Relay-based quantum key distribution method and system

Abstract

The invention provides a relay-based quantum key distribution method and system, and the method comprises the steps: fixing one node in any two adjacent nodes through a selection function, and preferentially executing a key selection and use process; and then the other node in the two adjacent nodes correspondingly selects the shared quantum key to realize a relay process related to the two adjacent nodes, so that a key contention situation is avoided, and quantum key distribution between any two nodes is allowed to be realized simply and directly by means of the relay process. Therefore, the distribution efficiency of the quantum keys is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and more particularly to a method for distributing quantum keys implemented based on a relay process and a corresponding quantum key distribution system. Background Art

[0002] The key relay method was first proposed by Elliott of BBN. Its basic idea is to use the OTP algorithm to transfer keys between multiple relay nodes and finally reach the destination user.

[0003] Figure 1 Fig. shows a quantum key relay process in the prior art. Among them, based on the pairwise shared quantum keys K A1 , K 12 , K B2 between adjacent nodes, these shared quantum keys between nodes are used to perform an exclusive OR operation on the key K, and the key K is transmitted from node A to node D in an encrypted manner, thereby forming a shared key K between node A and node D.

[0004] In addition, the prior art has also proposed some other variant quantum key relay methods. For example Figure 2 shown, first use the corresponding shared quantum keys on the relay link nodes to perform an exclusive OR operation Then, the corresponding exclusive OR operation results of each node are all centralized to node D and then an exclusive OR operation is performed Thereby, a shared key K between node A and node D can also be formed. Of course, those skilled in the art can understand that it can also be all centralized to node A and then an exclusive OR operation is performed; or it can be centrally processed by an additional system and then notified to node A or node D as needed. The principle is similar.

[0005] However, there are some problems to be solved in the actual implementation of the current quantum key relay scheme. For example: If there are two key relay processes in opposite directions occurring simultaneously, there will be a contention problem for the use of the same segment of the key, because in the key relay process, each pair of keys can only be used once to ensure the security of the key. For example Figure 3 Fig. shows a key contention situation in a quantum key relay process. Among them, key relay process 1 and key relay process 2 will contend for the same pair of keys K 12 , resulting in the failure of the key relay process.

[0006] To solve such key contention problems, currently, before quantum key relay, one or some keys need to be negotiated to be used only in a single key relay direction. For example: key K 12-1 is only used for the leftward quantum key relay process, key K12-2 Only used for the right - hand quantum key relay process, etc. Specifically, the following solutions have been proposed in the prior art:

[0007] (1) The pre - negotiation method, that is: before the quantum key relay, the adjacent two nodes B and node C negotiate to determine the key K 12 for which key relay process.

[0008] (2) The two - way key pool method, that is: in advance in nodes B and C, the key K 12 is divided into a key pool K 12 left for the left - hand quantum relay process, and a key pool K 12 right for the right - hand quantum key relay process, and the two - way quantum key relay process uses its own key pool respectively.

[0009] Although the above - mentioned key contention solutions can solve the contention problem, in the actual process of solving the problem, the negotiation process is increased. It is necessary to lock the key of the single key pool for unidirectional use through the negotiation between two nodes, or expand the single key pool into a two - way key pool. Summary of the Invention

[0010] In view of the above - mentioned defects of the prior art, the present invention proposes a method for distributing quantum keys based on relay. Among them, by means of a selection function, a node is fixed in any two adjacent nodes to preferentially execute the key selection and use process, and then the other node among the two adjacent nodes correspondingly selects a shared quantum key to be used for realizing the relay process related to the two adjacent nodes, avoiding the occurrence of key contention situations, so that it is allowed to simply and directly realize the distribution of quantum keys between any two nodes by means of the relay process, thereby greatly improving the distribution efficiency of quantum keys.

[0011] Specifically, the first aspect of the present invention relates to a method for distributing quantum keys based on relay, which includes a relay path calculation step, a priority determination step, a key selection step, and a key distribution step;

[0012] The relay path calculation step is used to calculate the relay path between the first node and the second node, which includes the first node, the second node, and multiple relay nodes;

[0013] The priority determination step is used to, for any two adjacent nodes on the relay path, according to the output value of the selection function f(x, y), select one of them as the preferred selection node PR i for the two adjacent nodes, where the two input parameters of the selection function f(x, y) are respectively related to the two adjacent nodes, and the output value is related to one of the two input parameters;

[0014] The key selection step is used to, for any two adjacent nodes on the relay path, first select the shared quantum key K between the two adjacent nodes at the priority selection node PR i and then select the shared quantum key K at the other one of the two adjacent nodes i ; i ;

[0015] The key distribution step is used to select the shared quantum key between two adjacent nodes on the relay path as the key K; and, respectively starting from the two adjacent nodes where the key K is located, transmit the key K to the first node and the second node in an encrypted manner by means of the shared quantum key on the relay path, so as to distribute the key K between the first node and the second node.

[0016] Further, in the key distribution step, according to the first sub-relay path, the key K is relayed and transmitted to the first node in an encrypted manner by means of the shared quantum key, where the first sub-relay path includes the first node, the node close to the first node where the key K is located, and the relay nodes between the two on the relay path; and / or, according to the second sub-relay path, the key K is relayed and transmitted to the second node in an encrypted manner by means of the shared quantum key, where the second sub-relay path includes the second node, the node close to the second node where the key K is located, and the relay nodes between the two on the relay path.

[0017] Further, the selection function f(x, y) is set such that for two input parameters, its output value is fixed to one of the two input parameters.

[0018] Preferably, the selection function f(x, y) is the function max(x, y) or min(x, y).

[0019] Further, the priority selection node PR i is selected to be associated with the output value of the selection function f(x, y).

[0020] Further, the relayed transmission of the key K is realized in an encrypted manner by means of the exclusive OR operation of the shared quantum key.

[0021] Further, in the key distribution step, the starting node on the first sub-relay path generates an exclusive OR operation result by performing an exclusive OR operation on its shared quantum key with respect to the next node and the key K. The relay nodes on the first sub-relay path generate an exclusive OR operation result by performing an exclusive OR operation on their shared quantum key with respect to the previous node and their shared quantum key with respect to the next node, and transmit the exclusive OR operation result to the first node. The first node performs an exclusive OR operation on its shared quantum key with respect to the previous node and the received exclusive OR operation result to obtain the key K; and / or, the starting node on the second sub-relay path generates an exclusive OR operation result by performing an exclusive OR operation on its shared quantum key with respect to the next node and the key K. The relay nodes on the second sub-relay path generate an exclusive OR operation result by performing an exclusive OR operation on their shared quantum key with respect to the previous node and their shared quantum key with respect to the next node, and transmit the exclusive OR operation result to the second node. The second node performs an exclusive OR operation on its shared quantum key with respect to the previous node and the received exclusive OR operation result to obtain the key K.

[0022] Optionally, the quantum key distribution method of the present invention can be a centralized quantum key relay or a multi-path quantum key relay.

[0023] Optionally, the quantum key distribution method of the present invention can be a unidirectional quantum key relay or a bidirectional quantum key relay.

[0024] The second aspect of the present invention relates to a quantum key distribution system, which is configured to realize the distribution of quantum keys between the first and second nodes by means of the quantum key distribution method as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematically shows a quantum key relay process in the prior art;

[0026] Figure 2 Schematically shows another quantum key relay process in the prior art;

[0027] Figure 3 Schematically shows a key contention situation in the quantum key relay process in the prior art;

[0028] Figure 4 Schematically shows an example of the quantum key relay method according to the present invention in a unidirectional relay process;

[0029] Figure 5 Schematically shows an example of the quantum key relay method according to the present invention in a bidirectional relay process;

[0030] Figure 6An example of a method for distributing quantum keys according to the present invention is schematically shown. Detailed implementation mode

[0031] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so as to fully convey the spirit of the present invention to those skilled in the art to which the present invention pertains. Therefore, the present invention is not limited to the embodiments disclosed herein.

[0032] The present invention discloses a quantum key relay method, which, by introducing certain strategies, enables any two adjacent nodes to first select a shared quantum key for the relay process at a fixed one of the two adjacent nodes during any quantum key relay process, and then the other of the two adjacent nodes correspondingly selects a shared quantum key to be used to implement the relay process related to the two adjacent nodes. Thus, the above-mentioned contention problem can be simply and effectively solved without the need for a prior negotiation process between adjacent nodes, thereby reducing the complexity of quantum key relay and improving its efficiency.

[0033] Specifically, the quantum key relay method of the present invention may include steps such as a relay path calculation step, a priority determination step, a key selection step, and a key relay step.

[0034] To implement the relay of quantum keys, first, it is necessary to calculate and determine a relay path for the key K from the starting node to the destination node with the help of the relay path calculation step. Usually, in addition to the starting node and the destination node, it will also include multiple relay nodes.

[0035] After determining the relay path, shared quantum keys can be selected at each node on the relay path as relay keys for encrypted relay transmission of quantum keys.

[0036] According to the present invention, to avoid contention problems during the selection of shared quantum keys, before selecting the shared quantum keys, the priority determination step will also be used to determine which one of the two adjacent nodes on the relay path will select the shared quantum key for the relay process first when selecting their shared quantum keys for the relay process. By fixing the selection order of the shared quantum keys between the two adjacent nodes, contention problems in, for example, a two-way quantum key relay process can be effectively solved.

[0037] Further, in the priority determination step of the present invention, by introducing a selection function f(x,y), it can be automatically realized that for any two adjacent nodes, one node (i.e., the preferred selection node) can always be fixed to preferentially select the shared quantum key, and after the preferred selection node has completed the selection of the shared quantum key, the other node among the two adjacent nodes can then correspondingly select the shared quantum key. This avoids the problem that in particular during the two-way key relay process, different nodes among two adjacent nodes simultaneously select the same quantum key for different relay directions.

[0038] Specifically, for any two adjacent nodes on the relay path, two parameters respectively related to these two adjacent nodes can be used as the input parameters of the selection function f(x,y), and a unique output value related to one of the two input parameters can be obtained, and based on this unique output value, it can be determined which one of the two nodes should be preferentially used (which will be referred to as the preferred selection node PR hereinafter) when selecting the shared quantum key for these two nodes i ) to perform the key selection task.

[0039] As a preferred example, the node associated with the output value of the selection function f(x,y) can be selected as the preferred selection node PR i .

[0040] As a preferred example, the selection function f(x,y) can be configured such that for two input parameters, its output value is fixed to one of the two input parameters. For example, the selection function f(x,y) can include but is not limited to functions such as max(x,y), min(x,y), etc.

[0041] Therefore, in one example, for adjacent nodes A and B, B and C, C and D on the relay path, with the help of this selection function, node A can be fixedly selected as the preferred selection node between node A and node B, that is, f(A,B) = A; node C can be fixedly selected as the preferred selection node between node B and node C, that is, f(B,C) = C; or, node C can be fixedly selected as the preferred selection node between node C and node D, that is, f(C,D) = C.

[0042] After determining the preferred selection node PR for the process of selecting the shared quantum key between any two adjacent nodes on the relay path by means of the priority determination step i , and determining the execution order of selecting the key to use, the key selection step can then be executed to select the shared quantum key for the current key relay process between all adjacent nodes on the relay path.

[0043] Specifically, in the key selection step, for all pairs of adjacent nodes on the relay path, the preferred selection node PR among the adjacent nodes can be selected firsti select a shared quantum key at this point, and then according to the preferred selection node PR i For the selected shared quantum key, select the corresponding shared quantum key at another node among the adjacent nodes.

[0044] As a preferred example, in the key selection step, all the preferred selection nodes PR on the relay path i have no order requirement in execution; correspondingly, after the preferred selection node PR i completes the selection of the shared quantum key, the other nodes on the relay path have no order requirement in execution.

[0045] After completing the selection of the shared quantum key (i.e., the relay key) between all adjacent nodes on the relay path by means of the key selection step, the key relay step can be executed. Using the selected shared quantum key, the key K is relayed from the source node to the destination node in an encrypted manner.

[0046] As an example, in this key relay step, at each node on the relay path, the exclusive OR operation can be performed using the selected shared quantum key (for example, the source node performs the exclusive OR operation on the key K and its shared quantum key for the next node, and the relay node performs the exclusive OR operation on its shared quantum key for the previous node and its shared quantum key for the next node), and then the exclusive OR operation results generated at each node are centrally transmitted to the destination node. The destination node performs the exclusive OR operation on the shared quantum key it selects for the previous node and all the exclusive OR operation results to finally obtain the plaintext of the key K, thereby realizing the relay of the key K from the source node to the destination node.

[0047] Furthermore, since all the preferred selection nodes PR on the relay path i have no order requirement in performing the key selection task, therefore, for the source node determined as the preferred selection node according to the selection function, and those (relay) nodes determined as the preferred selection node with respect to both its previous node and the next node, the key selection can be performed simultaneously to obtain all the shared quantum keys required for the relay process. For example: the source node as the preferred selection node can preferentially select the shared quantum key for its next node; the node determined as the preferred selection node with respect to both its previous node and the next node can preferentially select the shared quantum key for its previous node and the shared quantum key for its next node. Therefore, on the relay path, the above nodes as the preferred selection nodes can perform the exclusive OR operation using the shared quantum keys they preferentially select to generate the exclusive OR operation results, and at the same time transmit these exclusive OR operation results to the destination node, providing parallel transmission of the exclusive OR operation results, thereby greatly improving the efficiency of key relay.

[0048] To better understand the present invention, the following will describe each step of the quantum key relay method of the present invention by way of example in conjunction with Figure 4 and Figure 5 .

[0049] Figure 4 FIG. shows the application of the quantum key relay method according to the present invention in a one-way relay process, which is used to relay the key K from the starting node A to the destination node D.

[0050] As Figure 4 shown, first, the relay path of the key K can be determined by means of a relay path calculation step, which includes the starting node A, the destination node D, and the relay nodes B and C.

[0051] On this basis, in the priority determination step, the parameters related to the adjacent nodes A and B, nodes B and C, and nodes C and D in the relay path are used as the input parameters of the function f(x, y), and the corresponding output values f(A, B)=A, f(B, C)=C, f(C, D)=C are utilized. According to the correlation with the output values, the preferred selection node PR1 among the adjacent nodes A and B is determined to be node A, the preferred selection node PR2 among the adjacent nodes B and C is determined to be node C, and the preferred selection node PR3 among the adjacent nodes C and D is determined to be node C.

[0052] Therefore, in the key selection step, for the adjacent nodes A and B, the shared quantum key K for key relay can be first selected at node A A1 , and then the corresponding shared quantum key K can be selected at node B A1 ; for the adjacent nodes B and C, the shared quantum key K for key relay can be first selected at node C 12 , and then the corresponding shared quantum key K can be selected at node B 12 ; for the adjacent nodes C and D, the shared quantum key K for key relay can be first selected at node C B2 , and then the corresponding shared quantum key K can be selected at node D B2 .

[0053] Finally, in the key relay step, the exclusive OR operation can be first performed using the shared quantum keys at each node on the relay path. For example, the operation of is performed at node A, the operation of is performed at node B, and the operation of is performed at node C; then the corresponding exclusive OR operation results of each node are all concentrated at node D and then the exclusive OR operation is performed, thereby realizing the relay of the key K from the starting node A to the destination node D in an encrypted manner.

[0054] Among them, to further improve the efficiency of key relay, since the starting node A is determined as the preferred node, and the relay node C is determined as the preferred node relative to its previous node B and the next node D, therefore, the starting node A and the relay node C can simultaneously select all the shared quantum keys required for key relay. That is, the starting node A selects the shared quantum key K about its next node A1 , and at the same time, the relay node C selects the shared quantum key K about its previous node 12 and the shared quantum key K about its next node B2 . Correspondingly, the starting node A can perform an exclusive OR operation to generate an exclusive OR operation result and at the same time, the relay node C can perform an exclusive OR operation to generate an exclusive OR operation result At this time, the starting node A and the relay node C can simultaneously transmit the exclusive OR operation result and the exclusive OR operation result to the destination node D, and improve the efficiency of key relay by means of parallel transmission of data.

[0055] Figure 5 Illustrates the application of the quantum key relay method according to the present invention in the two-way relay process, which is used to implement the rightward relay process of the key K1 from the starting node A to the destination node D, and the leftward relay process of the key K2 from the starting node D to the destination node A.

[0056] As Figure 5 shown, it is also necessary to first determine the relay path of the key K1 through the relay path calculation step, which includes the starting node A, the destination node D, and the relay nodes B and C; and determine the relay path of the key K2, which includes the starting node D, the destination node A, and the relay nodes C and B.

[0057] On this basis, in the priority determination step, the parameters related to the adjacent nodes A and B, nodes B and C, and nodes C and D in the relay path can be used as the input parameters of the function f(x, y), and the corresponding output values f(A, B) = A, f(B, C) = C, f(C, D) = C are used. According to the correlation with the output value, the preferred node PR1 in the adjacent nodes A and B is determined as node A, the preferred node PR2 in the adjacent nodes B and C is determined as node C, and the preferred node PR3 in the adjacent nodes C and D is determined as node C.

[0058] Therefore, in the key selection step, for the rightward key relay process, for the adjacent nodes A and B, the shared quantum key K for key relay can be first selected at node A A1-1 , and then the corresponding shared quantum key K can be selected at node B A1-1; For adjacent nodes B and C, a shared quantum key K for key relay can be first selected at node C 12-1 , and then the corresponding shared quantum key K can be selected at node B 12-1 ; For adjacent nodes C and D, a shared quantum key K for key relay can be first selected at node C B2-1 , and then the corresponding shared quantum key K can be selected at node D B2-1 . For the leftward key relay process, for the same adjacent nodes A and B, a shared quantum key K for key relay can also be first selected at node A A1-2 , and then the corresponding shared quantum key K can be selected at node B A1-2 ; For the same adjacent nodes B and C, a shared quantum key K for key relay can also be first selected at node C 12-2 , and then the corresponding shared quantum key K can be selected at node B 12-2 ; For the same adjacent nodes C and D, a shared quantum key K for key relay can also be first selected at node C B2-2 , and then the corresponding shared quantum key K can be selected at node D B2-2 .

[0059] Thus, by means of the priority determination step implemented using the function f(x, y) proposed in the present invention, even in the two-way relay process, for the selection of the shared quantum key in the same pair of adjacent nodes, whether it is the leftward key relay or the rightward key relay, it can be ensured that the shared quantum key is first selected from the same node, avoiding the key contention problem that may occur when the shared quantum key selection operation is performed at both nodes of the adjacent nodes simultaneously, resulting in the possibility of selecting the same key for use in key relay processes in different directions (for example, selecting the same key from node C and node B for use in the leftward and rightward relay processes).

[0060] Finally, in the key relay step, for the rightward relay process, the exclusive OR operation can be first performed using the shared quantum keys at each node on the relay path. For example, the operation is performed at node A , the operation is performed at node B , the operation is performed at node C ; Then, the corresponding exclusive OR operation results of each node are all concentrated at node D and then the exclusive OR operation is performed so as to realize the relay of the key K1 from the starting node A to the destination node D in an encrypted manner. For the leftward relay process, the exclusive OR operation can also be first performed using the shared quantum keys at each node on the relay path. For example, the operation is performed at node D The operation is performed at node C The operation is performed at node B The operation; then the corresponding XOR operation results of each node Are all concentrated at node A and then an XOR operation is performed Thereby realizing the relay of the key K2 from the starting node D to the destination node A in an encrypted manner.

[0061] Similarly, in this two-way key relay process, the XOR operation results can be sent to the destination node simultaneously in parallel at least in the preferred nodes in a similar manner to improve the relay efficiency. For the sake of brevity, it will not be elaborated here.

[0062] Based on the above, in the quantum key relay method of the present invention, by means of the selection function, one node is fixed in any two adjacent nodes to preferentially execute the key selection and use process, and then the other node in the two adjacent nodes correspondingly selects the shared quantum key to be used for realizing the relay process related to the two adjacent nodes, without the need for prior negotiation, and the contention problem of key use in the case of two-way key relay can be solved by means of a simple implementation process, avoiding key locking or constructing a two-way key pool, and reducing the implementation complexity. In addition, in the quantum key relay method of the present invention, it also allows the parallel transmission of the XOR operation results of some nodes on the relay node to the destination node, thereby further improving the key relay efficiency.

[0063] On the basis of avoiding the key contention problem by means of the above relay scheme, the present invention further proposes a quantum key distribution method, which can directly realize the distribution of the shared quantum key between any two non-adjacent nodes without pre-generating the key K in the starting node by means of the relay process.

[0064] The quantum key distribution method of the present invention may include a relay path calculation step, a priority determination step, a key selection step and a key distribution step.

[0065] In this quantum key distribution method, the starting node and the destination node in the relay path calculation step are the first node and the second node for which the shared quantum key is to be distributed. In addition, the relay path calculation step, the priority determination step and the key selection step are basically the same as those described in the above quantum key relay method, so they will not be elaborated here.

[0066] According to the present invention, after the selection of the shared quantum keys is completed at all adjacent nodes on the relay path between the first and second nodes by means of the key selection step, in the key distribution step, a pair of shared quantum keys on the relay path can be selected as the key K, and by means of the other shared quantum keys on the relay path, they are respectively relayed and transmitted to the first and second nodes as the shared quantum keys between the first and second nodes, thereby realizing the distribution of the quantum key between the first and second nodes. Specifically, in this key distribution step, the shared quantum keys between any two adjacent nodes on the relay path between the first and second nodes can be selected, which can be denoted as the key K. Then, starting from the two selected adjacent nodes respectively, by means of the shared quantum keys at each node on this relay path, the key K is encrypted and relayed and transmitted to the first node and the second node on the relay path.

[0067] As an example, one of the two adjacent nodes selected in the key distribution step is the first (or second) node. Therefore, the first (or second) node can directly use its shared quantum key K with the adjacent node as the shared quantum key between the first and second nodes. At the same time, for the second (or first) node, the node adjacent to the first (or second) node can be used as the starting node, and by means of the shared quantum keys at each node on the second (or first) sub-relay path, the key K is encrypted and relayed and transmitted to the second (or first) node according to the second (or first) sub-relay path, where the second (or first) sub-relay path starts from the node adjacent to the first (or second) node, the second (or first) node is the destination node, and the nodes in between on the relay path are relay nodes.

[0068] In the encrypted relay transmission of the key K, the starting node on the second (or first) sub-relay path can perform an exclusive OR operation on the shared quantum key of its next node and the key K to generate an exclusive OR operation result. The relay node on the second (or first) sub-relay path performs an exclusive OR operation on its shared quantum key of the previous node and its shared quantum key of the next node to generate an exclusive OR operation result, and each node on the sub-relay path transmits its exclusive OR operation result to the second (or first) node. The second (or first) node then obtains the key K by performing an exclusive OR operation on its shared quantum key of the previous node and the received exclusive OR operation result.

[0069] As another example, where both of the two adjacent nodes selected in the key distribution step are relay nodes on the relay path, therefore, a first sub-relay path for the first node can be formed by using the first node, the node among the two selected adjacent nodes that is closer to the first node, and the relay nodes on the relay path between the two. A second sub-relay path for the second node can be formed by using the second node, the node among the two selected adjacent nodes that is closer to the second node, and the relay nodes on the relay path between the two.

[0070] Thus, the shared quantum key K between the two selected adjacent nodes is encrypted and relayed to the first node via the first sub-relay path, and the shared quantum key K between the two selected adjacent nodes is encrypted and relayed to the second node via the second sub-relay path.

[0071] Similarly, in the encrypted relay transmission of the key K, the starting node on the first sub-relay path can perform an exclusive OR operation on the shared quantum key of the next node (on the first sub-relay path) with the key K to generate an exclusive OR operation result. The relay nodes on the first sub-relay path perform an exclusive OR operation on the shared quantum key of the previous node with the shared quantum key of the next node to generate an exclusive OR operation result, and each node on the first sub-relay path transmits the exclusive OR operation result therein to the first node. The first node then performs an exclusive OR operation on the shared quantum key of the previous node with the received exclusive OR operation result to obtain the key K.

[0072] Similarly, in the encrypted relay transmission of the key K, the starting node on the second sub-relay path can perform an exclusive OR operation on the shared quantum key of the next node (on the second sub-relay path) with the key K to generate an exclusive OR operation result. The relay nodes on the second sub-relay path perform an exclusive OR operation on the shared quantum key of the previous node with the shared quantum key of the next node to generate an exclusive OR operation result, and each node on the second sub-relay path transmits the exclusive OR operation result therein to the second node. The second node then performs an exclusive OR operation on the shared quantum key of the previous node with the received exclusive OR operation result to obtain the key K.

[0073] Figure 6 Schematically shows an example of the method for distributing quantum keys according to the present invention.

[0074] As Figure 6 shown, when the shared quantum key K for between node A and node B is selected at the first node A by means of the relay path calculation step, the priority determination step, and the key selection step A1 , and the shared quantum key K for between node A and node B is selected at the relay node BA1 and the shared quantum key K between node B and node C 12 , at relay node C, the shared quantum key K between node B and node C is selected 12 and the shared quantum key K between node C and node D B2 , and at the second node B, the shared quantum key K between node C and node D is selected B2 When this occurs, in the key distribution step, a pair of shared quantum keys K of two adjacent nodes B and C on the relay path can be selected 12 as the key K to be distributed.

[0075] Furthermore, node B will serve as the starting node and relay-transmit the shared quantum key K 12 along the first sub-relay path to the first node A. As Figure 6 shown, this first sub-relay path includes node B and the first node A as the destination node; correspondingly, node B generates an exclusive OR operation result and transmits it to the first node A. The first node A uses its shared quantum key K with respect to node B A1 to perform an exclusive OR operation with the received exclusive OR operation result to generate the key K 12 .

[0076] Correspondingly, node C will serve as the starting node and relay-transmit the shared quantum key K 12 along the second sub-relay path to the second node D. As Figure 6 shown, this second sub-relay path includes node C and the second node D as the destination node; correspondingly, node C generates an exclusive OR operation result and transmits it to the second node D. The second node D uses its shared quantum key K with respect to node C B2 to perform an exclusive OR operation with the exclusive OR operation result to generate the key K 12 .

[0077] Thus, simply by means of the relay process, the distribution of the shared quantum key K 12 between the first and second nodes is directly achieved.

[0078] It can be seen from this that in the quantum key distribution method of the present invention, by means of a selection function, a node is fixed in any two adjacent nodes to preferentially execute the key selection and use process, and then the other node in the two adjacent nodes correspondingly selects a shared quantum key to be used for implementing the relay process related to the two adjacent nodes, avoiding the occurrence of key contention situations, so that it is allowed to simply and directly achieve the distribution of quantum keys between any two nodes by means of the relay process, thereby greatly improving the distribution efficiency of quantum keys.

[0079] Furthermore, the present invention also proposes a quantum key distribution system implemented by means of the above-mentioned quantum key distribution method.

[0080] Although the present invention has been described through specific embodiments in combination with the accompanying drawings, those skilled in the art can easily recognize that the above embodiments are merely exemplary and are used to illustrate the principles of the present invention, which will not limit the scope of the present invention. Those skilled in the art can make various combinations, modifications, and equivalent replacements to the above embodiments without departing from the spirit and scope of the present invention.

Claims

1. A relay-based quantum key distribution method, which includes a relay path calculation step, a priority determination step, a key selection step, and a key distribution step; The relay path calculation step is used to calculate the relay path between the first node and the second node, which includes the first node, the second node, and multiple relay nodes; The priority determination step is used to select, for any two adjacent nodes on the relay path, one of them as the preferred node PR for the two adjacent nodes according to the output value of the selection function f(x, y). i , where The two input parameters of the selection function f(x, y) are respectively related to the two adjacent nodes, and the output value is related to one of the two input parameters; The key selection step is used for any two adjacent nodes on the relay path. First, select the shared quantum key K between the two adjacent nodes at the preferred node PR i and then select the shared quantum key K at the other one of the two adjacent nodes i ; i ​ The key distribution step is used to select the shared quantum key between two adjacent nodes on the relay path as the key K; and, respectively taking the two adjacent nodes where the key K is located as the starting nodes, and transmitting the key K to the first node and the second node in an encrypted manner by means of the shared quantum key on the relay path, so as to distribute the key K between the first node and the second node.

2. The quantum key distribution method according to claim 1, wherein, In the key distribution step, according to the first sub-relay path, the key K is relayed and transmitted to the first node in an encrypted manner by means of the shared quantum key, where the first sub-relay path includes the first node, the node close to the first node where the key K is located, and the relay nodes between the two on the relay path; and / or, according to the second sub-relay path, the key K is relayed and transmitted to the second node in an encrypted manner by means of the shared quantum key, where the second sub-relay path includes the second node, the node close to the second node where the key K is located, and the relay nodes between the two on the relay path.

3. The quantum key distribution method according to claim 1, wherein, The selection function f(x, y) is set such that for the two input parameters, its output value is fixed to one of the two input parameters.

4. The quantum key distribution method according to claim 3, wherein, The selection function f(x, y) is the function max(x, y) or min(x, y).

5. The quantum key distribution method according to claim 1, wherein, The preferred selection node PR i is selected to be associated with the output value of the selection function f(x,y).

6. The quantum key distribution method according to claim 2, wherein The relay transmission of the key K is realized in an encrypted manner by means of the exclusive OR operation of the shared quantum key.

7. The quantum key distribution method according to claim 6, wherein, In the key distribution step: The starting node on the first sub-relay path performs an exclusive OR operation on its shared quantum key with respect to the next node and the key K to generate an exclusive OR operation result. The relay nodes on the first sub-relay path perform an exclusive OR operation on their shared quantum key with respect to the previous node and their shared quantum key with respect to the next node to generate an exclusive OR operation result, and transmit the exclusive OR operation result to the first node. The first node performs an exclusive OR operation on its shared quantum key with respect to the previous node and the received exclusive OR operation result to obtain the key K; and / or, The starting node on the second sub-relay path performs an exclusive OR operation on its shared quantum key with respect to the next node and the key K to generate an exclusive OR operation result. The relay nodes on the second sub-relay path perform an exclusive OR operation on their shared quantum key with respect to the previous node and their shared quantum key with respect to the next node to generate an exclusive OR operation result, and transmit the exclusive OR operation result to the second node. The second node performs an exclusive OR operation on its shared quantum key with respect to the previous node and the received exclusive OR operation result to obtain the key K.

8. The quantum key distribution method according to any one of claims 1-7, which is a centralized quantum key relay or a multi-path quantum key relay.

9. The quantum key distribution method according to any one of claims 1-7 is either unidirectional quantum key relaying or bidirectional quantum key relaying.

10. A quantum key distribution system is configured to implement the distribution of quantum keys between a first and a second node by means of the quantum key distribution method according to any one of claims 1-9.

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