Quantum cryptography communication system, key management device, and key management method

Abstract

To more safely protect application keys used for encryption processing.SOLUTION: A quantum cryptographic communication system of an embodiment includes a first QKD apparatus and a first key management device. The first QKD apparatus shares a quantum cryptographic key with a second QKD apparatus using QKD (Quantum Key Distribution). The first key management device includes a receiving unit and a first HSM (Hardware Security Module). The receiving unit receives the quantum cryptographic key from the first QKD apparatus. The first HSM includes a storage unit, a generation unit, and a first encryption unit. The storage unit stores a first encryption key. The generation unit generates an application key used for encryption processing by an encryption application. The first encryption unit encrypts the application key transmitted to a second key management device connected to the second QKD apparatus with the first encryption key.SELECTED DRAWING: Figure 3A

Description

[Technical field]

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

[0002] With the advancement of information and communication technology, a wide variety of data is now being exchanged, and ensuring the confidentiality and security of the transmitted information has become a major issue. Quantum cryptography is expected to be put into practical use as an encryption technology that cannot be decrypted even with the improvement of computer computing power. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] ITU-T Y.3803:Quantum key distribution networks - Key management [Non-Patent Document 2] R. Takahashi, Y. Tanizawa and A. Dixon, “A high-speed key management method for quantum key distribution network,” 2019 Eleventh International Conference on Ubiquitous and Future Networks(ICUFN), Zagreb, Croatia, 2019, pp. 437-442 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional techniques, it has been difficult to more securely protect the application key used in encryption processing. [Means for solving the problem]

[0005] A quantum cryptography communication system according to an embodiment includes a first QKD device and a first key management device. The first QKD device shares a quantum cryptography key with a second QKD device by quantum key distribution (QKD). The first key management device includes a receiver and a first HSM (Hardware Security Module). The receiver receives the quantum cryptography key from the first QKD device. The first HSM includes a storage unit, a generator, and a first encryption unit. The storage unit stores a first encryption key. The generator generates an application key used in encryption processing by an encryption application. The first encryption unit encrypts the application key, which is transmitted to a second key management device connected to the second QKD device, with the first encryption key. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram for explaining an example of a basic configuration of a key management system. [Diagram 2] FIG. 1 is a diagram illustrating an example of a functional configuration of a conventional key management device. [Figure 3A] FIG. 2 is a diagram showing an example of the functional configuration of the quantum cryptography communication system according to the first embodiment. [Figure 3B] FIG. 2 is a diagram showing an example of the functional configuration of the quantum cryptography communication system according to the first embodiment. [Figure 4] 4 is a diagram for explaining an example of processing performed by the key management apparatus and the encrypted application execution device according to the first embodiment; [Diagram 5] 6 is a flowchart showing an example of an application key transmission process between locations in the first embodiment. [Figure 6] 10 is a flowchart showing an example of an application key supply process within a base in the first embodiment. [Figure 7A] FIG. 11 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a second embodiment. [Figure 7B] FIG. 11 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a second embodiment. [Figure 8A] FIG. 11 is a diagram for explaining an example of processing by the QKD device and key management device of the second embodiment. [Figure 8B]FIG. 11 is a diagram for explaining an example of processing by the QKD device and key management device of the second embodiment. [Figure 9] 13 is a flowchart showing an example of an application key transmission process between locations in the second embodiment. [Figure 10A] FIG. 11 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a third embodiment. [Figure 10B] FIG. 11 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a third embodiment. [Figure 11] 13 is a flowchart showing an example of an application key transmission process between locations according to the third embodiment. [Figure 12A] FIG. 13 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a fourth embodiment. [Figure 12B] FIG. 13 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a fourth embodiment. [Figure 13] 13 is a flowchart showing an example of an application key transmission process between locations according to the fourth embodiment. [Figure 14A] FIG. 13 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a fifth embodiment. [Figure 14B] FIG. 13 is a diagram showing an example of the functional configuration of a quantum cryptography communication system according to a fifth embodiment. [Figure 15] 13 is a flowchart showing an example of processing for switching encryption methods between bases according to the fifth embodiment; [Figure 16] FIG. 13 shows a first modification example in which an HSM is shared. [Figure 17] FIG. 13 is a diagram showing a second modification example in which an HSM is shared. [Figure 18] A diagram showing an example of the hardware configuration of the main parts of the QKD equipment of the first to fifth embodiments. [Figure 19] FIG. 13 is a diagram showing an example of the hardware configuration of the main parts of the key management apparatus and encrypted application execution device according to the first and fifth embodiments, and the QKDN manager according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a quantum cryptography communication system, a key management device, and a key management method will be described in detail with reference to the accompanying drawings.

[0008] From the viewpoint of information security, quantum cryptography communication systems need to take measures against various security attacks and operate safely. Possible security attacks against key management systems include unauthorized access to the key management system and the theft of quantum cryptography keys when they are generated in the key management system, when they are stored in the key management system, or when the quantum cryptography keys are transferred. Therefore, measures against these attacks are necessary.

[0009] There is a security device called HSM (Hardware Security Module). HSM can safely store encryption keys and perform encryption processing from the viewpoint of information security, and if it detects any unauthorized access such as physical access, it can detect the abnormality and take action such as erasing the stored encryption key. By performing key generation, key storage, and encryption during key transfer within HSM, the possibility of plaintext keys being stolen is extremely small.

[0010] First, an example of the structure of a key management system for quantum cryptography communication will be described.

[0011] [Basic configuration example] Fig. 1 is a diagram for explaining an example of the basic configuration of a key management system, which is described in Non-Patent Document 1 as a basic configuration diagram of a key management system.

[0012] KM stands for Key Management and is a key management system (key management device). The QKD module is a quantum cryptography communication device (Quantum Key Distribution device) and is a device that generates quantum cryptography keys. A cryptographic application is an encryption application that receives a key (quantum cryptography key or application key (hereinafter simply referred to as "application key")) stored in the key management system from the KM and executes the application securely while performing encrypted communication. The QKDN controller is a device that controls devices related to quantum cryptography communication, and the QKDN manager is a device that manages the entire quantum cryptography communication network (QKDN: Quantum Key Distribution Network).

[0013] Next, we will explain the internal structure of KM. KMA stands for Key Management Agent, and represents the entire key management function. KSA stands for Key Supply Agent, and represents the entire key supply function.

[0014] Key storage is a function that stores keys (quantum cryptography keys or application keys). Generally, application keys are stored, but quantum cryptography keys may be stored if the keys are shared between sites that are equipped with quantum cryptography communication devices and are directly connected via QKD links.

[0015] The key relay is a function that transfers the application key to another point, encrypts it using quantum cryptography communication, and transfers the application key to another point. For example, Non-Patent Document 2 can be mentioned as an implementation example of the key relay.

[0016] Key supply is a function that supplies keys to encryption applications. Key control and management is a function that controls and manages the key management system.

[0017] The functions of key life cycle management, key combination, and key exchange are outside the scope of this embodiment, so a description thereof will be omitted (dotted line portion).

[0018] Next, in order to clearly show the difference from the configuration of the first embodiment, the functional configuration of a conventional key management device that performs the processing of KM in FIG. 1 will be described.

[0019] [Previous function configuration] 2 is a diagram illustrating the functional configuration of conventional key management devices 220a and 220b. The process of storing a key at site A will be described. First, generation unit 226a at site A generates an application key in a plaintext state. Next, encryption unit 227a performs encryption for DB protection, and stores the encrypted application key in encrypted application key DB 228a.

[0020] Next, the process of transferring the application key from site A to site B will be described. First, the application key is OTP (One Time Pad) encrypted in order to transfer it to site B securely. Specifically, the receiver 222a receives the quantum encryption key in a plaintext state from the QKD device 210a. Then, the relay unit 224a performs OTP encryption using the quantum encryption key on the application key in a plaintext state to generate an OTP-encrypted application key. The relay unit 224a transmits the OTP-encrypted application key to site B.

[0021] In the key management device 220b at site B, when the relay unit 224b receives the OTP-encrypted application key from the key management device 220a at site A, the relay unit 224b performs OTP decryption using the quantum encryption key in the quantum encryption key DB 225b to obtain the application key in plaintext.

[0022] Regarding the key storage process in site B, encryption unit 227b encrypts the application key in a plaintext state for DB protection purposes, and stores the encrypted application key in encrypted application key DB 228b.

[0023] Next, an operation of transferring an application key from key management apparatus 220a to encrypted application execution device 250a when encrypted application execution device 250a at site A requests an application key will be described. First, decryption unit 229a reads the encrypted application key from encrypted application key DB 228a, performs decryption, and obtains the application key in plaintext. Then, supply unit 241a transfers the application key encrypted by encrypted communication to encrypted application execution device 250a.

[0024] When encrypted application execution device 250b at site B requests an application key, the operation of transferring the application key from key management apparatus 220b to encrypted application execution device 250b is the same as that at site A.

[0025] For example, https communication is used for encrypted communication when transferring the application key from the key management device 220a (220b) to the encrypted application execution device 250a (250b). Similarly, for example, https communication is used for encrypted communication when transferring the quantum cryptography key from the QKD device 210a (210b) to the key management device 220a (220b). For example, AES (Advanced Encryption Standard) is used as the encryption algorithm of the encryption unit 227a (227b).

[0026] The above is the overall operation, but the application key exists in plaintext immediately after the generation unit 226a in the KMA 221a generates an application key, and immediately after the decryption units 229a and 229b in the KMAs 221a and 221b decrypt the encrypted application key. Generally, this application key exists in a volatile memory of a computer, and if an attacker illegally accesses the key management devices 220a and 220b and takes over the management authority, he or she can access the volatile memory and seize the application key in plaintext. In the following embodiments, a mechanism for solving these problems will be described.

[0027] (First embodiment) A quantum cryptography communication system according to a first embodiment will be described.

[0028] [Example of functional configuration] 3A and 3B are diagrams illustrating an example of a functional configuration of the quantum cryptography communication system 100 according to the first embodiment.

[0029] The quantum cryptography communication system 100 of the first embodiment includes, at site A, a QKD device 10a, a key management apparatus 20a, and an encrypted application execution device 50a, and, at site B, a QKD device 10b, a key management apparatus 20b, and an encrypted application execution device 50b.

[0030] The key management device 20a at site A includes a KMA 21a and a KSA 40a. The KMA 21a includes a receiver 22a, a key storage unit 23a, and a relay unit 24a. The key storage unit 23a includes a quantum encryption key DB 25a, an HSM 26a, and an encrypted application key DB 30a. The HSM 26a includes a generator 27a, a first encryption unit 28a, a second encryption unit 29a, a second decryption unit 31a, and a third encryption unit 32a. The HSM 26a also includes a storage unit therein that stores an inter-site encryption key (first encryption key), a DB protection encryption key (second encryption key), and an intra-site encryption key (third encryption key). The KSA 40a includes a supplier 41a.

[0031] The key management device 20b at site B includes a KMA 21b and a KSA 40b. The KMA 21b includes a receiver 22b, a key storage unit 23b, and a relay unit 24b. The key storage unit 23b includes a quantum encryption key DB 25b, an HSM 26b, and an encrypted application key DB 30b. The HSM 26b includes a first decryption unit 28b, a second encryption unit 29b, a second decryption unit 31b, and a third encryption unit 32b. The HSM 26b also includes a storage unit therein that stores an inter-site encryption key (first encryption key), a DB protection encryption key (second encryption key), and an intra-site encryption key (third encryption key). The KSA 40b includes a supplier 41b.

[0032] The HSM 26a (26b) of the key management apparatus 20a (20b) may be connected to the key management apparatus 20a (20b) via a PCI connection or the like, or may be connected to the key management apparatus 20a via a LAN connection or the like.

[0033] The quantum cryptography communication system of the first embodiment has the following three features.

[0034] The first feature is that random numbers for the application key are generated within the HSM. The second feature is that when the application key is transmitted between sites, encryption for transmission between sites is performed within the HSM in addition to the OTP encryption performed in the relay unit. The third feature is that application encryption is performed within the HSM when the application key is transferred to encrypted application execution device 50a (50b).

[0035] The effect of the first feature will be described. In conventional cases, the application key in plaintext state is stored in volatile memory immediately after random number generation for the application key is performed. Therefore, in quantum cryptography communication system 100 of the first embodiment, random number generation for the application key is performed in the HSM. As a result, the application key in plaintext state is stored in the HSM, and can be protected by the HSM.

[0036] The effect of the second feature will be described. In the conventional case, the application key was in a plaintext state immediately before OTP cryptographic communication was performed in the relay unit 224a (see FIG. 2). Therefore, in the quantum cryptographic communication system 100 of the first embodiment, the first encryption unit 28a performs encryption for transmission between bases in the HSM 26a. This makes it possible to prevent the application key from becoming a plaintext state even immediately before OTP cryptographic communication is performed.

[0037] The effect of the third feature will now be described. In the conventional case, the application key was in a plaintext state immediately before the supply unit 41a performed encrypted communication. Therefore, in the quantum cryptography communication system 100 of the first embodiment, the third encryption unit 32a performs transmission encryption for the application in the HSM. This makes it possible to prevent the application key from becoming a plaintext state even immediately before performing encrypted communication.

[0038] The following describes the process of transmitting an application key between sites in the first embodiment. When transmitting an application key between sites, when the quantum cryptography communication system 100 is initially set up, an inter-site encryption key (i.e., a common key in which the encryption key and decryption key are the same) is shared between the HSM 26a and the HSM 26b before the transmission.

[0039] After the key sharing, the first encryption unit 28a encrypts the application key generated by the generation unit 27a at each site. between The relay unit 24a performs further OTP encryption processing using the quantum encryption key in the quantum encryption key DB 25a, and transfers the double encrypted application key to the key management device 20b at site B.

[0040] When relay unit 24b of key management device 20b receives the doubly encrypted application key, it performs decryption processing on the OTP encrypted communication and transfers the encrypted application key to HSM 26b. In HSM 26b, first decryption unit 28b performs decryption for inter-site transmission using the inter-site encryption key to obtain the application key. Next, second encryption unit 29b encrypts the application key using the DB protection encryption key, and stores the application key in the DB protection encrypted state in encrypted application key DB 30b. This completes the process of inter-site transmission of an application key in the first embodiment.

[0041] Next, a process performed in cooperation between the key management apparatus 20a and the encrypted application execution device 50a according to the first embodiment will be described.

[0042] 4 is a diagram for explaining an example of processing by the key management apparatus 20a and the encrypted application executing device 50a according to the first embodiment. The encrypted application executing device 50a includes an encrypted application 51a and an HSM 52a. The encrypted application 51a includes a receiving unit 53a and an executing unit 55a. The HSM 52a includes a decrypting unit 54a.

[0043] First, when the quantum cryptography communication system 100 is initially set up, an intra-site encryption key (that is, a common key in which the encryption key and the decryption key are the same) is shared between the HSM 26a and the HSM 52a.

[0044] After the key is shared, when the key management device 20a receives a request for an application key from the encrypted application executing device 50a, the key management device 20a transmits the application key to the encrypted application executing device 50a. First, in the HSM 26a, the second decryption unit 31a reads the encrypted application key stored in the encrypted application key DB 30a and decrypts it with a DB protection encryption key (i.e., a common key in which the encryption key and the decryption key are the same) to obtain the application key. The third encryption unit 32a performs transmission encryption on the application key using the intra-site encryption key to generate an encrypted application key. Then, the supply unit 41a further encrypts the encrypted application key and transmits the doubly encrypted application key to the encrypted application executing device 50a.

[0045] In the encrypted application executing device 50a, the receiving unit 53a performs decryption processing for the encrypted communication on the double encrypted application key, obtains an encrypted application key, and transmits the encrypted application key to the HSM 52a. Then, in the HSM 52a, the decrypting unit 54a performs decryption processing using an intra-site encryption key (i.e., a common key in which the encryption key and decryption key are the same), obtains an application key, and transmits the application key to the encrypted application 51a. Then, in the encrypted application 51a, the executing unit 55a executes application processing while performing encryption using the application key.

[0046] The above operation is similar at site B.

[0047] The method of sharing the inter-site encryption key between the HSM 26a and the HSM 26b may be, for example, the Diffie-Hellman (DH) method or the Rivest-Shamir-Adleman (RSA) method. The method of sharing the intra-site encryption key (A) between the HSM 26a and the HSM 52a and the method of sharing the intra-site encryption key between the HSM 26b of the key management device 20b at site B and the HSM of the encrypted application execution device 50b at site B are similar to the method of sharing the inter-site encryption key.

[0048] The doubly encrypted application key is in a doubly encrypted state, having been encrypted by third encryption unit 32a and by supplying unit 41a. Since the application key is already in an encrypted state immediately before entering supplying unit 41a, if the encryption process of the application key places a burden on supplying unit 41a, it is not necessary for supplying unit 41a to encrypt the application key.

[0049] [Example of application key transmission processing between bases] 5 is a flowchart showing an example of an application key transmission process between locations in the first embodiment. First, the receiver 22a receives an encrypted quantum encryption key encrypted by cryptographic communication such as HTTP from the QKD device 10a (step S1). Next, the receiver 22a stores the quantum encryption key received by the process of step S1 in the quantum encryption key DB 25a (step S2). Next, the generator 27a generates an application key based on a random number (step S3). Next, the first encryption unit 28a encrypts the application key using the inter-location encryption key (step S4). Next, the relay unit 24a further OTP-encrypts the encrypted application key encrypted by the process of step S4 using the quantum encryption key in the quantum encryption key DB 25a, and transmits the double encrypted application key to location B (step S5).

[0050] [Example of application key supply process within a site] 6 is a flowchart showing an example of an application key supply process within a base in the first embodiment. First, the second encryption unit 29a encrypts the application key generated by the generation unit 27a using the DB protection encryption key (step S11), and stores the encrypted application key in the encrypted application key DB 30a (step S12). Next, the second decryption unit 31a decrypts the encrypted application key in the encrypted application key DB 30a using the DB protection encryption key as a decryption key (step S13). Next, the third encryption unit 32a encrypts the application key using the base encryption key (step S14). Next, the supply unit 41a transmits the double encrypted application key to the encrypted application execution device 50a by encrypting and transmitting the encrypted application key by encryption communication such as HTTP (step S15).

[0051] As described above, in the quantum cryptography communication system 100 of the first embodiment, the key management device 20a (first key management device) includes a receiver 22a that receives a quantum encryption key from the QKD device 10a (first QKD device), and an HSM 26a (first HSM). The HSM 26a includes a storage unit that stores an inter-site encryption key (first encryption key), a generator 27a that generates an application key used in encryption processing by the encryption application 51a, and a first encryption unit 28a that encrypts, with the inter-site encryption key, the application key transmitted to the key management device 20b (second key management device) connected to the QKD device 10b (second QKD device).

[0052] As a result, according to the quantum cryptography communication system 100 of the first embodiment, it is possible to more safely protect the application key used in the encryption process.

[0053] Second embodiment Next, a second embodiment will be described. In the description of the second embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts different from the first embodiment will be described.

[0054] [Example of functional configuration] 7A and 7B are diagrams showing an example of the functional configuration of a quantum cryptography communication system 100-2 according to the second embodiment. The difference from the first embodiment is that the QKD device 10a (10b) transfers the quantum cryptography key to the key management device 20a (20b) in a double-encrypted state.

[0055] Before performing the actual operation, the QKD encryption key is stored in the HSM 26a at site A, and the QKD encryption key is shared between the key management device 20a and the QKD device 10a, and then encryption is performed on the quantum encryption key using the QKD encryption key. This allows the quantum encryption key to be transmitted more securely between the QKD device 10a and the key management device 20a. The same operation as at site A is also performed at site B, allowing the quantum encryption key to be encrypted and transmitted between the QKD device 10b and the key management device 20b.

[0056] This ensures that quantum cryptography keys in plaintext will not exist in the key management devices 20a and 20b, and security is further enhanced, particularly when quantum cryptography keys are stored in the key management devices 20a and 20b (quantized cryptography key DB 25a-2 (25b-2)).

[0057] Next, an operation in the second embodiment in which the quantum cryptography key is transferred from the QKD device 10a to the key management device 20a, and an operation in which the relay unit 24a in the key management device 20a receives the quantum cryptography key will be described.

[0058] 8A and 8B are diagrams for explaining an example of processing by the QKD device 10a (10b) and the key management device 20a (20b) of the second embodiment.

[0059] In the second embodiment, the QKD device 10a also includes an HSM 12a. Before transmitting a quantum encryption key, the key management device 20a transfers a QKD encryption key created in the HSM 26a to the HSM 12a as an initial setting, and shares the QKD encryption key between the HSM 26a and the HSM 12a.

[0060] In the QKD device 10a, the generation unit 11a cooperates with the generation unit 11b to generate a quantum cryptography key. The generation unit 11a then transfers the quantum cryptography key to the HSM 12a, and the encryption unit 14a encrypts the quantum cryptography key using the QKD encryption key to generate an encrypted quantum cryptography key. The supply unit 13a then performs further encryption communication on the encrypted quantum cryptography key and transfers the double-encrypted quantum cryptography key to the key management device 20a.

[0061] In the key management device 20a, when the receiver 22a receives the double-encrypted quantum encryption key, it decrypts the encryption applied by the encrypted communication and stores the encrypted quantum encryption key in the encrypted quantum encryption key DB 25a-2. Then, in the HSM 26a, the third decryption unit 33a decrypts the encrypted quantum encryption key using a QKD encryption key (i.e., a common key in which the encryption key and the decryption key are the same) to generate a quantum encryption key. Then, the relay unit 24a accepts the quantum encryption key from the third decryption unit 33a.

[0062] The subsequent operations are the same as those in the first embodiment. Moreover, the operations between the QKD device 10b and the key management device 20b at point B are the same as those at point A.

[0063] The QKD encryption key is shared between the HSM 12a and the HSM 26a by, for example, the DH method or the RSA method.

[0064] The doubly encrypted quantum cryptography key is in a doubly encrypted state, that is, encrypted by the encryption unit 14a and encrypted by the supply unit 13a. If the burden of further encrypting the encrypted quantum cryptography key is large on the supply unit 13a, the supply unit 13a does not need to perform encryption since the quantum cryptography key is already in an encrypted state.

[0065] [Example of application key transmission processing between bases] 9 is a flowchart showing an example of an application key transmission process between locations in the second embodiment. First, the receiver 22a receives a double-encrypted quantum cryptography key obtained by further encrypting the encrypted quantum cryptography key by cryptographic communication such as HTTP from the QKD device 10a (step S21). Next, the receiver 22a stores the encrypted quantum cryptography key received by the cryptographic communication in step S21 in the encrypted quantum cryptography key DB 25a-2 (step S22).

[0066] Next, the generation unit 27a generates an application key based on a random number (step S23). Next, the first encryption unit 28a encrypts the application key using the inter-site encryption key (step S24). Next, the third decryption unit 33a decrypts the encrypted quantum encryption key using the QKD encryption key (step S25). Next, the relay unit 24a further OTP-encrypts the encrypted application key encrypted by the process of step S24 using the quantum encryption key decrypted by the process of step S25, and transmits the doubly encrypted application key to site B (step S26).

[0067] Third embodiment Next, a third embodiment will be described. In the description of the third embodiment, the description of the same parts as in the first embodiment will be omitted, and only the parts different from the first embodiment will be described.

[0068] [Example of functional configuration] 10A and 10B are diagrams showing an example of a functional configuration of a quantum cryptography communication system 100-3 according to the third embodiment. The difference from the first embodiment is that the OTP encryption performed in the relay unit 24a is performed in the HSM 26a. This makes it possible to perform the OTP encryption more safely in terms of information security.

[0069] The application key transmission process in the third embodiment will be described. At site A, first, the generation unit 27a generates an application key. Next, the first encryption unit 28a performs OTP encryption on the application key using the quantum encryption key in the quantum encryption key DB 25a to generate an encrypted application key. Then, the relay unit 24a further performs encryption by encrypted communication and transfers the doubly encrypted application key to site B.

[0070] At site B, first, the relay unit 24b transfers the encrypted application key obtained by the decryption process of the encrypted communication of the doubly encrypted application key to the HSM 26b. In the HSM 26b, the first decryption unit 28b decrypts the encrypted application key using the quantum encryption key in the quantum encryption key DB 25b to obtain the application key. The subsequent operations are the same as in the first embodiment, and therefore description thereof is omitted.

[0071] The doubly encrypted application key is doubly encrypted, through OTP encryption by first encryption unit 28a and encryption by relay unit 24a. Because the application key is protected by OTP encryption before entering relay unit 24a, if the processing load of encrypting the application key is large in relay unit 24a, it is not necessary for relay unit 24a to encrypt the application key.

[0072] [Example of application key transmission processing between bases] 11 is a flowchart showing an example of an application key transmission process between locations in the third embodiment. First, the receiver 22a receives an application key from the QKD device 10a. ,amount The child encryption key is encrypted using HTTP etc. Dark Encoded Dark Next, the receiver 22a receives the encrypted quantum cryptographic key (step S31). 3 1 was received by encrypted communication. Amount Child encryption key ,amount Child encryption key DB25 a Store (step S32).

[0073] Next, the generation unit 27a generates an application key based on a random number (Step S33). Next, the first encryption unit 28a OTP-encrypts the application key using the quantum encryption key (Step S34). Next, the relay unit 24a further encrypts the encrypted application key OTP-encrypted by the process of Step S34 using encrypted communication such as HTTP, and transmits the doubly encrypted application key to site B (Step S35).

[0074] (Fourth embodiment) Next, a fourth embodiment will be described. The fourth embodiment is a combination of the first to third embodiments.

[0075] [Example of functional configuration] 12A and 12B are diagrams showing an example of a functional configuration of a quantum cryptography communication system 100-4 according to the fourth embodiment. In the fourth embodiment, in the key management device 20a (20b), the quantum cryptography key in a plaintext state and the application key in a plaintext state are present in the HSM 26a (26b), and the management of each key in the key management device 20a (20b) is further strengthened in terms of security. That is, in the fourth embodiment, all the effects of the first to third embodiments can be obtained.

[0076] [Example of application key transmission processing between bases] 13 is a flowchart showing an example of an application key transmission process between locations in the fourth embodiment. First, the receiver 22a receives a double-encrypted quantum cryptography key obtained by further encrypting the encrypted quantum cryptography key by cryptographic communication such as HTTP from the QKD device 10a (step S41). Next, the receiver 22a stores the encrypted quantum cryptography key received by the cryptographic communication in step S21 in the encrypted quantum cryptography key DB 25a-2 (step S42).

[0077] Next, the generation unit 27a generates an application key based on a random number (step S43). Next, the third decryption unit 33a decrypts the encrypted quantum encryption key using the QKD encryption key (step S44). Next, the first encryption unit 28a OTP-encrypts the application key using the quantum encryption key (step S45). Next, the relay unit 24a further encrypts the encrypted application key OTP-encrypted by the process of step S45 using encrypted communication such as HTTP, and transmits the doubly encrypted application key to site B (step S46).

[0078] Fifth embodiment Next, a fifth embodiment will be described. In the description of the fifth embodiment, the description of the same parts as in the fourth embodiment will be omitted, and only the parts different from the fourth embodiment will be described.

[0079] [Example of functional configuration] 14A and 14B are diagrams showing an example of a functional configuration of a quantum cryptography communication system 100-5 according to the fifth embodiment. The main difference from the fourth embodiment is that the site-to-site encryption method using a quantum cryptography key implemented in the HSM 26a (26b) for transferring an application key between sites is made variable in the fifth embodiment. In the fourth embodiment, the site-to-site encryption method using a quantum cryptography key is fixed to the OTP encryption method, but in the fifth embodiment, the encryption method is changed according to the application key savings information and the quantum cryptography key savings information. Candidates for the encryption method include, for example, OTP and AES.

[0080] The inter-site encryption method switching process, which is a main feature of the fifth embodiment, will now be described. First, the acquisition unit 72a acquires application key savings information from the encrypted application key DB 30a, and acquires quantum encryption key savings information from the encrypted quantum encryption key DB 25a-2. The application key savings information indicates the amount of application keys saved in the encrypted application key DB 30a, etc. The quantum encryption key savings information indicates the amount of quantum encryption keys saved in the encrypted quantum encryption key DB 25a-2, etc.

[0081] Next, the acquisition unit 72a transmits the key savings information (the application key savings information and the quantum encryption key savings information) to the QKDN manager 60 at site X. The QKDN manager 60 determines an inter-site encryption method using the quantum encryption key based on at least one of the application key savings information and the quantum encryption key savings information, and transmits the inter-site encryption method using the quantum encryption key to the QKDN controller 70a at site A and the QKDN controller 70b at site B.

[0082] Then, the QKDN controller 70a (70b) notifies the inter-site encryption method to the encryption method control unit 73a (73b). The encryption method control unit 73a (73b) notifies the setting unit 74a (74b) in the KMA 21a (21b). Finally, the setting unit 74a at site A sets the inter-site encryption method of the first encryption unit 28a implemented in the HSM 26a, and the setting unit 74b at site B sets the inter-site encryption method to be decrypted by the first decryption unit 28b of the HSM 26b. This concludes the description of the inter-site encryption method switching process.

[0083] Next, a method for switching (determining) the encryption method between sites performed by the QKDN manager 60 will be described. First, candidates for encryption methods will be described. As described above, OTP and AES are considered as candidates for encryption methods. In the case of OTP, the quantum encryption key is consumed at a speed equivalent to the application key generation speed (random number generation speed) of the generation unit 27a. On the other hand, in the case of AES, the consumption speed of the quantum encryption key is kept very low compared to OTP. For example, in the case of AES 256 bits, when the encryption key for AES is switched every minute, only 256 bits of the quantum encryption key are consumed per minute.

[0084] Next, an example of a specific switching method implemented by the QKDN manager 60 will be described.

[0085] In the first method, a threshold QA is prepared as a threshold for the amount of stored quantum cryptography keys. If the amount of stored quantum cryptography keys is equal to or less than the threshold QA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum cryptography keys to be the first encryption method, and if the amount of stored quantum cryptography keys is greater than the threshold QA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum cryptography keys to be the second encryption method, which consumes the quantum cryptography keys faster than the first encryption method. For example, if the amount of stored quantum cryptography keys is equal to or less than the threshold QA, the QKDN manager 60 sets the inter-site encryption method to AES, and if the amount of stored quantum cryptography keys is greater than the threshold QA, the QKDN manager 60 sets the inter-site encryption method to OTP.

[0086] The second method will be described. In the second method, a threshold QA and a threshold QB are prepared as thresholds for the amount of stored quantum cryptography keys. When the amount of stored quantum cryptography keys becomes equal to or less than the threshold QA, the QKDN manager 60 determines the encryption method of the encryption process using the quantum cryptography keys to be the first encryption method, and when the amount of stored quantum cryptography keys exceeds the threshold QB (QB>QA), the QKDN manager 60 determines the encryption method of the encryption process using the quantum cryptography keys to be the second encryption method, which consumes the quantum cryptography keys faster than the first encryption method, and keeps the encryption method of the encryption process using the quantum cryptography keys as the second encryption method until the amount of stored quantum cryptography keys becomes equal to or less than the threshold QA again. For example, when the amount of stored quantum cryptography keys becomes equal to or less than the threshold QA, the QKDN manager 60 sets the inter-site encryption method to AES, and when the amount of stored quantum cryptography keys exceeds the threshold QB, the QKDN manager 60 sets the inter-site encryption method to OTP. Then, the QKDN manager 60 sets the inter-site encryption method to OTP until the saved amount of quantum encryption keys again becomes equal to or less than the threshold QA. Naturally, in the second method, the threshold QB needs to be a value larger than the threshold QA.

[0087] The third method will be described. In the third method, a threshold value GA is prepared as a threshold value for the saved amount of the application key. If the saved amount of the application key is equal to or less than the threshold value GA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum encryption key to be the first encryption method, and if the saved amount of the application key is greater than the threshold value GA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum encryption key to be the second encryption method, which consumes the quantum encryption key at a faster rate than the first encryption method. For example, if the saved amount of the application key is equal to or less than the threshold value GA, the QKDN manager 60 sets the inter-site encryption method to AES, and if the saved amount of the application key exceeds the threshold value GA, the QKDN manager 60 sets the inter-site encryption method to OTP.

[0088] The fourth method will be described. In the fourth method, a threshold GA and a threshold GB are prepared as thresholds for the saved amount of the application key. Then, when the saved amount of the application key becomes equal to or less than the threshold GA, the QKDN manager 60 determines the encryption method of the encryption process using the quantum encryption key to be the first encryption method, and when the saved amount of the application key exceeds the threshold GB (GB>GA), the QKDN manager 60 determines the encryption method of the encryption process using the quantum encryption key to be the second encryption method, which consumes the quantum encryption key faster than the first encryption method, and keeps the encryption method of the encryption process using the quantum encryption key as the second encryption method until the saved amount of the application key becomes equal to or less than the threshold GA again. For example, when the saved amount of the application key becomes equal to or less than the threshold GA, the QKDN manager 60 sets the inter-site encryption method to AES, and when the saved amount of the application key exceeds the threshold GB, the QKDN manager 60 sets the inter-site encryption method to OTP. Then, the QKDN manager 60 keeps the inter-site encryption method as OTP until the saved amount of the application key becomes equal to or less than the threshold GA again. Naturally, in the fourth method, the threshold value GB must be greater than the threshold value GA.

[0089] The fifth method will be described. The fifth method is a switching method that combines the first and third methods, and prepares a threshold QA for the amount of saved quantum cryptography keys and a threshold GA for the amount of saved application keys. When the amount of saved quantum cryptography keys is equal to or less than the threshold QA and the amount of saved application keys is equal to or less than the threshold GA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum cryptography keys to be the first encryption method, and when the amount of saved quantum cryptography keys is greater than the threshold QA or the amount of saved application keys is greater than the threshold GA, the QKDN manager 60 determines the encryption method for the encryption process using the quantum cryptography keys to be the second encryption method, which consumes the quantum cryptography keys faster than the first encryption method. For example, when the amount of saved quantum cryptography keys is equal to or less than the threshold QA and the amount of saved application keys is equal to or less than the threshold GA, the QKDN manager 60 sets the inter-site encryption method to AES, and otherwise sets the inter-site encryption method to OTP.

[0090] The sixth method will be described. The sixth method is a switching method that combines the second and fourth methods, and prepares thresholds QA and QB for the saved amount of quantum cryptography keys, and thresholds GA and GB for the saved amount of application keys. When the saved amount of quantum cryptography keys is equal to or less than the threshold QA and the saved amount of application keys is equal to or less than the threshold GA, the QKDN manager 60 determines the encryption method for encryption processing using the quantum cryptography keys to be the first encryption method, and when the saved amount of quantum cryptography keys exceeds the threshold QB (QB>QA) and the saved amount of application keys exceeds the threshold GB (GB>GA), the QKDN manager 60 determines the encryption method for encryption processing using the quantum cryptography keys to be the second encryption method, which consumes the quantum cryptography keys at a faster rate than the first encryption method, and again sets the encryption method for encryption processing using the quantum cryptography keys to the second encryption method until the saved amount of quantum cryptography keys becomes equal to or less than the threshold QA and the saved amount of application keys becomes equal to or less than GA. For example, the QKDN manager 60 sets the inter-site encryption method to AES when the saved amount of quantum encryption keys is equal to or less than the threshold QA and the saved amount of application keys is equal to or less than the threshold GA, and switches the inter-site encryption method to OTP when the saved amount of quantum encryption keys exceeds the threshold QB and the saved amount of application keys exceeds the threshold GB. The QKDN manager 60 then sets the inter-site encryption method to OTP again until the saved amount of quantum encryption keys is equal to or less than the threshold QA and the saved amount of application keys is equal to or less than GA. Naturally, in the sixth method, the threshold QB needs to be a value greater than the threshold QA, and the threshold GB needs to be a value greater than the threshold GA.

[0091] Furthermore, when the site-to-site encryption method is AES, the update frequency (switching frequency) of the quantum encryption key used for AES encryption may be adjusted. When the update frequency of the quantum encryption key is reduced, the consumption speed of the quantum encryption key by AES decreases, so the quantum encryption key can be saved more quickly than when the update frequency of the quantum encryption key is high. For example, when the encryption method of the encryption process using the quantum encryption key is set to AES, the QKDN manager 60 reduces the update frequency of the quantum encryption key used for encryption by AES as the amount of saved quantum encryption key decreases.

[0092] [Example of switching between encryption methods between bases] 15 is a flowchart showing an example of a process of switching the encryption method between locations in the fifth embodiment. First, the acquisition unit 72a acquires the savings information of the application key from the encrypted application key DB 30a (step S51). Next, the acquisition unit 72a acquires the savings information of the quantum encryption key from the encrypted quantum encryption key DB 25a-2 (step S52). Next, the acquisition unit 72a transmits the key savings information (the savings information of the application key and the savings information of the quantum encryption key) to the QKDN manager 60 (step S53).

[0093] Next, the QKDN manager 60 determines the inter-site encryption method by the above-mentioned method based on the application key savings information and the quantum encryption key savings information (step S54). Next, the QKDN manager 60 transmits the inter-site encryption method to the QKDN controller 70a at site A and the QKDN controller 70b at site B (step S55). Next, the QKDN controller 70a transmits the inter-site encryption method to the encryption method control unit 73a, and the QKDN controller 70b transmits the inter-site encryption method to the encryption method control unit 73b (step S56). Next, the encryption method control unit 73a transmits the inter-site encryption method to the setting unit 74a, and the encryption method control unit 73b transmits the inter-site encryption method to the setting unit 74b (step S57). Next, the setting unit 74a at site A sets the inter-site encryption method for the first encryption unit 28a implemented in HSM 26a, and the setting unit 74b at site B sets the inter-site encryption method to be decrypted by the first decryption unit 28b of HSM 26b (step S58).

[0094] (Modification) In the above embodiment, the HSM 12a is prepared for the QKD device 10a, the HSM 26a is prepared for the key management device 20a, and the HSM 52a is prepared for the encrypted application execution device 50a. If no security issues arise, the QKD device 10a or the encrypted application execution device 50a may share the HSM 26a for the key management device 20a at site A. The same applies to the case of site B.

[0095] First, an example will be described in which the QKD device 10a shares the HSM 26a of the key management device 20a.

[0096] Fig. 16 is a diagram showing a first modified example in which the HSM 26a is shared. In the example of Fig. 16, after the generation unit 11a generates a quantum cryptography key, it transmits the quantum cryptography key to the HSM transfer unit 15a. The HSM transfer unit 15a transfers the encrypted quantum cryptography key by cryptographic communication to the HSM 26a. In the HSM 26a, when the encryption transfer unit 34a receives the encrypted quantum cryptography key from the HSM transfer unit 15a, it decrypts the encrypted quantum cryptography key. Then, the encryption transfer unit 34a further encrypts the encrypted quantum cryptography key encrypted using the QKD cryptography key into a double encrypted quantum cryptography key by cryptographic communication, and transfers the double encrypted quantum cryptography key to the QKD device 10a.

[0097] After receiving the double-encrypted quantum encryption key from the HSM 26a, the HSM transfer unit 15a performs a decryption process on the encrypted communication to obtain an encrypted quantum encryption key. The HSM transfer unit 15a transfers the encrypted quantum encryption key to the supply unit 13a. The subsequent operations are the same as those in the above-mentioned embodiment. The configuration of the site B is also the same as that of the site A.

[0098] Next, an example in which the encrypted application executing device 50a shares the HSM 26a of the key management apparatus 20a will be described.

[0099] Fig. 17 is a diagram showing Variation 2 in which the HSM 26a is shared. In the example of Fig. 17, when receiver 53a of encrypted application 51a receives the double encrypted application key, it performs decryption processing on the encrypted communication to obtain the encrypted application key. Receiver 53a transmits the encrypted application key to HSM transfer unit 56a. HSM transfer unit 56a further encrypts the encrypted application key by encrypted communication, and transfers the double encrypted application key to HSM 26a.

[0100] Then, in the HSM 26a, the decryption and transfer unit 35a encrypts the application key obtained by decrypting the application using the application encryption key through encrypted communication, and transfers the encrypted application key to the encrypted application 51a. In the encrypted application 51a, when the HSM transfer unit 56a receives the encrypted application key from the HSM 26a, it performs decryption processing on the encrypted communication to obtain the application key. The subsequent operations are the same as in the above-mentioned embodiment. The configuration of site B is also the same as the configuration of site A.

[0101] In the above-described embodiment, a QKD encryption key is used when transferring a quantum encryption key between the QKD device 10a (10b) and the key management device 20a (20b), and an application encryption key is used when transferring an application key between the key management device 20a (20b) and the encrypted application execution device 50a (50b). However, when there are a large number of transfer destination devices within site A (B) and a large number of encryption keys are stored in the HSM 26a (26b), a common encryption key for transfer within the site may be used.

[0102] In the case of the above-described embodiment, for example, an intra-site encryption key is prepared and shared in place of an application encryption key and a QKD encryption key at site A. The same is true at site B.

[0103] Furthermore, in the first and second embodiments, the more the number of destination bases for the application key, the more keys need to be stored in the HSM 26a. When many types of keys are stored in the HSM 26a, a plurality of bases may be bundled into one area, and a common inter-base encryption key may be used when transferring the application key within that area. In this case, the HSM 26a stores the inter-base encryption key corresponding to the destination area. When transferring the application key from the source base A to a base in a different area, the relay unit 24a performs encryption and transfer using the inter-base encryption key corresponding to the destination area.

[0104] For example, the HSM at the destination location can be connected to the HSM at the location corresponding to the source area. between Another method is to store the encryption key and encrypt and transfer the data using an inter-site encryption key corresponding to the source area.

[0105] In the above embodiment, the case where an application key is generated at location A has been described. However, the configuration of location B when an application key is generated at location B is similar to the configuration of location A.

[0106] Finally, an example of the hardware configuration of the QKD device 10a (10b), the key management device 20a (20b), and the encrypted application execution device 50a (50b) of the first to fifth embodiments, and the QKDN manager 60 of the fifth embodiment will be described.

[0107] [Example of hardware configuration] 18 is a diagram showing an example of the hardware configuration of the main parts of the QKD device 10a (10b) of the first to fifth embodiments. The QKD device 10a (10b) of the first to fifth embodiments includes a control device 301, a main memory device 302, an auxiliary memory device 303, a display device 304, an input device 305, a quantum communication IF (Interface) 306, and a classical communication IF 307.

[0108] The control device 301 , the main memory device 302 , the auxiliary memory device 303 , the display device 304 , the input device 305 , the quantum communication IF 306 and the classical communication IF 307 are connected via a bus 310 .

[0109] The control device 301 executes a program read from the auxiliary storage device 303 to the main storage device 302. The main storage device 302 is a 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 memory card, or the like.

[0110] The display device 304 displays the status of the QKD device 10a (10b), etc. The input device 305 accepts input from the user.

[0111] The quantum communication IF 306 is an interface for connecting to a QKD link through which photons are transmitted, and the classical communication IF 307 is an interface for connecting to a transmission line through which control signals and the like are transmitted.

[0112] FIG. 19 shows an example of the hardware configuration of the main parts of the key management device 20a (20b) and the encrypted application execution device 50a (50b) of the first and fifth embodiments, and the QKDN manager 60 of the fifth embodiment. In the figure The key management apparatus 20a (20b) and the encrypted application execution device 50a (50b) of the first and fifth embodiments, and the QKDN manager 60 of the fifth embodiment include a control device 401, a main storage device 402, an auxiliary storage device 403, a display device 404, an input device 405, and a communication IF 406.

[0113] The control device 401 , the main memory device 402 , the auxiliary memory device 403 , the display device 404 , the input device 405 and the communication IF 406 are connected via a bus 410 .

[0114] The control device 401 executes a program read from the auxiliary storage device 403 to the main storage device 402. The main storage device 402 is a memory such as a ROM and a RAM. The auxiliary storage device 403 is a HDD, a memory card, or the like.

[0115] The display device 404 displays the status of the key management device 20a (20b), the encrypted application execution device 50a (50b), and the QKDN manager 60. The input device 405 accepts input from the user.

[0116] The communication IF 406 is an interface for connecting to a transmission line.

[0117] The programs executed by the QKD equipment 10a (10b), key management device 20a (20b), and encryption application execution device 50a (50b) of the first to fifth embodiments, as well as the QKDN manager 60 of the fifth embodiment, are stored in an installable or executable format on a computer-readable storage medium such as a CD-ROM, memory card, CD-R, or DVD (Digital Versatile Disc) and provided as a computer program product.

[0118] In addition, the programs executed by the QKD equipment 10a (10b), key management device 20a (20b), and encrypted application execution device 50a (50b) of the first to fifth embodiments, as well as the QKDN manager 60 of the fifth embodiment, may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network.

[0119] In addition, the programs executed by the QKD equipment 10a (10b), key management device 20a (20b), and encrypted application execution device 50a (50b) of the first to fifth embodiments, as well as the QKDN manager 60 of the fifth embodiment, may be configured to be provided via a network such as the Internet without being downloaded.

[0120] In addition, the programs executed by the QKD equipment 10a (10b), key management device 20a (20b), and encrypted application execution device 50a (50b) of the first to fifth embodiments, as well as the QKDN manager 60 of the fifth embodiment, may be configured to be provided by being pre-installed in a ROM or the like.

[0121] The program executed by the QKD device 10a (10b) has a modular configuration including functions that can be realized by the program among the functional configuration of the QKD device 10a (10b). The function realized by the program is loaded into the main memory device 302 by the control device 301 reading and executing the program from a storage medium such as the auxiliary memory device 303. In other words, the function realized by the program is generated on the main memory device 302.

[0122] Furthermore, the programs executed by the key management apparatus 20a (20b) and the encrypted application executing device 50a (50b), and the QKDN manager 60 of the fifth embodiment have a modular configuration including functions that can be realized by the programs among the functional configurations of the key management apparatus 20a (20b) and the encrypted application executing device 50a (50b), and the QKDN manager 60 of the fifth embodiment. The functions realized by the programs are loaded into the main memory device 402 by the control device 401 reading and executing the programs from a storage medium such as the auxiliary storage device 403. In other words, the functions realized by the programs are generated on the main memory device 402.

[0123] Some or all of the functions of the QKD device 10a (10b), the key management device 20a (20b), the encrypted application execution device 50a (50b), and the QKDN manager 60 may be realized by hardware such as an integrated circuit (IC). The IC is, for example, a processor that executes dedicated processing.

[0124] Furthermore, when multiple processors are used to realize the respective functions, each processor may realize one of the respective functions, or may realize two or more of the respective functions.

[0125] Furthermore, any operation form may be used for the QKD device 10a (10b), the key management device 20a (20b), the encrypted application executing device 50a (50b), and the QKDN manager 60. The QKD device 10a (10b), the key management device 20a (20b), the encrypted application executing device 50a (50b), and the QKDN manager 60 may be operated as a quantum cryptography communication system that realizes, for example, cryptographic communication of a cloud system on a network.

[0126] Although some 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 implemented 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 in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0127] 10a,10b QKD equipment 20a,20b Key management device 21a,21b KMA 40a, 40b KSA 50a, 50b Encryption application execution device 60 QKDN Manager 70a,70b QKDN Controller 100 Quantum cryptography communication system 301 Control device 302 Main storage 303 Auxiliary storage device 304 Display device 305 Input Device 306 Quantum Communication Interface 307 Classic Communication IF 310 Bus 401 Control device 402 Main storage 403 Auxiliary storage 404 Display device 405 Input Device 406 Communication Interface 410 Bus

Claims

1. A first QKD device that shares a quantum cryptographic key with a second QKD device by quantum key distribution (QKD); a first key management device, The first key management device A receiver for receiving the quantum cryptography key from the first QKD device; A first HSM (Hardware Security Module); The first HSM is a storage unit that stores a first device key and a second device key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a second encryption unit that encrypts the application key stored in the first key management device with the second encryption key; A quantum cryptography communication system comprising:

2. A first QKD device that shares a quantum cryptographic key with a second QKD device by quantum key distribution (QKD); a first key management device, The first key management device A receiver for receiving the quantum cryptography key from the first QKD device; A first HSM (Hardware Security Module); The first HSM is a storage unit that stores a first device key and a third device key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a third encryption unit that encrypts the application key, which is supplied to an encrypted application execution device that executes the encrypted application, with the third encryption key; A quantum cryptography communication system comprising:

3. A first QKD device that shares a quantum cryptographic key with a second QKD device by quantum key distribution (QKD); a first key management device, The first key management device A receiver for receiving the encrypted quantum encryption key from the first QKD device; A first HSM (Hardware Security Module); The first HSM is a storage unit that stores a first encryption key and a decryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a decryption unit that decrypts the encrypted quantum encryption key using the decryption key; A quantum cryptography communication system comprising:

4. A first QKD device that shares a quantum cryptographic key with a second QKD device by quantum key distribution (QKD); a first key management device, The first key management device A receiver for receiving the quantum cryptography key from the first QKD device; a first HSM (Hardware Security Module); A relay unit, The first HSM is a storage unit that stores a first encryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; the relay unit further encrypts, with the quantum encryption key, the application key encrypted with the first encryption key, and transmits the application key doubly encrypted with the first encryption key and the quantum encryption key to the second key management device. Quantum cryptography communication system.

5. A first QKD device that shares a quantum cryptographic key with a second QKD device by quantum key distribution (QKD); A first key management device; A Quantum Key Distribution Network (QKDN) manager; The first key management device A receiver for receiving the quantum cryptography key from the first QKD device; a first HSM (Hardware Security Module); a setting unit that sets the encryption method determined by the QKDN manager as the encryption method of the encryption process using the quantum encryption key; The first HSM is a storage unit that stores a first encryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; the QKDN manager determines an encryption method for encryption processing using the quantum encryption key based on at least one of a stored amount of the application key stored in the first key management device and a stored amount of the quantum encryption key stored in the first key management device; Quantum cryptography communication system.

6. the first HSM shares the first encryption key with the second HSM of the second key management device when an initial setting of the quantum cryptography communication system is performed; The quantum cryptography communication system according to any one of claims 1 to 5.

7. the first HSM shares the third encryption key with a third HSM of the encrypted application execution device when an initial setting of the quantum cryptography communication system is performed; The quantum cryptography communication system according to claim 2 .

8. The first encryption unit uses the quantum encryption key as the first encryption key. The quantum cryptography communication system according to any one of claims 1 to 3.

9. The first encryption unit uses the quantum encryption key as the first encryption key. The quantum cryptography communication system according to claim 5 .

10. a Quantum Key Distribution Network (QKDN) manager that determines an encryption method for encryption processing using the quantum encryption key based on at least one of a stored amount of the application key stored in the first key management device and a stored amount of the quantum encryption key stored in the first key management device, The first key management device A setting unit that sets the encryption method determined by the QKDN manager as the encryption method for the encryption process using the quantum encryption key; The quantum cryptography communication system according to claim 4, further comprising:

11. When the saved amount of the quantum cryptography key is equal to or less than a threshold QA, the QKDN manager determines the encryption method of the encryption process using the quantum cryptography key to be a first encryption method, and when the saved amount of the quantum cryptography key is greater than the threshold QA, determines the encryption method of the encryption process using the quantum cryptography key to be a second encryption method having a faster consumption speed of the quantum cryptography key than the first encryption method.

11. The quantum cryptography communication system according to claim 5, 9, or 10.

12. When the saved amount of the quantum cryptography key becomes equal to or less than a threshold QA, the QKDN manager determines the encryption method of the encryption process using the quantum cryptography key to be a first encryption method, and when the saved amount of the quantum cryptography key exceeds a threshold QB (QB>QA), the QKDN manager determines the encryption method of the encryption process using the quantum cryptography key to be a second encryption method having a faster consumption speed of the quantum cryptography key than the first encryption method, and keeps the encryption method of the encryption process using the quantum cryptography key as the second encryption method until the saved amount of the quantum cryptography key becomes equal to or less than the threshold QA again.

11. The quantum cryptography communication system according to claim 5, 9, or 10.

13. When the saved amount of the application key is equal to or less than a threshold value GA, the QKDN manager determines the encryption method for the encryption process using the quantum cryptography key to be a first encryption method, and when the saved amount of the application key is greater than the threshold value GA, determines the encryption method for the encryption process using the quantum cryptography key to be a second encryption method having a faster consumption speed of the quantum cryptography key than the first encryption method.

11. The quantum cryptography communication system according to claim 5, 9, or 10.

14. when the saved amount of the application key becomes equal to or less than a threshold value GA, the QKDN manager determines the encryption method of the encryption process using the quantum cryptography key to be a first encryption method, and thereafter, when the saved amount of the application key exceeds a threshold value GB (GB>GA), determines the encryption method of the encryption process using the quantum cryptography key to be a second encryption method which consumes the quantum cryptography key at a faster rate than the first encryption method, and keeps the encryption method of the encryption process using the quantum cryptography key as the second encryption method until the saved amount of the application key becomes equal to or less than the threshold value GA again.

11. The quantum cryptography communication system according to claim 5, 9, or 10.

15. the QKDN manager determines the encryption method for the encryption process using the quantum cryptography key to be a first encryption method when the saved amount of the quantum cryptography key is equal to or less than a threshold QA and the saved amount of the application key is equal to or less than a threshold GA, and determines the encryption method for the encryption process using the quantum cryptography key to be a second encryption method having a faster consumption speed of the quantum cryptography key than the first encryption method when the saved amount of the quantum cryptography key is greater than the threshold QA or the saved amount of the application key is greater than the threshold GA; 11. The quantum cryptography communication system according to claim 5, 9, or 10.

16. the QKDN manager determines the encryption method of the encryption process using the quantum cryptography key to be a first encryption method when the saved amount of the quantum cryptography key is equal to or less than a threshold QA and the saved amount of the application key is equal to or less than a threshold GA, and determines the encryption method of the encryption process using the quantum cryptography key to be a second encryption method having a faster consumption speed of the quantum cryptography key than the first encryption method when the saved amount of the quantum cryptography key exceeds a threshold QB (QB>QA) and the saved amount of the application key exceeds a threshold GB (GB>GA), and sets the encryption method of the encryption process using the quantum cryptography key to the second encryption method again until the saved amount of the quantum cryptography key is equal to or less than the threshold QA and the saved amount of the application key is equal to or less than GA; 11. The quantum cryptography communication system according to claim 5, 9, or 10.

17. the first encryption method is AES (Advanced Encryption Standard), The second encryption method is OTP (One Time Pad).

17. A quantum cryptography communication system according to any one of claims 11 to 16.

18. When the encryption method of the encryption process using the quantum encryption key is set to AES, the QKDN manager reduces the frequency of updating the quantum encryption key used for encryption by AES as the saved amount of the quantum encryption key decreases. The quantum cryptography communication system according to claim 17.

19. A receiver that receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by quantum key distribution (QKD); A hardware security module (HSM), The HSM is a storage unit that stores a first device key and a second device key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a second encryption unit that encrypts the application key stored in the device itself using the second encryption key; A key management device comprising:

20. A receiver that receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by quantum key distribution (QKD); A hardware security module (HSM), The HSM is a storage unit that stores a first device key and a third device key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a third encryption unit that encrypts the application key, which is supplied to an encrypted application execution device that executes the encrypted application, with the third encryption key; A key management device comprising:

21. A receiver that receives an encrypted quantum encryption key from a first QKD device that shares a quantum encryption key with a second QKD device by QKD (Quantum Key Distribution); A hardware security module (HSM), The HSM is a storage unit that stores a first encryption key and a decryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a decryption unit that decrypts the encrypted quantum encryption key using the decryption key; A key management device comprising:

22. A receiver that receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by quantum key distribution (QKD); A hardware security module (HSM), The HSM is a storage unit that stores a first encryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a relay unit that further encrypts, by the quantum encryption key, an application key encrypted by the first encryption key, and transmits, to the second key management device, the application key that has been doubly encrypted by the first encryption key and the quantum encryption key; A key management device comprising:

23. A receiver that receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by quantum key distribution (QKD); HSM (Hardware Security Module), a setting unit that sets an encryption method determined by a QKDN (Quantum Key Distribution Network) manager as an encryption method for encryption processing using the quantum encryption key; The HSM is a storage unit that stores a first encryption key; a generation unit for generating an application key used in an encryption process by an encryption application; a first encryption unit that encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; The encryption method determined by the QKDN manager is determined based on at least one of the amount of the application key stored in the device itself and the amount of the quantum encryption key stored in the device itself. Key management device.

24. A receiving unit receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by QKD (Quantum Key Distribution); A storage unit of an HSM (Hardware Security Module) stores a first encryption key and a second encryption key; A generation unit of the HSM generates an application key used in encryption processing by an encryption application; A step in which a first encryption unit of the HSM encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a second encryption unit of the HSM encrypting the application key stored in the HSM with the second encryption key; 16. A key management method comprising:

25. A receiving unit receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by QKD (Quantum Key Distribution); a storage unit of an HSM (Hardware Security Module) storing a first encryption key and a third encryption key; A generation unit of the HSM generates an application key used in encryption processing by an encryption application; A step in which a first encryption unit of the HSM encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a third encryption unit of the HSM encrypting the application key, which is to be provided to an encrypted application execution device that executes the encrypted application, with the third encryption key; 16. A key management method comprising:

26. A receiving unit receives an encrypted quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by QKD (Quantum Key Distribution); A storage unit of an HSM (Hardware Security Module) stores a first encryption key and a decryption key; A generation unit of the HSM generates an application key used in encryption processing by an encryption application; A step in which a first encryption unit of the HSM encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; A decryption unit of the HSM decrypts the encrypted quantum encryption key using the decryption key; 16. A key management method comprising:

27. A receiving unit receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by QKD (Quantum Key Distribution); A storage unit of a hardware security module (HSM) stores a first encryption key; A generation unit of the HSM generates an application key used in encryption processing by an encryption application; A step in which a first encryption unit of the HSM encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; a relay unit further encrypting, by the quantum encryption key, the application key encrypted by the first encryption key, and transmitting the application key doubly encrypted by the first encryption key and the quantum encryption key to the second key management device; 16. A key management method comprising:

28. A receiving unit receives a quantum cryptography key from a first QKD device that shares a quantum cryptography key with a second QKD device by QKD (Quantum Key Distribution); A storage unit of a hardware security module (HSM) stores a first encryption key; A generation unit of the HSM generates an application key used in encryption processing by an encryption application; A step in which a first encryption unit of the HSM encrypts the application key transmitted to a second key management device connected to the second QKD device using the first encryption key; A quantum key distribution network (QKDN) manager determines an encryption method for encryption processing using the quantum encryption key based on at least one of a stored amount of the application key stored in the QKDN manager and a stored amount of the quantum encryption key stored in the QKDN manager; A setting unit sets the encryption method determined by the QKDN manager as the encryption method for encryption processing using the quantum encryption key; 16. A key management method comprising:

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