calculation formula, but since the key length calculation formula also uses parameters other than the number of detected photons and QBER, the state of quantum communication may also include those parameters.

[0040] Furthermore, for example, when a decoy system is adopted as a QKD protocol, the number of detected decoy pulses may be included in the quantum communication state. In this case, the control unit 512 determines to allocate more resources to a key distillation unit 22 that performs key distillation on photons received by a receiving device 21 where the difference between the number of detected decoy pulses and a predetermined value is a second value that is larger than the first value, for example, than to a key distillation unit 22 that performs key distillation on photons received by a receiving device 21 where the difference between the number of detected decoy pulses and a predetermined value is a first value.

[0041] For example, the resource is a processing device of the receiving server device 4 that is used by the key distillation unit 22. Specifically, the resource is a processor of the receiving server device 4 that is used by the key distillation unit 22, for example.

[0042] Also, for example, the resource is a storage device of the receiving server device 4 used by the key distillation unit 22. Specifically, the resource is, for example, a main storage device of the receiving server device 4 used by the key distillation unit 22. Also, for example, the resource is an auxiliary storage device of the receiving server device 4 used by the key distillation unit 22.

[0043] It should be noted that the more types of quantum communication states are considered when allocating resources, the more accurate the allocation becomes, but the higher the computational costs become.

[0044] Furthermore, information other than the state of quantum communication may be acquired from the receiving device 21. For example, information on the hardware of the receiving device 21 may be acquired.

[0045] The hardware information is, for example, numerical information indicating the performance of the hardware of the receiving device 21. Specifically, the numerical information of the hardware of the receiving device 21 includes, for example, the photon detection sensitivity of the receiving device 21 (related to the number of detected photons) and the noise level at the time of detection (related to QBER).

[0046] Furthermore, for example, the hardware information includes information indicating the operating status of the hardware of the receiving device 21. Specifically, the information indicating the operating status of the hardware includes, for example, information indicating whether the hardware is operating normally, the length of time that the hardware has been operating normally since it started operating, whether the hardware has stopped, whether it has broken down, etc. This information is not reflected in the key length calculation formula, but can be used as reference information for resource allocation.

[0047] For example, the control unit 512 further acquires first operation information indicating the operation status of the receiving device 21a from the receiving device 21a, and further acquires second operation information indicating the operation status of the receiving device 21b from the receiving device 21b. For example, if the period during which the receiving device 21b, indicated by the operation status of the second operation information, is operating normally is longer than the period during which the receiving device 21a, indicated by the operation status of the first operation information, the control unit 512 determines to allocate more resources to the key distillation unit 22b, which performs key distillation on photons received by the receiving device 21b, than to the key distillation unit 22a, which performs key distillation on photons received by the receiving device 21a. Also, for example, if the first operation information indicates that the receiving device 21a is not operating, the control unit 512 determines not to allocate resources to the key distillation unit 22a.

[0048] The control unit 512 calculates the resource allocation to be assigned to each key distillation unit 12 and 22 based on the quantum communication state of each optical fiber link 101 acquired by the collection unit 511, and issues resource allocation instructions to the transmitting server device 3 and the receiving server device 4.

[0049] The transmission server device 3 allocates resources to each key distillation unit 12 based on a resource allocation instruction from the control device 5 .

[0050] Similarly, the receiving server device 4 allocates resources to each key distillation unit 22 based on a resource allocation instruction from the control device 5 .

[0051] The control device 5 constantly acquires the dynamically changing state of quantum communication and dynamically changes resource allocation based on the state of quantum communication, thereby realizing optimal resource allocation to the key distillation units 12 and 22.

[0052] The acquiring unit 52 acquires data by wireless or wired communication. For example, the acquiring unit 52 acquires the state of quantum communication of the optical fiber link 101 from each receiving device 21.

[0053] The output unit 53 outputs data by communicating wirelessly or via a wired system. For example, the output unit 53 outputs resource information indicating resources allocated to the multiple key distillation units 12 and 22 to the transmitting server device 3 and the receiving server device 4.

[0054] For example, the resource information includes at least one of information indicating the proportion of processor usage in the transmitting server device 3 and the receiving server device 4, information indicating the proportion of main memory usage in the transmitting server device 3 and the receiving server device 4, and information indicating the proportion of auxiliary memory usage in the transmitting server device 3 and the receiving server device 4.

[0055] In the example of FIG. 4, the control device 5 is realized as one device, but it may be implemented as software on the transmission server device 3 or the reception server device 4.

[0056] [Example of control method] 5 is a flowchart showing an example of the control method of the first embodiment. First, the collection unit 511 acquires information indicating the state of quantum communication from each receiving device 21 (step S1).

[0057] Next, the control unit 512 calculates the final key length of the encryption key based on the information indicating the state of quantum communication acquired in step S1 (step S2). The key length may be calculated, for example, according to the key length calculation formula used in the PA processing described above, or may be a separately set formula. For example, the longer the key length calculated based on the number of detected photons and the QBER, the higher the load on the key distillation process, and therefore more resources are required. Qualitatively, the more photon detections there are, the longer the key length becomes, and the higher the QBER, the shorter the key length becomes. When the QBER reaches a certain value, for example, 10%, or more, the key length becomes zero.

[0058] Next, the control unit 512 determines resources to be allocated to each key distillation process based on the key lengths calculated in step S2 (step S3). For example, the control unit 512 may determine resource allocation in proportion to the key lengths. For example, assume that the key length of the encryption key generated from photons received via the optical fiber link 101a is 3 (any unit may be used, such as bits, bytes, or the length of the encryption key generated per unit time), the key length of the encryption key generated from photons received via the optical fiber link 101b is 2, and the key length of the encryption key generated from photons received via the optical fiber link 101c is 0. In this case, the control unit 512 allocates 60% of the total resources (100%) to the key distillation unit 22a, 40% to the key distillation unit 22b, and 0% (no key distillation process) to the key distillation unit 22c.

[0059] In other words, the control unit 512 decides to allocate more resources to the key distillation unit 22 that performs key distillation on photons whose key length calculated based on the number of detected photons and the QBER is a first value than to the key distillation unit 22 that performs key distillation on photons whose key length is a second value longer than the first value.

[0060] Next, when the resource allocation is determined in step S3, the output unit 53 outputs the resource information to the transmission server device 3 and the reception server device 4, thereby issuing instructions for the determined resource allocation (step S4).

[0061] In the example of Figure 5, a method of determining resource allocation from the key length calculated based on the key length calculation formula is used as the resource allocation method, but other methods may also be used. Resource allocation based on key length is a method that focuses on the PA processing load, but there are also methods that focus on the EC processing load, for example. The EC processing load changes depending on the QBER, and the EC processing load increases as the QBER increases. Therefore, a method may be used that allocates more resources to links with higher QBERs.

[0062] However, if the QBER is equal to or greater than a certain value at this time, the EC process fails. Therefore, the control unit 512 does not allocate resources to the key distillation units 12 and 22 that perform key distillation on photons transmitted and received via the optical fiber link 101 whose QBER is equal to or greater than a certain value. Specifically, the control unit 512 determines to allocate more resources to the key distillation unit 22 that performs key distillation on photons received via the optical fiber link 101 whose QBER is a second value greater than the first value and equal to or less than a certain value than to the key distillation unit 22 that performs key distillation on photons received via the optical fiber link 101 whose QBER is a first value equal to or less than a certain value. Then, the control unit 512 determines not to allocate resources to the key distillation unit 22 that performs key distillation on photons received via the optical fiber link 101 whose QBER exceeds a certain value.

[0063] Resource allocation may also be changed depending on the error correction algorithm used in the EC process. Examples of error correction algorithms include the cascade method and the LDPC (Low Density Parity Check) method. The cascade method can efficiently correct errors at a higher QBER, while the LDPC method can efficiently correct errors at a lower QBER.

[0064] Therefore, resource allocation may be performed taking into consideration the type of error correction algorithm used in the EC process. For example, when the error correction algorithm is a cascade system, the control unit 512 allocates resources more gradually in response to an increase in QBER than when the error correction algorithm is an LDPC system. Specifically, when the error correction algorithm is an LDPC system, the control unit 512 allocates more resources when the QBER increases from a first value to a second value than when the error correction algorithm is a cascade system.

[0065] As described above, in the first embodiment, the processing unit 51 of the control device 5 acquires information indicating the state of quantum communication from multiple receiving devices 21 that receive photons via a quantum communication path (optical fiber link 101 in the example of FIG. 4), and determines resources to be allocated to multiple key distillation units 12 and multiple key distillation units 22 of a server device (transmitting server device 3 and receiving server device 4 in the example of FIG. 4) based on the information indicating the state of quantum communication. Then, the output unit 53 of the control device 5 outputs resource information indicating the resources to be allocated to the multiple key distillation units 12 and multiple key distillation units 22 to the server device.

[0066] As a result, according to the first embodiment, it is possible to more appropriately determine the resources to be allocated to the multiple key distillation units 12 and the multiple key distillation units 22. Specifically, there is no shortage or surplus of resources allocated to the multiple key distillation units 12 (key distillation units 22) operating on a single transmitting server device 3 (receiving server device 4), and optimal allocation can be achieved. As a result, malfunctions or processing delays due to resource shortages do not occur in the key distillation processing of the key distillation units 12 and 22. Furthermore, because there is no waste in resource allocation, the specifications required for the transmitting server device 3 and the receiving server device 4 can be minimized, leading to cost reductions.

[0067] (Second embodiment) Next, a second embodiment will be described. In the description of the second embodiment, the same description as in the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0068] [Example of equipment configuration] 6 is a diagram showing an example of the device configuration of a quantum cryptography communication system 200-2 according to the second embodiment. The quantum cryptography communication system 200-2 according to the second embodiment includes a plurality of transmitting devices 11, a plurality of receiving devices 21, a transmitting server device 3, a receiving server device 4, a control device 5, multiplexing devices 6a and 6b, and optical fiber links 101 (quantum communication paths) and 102 (classical communication paths).

[0069] The difference from the configuration of the first embodiment (Figure 4) is that multiplexing devices 6a and 6b (e.g., multiplexing modules) are installed to optically wavelength-multiplex signals from multiple transmitting devices 11, and the number of optical fiber links 101 and 102 between transmitting and receiving devices is reduced to two.

[0070] The multiplexer 6a (first multiplexer) optically multiplexes photons transmitted from a plurality of transmitters 11. The multiplexer 6b (second multiplexer) receives the optically multiplexed photons.

[0071] 6, differences in the state of quantum communication for each quantum communication channel are less likely to occur, and differences in resource allocation due to the state of quantum communication are less likely to occur, but it is still necessary to adjust resources due to differences in performance between transmitting device 11 and receiving device 21. For example, when processing unit 51 further acquires, from receiving device 21a, first numerical information indicating the hardware performance of receiving device 21a, and further acquires, from receiving device 22a, second numerical information indicating that the hardware performance is higher than the first numerical information, processing unit 51 determines to allocate more resources to key distillation unit 22b, which performs key distillation on photons received by receiving device 21b, than to key distillation unit 22a, which performs key distillation on photons received by receiving device 21a.

[0072] (Third embodiment) Next, a third embodiment will be described. In the description of the third embodiment, the same description as in the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0073] [Example of equipment configuration] 7 is a diagram showing an example of the device configuration of a quantum cryptography communication system 200-3 of the third embodiment. The quantum cryptography communication system 200-5 of the third embodiment includes a plurality of transmitting devices 11, a plurality of receiving devices 21, a plurality of transmitting server devices 3, a receiving server device 4, a control device 5, and a plurality of optical fiber links 101 (quantum communication paths) and 102 (classical communication paths). The difference from the configuration of the first embodiment (FIG. 4) is that there are a plurality of transmitting server devices 3, and the plurality of transmitting server devices 3 communicate with one receiving server device 4. This assumes that the transmitting server devices 3 are installed at a plurality of different bases.

[0074] In this case, one key distillation unit 12 operates on each transmitting server device 3, and multiple key distillation units 22 operate on each receiving server device 4. Therefore, in the third embodiment, resource allocation is performed for the receiving server device 4.

[0075] 7 shows a case where one receiving server device 4 is connected to a plurality of transmitting server devices 3 via a plurality of receiving devices 21, a plurality of optical fiber links 101 (quantum communication paths), and a plurality of transmitting devices 11, but one transmitting server device 3 may be connected to a plurality of receiving server devices 4. In other words, one transmitting server device 3 may be connected to a plurality of receiving server devices 4 via a plurality of transmitting devices 11, a plurality of optical fiber links 101 (quantum communication paths), and a plurality of receiving devices 21.

[0076] (Fourth embodiment) Next, a fourth embodiment will be described. In the description of the fourth embodiment, the same description as in the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0077] [Example of equipment configuration] 8 is a diagram showing an example of the device configuration of a quantum cryptography communication system 200-4 according to the fourth embodiment. The quantum cryptography communication system 200-4 according to the fourth embodiment includes a plurality of transmitting devices 11, a plurality of receiving devices 21, a transmitting server device 3, a receiving server device 4, a control device 5, a plurality of optical fiber links 101 (quantum communication paths) and 102 (classical communication paths), as well as an information processing device 7 (7a and 7b) and a user network 103.

[0078] The information processing device 7a is connected to a transmission server device 3 that includes a plurality of key distillation units 12. The information processing device 7b is connected to a reception server device 4 that includes a plurality of key distillation units 22.

[0079] The information processing device 7a includes an acquisition unit 71a and an application 72a. The acquisition unit 71a acquires, from the transmission server device 3, encryption keys that have been key-distilled using resources allocated to multiple key distillation units 12, based on information indicating the state of quantum communication acquired from multiple receiving devices 21 that receive photons via an optical fiber link 101 (quantum communication path).

[0080] The application 72a uses the encryption key obtained from the transmission server device 3 to perform encrypted communication with the application 72b via the user network 103. The user network 103 is, for example, the Internet.

[0081] The operations of the acquisition unit 71b and the application 72b are similar to those of the acquisition unit 71a and the application 72a, and therefore a description thereof will be omitted.

[0082] A key management device for managing encryption keys may be installed between the transmitting server device 3 and the information processing device 7a. Similarly, a key management device for managing encryption keys may be installed between the receiving server device 4 and the information processing device 7b.

[0083] 9 is a diagram showing an example of the configuration of the key management device 8 of the fourth embodiment. The key management device 8 of the fourth embodiment includes an acquisition unit 81, a storage unit 82, and an output unit 83.

[0084] The acquiring unit 81 acquires data by wireless or wired communication. For example, the acquiring unit 81 acquires, from the transmitting server device 3 or the receiving server device 4, an encryption key that has been key-distilled using resources allocated to the multiple key distillations units 12 and 22, based on information indicating the state of quantum communication acquired from the multiple receiving devices 21 that receive photons via the optical fiber link 101 (quantum communication path).

[0085] The storage unit 82 stores the encryption key acquired from the transmission server device 3 or the reception server device 4. The storage unit 82 is realized by, for example, a main storage device and an auxiliary storage device (see FIG. 9, which will be described later).

[0086] The output unit 83 outputs data by wireless or wired communication. For example, the output unit 83 outputs an encryption key to the application 7a or 7b that performs encrypted communication using the encryption key.

[0087] Finally, examples of the hardware configurations of the transmitting server device 3, the receiving server device 4, and the control device 5 of the first to fourth embodiments, and the information processing device 7 and the key management device 8 of the fourth embodiment will be described.

[0088] [Example of hardware configuration] FIG. 10 is a diagram showing an example of the hardware configuration of the transmitting server device 3, the receiving server device 4, and the control device 5 of the first to fourth embodiments, and the information processing device 7 and the key management device 8 of the fourth embodiment.

[0089] The transmitting server device 3, the receiving server device 4, and the control device 5 of the first to fourth embodiments, and the information processing device 7 and the key management device 8 of the fourth embodiment each include a processor 301, a main storage device 302, an auxiliary storage device 303, a display device 304, an input device 305, and a communication device 306. The processor 301, the main storage device 302, the auxiliary storage device 303, the display device 304, the input device 305, and the communication device 306 are connected via a bus 310.

[0090] The processor 301 executes a program read from the auxiliary storage device 303 to the main storage device 302. The main storage device 302 is memory such as a read-only memory (ROM) and a random access memory (RAM). The auxiliary storage device 303 is a hard disk drive (HDD), a solid state drive (SSD), a memory card, or the like.

[0091] The display device 304 displays display information. The display device 304 is, for example, a liquid crystal display. The input device 305 is an interface for operating the transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8. The input device 305 is, for example, a keyboard or a mouse. The communication device 306 is an interface for communicating with other devices.

[0092] The transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8 may not necessarily have the display device 304 and the input device 305. In this case, for example, the display function and input function of a terminal connected to the transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8 via the communication device 306 may be used.

[0093] The programs executed by the sending server device 3, the receiving server device 4, the control device 5, the information processing device 7 and the key management device 8 are provided as computer program products recorded in installable or executable format files on computer-readable storage media such as CD-ROMs, memory cards, CD-Rs and DVDs (Digital Versatile Discs).

[0094] The programs executed by the transmitting server device 3, receiving server device 4, control device 5, information processing device 7, and key management device 8 may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. The programs executed by the transmitting server device 3, receiving server device 4, control device 5, information processing device 7, and key management device 8 may also be provided via a network such as the Internet without being downloaded.

[0095] Furthermore, the programs executed by the transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8 may be provided by being pre-installed in a ROM or the like.

[0096] The programs executed by the transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8 have a modular configuration including functional blocks that can also be realized by the programs, among the functional configurations (functional blocks) of the transmitting server device 3, the receiving server device 4, the control device 5, the information processing device 7, and the key management device 8. As for each functional block, as actual hardware, the processor 301 reads out the program from a storage medium and executes it, and the above functional block is loaded onto the main storage device 302. In other words, the above functional block is generated on the main storage device 302.

[0097] Note that some or all of the above-described functional blocks may be realized by hardware such as an integrated circuit (IC) instead of by software.

[0098] Furthermore, when each function is realized using a plurality of processors, each processor may realize one of the functions, or may realize two or more of the functions.

[0099] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0100] (Addendum) The above-described embodiments can be summarized as the following technical proposals.

[0101] Technical proposal 1 a processing unit that acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of the server device based on the information indicating the state of quantum communication; an output unit that outputs resource information indicating resources allocated to the plurality of key distillation units to the server device; A control device comprising:

[0102] Technical proposal 2 the resource information includes at least one of information indicating a ratio of use of the processor of the server device, information indicating a ratio of use of the main storage device of the server device, and information indicating a ratio of use of the auxiliary storage device of the server device; The control device described in Technical Proposal 1.

[0103] Technical proposal 3 The information indicating the state of the quantum communication includes a QBER (Quantum Bit Error Rate), the processing unit determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received via a second quantum communication channel where the QBER is a second value that is greater than the first value and is not greater than the predetermined value than to a first key distillation unit that performs key distillation on photons received via a first quantum communication channel where the QBER is a first value that is not greater than a predetermined value; determining not to allocate the resource to a third key distillation unit that performs key distillation on photons received via a third quantum communication channel whose QBER exceeds the predetermined value; The control device according to Technical Scheme 1 or 2.

[0104] Technical proposal 4 The information indicating the state of the quantum communication further includes the number of detected photons and a QBER (Quantum Bit Error Rate), the processing unit determines to allocate more of the resources to a second key distillation unit that performs photon key distillation such that the key length calculated based on the number of detected photons and the QBER is a first value than to a first key distillation unit that performs photon key distillation such that the key length is a second value longer than the first value. A control device according to any one of technical proposals 1 to 3.

[0105] Technical proposal 5 The information indicating the state of the quantum communication includes a QBER (Quantum Bit Error Rate), the processing unit increases the amount of resource allocation when the QBER increases from the first value to the second value when the error correction algorithm is LDPC (Low Density Parity Check) compared to the amount of resource allocation when the QBER increases from the first value to the second value when the error correction algorithm is a cascade method. A control device according to any one of technical proposals 1 to 4.

[0106] Technical proposal 6 The information indicating the state of the quantum communication further includes the number of detected decoy pulses, the processing unit determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by a second receiving device, where the difference between the number of detected decoy pulses and a predetermined value is a second value that is larger than the first value, than to a first key distillation unit that performs key distillation on photons received by a first receiving device, where the difference between the number of detected decoy pulses and a predetermined value is a first value. A control device according to any one of technical proposals 1 to 5.

[0107] Technical proposal 7 the processing unit further acquires, from a first receiving device, first numerical information indicating hardware performance of the first receiving device, and further acquires, from a second receiving device, second numerical information indicating that hardware performance is higher than the first numerical information, and determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by the second receiving device than to a first key distillation unit that performs key distillation on photons received by the first receiving device. A control device according to any one of technical proposals 1 to 6.

[0108] Technical proposal 8 The processing unit further acquires, from a first receiving device, first operation information indicating an operation state of the first receiving device, and further acquires, from a second receiving device, second operation information indicating an operation state of the second receiving device; when a period during which the second receiving device is operating normally, which is indicated by the operation state of the second operation information, is longer than a period during which the first receiving device is operating normally, which is indicated by the operation state of the first operation information, decides to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by the second receiving device than to a first key distillation unit that performs key distillation on photons received by the first receiving device; determining not to allocate the resource to the first key distillation unit when the first operation information indicates that the first receiving device is not operating; A control device according to any one of technical proposals 1 to 7.

[0109] Technical proposal 9 A control device according to any one of technical proposals 1 to 8; a plurality of transmitting devices that transmit the photons via the quantum communication channel; a transmission server device connected to the plurality of transmission devices; the plurality of receiving devices receiving the photons via the quantum communication channel; a receiving server device connected to the plurality of receiving devices; A quantum cryptography communication system comprising:

[0110] Technical proposal 10 the receiving server device is connected to the plurality of transmitting server devices via the plurality of receiving devices, the quantum communication channel, and the plurality of transmitting devices; A quantum cryptography communication system described in Technical Proposal 9.

[0111] Technical proposal 11 the transmitting server device is connected to the plurality of receiving server devices via the plurality of transmitting devices, the quantum communication channel, and the plurality of receiving devices; A quantum cryptography communication system according to Technical Proposal 9 or 10.

[0112] Technical proposal 12 the quantum communication channel is composed of a plurality of optical fiber links; the plurality of transmitting devices and the plurality of receiving devices are connected by the plurality of optical fiber links; A quantum cryptography communication system according to any one of technical proposals 9 to 11.

[0113] Technical proposal 13 a first multiplexing device that optically multiplexes photons transmitted from the plurality of transmitting devices; a second multiplexing device that receives the optical wavelength-multiplexed photons; The quantum communication channel is composed of one optical fiber link. A quantum cryptography communication system according to any one of technical proposals 9 to 11.

[0114] Technical proposal 14 connected to a server device having a plurality of key distillation units, an acquisition unit that acquires, from the server device, a cryptographic key that has been key-distilled using resources allocated to the plurality of key distillations units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; an application that performs encrypted communication using the encryption key; An information processing device comprising:

[0115] Technical proposal 15 connected to a server device having a plurality of key distillation units, an acquisition unit that acquires, from the server device, a cryptographic key that has been key-distilled using resources allocated to the plurality of key distillations units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; a storage unit that stores the encryption key; an output unit that outputs the encryption key to an application that performs encrypted communication using the encryption key; A key management device comprising:

[0116] Technical proposal 16 a step in which a control device acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of a server device based on the information indicating the state of quantum communication; a step of the control device outputting, to the server device, resource information indicating resources allocated to the plurality of key distillation units; A control method comprising:

[0117] Technical proposal 17 An information processing method of an information processing device connected to a server device having a plurality of key distillation units, a step in which the information processing device acquires, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillation units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; a step of the information processing device performing encrypted communication using the encryption key; An information processing method including:

[0118] Technical proposal 18 A key management method for a key management device connected to a server device having a plurality of key distillation units, comprising: the key management device acquiring, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillation units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; the key management device storing the encryption key; a step of the key management device outputting the encryption key to an application that performs encrypted communication using the encryption key; A key management method comprising:

[0119] Technical proposal 19 Computer, a processing unit that acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of the server device based on the information indicating the state of quantum communication; an output unit that outputs resource information indicating resources allocated to the plurality of key distillation units to the server device; A program to function as a [Explanation of symbols]

[0120] 1. Transmitting device 2. Receiving device 3. Transmission server device 4. Receiving server device 5. Control device 6 Multiplexer 7. Information processing equipment 8 Key management device 11 Transmitter 12 Key Distillation Department 21 Receiving unit 22 Key Distillation Department 51 Processing section 52 Acquisition Department 53 Output section 71 Acquisition Department 72 Applications 81 Acquisition Department 82 Memory section 83 Output section 100 QKD Systems 101 Fiber Optic Link 102 Fiber Optic Link 103 User Network 301 processor 302 Main storage 303 Auxiliary storage device 304 Display device 305 Input Device 306 Communication Equipment 310 Bus 511 Collection Department 512 control section

Claims

1. A processing unit that acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of a server device based on the information indicating the state of quantum communication; an output unit that outputs resource information indicating resources allocated to the plurality of key distillation units to the server device; A control device comprising:

2. the resource information includes at least one of information indicating a ratio of use of the processor of the server device, information indicating a ratio of use of the main storage device of the server device, and information indicating a ratio of use of the auxiliary storage device of the server device; The control device according to claim 1 .

3. the information indicating the state of quantum communication includes a Quantum Bit Error Rate (QBER), the processing unit determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received via a second quantum communication channel where the QBER is a second value that is greater than the first value and is not greater than the predetermined value than to a first key distillation unit that performs key distillation on photons received via a first quantum communication channel where the QBER is a first value that is not greater than a predetermined value, determining not to allocate the resource to a third key distillation unit that performs key distillation on photons received via a third quantum communication channel whose QBER exceeds the predetermined value; The control device according to claim 1 or 2.

4. the information indicating the state of the quantum communication further includes the number of detected photons and a QBER (Quantum Bit Error Rate); the processing unit determines to allocate more of the resources to a second key distillation unit that performs photon key distillation so that the key length calculated based on the number of detected photons and the QBER is a first value than to a first key distillation unit that performs photon key distillation so that the key length is a second value longer than the first value. The control device according to claim 1 or 2.

5. the information indicating the state of quantum communication includes a Quantum Bit Error Rate (QBER), the processing unit increases the amount of resource allocation when the QBER increases from the first value to the second value when the error correction algorithm is LDPC (Low Density Parity Check) compared to the amount of resource allocation when the QBER increases from the first value to the second value when the error correction algorithm is a cascade algorithm; The control device according to claim 1 or 2.

6. The information indicating the state of the quantum communication further includes the number of detected decoy pulses, the processing unit determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by a second receiving device, the difference between the number of detected decoy pulses and a predetermined value being a second value that is larger than the first value, than to a first key distillation unit that performs key distillation on photons received by a first receiving device, the difference between the number of detected decoy pulses and a predetermined value being a first value. The control device according to claim 1 or 2.

7. the processing unit further acquires, from a first receiving device, first numerical information indicating hardware performance of the first receiving device, and further acquires, from a second receiving device, second numerical information indicating that hardware performance is higher than the first numerical information, and determines to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by the second receiving device than to a first key distillation unit that performs key distillation on photons received by the first receiving device. The control device according to claim 1 or 2.

8. The processing unit further acquires, from a first receiving device, first operation information indicating an operation state of the first receiving device, and further acquires, from a second receiving device, second operation information indicating an operation state of the second receiving device; when a period during which the second receiving device is operating normally, which is indicated by the operation state of the second operation information, is longer than a period during which the first receiving device is operating normally, which is indicated by the operation state of the first operation information, decides to allocate more of the resources to a second key distillation unit that performs key distillation on photons received by the second receiving device than to a first key distillation unit that performs key distillation on photons received by the first receiving device; determining not to allocate the resource to the first key distillation unit when the first operation information indicates that the first receiving device is not operating; The control device according to claim 1 or 2.

9. The control device according to claim 1 or 2; a plurality of transmitting devices that transmit the photons via the quantum communication channel; a transmission server device connected to the plurality of transmission devices; the plurality of receiving devices receiving the photons via the quantum communication channel; a receiving server device connected to the plurality of receiving devices; A quantum cryptography communication system comprising:

10. the receiving server device is connected to the plurality of transmitting server devices via the plurality of receiving devices, the quantum communication channel, and the plurality of transmitting devices; The quantum cryptography communication system according to claim 9.

11. the transmitting server device is connected to the plurality of receiving server devices via the plurality of transmitting devices, the quantum communication channel, and the plurality of receiving devices; The quantum cryptography communication system according to claim 9.

12. the quantum communication channel is composed of a plurality of optical fiber links; the plurality of transmitting devices and the plurality of receiving devices are connected by the plurality of optical fiber links; The quantum cryptography communication system according to claim 9.

13. a first multiplexing device that optically multiplexes photons transmitted from the plurality of transmitting devices; a second multiplexing device that receives the optical wavelength-multiplexed photons; the quantum communication channel is composed of one optical fiber link; The quantum cryptography communication system according to claim 9.

14. connected to a server device having a plurality of key distillation units, an acquisition unit that acquires, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillations units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; an application that performs encrypted communication using the encryption key; An information processing device comprising:

15. connected to a server device having a plurality of key distillation units, an acquisition unit that acquires, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillations units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; a storage unit that stores the encryption key; an output unit that outputs the encryption key to an application that performs encrypted communication using the encryption key; A key management device comprising:

16. a step in which a control device acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication path, and determines resources to be allocated to a plurality of key distillation units of a server device based on the information indicating the state of quantum communication; a step of the control device outputting, to the server device, resource information indicating resources allocated to the plurality of key distillation units; A control method comprising:

17. An information processing method of an information processing device connected to a server device having a plurality of key distillation units, a step in which the information processing device acquires, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillation units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; a step of the information processing device performing encrypted communication using the encryption key; An information processing method including:

18. A key management method for a key management device connected to a server device having a plurality of key distillation units, comprising: the key management device acquiring, from the server device, encryption keys that have been key-distilled using resources allocated to the plurality of key distillation units, based on information indicating a state of quantum communication acquired from a plurality of receiving devices that receive photons via a quantum communication channel; the key management device storing the encryption key; a step of the key management device outputting the encryption key to an application that performs encrypted communication using the encryption key; A key management method comprising:

19. Computer, a processing unit that acquires information indicating a state of quantum communication from a plurality of receiving devices that receive photons via a quantum communication channel, and determines resources to be allocated to a plurality of key distillation units of the server device based on the information indicating the state of quantum communication; an output unit that outputs resource information indicating resources allocated to the plurality of key distillation units to the server device; A program to function as a

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