Quantum key relay method and key distribution system

Abstract

The invention discloses a quantum key relay method and a corresponding key distribution system, and the method comprises the steps: fixing one node in any two adjacent nodes through a specific selection function, and preferentially executing a key selection and use process; and then the other node of the two adjacent nodes correspondingly selects the shared quantum key to realize a relay process related to the two adjacent nodes, so that negotiation in advance is not needed, and the contention problem of key use under the condition of bidirectional key relay is solved by means of a simple implementation process; and key locking or construction of a bidirectional key pool is avoided, so that the implementation complexity is reduced. In addition, parallel transmission of XOR operation results of part of nodes on the relay node to the destination node is also allowed, so that the key relay efficiency is further improved.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication technology, and more particularly to a method for relaying quantum keys and a corresponding 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, some other variant quantum key relay methods have also been proposed in the prior art. For example Figure 2 shown, first perform an exclusive OR operation using the corresponding shared quantum keys on the relay link nodes and then perform an exclusive OR operation on the corresponding exclusive OR operation results of each node after all are concentrated at node D. Thus, 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 concentrated at node A for exclusive OR operation; or 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 keys, because in the process of key relay, each pair of keys can only be used once to ensure the security of the keys. 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 and thus cause the key relay process to fail.

[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 K 12-2Only used for the rightward 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 the key pool K 12 left for the leftward quantum relay process, and the key pool K 12 right for the rightward quantum key relay process, and the two-way quantum key relay process uses its own key pool respectively.

[0009] Although the above 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 to be used unidirectionally through the negotiation between the two nodes, or expand the single key pool into a two-way key pool. Summary of the Invention

[0010] In view of the above defects of the prior art, the present invention proposes a quantum key relay method and a corresponding key distribution system. 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 another node in the two adjacent nodes correspondingly selects a shared quantum key to be used to implement the relay process related to the two adjacent nodes. It can solve the contention problem of key use in the case of two-way key relay without prior negotiation, avoid key locking or constructing a two-way key pool, and reduce the implementation complexity. In addition, in the quantum key relay method of the present invention, it is also allowed to parallelly transmit the exclusive OR operation results of some nodes on the relay node to the destination node, thereby further improving the efficiency of key relay.

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

[0012] The relay path calculation step is used to calculate the relay path for the key K;

[0013] The priority determination step is used to, for any two adjacent nodes on the relay path, select one 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;

[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 preferred selection node PR i as the relay key, and then select the shared quantum key K i as the relay key at the other one of the two adjacent nodes; i

[0015] The key relay step is used to, according to the relay path, implement the relay of the key K in an encrypted manner by using the shared quantum key K i

[0016] Furthermore, 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.

[0017] Preferably, the selection function f(x, y) is the function max(x, y) or min(x, y).

[0018] Furthermore, the preferred selection node PR i is selected to be associated with the output value of the selection function f(x, y).

[0019] Furthermore, by means of the exclusive OR operation of the shared quantum key K i the relay of the key K is implemented in an encrypted manner.

[0020] Furthermore, in the key relay step, the starting node on the relay path generates an exclusive OR operation result by performing an exclusive OR operation on the shared quantum key about the next node it selects and the key K, and the relay node generates an exclusive OR operation result by performing an exclusive OR operation on the shared quantum key about the previous node it selects and the shared quantum key about the next node it selects, and transmits the exclusive OR operation result to the destination node; and, the destination node performs an exclusive OR operation on the shared quantum key about the previous node it selects and the exclusive OR operation result to obtain the key K.

[0021] Furthermore, in the key relay step, the node that is a preferred selection node with respect to both its previous node and its next node on the relay path transmits the exclusive OR operation result it generates to the destination node in a parallel manner.

[0022] Optionally, the quantum key relay method of the present invention is used for centralized quantum key relay or multi-path quantum key relay.

[0023] Optionally, the quantum key relay method of the present invention is used for unidirectional quantum key relay or bidirectional quantum key relay.

[0024] ​​The second aspect of the present invention relates to a key distribution system, which is configured to relay the key K between the starting node and the destination node by means of the quantum key relay method as described above. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0028] Figure 4 FIG. 4 schematically shows an example of the quantum key relay method according to the present invention in a one-way relay process;

[0029] Figure 5 FIG. 5 schematically shows an example of the quantum key relay method according to the present invention in a two-way relay process. DETAILED DESCRIPTION OF THE INVENTION

[0030] 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 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.

[0031] 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 negotiation process in advance between adjacent nodes, thereby reducing the complexity of quantum key relay and improving its efficiency.

[0032] 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.

[0033] To implement the relay of the quantum key, first, it is necessary to calculate and determine the relay path for the key K from the starting node to the destination node by means of the relay path calculation step, which usually includes multiple relay nodes in addition to the starting node and the destination node.

[0034] After determining the relay path, a shared quantum key can be selected at each node on the relay path as the relay key for encrypted relay transmission of the quantum key.

[0035] According to the present invention, to avoid contention problems during the selection process of the shared quantum key, before selecting the shared quantum key, a priority determination step will also be used to determine which of any two adjacent nodes on the relay path will select the shared quantum key for the relay process first. By fixing the selection order of the shared quantum key between two adjacent nodes, contention problems in, for example, two-way quantum key relay processes can be effectively solved.

[0036] Furthermore, in the priority determination step of the present invention, by introducing a selection function f(x, y), it can be automatically ensured that for any two adjacent nodes, one node (i.e., the preferred selection node) is always fixed to select the shared quantum key first, and the other node among the two adjacent nodes will select the shared quantum key accordingly after the preferred selection node has completed the selection of the shared quantum key. This avoids the problem that different nodes among two adjacent nodes simultaneously select the same quantum key for different relay directions, especially in two-way key relay processes.

[0037] 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) to obtain a unique output value related to one of the two input parameters, and based on this unique output value, it is determined which of these two nodes (which will be referred to as the preferred selection node PR i ) will perform the key selection task.

[0038] 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 .

[0039] 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.

[0040] Thus, in one example, for adjacent nodes A and B, B and C, and C and D on the relay path, with the aid of this selection function, node A can be fixedly selected as the preferred node between node A and node B, i.e., f(A, B) = A; node C can be fixedly selected as the preferred node between node B and node C, i.e., f(B, C) = C; or, node C can be fixedly selected as the preferred node between node C and node D, i.e., f(C, D) = C.

[0041] In the step of determining the priority, a preferred node PR is determined for the process of selecting the shared quantum key between any two adjacent nodes on the relay path. i After determining the execution order of using the selected key, the key selection step can be executed to select the shared quantum key for the current key relay process between all adjacent nodes on the relay path.

[0042] Specifically, in the key selection step, for all pairs of adjacent nodes on the relay path, the shared quantum key can be first selected at the preferred node PR i among the adjacent nodes, and then, according to the shared quantum key selected by the preferred node PR i the corresponding shared quantum key is selected at the other node among the adjacent nodes.

[0043] As a preferred example, in the key selection step, there is no order requirement for the execution of all the preferred nodes PR i on the relay path; correspondingly, after the preferred node PR i completes the selection of the shared quantum key, there is no order requirement for the execution of the other nodes on the relay path.

[0044] After the key selection step is used to complete the selection of the shared quantum key (i.e., the relay key) between all adjacent nodes on the relay path, the key relay step can be executed to use the selected shared quantum key to realize the relay of the key K from the start node to the destination node in an encrypted manner.

[0045] 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 start node performs the exclusive OR operation on the key K and its shared quantum key with the next node, and the relay node performs the exclusive OR operation on its shared quantum key with the previous node and its shared quantum key with the next node), and then the results of the exclusive OR operations generated at each node are centrally transmitted to the destination node, where the destination node performs the exclusive OR operation on the shared quantum key it selects with the previous node and all the results of the exclusive OR operations, and finally obtains the plaintext of the key K, thus realizing the relay of the key K from the start node to the destination node.

[0046] Further, since there is no order requirement for all the preferred nodes PR on the relay path i when performing the key selection task, therefore, for the starting node determined as a preferred node according to the selection function, and those (relay) nodes determined as preferred nodes with respect to both its previous node and next node, key selection can be performed simultaneously to obtain all the shared quantum keys required for the relay process. For example: the starting node as a preferred node can preferentially select and obtain the shared quantum key regarding its next node; the node determined as a preferred node with respect to both its previous node and next node can preferentially select and obtain the shared quantum key regarding its previous node and the shared quantum key regarding its next node. Therefore, on the relay path, the above nodes as preferred nodes can perform XOR operations on the shared quantum keys they preferentially select to generate XOR operation results, and simultaneously transmit these XOR operation results to the destination node, providing parallel transmission of the XOR operation results, thereby greatly improving the efficiency of key relay.

[0047] To better understand the present invention, the following will combine Figure 4 and Figure 5 to describe each step of the quantum key relay method of the present invention in an example manner.

[0048] 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.

[0049] As Figure 4 shown, first, the relay path of the key K can be determined by means of the relay path calculation step, which includes the starting node A, the destination node D, and the relay nodes B and C.

[0050] 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) respectively. Using the corresponding output values f(A, B) = A, f(B, C) = C, f(C, D) = C, according to the correlation with the output values, 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.

[0051] 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 adjacent nodes B and C, a 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 adjacent nodes C and D, a 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 .

[0052] 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 is performed at node A , the operation is performed at node B , and the operation is performed at node C ; Then, the corresponding exclusive OR operation results of each node are all centralized 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.

[0053] Among them, to further improve the key relay efficiency, since the starting node A is determined as the preferred node, and the relay node C is determined as the preferred node with respect to both its previous node B and its 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 A1 regarding its next node, and at the same time, the relay node C selects the shared quantum key K 12 regarding its previous node and the shared quantum key K B2 regarding its next node. Correspondingly, the starting node A can perform the exclusive OR operation to generate the exclusive OR operation result while the relay node C can perform the exclusive OR operation to generate the 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 the parallel transmission of data is used to improve the key relay efficiency.

[0054] Figure 5 shows 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.

[0055] As Figure 5As shown, it is also necessary to first determine the relay paths of the keys K1 and K2 by means of the relay path calculation steps. The relay path of key K1 includes the starting node A, the destination node D, and the relay nodes B and C; and the relay path of key K2 includes the starting node D, the destination node A, and the relay nodes C and B.

[0056] 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 utilized. According to the correlation with the output values, the preferred node PR1 among the adjacent nodes A and B is determined to be node A, the preferred node PR2 among the adjacent nodes B and C is determined to be node C, and the preferred node PR3 among the adjacent nodes C and D is determined to be node C.

[0057] 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 the adjacent nodes B and C, the 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 the adjacent nodes C and D, the 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, the 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, the 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, the 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 .

[0058] Thus, by means of the priority determination step implemented using the function f(x, y) proposed in the present invention, even in the process of two-way relaying, for the selection of the shared quantum key in the same pair of adjacent nodes, whether it is the leftward key relaying or the rightward key relaying, 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 two nodes of adjacent nodes simultaneously, resulting in the selection of the same key for use in the key relaying processes in different directions respectively (for example, selecting the same key from node C and node B for the leftward and rightward relaying processes).

[0059] Finally, in the key relaying step, for the rightward relaying process, the exclusive OR operation can be first performed using the shared quantum keys at each node on the relaying path. For example, at node A, perform the operation, at node B, perform the operation, and at node C, perform the operation; 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 relaying of the key K1 from the starting node A to the destination node D in an encrypted manner. For the leftward relaying process, similarly, the exclusive OR operation can be first performed using the shared quantum keys at each node on the relaying path. For example, at node D, perform the operation, at node C, perform the operation, and at node B, perform the operation; then, the corresponding exclusive OR operation results of each node are all concentrated at node A and then the exclusive OR operation is performed so as to realize the relaying of the key K2 from the starting node D to the destination node A in an encrypted manner.

[0060] Similarly, in this two-way key relaying process, the exclusive OR operation results can be sent to the destination node simultaneously in parallel at least among the priority selection nodes to improve the relaying efficiency. For the sake of brevity, it will not be elaborated here.

[0061] Based on the above, in the quantum key relay method of the present invention, by means of a selection function, a node is fixed to preferentially execute the key selection and use process among any two adjacent nodes, and then the other node among the two adjacent nodes correspondingly selects a shared quantum key to be used for implementing the relay process related to the two adjacent nodes, which can avoid prior negotiation and solve the contention problem of key use in the case of two-way key relay by means of a simple implementation process, avoid key locking or constructing a two-way key pool, and reduce 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 efficiency of key relay.

[0062] Furthermore, the present invention also proposes a key distribution system, which can implement the required quantum key relay process by means of the above quantum key relay method.

[0063] Although the present invention has been described above with reference to specific embodiments in conjunction with the accompanying drawings, it is easy for those skilled in the art to recognize that the above embodiments are merely exemplary and are used to illustrate the principle 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 quantum key relay method, which includes a relay path calculation step, a priority determination step, a key selection step, and a key relay step; The relay path calculation step is used to calculate a relay path for the key K; 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 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 as the relay key, and then select the shared quantum key K i as the relay key at another one of the two adjacent nodes; i ​ The key relay step is used to relay the key K in an encrypted manner according to the relay path by using the shared quantum key K i ​ 2. The quantum key relay 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.

3. The quantum key relay method according to claim 2, wherein The selection function f(x, y) is the function max(x, y) or min(x, y).

4. The quantum key relay method according to claim 1 or 2, wherein The preferred selection node PR i is selected to be associated with the output value of the selection function f(x, y).

5. The quantum key relay method according to claim 1, wherein, By means of the exclusive OR operation of the shared quantum key K i the relay of the key K is realized in an encrypted manner.

6. The quantum key relay method according to claim 5, wherein, In the key relay step, the starting node on the relay path uses the shared quantum key it selects for the next node to perform an exclusive OR operation with the key K to generate an exclusive OR operation result. The relay node uses the shared quantum key it selects for the previous node and the shared quantum key it selects for the next node to perform an exclusive OR operation to generate an exclusive OR operation result, and transmits the exclusive OR operation result to the destination node; and, the destination node performs an exclusive OR operation on the shared quantum key it selects for the previous node and the exclusive OR operation result to obtain the key K.

7. The quantum key relay method according to claim 6, wherein, In the key relay step, the node that is a preferred node with respect to both its previous node and the next node on the relay path transmits the exclusive OR operation result it generates to the destination node in a parallel manner.

8. The quantum key relay 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 relay method according to any one of claims 1-7, which is a unidirectional quantum key relay or a bidirectional quantum key relay.

10. A key distribution system, which is configured to realize the relay of the key K between the starting node and the destination node by means of the quantum key relay method according to any one of claims 1-9.

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