Quantum key delivery network, link setting method for key relay, data relay system, and data relay method

Abstract

A quantum key delivery network (NWQKD) comprises: a plurality of QKD nodes (10) that perform key relays by means of a quantum key delivery link (L) and a network thereof; and a QKDN controller (20) that, with the plurality of QKD nodes (10) divided into a plurality of independent colonies (C) so as to equalize the throughput in the key relay, sets a path from a colony (CS) including a QKD node (10S) at the start point of the key relay to a colony (CR) including a QKD node (10R) at the end point to be a path like the one in which one QKD node (10) may not supply the key to the plurality of paths via a colony (C) that is different for each independent key.

Description

Quantum key distribution network, key relay link setting method, data relay system, and data relay method

[0001] The present invention relates to a quantum key distribution network, a key relay link setting method, a data relay system, and a data relay method.

[0002] A quantum key distribution (QKD) network relays encryption keys at nodes (QKD nodes) that are "trusted stations," and by combining this with one-time pad (OTP) cryptography, it is possible to transmit data with information-theoretic security. For example, as shown in FIG. 8, a key sender node N １ From the key recipient node N ４ The encryption key K １ , node N ２ , N ３ is distributed by key relay using the relay node.

[0003] In the example of FIG. 8, the node N １ -N ２ In between is the key K １ is shared, and node N ２ -N ３ In between is the key K ２ is shared, and node N ３ -N ４ In between is the key K ３ is shared. Then, node N ２ is key K １ , K ２ The exclusive OR value of ３ and transmits it to node N ３ is key K １ , K ３ The exclusive OR value of ４ Node N ４ is the key K obtained via the communication line. １ , K ３ The value of the exclusive OR of the quantum key distribution node N ３ The key K shared with ３ By performing an exclusive OR with １ Get.

[0004] In this case, some trouble may cause the node to be compromised, and the key may be leaked. ３ is compromised, and the key K shared by quantum key distribution ２ , K ３ If the information is leaked, an eavesdropper E can obtain the key K transmitted via the communication line. １ , K ３ The exclusive OR value of １ , K ３ The key K can be easily obtained from the exclusive OR value of １ In order to minimize such risks, there is a danger that the security requirements for a node to be a "trusted station" will become infinitely high.

[0005] Therefore, a method is known in which multiple keys are distributed by key relay through multiple different routes, which allows key relay to be performed with a relaxed level of security required for a "trusted station." For example, as shown in FIG. １ From the key recipient node N ４ The encryption key (key K １ , K ２ multiple keys K for generating １ and Key K ２ In the example of FIG. 9, the key K １ is node N １ →N ２ →N ４ The key is relayed through the route, and the key K ２ is node N １ →N ３ →N ４ In this case, the key is relayed through the route ２ is compromised, and key K １ , K ３ Even if the key K is leaked, ２ is delivered via a different route, the eavesdropper E cannot obtain the encryption key (key K １ , K ２ It is not possible to obtain the exclusive OR of

[0006] In this method, multiple keys are distributed via different routes, so a relay node must not participate in key relays on different routes. Furthermore, the Dijkstra algorithm is usually used to find the route with the least key consumption (see Non-Patent Documents 1 and 2).

[0007] J. Jia, B. Dong, L. KangLe, H. 35, pp. 599-620, 2006.

[0008] Conventional methods for relaying multiple keys over multiple different routes use Dijkstra's algorithm to sequentially search for optimal routes under the condition that relay nodes do not participate in key relays over different routes. This has resulted in a problem in which the performance of the entire system is limited to the route with the worst throughput among the multiple routes searched. Therefore, an objective of the present invention is to provide a quantum key distribution network, a key relay link setting method, a data relay system, and a data relay method that can equalize the throughput efficiency across multiple routes in key relay over multiple routes in quantum key distribution.

[0009] In order to solve the above problem, the quantum key distribution network of the present invention is a quantum key distribution network that independently distributes multiple keys for generating a common encryption key by quantum key distribution, and includes quantum key distribution links and multiple nodes that perform key relay through the network, and a controller that manages the network, wherein the controller divides the multiple nodes into multiple independent node aggregates so as to equalize throughput in the key relay, and sets a route from a node aggregate including a start node of the key relay to a node aggregate including an end node so that each key passes through a different node aggregate, so that one node does not supply keys to multiple routes, and key relay is performed from the start node to the end node for each key via different routes set by the controller, and the start node and the end node generate the common encryption key by exclusive ORing or concatenating the multiple keys.

[0010] According to this configuration, the quantum key distribution network distributes multiple keys for generating encryption keys independently along different routes from a node assembly including a start node to a node assembly including a destination node in a node assembly divided so as to equalize throughput. Since the node assembly is divided so as to equalize throughput, the quantum key distribution network equalizes the quantum key distribution throughput for each key even if key relay is performed for multiple keys along different routes.

[0011] In addition, in order to solve the above-mentioned problems, the key relay link setting method of the present invention is a key relay link setting method for independently distributing multiple keys in a quantum key distribution network composed of quantum key distribution links and multiple nodes that perform key relay through the network, wherein a controller that manages the quantum key distribution network divides the multiple nodes into multiple independent node aggregates so as to equalize the throughput in the key relay, and sets a route from a node aggregate including a start node of the key relay to a node aggregate including an end node thereof so that the route passes through different node aggregates for each key, preventing one node from supplying keys to multiple routes.

[0012] According to this method, in a node aggregate divided so as to equalize throughput, key relay links can be set for multiple keys along different routes from a node aggregate including a start node to a node aggregate including an end node. As a result, the key relay link setting method can set independent key relay links for multiple keys so that the throughput is approximately equal.

[0013] and a controller that performs network management to set a route from a node aggregate including a start node of the key relay to a node aggregate including an end node of the key relay so that the route passes through different node aggregates for each of a plurality of keys for generating an encryption key, so that a single node does not supply keys to multiple routes. The data relay system relays data in a communication network and is supplied with an encryption key through a quantum key distribution network including: a quantum key distribution link and a plurality of nodes that relay keys through the network; and a controller that performs network management to set a route from a node aggregate including a start node of the key relay to a node aggregate including an end node of the key relay so that the route passes through different node aggregates for each of a plurality of keys for generating an encryption key, so that a single node does not supply keys to multiple routes. The data relay system is configured to relay data in a communication network and is supplied with the encryption key through a quantum key distribution network including: a transmitting device that corresponds to the start node and encrypts original data with the encryption key, distributes the data into a plurality of shares using a secret sharing scheme, and transmits the distributed data; a relay device that corresponds to nodes on different routes for the multiple keys and relays the plurality of shares; and a receiving device that corresponds to the end node and receives the plurality of shares, restores the data using a secret sharing scheme, and decrypts the original data using the encryption key.

[0014] With this configuration, the data relay system relays multiple keys for generating encryption keys in a quantum key distribution network via node aggregates that are divided so as to equalize the throughput, thereby equalizing the throughput of the entire key relay. Furthermore, the data relay system relays data using secret-shared shares corresponding to the key relay routes with equalized throughput, allowing the original data to be efficiently restored from each share.

[0015] In order to solve the above-mentioned problems, the present invention provides a data relay method for relaying data in a communication network, in which an encryption key is supplied through a quantum key distribution network including: a quantum key distribution link and a plurality of nodes that relay keys through the network; and a controller that performs network management to divide the plurality of nodes into a plurality of independent node aggregates so as to equalize throughput in the key relay, and to set a route from a node aggregate including a start node of the key relay to a node aggregate including an end node, such that the route passes through different node aggregates for each of a plurality of keys for generating an encryption key, so that a single node does not supply keys to multiple routes. The data relay method is characterized in that a transmitting device corresponding to the start node encrypts original data with the encryption key and distributes the plurality of shares by a secret sharing scheme, distributes the plurality of shares to each relay device corresponding to a node on a different route for the multiple keys, and relays the distributed plurality of shares through the communication network, and a receiving device corresponding to the end node receives the plurality of shares and restores them by a secret sharing scheme, and decrypts the original data with the encryption key.

[0016] According to this method, in a quantum key distribution network, the key relay is performed via a node group divided so as to equalize the throughput for multiple keys for generating encryption keys, thereby equalizing the throughput of the entire key relay. Furthermore, the data relay method relays shares of secretly shared data corresponding to key relay routes with equalized throughput, thereby enabling efficient restoration of original data from each share.

[0017] According to the present invention, in key relay of multiple keys on different routes in quantum key distribution, it is possible to equalize the throughput efficiency across the multiple routes.

[0018] FIG. 1 is a configuration diagram showing the overall configuration of a quantum key distribution network according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a colony (node ​​aggregate). FIG. 3 is an explanatory diagram for explaining an example of key relay. FIG. 4 is an explanatory diagram for explaining key relay via a colony. FIG. 5 is a sequence diagram showing the operation of key relaying a plurality of keys in the quantum key distribution network according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram for explaining the process of relaying data in a distributed manner in the data relay system of FIG. 6. FIG. 7 is an explanatory diagram for explaining key relay in conventional quantum key distribution. FIG. 8 is an explanatory diagram for explaining key relay for transmitting a plurality of keys via different routes in conventional quantum key distribution.

[0019] [Configuration of Quantum Key Distribution Network] First, referring to FIG. 1, a quantum key distribution network (QKDN) NW according to a first embodiment of the present invention will be described. ＱＫＤ The configuration of the quantum key distribution network NW will be explained. ＱＫＤ Here, the quantum key distribution network NW ＱＫＤ The encryption key (key K) is supplied from the user network NW Ｕ A transmitter 1 above communicates with a receiver 2 in a secret manner.

[0020] The transmitting device 1 is connected to a quantum key distribution network NW ＱＫＤ (Here, QKD node 10 Ｓ The data is encrypted (one-time pad encryption) using an encryption key (key K) supplied from the encryption device 1 and transmitted to the receiving device 2 via secret communication.

[0021] The receiving device 2 transmits the encrypted data received from the transmitting device 1 to the quantum key distribution network NW ＱＫＤ (Here, QKD node 10 Ｒ The common encryption key (key K) supplied to the transmitter 1 and the receiver 2 is transmitted through the quantum key distribution network NW ＱＫＤ QKD node 10 Ｓ to QKD node 10 ＲThe key is delivered to the corresponding QKD node 10 (10 Ｓ , 10 Ｒ ) may be integrated into the device.

[0022] Quantum key distribution network NW ＱＫＤ The quantum key distribution network NW ＱＫＤ The system comprises a quantum key distribution link (QKD link) L and a plurality of QKD nodes 10 that share keys in the network, and a QKD controller 20 that manages the network and notifies the QKD nodes 10 of key relay route information.

[0023] [QKD Node] The QKD node (node) 10 shares a key of a random number sequence by quantum key distribution via a QKD link L. As shown in Figure 3, the QKD node 10 includes a key management device 11 and a quantum key distribution module (QKD module) 12.

[0024] The key management device 11 holds the keys generated by the QKD module 12 and supplies the keys to applications (such as the transmitting device 1 and the receiving device 2) as needed. The key management device 11 also executes key relay according to the routing information notified by the QKDN controller 20.

[0025] The QKD module 12 transmits and receives photon pulses to and from the QKD modules 12 of other QKD nodes 10 via an optical fiber QKD link L, and shares keys by extracting a secure, error-free random number sequence of a predetermined data length by key distillation. Note that quantum key distribution is a well-known technology, and therefore a detailed description thereof will be omitted here.

[0026] [QKDN Controller] The QKDN controller (controller) 20 controls the quantum key distribution network NW ＱＫＤThe QKDN controller 20 requests the QKD nodes 10 to generate a shared key via a communication line (not shown), and notifies them of routing information indicating the order of the nodes in the key relay.

[0027] The QKDN controller 20 sets a route from a colony C including the starting node (QKD node 10) of the key relay to a colony C including the ending node (QKD node 10) such that multiple keys pass through different colonies C.

[0028] (Colony) Now, referring to Fig. 2, the colony C will be described. The colony C is a group of multiple independent nodes obtained by dividing all the QKD nodes 10 so as to equalize the throughput in the key relay. Here, "independent" means that one colony C does not belong to multiple node groups.

[0029] Equalizing throughput means that predetermined criteria, such as geographical factors and key supply volume, are roughly equal. Here, the geographical factors are, for example, division criteria for dividing colonies C so that the distances between colonies C are roughly equal. This works to roughly equalize the respective path distances when key relay is performed for multiple keys via different routes. Furthermore, the key supply volume is a division criterion based on, for example, the number of QKD modules 12 that can supply keys belonging to a colony C. This works to reduce key generation delays on each route and to efficiently perform key relay when key relay is performed for multiple keys via different routes. The division criterion does not need to be a single criterion; multiple criteria may be combined using weights based on priority. Colonies C are defined in advance by dividing them according to such division criteria.

[0030] The inside of the colony C is a network in which QKD modules 12 are connected by QKD links L. The QKD nodes 10 that are the end points (edges) between the colonies C are determined in advance. For example, as shown in FIG. 2, the QKD nodes 10 at the east, west, north, and south end points within the colony C areＥ , 10 Ｗ , 10 Ｓ , 10 Ｎ are four endpoints connecting to other colonies. This number of endpoints is an example, and two, three, or five or more endpoints may be defined. Colony C performs key relay between the endpoints of other colonies, and within the colony, it performs key relay from the input endpoint to the output endpoint.

[0031] (Key Relay) Here, an example of a general key relay will be described with reference to FIG. 3. Here, the QKD node 10 Ａ to QKD node 10 Ｄ Until QKD node 10 Ｂ , 10 Ｃ as relay nodes, and one key K ＡＢ This will be explained using an example where the QKD node 10 relays the Ａ and 10 Ｂ QKD module 12 Ａ and 12 Ｂ１ Between ＡＢ QKD node 10 Ａ Key management device 11 Ａ QKD module 12 Ａ The key K generated by ＡＢ This key K is stored in a storage device (not shown). ＡＢ is supplied to an application (for example, the transmitting device 1 (FIG. 1)) as needed.

[0032] QKD node 10 Ｂ and 10 Ｃ QKD module 12 Ｂ２ and 12 Ｃ１ Between ＢＣ QKD node 10 Ｂ Key management device 11 Ｂ QKD module 12 Ｂ１ The key K generated by ＡＢ and QKD module 12 Ｂ２ The key K generated by ＢＣ The key management device 11 calculates the exclusive OR (XOR) with Ｂ is the calculation result (K ＡＢ (XOR)KＢＣ ) is notified as route information from the QKDN controller 20 to the link destination (QKD node 10 Ｃ ) via a communication line.

[0033] QKD node 10 Ｃ and 10 Ｄ QKD module 12 Ｃ２ and 12 Ｄ Between ＣＤ QKD node 10 Ｃ Key management device 11 Ｃ QKD module 12 Ｃ１ The key K generated by ＢＣ and QKD module 12 Ｃ２ The key K generated by ＣＤ The key management device 11 calculates the exclusive OR (XOR) with Ｃ Further, the calculation result (K ＢＣ (XOR)K ＣＤ ) and QKD node 10 Ｂ Key management device 11 Ｂ The calculation result (K ＡＢ (XOR)K ＢＣ ) and calculates the exclusive OR (XOR) with the key management device 11. Ｃ is the calculation result (K ＡＢ (XOR)K ＣＤ ) is notified as route information from the QKDN controller 20 to the link destination (QKD node 10 Ｄ ) via a communication line.

[0034] QKD node 10 Ｄ Key management device 11 Ｄ QKD node 10 Ｃ The calculation result (K ＡＢ (XOR)K ＣＤ ) and QKD module 12 Ｄ The key K generated by ＣＤ The key management device 11 calculates the exclusive OR (XOR) with Ｄ is the calculation result (K ＡＢ ) is stored in a storage device (not shown). ＡＢis supplied to an application (for example, the receiving device 2 (FIG. 1)) as needed. ＡＢ QKD node 10 Ａ to QKD node 10 Ｄ Until QKD node 10 Ｂ , 10 Ｃ The QKDN controller 20 will be described again with reference to FIG.

[0035] As a method for setting up a link for the key relay, the QKD controller 20 sets up the key relay illustrated in FIG. 3 as a link for the starting QKD node (here, the QKD node 10 Ｓ ) containing colony C Ｓ to the destination node (here, QKD node 10 Ｒ ) containing colony C Ｒ The route is set to pass through different colonies C for each of the multiple keys.

[0036] The multiple keys referred to here are keys (subkeys) for generating an encryption key that the QKD node 10 supplies to an application such as the transmitting device 1, and the original key can only be reproduced from all of the subkeys. For example, when generating a key K of a certain bit length at the starting node, three keys (subkeys) K of the same bit length as the key K are generated. １ , K ２ , K ３ In this case, the terminal node generates three keys K １ , K ２ , K ３ The key (encryption key) K can only be reproduced by obtaining the key K of a certain bit length and calculating the exclusive OR. For example, at the starting node, a key K of a certain bit length is divided into three keys (sub-keys) K of a shorter bit length than the key K. １ , K ２ , K ３ In this case, the terminal node generates three independent keys K １ , K ２ , K ３ The only way to reproduce the key (encryption key) K is to obtain and concatenate the above.

[0037] The QKDN controller 20 sets routes so that these multiple keys are relayed independently via different colonies C, and notifies the QKD node 10 of this route information. The QKDN controller 20 regards each colony C as a single node and sets different routes for each of the multiple keys, so that one QKD node 10 does not supply keys to multiple routes. At this time, each colony C can only participate in key relay for one route. Furthermore, each colony C is a one-input, one-output system that inputs and outputs only one key (subkey). Within a colony C, multiple key relays are performed by each QKD node 10.

[0038] When setting up a route between colonies C, the QKD controller 20 sets up a route that uses the least amount of keys based on the key supply amount for the entire colony C. The input / output endpoints of a colony C are, for example, the QKD nodes 10 that are closest to the other colonies C that are the destinations of the route.

[0039] These routes may be predetermined if the start and end points are known, or may be searched in real time by QKDN controller 20. This allows multiple keys to be relayed over multiple different routes, for example, as shown in Figure 4.

[0040] In the example of FIG. 4, the starting colony C Ｓ From the terminal colony C Ｒ Multiple keys K １ , K ２ , K ３ However, each has a different key relay route RR Ｋ１ , R.R. Ｋ２ , R.R. Ｋ３ The key will be relayed via the key relay route RR. Ｋ１ is key K １ Multiple colonies C relaying the key Ｋ１ The key relay route RR is composed of Ｋ２ is key K ２ Multiple colonies C relaying the key Ｋ２ The key relay route RR is composed of Ｋ３ is key K ３ Multiple colonies C relaying the key Ｋ３This allows the QKDN controller 20 to relay multiple keys through different key relay routes RR, ensuring information-theoretic security. Furthermore, since colony C is a node group divided to equalize throughput, the efficiency of key relay can be roughly equalized regardless of which key relay route RR is used.

[0041] [Operation of quantum key distribution network] Next, referring to FIG. 5 (and also referring to FIG. 1 and FIG. 3 as appropriate), the quantum key distribution network NW ＱＫＤ Here, the operation of key relaying a plurality of keys via a plurality of routes for generating an encryption key used when transmitting encrypted data from the transmitting device 1 to the receiving device 2 will be described.

[0042] In step S1, the QKDN controller 20 requests the multiple QKD modules 12 of the QKD node 10 to generate a key to be shared between the opposing QKD modules 12 via a QKD link L that has been connected in advance.

[0043] In step S2, the multiple QKD modules 12 of the QKD node 10 generate a shared key by transmitting and receiving photon pulses via the QKD link L and extracting a secure, error-free random number sequence of a predetermined data length by key distillation. At this time, the QKD node 10 generates multiple keys for each QKD link L according to the number of multiple QKD modules 12.

[0044] In step S3, the multiple QKD modules 12 of the QKD node 10 supply the multiple keys they have generated to the key management device 11. In step S4, the key management device 11 stores the keys supplied in step S3 in storage (not shown).

[0045] In step S5, the QKD controller 20 detects the originating QKD node 10 corresponding to the transmitting device 1. Ｓ Colony C containing Ｓ From the QKD node 10 at the end corresponding to the receiving device 2 Ｒ Colony C containing ＲIn step S7, the QKD node 10 stores the route information notified in step S6, via different colonies, so that one QKD node 10 does not supply keys to multiple routes. In step S6, the QKDN controller 20 notifies the key management device 11 of the QKD node 10 of the route information set in step S5. In step S7, the key management device 11 of the QKD node 10 stores the route information notified in step S6.

[0046] In step S8, the transmitting device 1 requests a key from the key management device 11 of the corresponding starting QKD node 10. Here, the transmitting device 1 requests three keys (sub-keys) K １ , K ２ , K ３ The key management device 11 is requested to provide the key K, which is the exclusive OR of the above.

[0047] In step S9, the receiving device 2 requests a key from the key management device 11 of the corresponding end point QKD node 10. Here, the receiving device 2, like the transmitting device 1, requests three keys (sub-keys) K １ , K ２ , K ３ In step S10, the key management device 11 combines the multiple keys stored in step S4. Here, in the example of FIG. 4, three keys K are combined. １ , K ２ , K ３ and generates an encryption key (key K) that is shared with the receiving device 2. In step S11, the key management device 11 supplies the synthesized encryption key (key K) to the transmitting device 1.

[0048] In step S12, the key management device 11 executes key relay for each of the keys used to generate the encryption key K in step S10, using different paths, in accordance with the path information stored in step S7. In the example of FIG. 4, the key management device 11 executes key relay for each of the keys K used to generate the encryption key K in step S10, using different paths. １ , K ２ , K ３ , respectively, by using different key relay routes RR Ｋ１ , R.R. Ｋ２ , R.R.Ｋ３ This allows the key management device 11 of the end point QKD node 10 corresponding to the receiving device 2 to obtain multiple keys via different key relay paths.

[0049] In step S13, the key management device 11 combines the multiple keys acquired in step S12. Here, in the example of FIG. 4, three keys K １ , K ２ , K ３ and generates an encryption key (key K) that is shared with the transmitting device 1. In step S14, the key management device 11 supplies the combined encryption key (key K) to the receiving device 2.

[0050] This allows the transmitter 1 and receiver 2 to transmit and receive encrypted data using a common encryption key and one-time pad encryption. At this time, multiple keys are relayed through predetermined routes so as to equalize the throughput in the key relay. Therefore, the quantum key distribution network NW ＱＫＤ In this case, a single key relay does not cause a large delay, and the encryption key to be used by the receiving device 2 can be efficiently supplied.

[0051] [Configuration of Data Relay System] Next, the configuration of a data relay system 100 according to the second embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 shows the quantum key distribution network NW ＱＫＤ FIG. 1 is a block diagram showing an example of a data relay system 100 configured as above. ＱＫＤ The configuration is the same as that explained in FIG. 1, so the explanation will be omitted.

[0052] Here, the data relay system 100 is a user network NW, which is an existing communication network (such as the Internet). Ｕ The data is distributed from the transmitter 1B to the receiver 2B by a secret sharing scheme, and the distributed shares are relayed via different routes via the relay device 3. The share routes from the transmitter 1B to the receiver 2B are connected to the quantum key distribution network NW ＱＫＤThe key relay route is the same as that in the previous example, and is managed collectively by the QKDN controller 20.

[0053] The transmitting device 1B is connected to the quantum key distribution network NW ＱＫＤ The transmitter 1B encrypts (using one-time pad encryption) original data using an encryption key (key K) supplied from the transmitter 1B, distributes the encrypted data into multiple data (shares) using a secret sharing scheme, and transmits each share to the receiver 2B via a different route. A common secret sharing scheme may be used. For example, the transmitter 1B uses a (k, n) threshold scheme as the secret sharing scheme, distributing the encrypted data into n shares so that the original data cannot be restored with k-1 shares. The colony C corresponding to the transmitter 1B performs key relay by routing multiple keys for generating encryption keys via different routes. The transmitter 1B generates the same number of shares from the encrypted data (encrypted original data) as the number of keys for generating the encryption keys.

[0054] The receiving device 2B receives the distributed shares via the relay device 3, restores the encrypted data using the secret sharing scheme, and transmits the data to the quantum key distribution network NW ＱＫＤ The encrypted data is decrypted using an encryption key (key K) supplied from the encryption key server 100, thereby recovering the original data.

[0055] The relay device 3 relays the distributed shares between the sending device 1B and the receiving device 2B. The relay device 3 may also serve as a shareholder that stores the received shares and distributes them upon request. The sending device 1B, the receiving device 2B, and the relay device 3 are each connected to the quantum key distribution network NW ＱＫＤ The transmitting device 1B, the relay device 3 and the receiving device 2B correspond to QKD nodes 10 belonging to different colonies C. It should be noted that the transmitting device 1B, the relay device 3 and the receiving device 2B may be integrated with the corresponding QKD nodes 10 as devices.

[0056] [Data Relay Method of Data Relay System] A data relay method of the data relay system 100 will be specifically described with reference to Fig. 7. Here, similar to the key relay route described in Fig. 4, Ｓ From the terminal colony CＲ Multiple keys K １ , K ２ , K ３ However, each has a different key relay route RR Ｋ１ , R.R. Ｋ２ , R.R. Ｋ３ The key is relayed via the key K. １ , K ２ , K ３ The key relay in is the same as the key relay described in FIG.

[0057] User network NW Ｕ Above is the starting colony C Ｓ The transmitter 1B is arranged corresponding to the QKD node (not shown) belonging to the terminal colony C Ｒ A receiving device 2B is arranged corresponding to a QKD node (not shown) belonging to the QKD node 2B.

[0058] In addition, relay device 3 relaying share s1 １ is key K １ Key relay route RR that relays the key Ｋ１ The relay device 3 is arranged corresponding to the QKD node (not shown) belonging to the colony C corresponding to the share s2. ２ is key K ２ Key relay route RR that relays the key Ｋ２ The relay device 3 is arranged corresponding to the QKD node (not shown) belonging to the colony C corresponding to the share s3. ３ is key K ３ Key relay route RR that relays the key Ｋ３ , and are arranged corresponding to the QKD nodes (not shown) belonging to the colony C corresponding to the colony C.

[0059] The transmitter 1B is connected to the starting colony C. Ｓ The transmission device 1B receives an encryption key (key K) from a QKD node belonging to the group 1B, and encrypts (one-time pad cipher) the original data d with the encryption key K. The transmission device 1B distributes the encrypted data encrypted with the encryption key K into three shares (shares s1 to s3) using a secret sharing scheme.

[0060] Then, the transmitting device 1B sets the key relay route RR Ｋ１ Key K １Colony C relays Ｋ１ Relay device 3 installed corresponding to １ The transmitter 1B relays the share s1 via the key relay route RR Ｋ２ Key K ２ Relay device 3 installed corresponding to the colony that relays ２ The transmitter 1B relays the share s2 via the key relay route RR Ｋ３ Key K ３ Relay device 3 installed corresponding to the colony that relays ３ The share s3 is relayed by

[0061] The receiving device 2B receives the relayed three shares (shares s1 to s3) and generates the original encrypted data using the secret sharing scheme. Ｒ By receiving an encryption key (key K) from a QKD node belonging to the quantum key distribution network NW, the data relay system 100 decrypts the encrypted data and generates restored data d' by restoring the original data d. This allows the data relay system 100 to distribute and transmit data using a secret sharing scheme while equalizing the throughput of multiple key relay routes. Since each share is relayed via a different route corresponding to the key relay route, data can be restored even if an incident occurs in a QKD node corresponding to a certain share. In this way, the data relay system 100 operates in a quantum key distribution network NW ＱＫＤ By using the key relay and secret sharing of data using one-time pad cryptography, it is possible to realize information-theoretically secure and highly efficient data relay.

[0062] As explained above, the quantum key distribution network NW ＱＫＤ By introducing the concept of colony into the quantum key distribution network (QKD), and by equalizing the throughput and key relay efficiency of each route, the present invention can equalize the throughput and key relay efficiency of the entire system. Furthermore, the present invention can lower the security requirements for a QKD node to be a "trusted station," and the quantum key distribution network (NW) ＱＫＤ This will accelerate the realization of key supply businesses using this technology.

[0063] N.W. ＱＫＤ Quantum key distribution network NW Ｕ REFERENCE SIGNS LIST User network (communication network) 1 Transmitter 2 Receiver 10 QKD node (node) 11 Key management device 12 QKD module 20 QKDN controller (controller) C Colony (node ​​collection) L QKD link (quantum key distribution link) RR Key relay path 100 Data relay system 1B Transmitter 2B Receiver 3 Relay devices s1, s2, s3 Share

Claims

1. A quantum key distribution network that distributes multiple keys for generating a common encryption key independently through quantum key distribution, comprising: a plurality of nodes that perform key relay through quantum key distribution links and the network; and a controller that manages the network, wherein the controller divides the multiple nodes into multiple independent node aggregates so as to equalize the throughput in the key relay, and sets a route from a node aggregate including a start node of the key relay to a node aggregate including an end node such that a single node does not supply keys to multiple routes via different node aggregates for each key, and performs key relay from the start node to the end node via different routes set by the controller for each key, and the start node and the end node generate the common encryption key by exclusive ORing or concatenating the multiple keys.

2. A method for setting up a key relay link in a quantum key distribution network consisting of quantum key distribution links and multiple nodes that perform key relay through the network, the method being characterized in that a controller that manages the quantum key distribution network divides the multiple nodes into multiple independent node aggregates so as to equalize the throughput in the key relay, and sets a route from a node aggregate including a start node of the key relay to a node aggregate including an end node thereof via different node aggregates for each key, so that one node does not supply keys to multiple routes.

3. A data relay system that relays data in a communication network and receives encryption keys through a quantum key distribution network including quantum key distribution links and a controller that divides the nodes into multiple independent node aggregates so as to equalize throughput in the key relay, and sets a route from a node aggregate including a start node of the key relay to a node aggregate including an end node via different node aggregates for each of multiple keys for generating an encryption key, so that a single node does not supply keys to multiple routes. The data relay system comprises: a transmitting device that corresponds to the start node and encrypts original data with the encryption key, distributes the data into multiple shares using a secret sharing scheme, and transmits the distributed data; a relay device that corresponds to nodes that serve as different routes for each of the multiple keys, and relays the multiple shares; and a receiving device that corresponds to the end node and receives the multiple shares, restores the data using a secret sharing scheme, and decrypts the original data with the encryption key.

4. A data relay method in a communication network in which data is relayed by receiving an encryption key through a quantum key distribution network including: a quantum key distribution link and a plurality of nodes that relay keys through the network; and a controller that performs network management to divide the plurality of nodes into a plurality of independent node aggregates so as to equalize the throughput in the key relay, and to set a route from a node aggregate including a start node of the key relay to a node aggregate including an end node via different node aggregates for each of a plurality of keys for generating an encryption key, such that a single node does not supply keys to multiple routes, wherein a transmitting device corresponding to the start node encrypts original data with the encryption key and distributes it into a plurality of shares by a secret sharing scheme, distributes the plurality of shares to each relay device corresponding to a node on a different route for each of the plurality of keys and relays the distributed shares through the communication network, and a receiving device corresponding to the end node receives the plurality of shares and restores them by a secret sharing scheme, and decrypts the original data with the encryption key.

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