Digital currency payment method and system based on quantum communication

Abstract

The present invention proposes a digital currency payment method and system based on quantum communication. By establishing a quantum communication link, confidential communication between the user terminal and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system is achieved; by designing an identity code authentication mechanism, the user terminal's identity authentication in the commercial bank digital currency system and anonymous transactions between the two parties to the transaction are achieved; by adding an anti-counterfeiting code to the digital currency, the security of the digital currency transmission and transaction process is achieved; and finally, quantum-resistant confidential communication is realized throughout the entire digital currency transaction process.

Description

Technical Field

[0001] The present invention relates to the field of digital currency, and in particular to a digital currency payment method based on quantum communication. Background Art

[0002] The central bank's digital currency has already begun small-scale internal testing in several regions across China. It's foreseeable that the development of digital currency will usher in a new round of financial revolution. Digital currency offers high portability and portability, as well as excellent traceability, effectively preventing financial illicit activities such as money laundering. It will also facilitate the implementation of monetary policy. The central bank can embed conditions for the currency's effectiveness into the digital currency, effectively ensuring that the digital currency flows to its intended target audience. However, digital currency relies heavily on cryptographic technology. Existing digital currency payment methods generally utilize cryptographic techniques such as digital certificate signatures, failing to integrate quantum communication technologies and therefore lacking resilience to quantum computing. With the development of quantum computing technology, current cryptographic systems will face significant instability, and digital currency payments will also face significant threats. Furthermore, when a user makes a payment from a payer to a payee, the payer needs to obtain the payee's account ID and then send a transaction instruction to the wallet server. This instruction must include the payer's and payee's account IDs, as well as the transaction amount. This exposes the true identities of both parties involved in the transaction, posing a risk of identity leakage. Summary of the Invention

[0003] Purpose of the invention: To overcome the shortcomings of the prior art, the present invention proposes a digital currency payment method and system based on quantum communication, which can achieve quantum-resistant computing throughout the entire digital currency transaction process while keeping user identity information confidential.

[0004] Summary of the invention: To achieve the above technical effects, the present invention proposes a digital currency payment method based on quantum communication, comprising the following steps:

[0005] (1) Establishing quantum communication links between the user terminals of both parties to the transaction and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system;

[0006] (2) Before the transaction, both parties register their identity information in the commercial bank digital currency system and obtain a unique identity code;

[0007] (3) During the transaction, both parties send their identity codes to the corresponding commercial bank digital currency system through their respective quantum communication links for identity authentication. After the identity authentication is passed, both parties establish a session with the corresponding commercial bank digital currency system. The commercial bank digital currency system uses the session key to encrypt the user's identity code as a call identifier.

[0008] (4) The payee encrypts his / her own identity code with the session key of the corresponding commercial bank digital currency system, and then sends the encrypted identity code and the bank information of his / her commercial bank digital currency system to the payer;

[0009] (5) The payer sends its own identity information, payment request and digital currency to the corresponding commercial bank digital currency system through the established session, and freezes the digital currency being traded; the payment request contains the payer's identity code encrypted with the payee's session key, the payee's identity code encrypted with the payee's session key, and the bank information of the commercial bank digital currency system to which the payee belongs; the digital currency includes a plaintext code and an anti-counterfeiting code, and the anti-counterfeiting code is obtained by encrypting the digital currency ownership information and the hash value of the digital currency plaintext code and ownership information using the anti-counterfeiting code key held by the central bank; the ownership information contains the identity information of the digital currency holder;

[0010] (6) The payer's commercial bank digital currency system verifies whether the digital currency is correct. After verification, the payer's identity information, payment request and digital currency are forwarded to the central bank digital currency system;

[0011] (7) The central bank’s digital currency system verifies the payer’s identity: decrypts the anti-counterfeiting code in the digital currency, verifies whether the identity information in the ownership information is consistent with the identity information of the payer received, then calculates the hash value of the plaintext part of the digital currency and verifies whether it is consistent with the hash value obtained after decryption; if they are consistent, the payer’s identity authentication is successful;

[0012] The central bank's digital currency system verifies the payee's identity: the central bank's digital currency system sends the payee's encrypted identity code to the payee's commercial bank digital currency system; after receiving the payee's encrypted identity code, the payee's commercial bank digital currency system matches the session identifier in the currently valid session. If the session identifier is consistent with the payee's encrypted identity code, the payee's identity code is confirmed and the payee's identity information is sent to the central bank's digital currency system via the quantum communication link;

[0013] After the central bank’s digital currency system authenticates the identities of the payer and payee, it responds to the payment request by generating digital currency for change for the payer and payment for the payee, which are then sent to the commercial bank digital currency systems of both parties.

[0014] (8) The commercial bank digital currency systems of both parties to the transaction verify the digital currency issued by the central bank digital currency system and send it to the corresponding transaction parties;

[0015] (9) Both parties to the transaction store the new digital currency, and the payer destroys the frozen original digital currency.

[0016] The present invention realizes anti-quantum computing in the digital currency transmission process by establishing quantum communication links between the user end and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system; in addition, the present invention designs an identity code authentication mechanism suitable for quantum communication links to replace the conventional digital certificate signature mechanism, and adds an anti-counterfeiting code based on quantum key encryption to the digital currency; through the above design, the present invention realizes anti-quantum computing in the entire process of digital currency transactions.

[0017] Several optional methods are also provided below, but they are not intended to be additional limitations on the above-mentioned overall solution. They are merely further supplements or optimizations. Under the premise that there are no technical or logical contradictions, each optional method can be combined separately for the above-mentioned overall solution, or multiple optional methods can be combined.

[0018] Optionally, the method further includes the following steps: after the transaction is completed, the payer and the payee respectively feedback the transaction completion information to the corresponding commercial bank digital currency system, and after the commercial bank digital currency system receives the transaction completion information, it saves the transaction record.

[0019] Optionally, in addition to anti-counterfeiting, the digital currency also includes a currency value code, a bank code, an ownership code and a supplementary code. The currency value code is used to indicate the value of the digital currency, the bank code indicates the bank information of the digital currency, the ownership code indicates the account information of the user end that owns the digital currency, and the supplementary code is encoded by the central bank's digital currency system according to demand and is used to expand the information carried by the digital currency.

[0020] Optionally, both the commercial bank digital currency system and the central bank digital currency system are equipped with QKD devices, and both parties conduct key negotiation through their respective QKD devices to achieve confidential communication.

[0021] Optionally, a plurality of relay nodes are further provided between the commercial bank digital currency system and the central bank digital currency system; the commercial bank digital currency system and the central bank digital currency system communicate confidentially in the following manner:

[0022] Take the commercial bank digital currency system / central bank digital currency system as the starting node and the central bank digital currency system / commercial bank digital currency system as the target node; divide the n relay nodes between the starting node and the target node into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay node of this relay node is regarded as an even node, and so on, until all relay nodes are divided; configure each relay node with its quantum key and the adjacent node; before the starting node sends data T to the target node, each odd node XORs the quantum key between itself and the two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and the two adjacent nodes and passes it to the target node; after receiving the key data transmitted by all odd nodes, the starting node uses its own quantum key to XOR the data T to be sent, and then XORs the calculation result with all the received key data to obtain encrypted data, and finally sends the encrypted data to the target node through classical communication; after receiving the key data transmitted by all even nodes, the target node uses its own quantum key to XOR all the received key data to obtain a decryption key, and uses the decryption key to decrypt the encrypted data from the starting node.

[0023] Optionally, the user terminal is configured with a QKD device, and performs key negotiation with the corresponding commercial bank digital currency system through their respective QKD devices to obtain a shared quantum key.

[0024] Optionally, on the basis of configuring the QKD device on the user terminal, a number of relay nodes are further provided between the user terminal and the corresponding commercial bank digital currency system, and the user terminal and the corresponding commercial bank digital currency system communicate confidentially in the following manner:

[0025] The user end / commercial bank digital currency system is the starting node, and the commercial bank digital currency system / user end is the target node;

[0026] The n relay nodes between the starting node and the target node are divided into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay nodes of this relay node are regarded as even nodes, and so on, until all relay nodes are divided; each relay node is configured with the quantum key of its adjacent nodes;

[0027] Before the starting node sends data T to the target node, each odd node XORs the quantum key between itself and the two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and the two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node uses its own quantum key to first XOR the data T to be sent, then XORs the calculation result with all the received key data to obtain the encrypted data, and finally sends the encrypted data to the target node through classical communication. After receiving the key data transmitted by all even nodes, the target node uses its own quantum key to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node.

[0028] Optionally, the user terminal does not configure the QKD setting, but instead issues a symmetric key in advance with the corresponding commercial bank digital currency system through a trusted third-party key issuance center, and then the two parties achieve confidential communication based on the shared symmetric key.

[0029] Optionally, under the premise that the user terminal is not configured with QKD settings, multiple relay nodes are set between the user terminal and the corresponding commercial bank digital currency system; the user terminal and the corresponding commercial bank digital currency system use the following method to perform confidential communication:

[0030] When the user sends a message, it encrypts the message T to be sent using the quantum key K shared in advance with the quantum key management center, and then transmits the encrypted message to the commercial bank digital currency system through the classical channel;

[0031] Taking the quantum key management center as the starting node and the commercial bank digital currency system as the target node, the n relay nodes between the starting node and the target node are divided into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay node of this relay node is regarded as an even node, and so on, until all relay nodes are divided; each relay node is configured with the quantum key of the relay node and the adjacent nodes;

[0032] Each odd node XORs the quantum key between itself and its two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and its two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node XORs all the received key data with its own quantum key and the quantum key of the adjacent relay node to obtain the encryption key. It then uses the encryption key to encrypt the shared key K between itself and the user end, and then sends the encrypted data to the target node via classical communication.

[0033] After receiving the key data transmitted by all even nodes, the target node uses its own quantum key and the quantum key of the adjacent relay node to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node to obtain the key K;

[0034] The target node negotiates a quantum key K′ with the commercial bank digital currency system, conducts confidential communication based on the negotiated quantum key K′, and transmits the key K to the commercial bank digital currency system. The commercial bank digital currency system uses the key K to decrypt the encrypted data sent by the user end and obtains T.

[0035] When the commercial bank digital currency system sends a message to the user end, the above steps are followed.

[0036] The present invention also proposes a digital currency payment system based on quantum communication, including: a user terminal, a commercial bank digital currency system, and a central bank digital currency system. The user terminal, the commercial bank digital currency system, and the central bank digital currency system perform digital currency payments according to the described method.

[0037] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0038] 1. In this application, confidential information is transmitted between the user terminal and the commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system through quantum communication links, realizing quantum computing-resistant transaction information transmission; the present invention also designs an identity code authentication mechanism, enabling the client to perform identity authentication and anonymous transactions with the commercial bank digital currency system through a quantum communication link; in addition, this application adds an anti-counterfeiting code to the digital currency and sets up a digital currency verification link to further ensure the independence, integrity and security of the digital currency.

[0039] 2. This application also designs a key agreement mechanism suitable for quantum communication links with relays, which can effectively reduce the security requirements for relay nodes in quantum communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flowchart of the method when the user terminal belongs to the same commercial bank digital currency system;

[0041] Figure 2 A flowchart of the method when the user terminal belongs to different commercial bank digital currency systems;

[0042] Figure 3 A system structure diagram when the user terminal belongs to the same commercial bank digital currency system;

[0043] Figure 4This is a system structure diagram when the user end belongs to the digital currency system of different commercial banks. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that the present invention may be implemented in various forms, and the following exemplary and non-limiting embodiments shown in the drawings and described below are not intended to limit the present invention to the specific embodiments described.

[0045] It should be understood that, where technically feasible, the technical features listed above for different embodiments may be combined with each other to form additional embodiments within the scope of the present invention. In addition, the specific examples and embodiments described in the present invention are non-limiting, and the structures, steps, and sequences described above may be modified accordingly without departing from the scope of protection of the present invention.

[0046] This invention aims to propose a digital currency payment solution that is quantum-resistant throughout the entire digital currency transaction process. To this end, the invention proposes a digital currency payment method based on quantum communication. The process of the method described in the invention is as follows:

[0047] (1) Establishing quantum communication links between the user terminals of both parties to the transaction and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system;

[0048] (2) Before the transaction, both parties register their identity information in the commercial bank digital currency system and obtain a unique identity code;

[0049] (3) During the transaction, both parties send their identity codes to the corresponding commercial bank digital currency system through their respective quantum communication links for identity authentication. After the identity authentication is passed, both parties establish a session with the corresponding commercial bank digital currency system. The commercial bank digital currency system uses the session key to encrypt the user's identity code as a call identifier.

[0050] (4) The payee encrypts his / her own identity code with the session key of the corresponding commercial bank digital currency system, and then sends the encrypted identity code and the bank information of his / her commercial bank digital currency system to the payer;

[0051] (5) The payer sends its own identity information, payment request and digital currency to the corresponding commercial bank digital currency system through the established session, and freezes the digital currency being traded; the payment request contains the payer's identity code encrypted with the payee's session key, the payee's identity code encrypted with the payee's session key, and the bank information of the commercial bank digital currency system to which the payee belongs; the digital currency includes a plaintext code and an anti-counterfeiting code, and the anti-counterfeiting code is obtained by encrypting the digital currency ownership information and the hash value of the digital currency plaintext code and ownership information using the anti-counterfeiting code key held by the central bank; the ownership information contains the identity information of the digital currency holder;

[0052] (6) The payer's commercial bank digital currency system verifies whether the digital currency is correct. After verification, the payer's identity information, payment request and digital currency are forwarded to the central bank digital currency system;

[0053] (7) The central bank’s digital currency system verifies the payer’s identity: decrypts the anti-counterfeiting code in the digital currency, verifies whether the identity information in the ownership information is consistent with the identity information of the payer received, then calculates the hash value of the plaintext part of the digital currency and verifies whether it is consistent with the hash value obtained after decryption; if they are consistent, the payer’s identity authentication is successful;

[0054] The central bank's digital currency system verifies the payee's identity: the central bank's digital currency system sends the payee's encrypted identity code to the payee's commercial bank digital currency system; after receiving the payee's encrypted identity code, the payee's commercial bank digital currency system matches the session identifier in the currently valid session. If the session identifier is consistent with the payee's encrypted identity code, the payee's identity code is confirmed and the payee's identity information is sent to the central bank's digital currency system via the quantum communication link;

[0055] After the central bank’s digital currency system authenticates the identities of the payer and payee, it responds to the payment request by generating digital currency for change for the payer and payment for the payee, which are then sent to the commercial bank digital currency systems of both parties.

[0056] (8) The commercial bank digital currency systems of both parties to the transaction verify the digital currency issued by the central bank digital currency system and send it to the corresponding transaction parties;

[0057] (9) Both parties to the transaction store the new digital currency, and the payer destroys the frozen original digital currency.

[0058] The principle of the above method is:

[0059] By establishing quantum communication links between the user end and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system, the digital currency transmission process is made quantum computing-resistant. In addition, the present invention designs an identity code authentication mechanism suitable for quantum communication links to replace the conventional digital certificate signature mechanism, and adds an anti-counterfeiting code to the digital currency. The anti-counterfeiting code is generated by the central bank digital currency system when generating digital currency. Its essence is a set of encrypted information. The central bank digital currency system uses an anti-counterfeiting code encryption key based on quantum random numbers to encrypt the digital currency ownership information and the digital currency hash value. The digital currency hash value is the result of hashing the digital currency plaintext part + ownership information, which is used to verify whether the data structure has been tampered with. Different anti-counterfeiting code encryption keys are used at different times, and the central bank digital currency system maintains a list of anti-counterfeiting code encryption keys at different times. Through the above design, the present invention achieves quantum computing-resistant transaction content, anonymity of the identities of both parties to the transaction, and digital currency anti-counterfeiting throughout the entire digital currency transaction process.

[0060] To implement the above method, the present invention has multiple implementations, and the following embodiments are only preferred implementations of the method.

[0061] Example 1:

[0062] This embodiment includes multiple user terminals, a commercial bank digital currency system, and a central bank digital currency system. Both user terminals involved in a transaction belong to the same commercial bank digital currency system. In this embodiment, digital currency is represented as a binary string of digits, including a currency value code, an anti-counterfeiting code, a bank code, and a supplementary code. The currency value code indicates the amount of the digital currency; the anti-counterfeiting code is an encrypted string of information that can be decrypted to reveal information such as the rights holder. The decryption key for the anti-counterfeiting code is stored only in the central bank digital currency system; the supplementary code allows for further expansion of the digital currency, such as recording the generation time of the digital currency and setting the conditions for its effectiveness. In this embodiment, the user terminal is a communication terminal installed with digital currency wallet software.

[0063] The user end needs to communicate securely with the commercial bank digital currency system, and the commercial bank digital currency system also needs to communicate securely with the central bank digital currency system. Therefore, we first need to establish quantum communication links between the user end and the commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system. Then, we need to design an identity authentication mechanism suitable for transmission over quantum communication links to complete the identity authentication of the user end in the commercial bank digital currency system.

[0064] To achieve this, the user must first register with the commercial bank's digital currency system. The system then issues an identity code to the user, which serves as a mutual identity verification mechanism. Simultaneously, the user and the commercial bank's digital currency system negotiate a shared quantum key through quantum key distribution. Both parties securely store the identity code and the shared quantum key, which is used for secure communication between the two parties and can be periodically updated.

[0065] The process of the digital currency payment method based on quantum communication described in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0066] When a digital currency payment transaction between two users is required, for example, user A wants to pay digital currency from their account to user B, user A and the commercial bank's digital currency system must first authenticate each other. User A sends an identity code encrypted with the communication key over the corresponding quantum communication link to the commercial bank's digital currency system for authentication. A can then obtain B's encrypted identity code through various channels, including in-person QR code scanning, NFC communication, Bluetooth communication, infrared communication, email, mobile phone text message, phone call, and mail. Because A and B each encrypt the identity code using their own communication keys, A and B are unaware of each other's true identities. The encrypted identity code not only contains the encrypted user's identity information, but also contains information about the commercial bank to which the identity code belongs, allowing the commercial bank to verify whether the user belongs to the bank.

[0067] After both parties have confirmed their identities, User A needs to transmit the digital currency payment request and the digital currency string to be paid to the commercial bank's digital currency system using the shared quantum key encryption between the two systems. The payment request includes the identity codes of User A and B, each encrypted using their respective communication keys. At this point, the status of the digital currency to be paid in User A's account will be changed to temporarily unavailable, that is, frozen.

[0068] After decryption, the commercial bank digital currency system obtains the payment request and the digital currency string to be paid from user terminal A. After the commercial bank digital currency system decrypts the identity code in the payment request and authenticates it, it verifies whether the format of the plain code part of the digital currency sent by A is correct. It can also determine whether the payment instruction of user terminal A is legal. Then the commercial bank digital currency system sends the identity information, payment request and digital currency string to be paid from user terminal A to the central bank digital currency system through a dedicated quantum communication channel.

[0069] After receiving and decrypting the identity information, payment request, and digital currency string to be paid from the commercial bank's digital currency system, the central bank's digital currency system needs to verify the authenticity of the digital currency. This is primarily done by locating the corresponding anti-counterfeiting code encryption key from the digital currency's generation time within the digital currency's supplementary code. This key is then used to decrypt the digital currency's anti-counterfeiting code, verifying that the identity information in the digital currency's anti-counterfeiting code is consistent with the true identity of the digital currency's sender, and verifying the correctness of the digital currency's hash value. To confirm B's identity, the central bank's digital currency system identifies the commercial bank to which the encrypted identity code belongs based on the payee's encrypted identity code and transmits the encrypted identity code to the commercial bank via a dedicated quantum channel. The commercial bank then searches all current communication sessions for sessions matching the encrypted identity code. Specifically, it encrypts the identity number corresponding to the communication session using the communication keys of all communication sessions. If a communication session with an encrypted value equal to the encrypted identity code is found, the payee's identity code, and therefore B's true identity, is confirmed. The commercial bank then transmits B's true identity to the central bank's digital currency system via a dedicated quantum channel. Once the central bank's digital currency system confirms the authenticity of the digital currency sent by user A and the required payment value, it generates a corresponding new digital currency. For example, if user A sends a digital currency value of 100 and requires payment of 50, the central bank's digital currency system will generate a payment digital currency value of 50 for user B and a change digital currency value of 50 for user A. The generated digital currency still includes a value code, anti-counterfeiting code, bank code, and supplementary code. The central bank's digital currency system transmits the generated new digital currency to the commercial bank's digital currency system via a dedicated quantum channel.

[0070] After receiving the new digital currency from the central bank's digital currency system, the commercial bank's digital currency system determines whether the currency value code and bank code are correct. If correct, the change digital currency is encrypted using the quantum key shared with user A and sent to user A. The payment digital currency is encrypted using the quantum key shared with user B and sent to user B. Before sending it to user B, the identity of user B must be verified using the identity code authentication method mentioned above.

[0071] After user terminal A receives the encrypted information sent by the commercial bank's digital currency system, it uses the shared quantum key between the two parties to decrypt it to obtain new digital currency. User terminal A compares the currency value code of the digital currency, and after the comparison is correct, it deposits it into its own digital wallet (obtained by the user from the commercial bank), and then destroys the originally frozen digital currency. At the same time, the user terminal feeds back payment completion information indicating that the digital currency has been successfully paid to the commercial bank's digital currency system.

[0072] After user terminal B receives the encrypted information sent by the commercial bank's digital currency system, it also uses the shared quantum key between the two parties to decrypt it to obtain the digital currency paid by user terminal A. User terminal B compares the currency value code of the digital currency and deposits it into its own digital wallet after the comparison is correct. At the same time, user terminal B feeds back payment completion information to the commercial bank's digital currency system indicating that the digital currency payment was successful.

[0073] The commercial bank digital currency system will receive payment completion information feedback from user terminals A and B. After confirmation, it will save the transaction records between user terminals A and B. At the same time, the commercial bank digital currency system will feedback payment success information to the central bank digital currency system, and the central bank digital currency system will save the transaction records.

[0074] As another scenario of this embodiment, user terminal A and user terminal B can also belong to two different commercial bank digital currency systems. In this case, the central bank digital currency system sends the digital currency actually paid by user terminal A and the digital currency for change to the corresponding commercial bank digital currency system respectively. The other processes remain the same as the above process. It is worth noting that in this case, neither A nor the commercial bank digital currency system corresponding to A knows the true identity of B; similarly, neither B nor the commercial bank digital currency system corresponding to B knows the true identity of A.

[0075] Example 2:

[0076] This embodiment includes multiple user terminals, a commercial bank digital currency system, and a central bank digital currency system, where both user terminals involved in the transaction belong to the same commercial bank digital currency system. The definition of digital currency in this embodiment is the same as in Example 1. In this embodiment, the user terminal is a communication terminal installed with digital currency wallet software.

[0077] The user end needs to communicate securely with the commercial bank digital currency system, and the commercial bank digital currency system also needs to communicate securely with the central bank digital currency system. Therefore, we first need to establish quantum communication links between the user end and the commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system. Then, we need to design an identity authentication mechanism suitable for transmission over quantum communication links to complete the identity authentication of the user end in the commercial bank digital currency system.

[0078] In this embodiment, both the commercial bank digital currency system and the central bank digital currency system are equipped with QKD equipment or other quantum communication equipment. Therefore, the commercial bank digital currency system can negotiate keys with the central bank digital currency system and then conduct quantum communication. The user end can be configured with QKD or not.

[0079] S1: When the user side is configured with QKD:

[0080] If the user terminal is directly connected to the commercial bank digital currency system, the user terminal can directly negotiate keys with the commercial bank digital currency system to achieve confidential communication; if the user terminal is indirectly connected to the commercial bank digital currency system, for example, through a relay configured with QKD, the user terminal and the commercial bank digital currency system can use the following methods to negotiate keys:

[0081] Assuming that the user end is the starting node and the commercial bank digital currency system is the target node, the n relay nodes between the starting node and the target node are divided into odd nodes and even nodes. The division rule is: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay node of this relay node is regarded as an even node, and so on, until all relay nodes are divided; among these n relay nodes, the relay node directly connected to the target node can be numbered as B1, and then numbered sequentially towards the starting node. The next relay node connected to the relay node B1 is numbered B2, and the next relay node connected to the relay node B2 is numbered B3..., and the relay node directly connected to the starting node is numbered Bn, then B1, B3, B5... are odd nodes, and the rest are even nodes.

[0082] Configure the quantum key between each relay node and its adjacent nodes. Here, the quantum key between adjacent nodes can be pre-stored in each node, or each node can be obtained by real-time negotiation before communicating with the adjacent node according to a preset key negotiation method. The negotiation method can include various methods, for example, the quantum key between adjacent nodes is obtained by negotiation based on the BB84 protocol, or the quantum key between adjacent nodes is obtained by negotiation using the BB84 protocol based on the decoy state. It should be noted that in the present invention, there is no restriction on the configuration (negotiation) method of the quantum key between adjacent nodes, and all feasible key generation methods should be included in the scope of protection of the present invention.

[0083] Before the starting node sends data T to the target node, each odd node XORs the quantum key between itself and the two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and the two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node uses its own quantum key to first XOR the data T to be sent, then XORs the calculation result with all the received key data to obtain the encrypted data, and finally sends the encrypted data to the target node through classical communication. After receiving the key data transmitted by all even nodes, the target node uses its own quantum key to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node.

[0084] S2: The user does not configure QKD

[0085] If the user end is not configured with QKD, the user end and the commercial bank digital currency system can directly share the symmetric key in advance to achieve confidential communication. For example, the symmetric key is issued by a trusted third-party key issuance center, and then the two parties communicate confidentially through the symmetric key. The user end can share the quantum key with a relay equipped with QKD in advance, and then the relay will negotiate the key with the quantum key management center. For example, if a relay equipped with QKD - the quantum key management center - is set up between user end A and the commercial bank digital currency system, the following methods can be used for confidential communication between user end A and the commercial bank digital currency system:

[0086] User A first shares a quantum key with the quantum key management center. User A encrypts its identity code to the commercial bank digital currency system using the quantum key K1 shared with the quantum key management center. The quantum key management center then transmits user A's shared quantum key K1 to the commercial bank digital currency system via a quantum channel, allowing the commercial bank digital currency system to obtain the encrypted information from the user. The commercial bank digital currency system then transmits confidential information to the user as follows: the commercial bank digital currency system and the quantum key management center negotiate quantum key K2 through quantum communication. The commercial bank digital currency system then encrypts the information with key K2 and sends it to the user. The quantum key management center then uses the quantum key K3 shared with the user (based on the one-time pad principle, the shared key between the quantum key management center and the user is replaced with K3 in this communication) to transmit the quantum key K2 to the user, allowing the user to obtain the encrypted information from the commercial bank digital currency system.

[0087] If there are other relays between the quantum key management center and the commercial bank digital currency system, the communication process between the user terminal and the commercial bank digital currency system is as follows:

[0088] When the user sends a message, it encrypts the message T to be sent using the quantum key K shared in advance with the quantum key management center, and then transmits the encrypted message to the commercial bank digital currency system through the classical channel;

[0089] Taking the quantum key management center as the starting node and the commercial bank digital currency system as the target node, the n relay nodes between the starting node and the target node are divided into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay node of this relay node is regarded as an even node, and so on, until all relay nodes are divided; each relay node is configured with the quantum key of the relay node and the adjacent nodes;

[0090] Each odd node XORs the quantum key between itself and its two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and its two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node XORs all the received key data with its own quantum key and the quantum key of the adjacent relay node to obtain the encryption key. It then uses the encryption key to encrypt the shared key K between itself and the user end, and then sends the encrypted data to the target node via classical communication.

[0091] After receiving the key data transmitted by all even nodes, the target node uses its own quantum key and the quantum key of the adjacent relay node to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node to obtain the key K;

[0092] The target node negotiates a quantum key K′ with the commercial bank digital currency system, conducts confidential communication based on the negotiated quantum key K′, and transmits the key K to the commercial bank digital currency system. The commercial bank digital currency system uses the key K to decrypt the encrypted data sent by the user end and obtains T.

[0093] When the commercial bank digital currency system sends a message to the user end, the above steps are followed.

[0094] If a relay connection is used between the commercial bank digital currency system and the central bank digital currency system, the method described in S2 can also be used.

[0095] After establishing a quantum communication link, the user must first register with the commercial bank's digital currency system. The system then issues an identity code to the user, which is used for mutual identity verification. Simultaneously, quantum key distribution is performed between the user and the commercial bank's digital currency system to negotiate a shared quantum key. Both parties separately store the identity code and the shared quantum key securely. The shared quantum key is used for secure communication between the two parties and can be periodically updated.

[0096] The following describes an example in which the user end does not configure QKD but has pre-shared the quantum key with the quantum key management center. The process of the digital currency payment method based on quantum communication in this application mainly includes:

[0097] When a digital currency payment transaction between two users is required, for example, user A wants to pay digital currency from its own account to user B, user A must initiate a digital currency payment request. First, user A and the commercial bank's digital currency system must authenticate each other. User A then sends an identity code encrypted with the current communication key to the commercial bank's digital currency system via the corresponding quantum communication link. Once both parties have confirmed their identities, user A encrypts the digital currency payment request and the digital currency string to be paid using a quantum key shared with the quantum key management center (QKMC). The payment request includes the user's identity code encrypted with the current communication key. The QKMC then transmits the shared quantum key used by user A to the commercial bank's digital currency system via quantum communication, allowing the commercial bank's digital currency system to receive the encrypted information. At this point, the status of the digital currency to be paid in user A's account is changed to temporarily unavailable.

[0098] After decrypting the information, the commercial bank's digital currency system obtains the payment request and the digital currency string to be paid from user A. It then decrypts the identity code in the payment request and authenticates it. It then verifies whether the plain text part of the digital currency sent by A is correct. It can also determine whether the payment instruction from user A is legal. Finally, the commercial bank's digital currency system sends the identity information, payment request and digital currency string to be paid from user A to the central bank's digital currency system through a dedicated quantum communication channel.

[0099] After receiving and decrypting the identity information, payment request, and digital currency string to be paid from the commercial bank digital currency system, the central bank digital currency system verifies the authenticity of the digital currency using the method described in Example 1. Once verified, the central bank digital currency system generates new digital currency based on the digital currency value sent by user A and the required payment value. For example, if the digital currency value sent by user A is 100 and the required payment value is 50, the central bank digital currency system will generate a payment digital currency with a value of 50 for user B and a change digital currency with a value of 50 for user A. The generated digital currency still includes the value code, anti-counterfeiting code, bank code, and supplementary code. The central bank digital currency system transmits the generated digital currency to the commercial bank digital currency system via a dedicated quantum channel.

[0100] After the commercial bank digital currency system receives the new digital currency from the central bank digital currency system, it determines whether the currency value code and bank code formats are correct. After confirming that they are correct, the quantum key management centers of user terminals A and B of the commercial bank digital currency system respectively conduct quantum key negotiation and negotiate shared quantum keys K1 and K2 respectively. Then, the commercial bank digital currency system uses the negotiated shared quantum key to encrypt the newly generated digital currency and send it to user terminals A and user terminals B respectively. At the same time, the quantum key management center of user terminal A uses the quantum key shared in advance with user terminal A to encrypt the quantum key K1 and send it to user terminal A. The quantum key management center of user terminal B uses the quantum key shared in advance with user terminal B to encrypt the quantum key K2 and send it to user terminal B.

[0101] Before the commercial bank digital currency system sends digital currency to user terminal B, the commercial bank digital currency system also needs to perform identity authentication with user terminal B. The specific method can be based on the above-mentioned identity confirmation method between user terminal A and the commercial bank digital currency system.

[0102] After user terminal A receives the encrypted information sent by the commercial bank's digital currency system, it uses the quantum key shared in advance with the quantum key management center to decrypt it to obtain new digital currency. The user terminal compares the currency value code of the digital currency, and after the comparison is correct, it deposits it into its own digital wallet, and then destroys the original digital currency to be paid. At the same time, the user terminal feedbacks the payment completion information of the successful payment of the digital currency to the commercial bank's digital currency system.

[0103] After user terminal B receives the encrypted information sent by the commercial bank's digital currency system, it decrypts it with the quantum key shared in advance with the quantum key management center (the quantum key management center of user terminal A and user terminal B may not be the same) to obtain the digital currency paid by user terminal A. User terminal B compares the currency value code of the digital currency and deposits it into the user terminal digital wallet after the comparison is correct. At the same time, user terminal B feedbacks the payment completion information of the successful payment of the digital currency to the commercial bank's digital currency system.

[0104] The commercial bank digital currency system will receive payment completion information from user terminals A and B, and after confirmation, it will record and save the transaction process. At the same time, the commercial bank digital currency system will feedback the user terminal payment success confirmation information to the central bank digital currency system, and the central bank digital currency system will save the transaction record.

[0105] As another scenario of this embodiment, user terminal A and user terminal B may also belong to two different commercial bank digital currency systems respectively. In this case, the central bank digital currency system sends the digital currency paid by user terminal A and the digital currency for change to the corresponding commercial bank digital currency system respectively. The other processes are consistent with the above process. The specific process is as follows Figure 2 shown.

[0106] The present invention also proposes a digital currency payment system based on quantum communication, which is used to implement the method, and is described below through two embodiments.

[0107] Example 3:

[0108] This embodiment also provides a digital currency payment system based on quantum communication, such as Figure 3 As shown in the figure, the system mainly includes user terminals (A and B), a commercial bank digital currency system, and a central bank digital currency system. Among them, the user terminals, the commercial bank digital currency system, and the central bank digital currency system are all equipped with QKD. Key negotiation can be achieved between the user terminals and the commercial bank digital currency system, as well as between the commercial bank digital currency system and the central bank digital currency system. User terminals A and B belong to the same commercial bank digital currency system.

[0109] Each user first registers with the commercial bank's digital currency system. The system then issues an identity code to the user for subsequent identity verification. Simultaneously, both parties perform quantum key distribution to negotiate a shared quantum key. Each party stores the identity code and shared quantum key separately. The identity code is used for mutual identity verification, while the shared quantum key is used for secure communication between the two parties. The shared quantum key can be periodically updated between the two parties.

[0110] When a digital currency payment transaction needs to be conducted between client A and client B, assuming client A is the payer, client A and the commercial bank's digital currency system first need to perform identity authentication. This involves client A sending an identity code encrypted with the current communication key to the commercial bank's digital currency system via the corresponding quantum communication link for identity authentication. After authentication, client A sends a payment request and the digital currency string to be paid to the commercial bank's digital currency system. The payment request includes the client's identity code encrypted with the current communication key.

[0111] After decrypting the information, the commercial bank's digital currency system obtains the payment request and the digital currency string to be paid from user A. It then decrypts the identity code in the payment request and authenticates it. It then verifies whether the plain text part of the digital currency sent by A is correct. It can also determine whether the payment instruction from user A is legal. Finally, the commercial bank's digital currency system sends the identity information, payment request and digital currency string to be paid from user A to the central bank's digital currency system through a dedicated quantum communication channel.

[0112] The central bank's digital currency system receives and decrypts the identity information, payment request, and digital currency string to be paid from the commercial bank's digital currency system. The central bank's digital currency system verifies the authenticity of the digital currency using the method described in Example 1. Once verified, the central bank's digital currency system generates corresponding new digital currency based on the digital currency value sent by user A and the required payment value. For example, if the digital currency value sent by user A is 100 and the required payment value is 50, the central bank's digital currency system will generate a payment digital currency value of 50 for user B and a change digital currency value of 50 for user A. The generated digital currency still includes the currency value code, anti-counterfeiting code, bank code, and supplementary code. The central bank's digital currency system transmits the generated new digital currency to the commercial bank's digital currency system via a dedicated quantum channel.

[0113] After receiving the new digital currency from the central bank's digital currency system, the commercial bank's digital currency system determines whether the currency value code and bank code are correct. If correct, the change digital currency is encrypted using the quantum key shared with user terminal A and sent to user terminal A. The payment digital currency is encrypted using the quantum key shared with user terminal B and sent to user terminal B. Before the commercial bank's digital currency system sends the digital currency to user terminal B, it is also necessary to conduct identity authentication with user terminal B. Specifically, the identity confirmation method between user terminal A and the commercial bank's digital currency system can be as described above.

[0114] After user terminal A receives the encrypted information sent by the commercial bank's digital currency system, it uses the shared quantum key between the two parties to decrypt it to obtain new digital currency. The user compares the currency value code of the digital currency, and after the comparison is correct, it is deposited into the user's digital wallet, and then the original digital currency to be paid is destroyed. At the same time, the user feedbacks the payment completion information of the successful payment of the digital currency to the commercial bank's digital currency system.

[0115] After user terminal B receives the encrypted information sent by the commercial bank's digital currency system, it also uses the shared quantum key between the two parties to decrypt it to obtain the digital currency paid by user terminal A. User terminal B compares the currency value code of the digital currency and deposits it into the user's digital wallet after the comparison is correct. At the same time, the user feedbacks the payment completion information indicating the successful payment of the digital currency to the commercial bank's digital currency system.

[0116] The commercial bank digital currency system will receive payment completion information from user terminals A and B. After confirmation, it will record and save the payment process. At the same time, the commercial bank digital currency system will feedback payment success information to the central bank digital currency system, and the central bank digital currency system will save the payment record.

[0117] As another scenario of this embodiment, user terminal A and user terminal B may also belong to two different commercial bank digital currency systems, such as Figure 3 As shown, at this time, the central bank's digital currency system sends the digital currency paid by user A and the digital currency for change to the corresponding commercial bank digital currency system respectively. Other processes refer to the above process.

[0118] Example 4:

[0119] This application also provides another digital currency payment system based on quantum communication, such as Figure 4 As shown in the figure, the system mainly includes user terminals (A and B), the commercial bank digital currency system, the central bank digital currency system, and the quantum key management center. User terminal A belongs to the digital currency system of commercial bank A, and user terminal B belongs to the digital currency system of commercial bank B.

[0120] In this embodiment, the commercial bank digital currency system, the central bank digital currency system, and the quantum key management center are all equipped with QKD equipment or other quantum communication equipment. Therefore, the commercial bank digital currency system can conduct key negotiation with the quantum key management center and the central bank digital currency system respectively, and then conduct quantum communication. The user end is not equipped with QKD. The user end and the quantum key management center pre-share a symmetric key issued by a trusted third-party key issuance center to achieve key sharing.

[0121] The user needs to register with the commercial bank's digital currency system. The commercial bank's digital currency system issues the user an identity code, which is stored confidentially by both parties. The identity code is used to verify each other's identities. The two parties communicate securely through a quantum key management center, and the identity code can be updated regularly.

[0122] When a digital currency payment transaction needs to be conducted between two users, for example, user terminal A pays the digital currency in its own account to user terminal B, user terminal A needs to initiate a digital currency payment request; first, user terminal A sends an identity code encrypted with the current communication key through the corresponding quantum communication link to the digital currency system of Commercial Bank A for identity authentication. The quantum communication process between the two parties is that user terminal A encrypts and transmits information to the digital currency system of the commercial bank through the quantum key K1 shared with the quantum key management center. The quantum key management center sends the shared quantum key K1 of user terminal A to the digital currency system of Commercial Bank A through quantum communication, and the digital currency system of Commercial Bank A can obtain the encrypted information sent by the user; the digital currency system of Commercial Bank A and the quantum key management center conduct quantum communication to negotiate the quantum key K2, and then the digital currency system of Commercial Bank A encrypts the information with key K2 and sends it to the user. The quantum key management center uses the shared quantum key K3 with the user to send the above quantum key K2 to the user, and the user can obtain the encrypted information sent by the digital currency system of Commercial Bank A.

[0123] After both parties confirm their identities, User A transmits the digital currency payment request and the digital currency string to be paid to Commercial Bank A's digital currency system using the quantum key shared with the Quantum Key Management Center. The payment request includes the user's identity code, encrypted using the current communication key. The Quantum Key Management Center then transmits the shared quantum key used by User A to Commercial Bank A's digital currency system via quantum communication. Bank A's digital currency system then receives the encrypted information. At this point, the status of the digital currency to be paid in User A's account is changed to temporarily unavailable.

[0124] After decrypting the information, the digital currency system of commercial bank A obtains the payment request and the digital currency string to be paid from user A. It then decrypts the identity code in the payment request and authenticates it. It then verifies whether the plain text part of the digital currency sent by A is correct. It can also determine whether the payment instruction of user A is legal. Finally, the digital currency system of the commercial bank sends the identity information, payment request and digital currency string to be paid from user A to the digital currency system of the central bank through a dedicated quantum communication channel.

[0125] After receiving and decrypting the true identity of User A, the payment request, and the digital currency string to be paid from Commercial Bank A's digital currency system, the PBOC digital currency system verifies the authenticity of the digital currency using the method described in Example 1. Once verified, the PBOC digital currency system generates corresponding new digital currency based on the digital currency value sent by User A and the required payment value. For example, if the digital currency value sent by User A is 100 and the required payment value is 50, the PBOC digital currency system will generate a payment digital currency value of 50 for User B and a change digital currency value of 50 for User A. The generated digital currency still includes the currency value code, anti-counterfeiting code, bank code, and supplementary code. The PBOC digital currency system transmits the generated new digital currency to Commercial Bank A and Commercial Bank B's digital currency systems via a dedicated quantum channel.

[0126] After the digital currency systems of commercial banks A and B receive the new digital currency from the central bank's digital currency system, they determine whether the currency value code and bank code are correct. After confirmation, the quantum communication terminals of the digital currency systems of commercial banks A and B and the quantum key management centers of user terminals A and B respectively conduct quantum key negotiation, and negotiate shared quantum keys K1 and K2 respectively. Then, the digital currency systems of commercial banks A and B use the negotiated shared quantum key to encrypt the newly generated digital currency and send it to user terminals A and B respectively. At the same time, the quantum key management center of user terminal A uses the quantum key shared in advance with user terminal A to send the quantum key K1 to user terminal A, and the quantum key management center of user terminal B uses the quantum key shared in advance with user terminal B to send the quantum key K2 to user terminal B.

[0127] Before the digital currency system of Commercial Bank B sends digital currency to user terminal B, the digital currency system of Commercial Bank B needs to perform identity authentication with user terminal B. The specific method can be based on the above-mentioned identity confirmation method between user terminal A and the commercial bank digital currency system.

[0128] After user terminal A receives the encrypted information sent by the digital currency system of Commercial Bank A, it uses the quantum key shared in advance with the quantum key management center to decrypt it to obtain the new digital currency. The user compares the currency value code of the digital currency, and after the comparison is correct, it deposits it into his own digital wallet, and then destroys the original digital currency to be paid. At the same time, user terminal A feeds back payment completion information to the digital currency system of Commercial Bank A indicating that the digital currency has been successfully paid.

[0129] After user terminal B receives the encrypted information sent by the digital currency system of Commercial Bank B, it decrypts it with the quantum key shared in advance with the quantum key management center (the quantum key management center of user terminal A and user terminal B may not be the same) to obtain the digital currency paid by user terminal A. User terminal B compares the currency value code of the digital currency and deposits it into its own digital wallet after the comparison is correct. At the same time, user terminal B feeds back payment completion information to the digital currency system of Commercial Bank B indicating that the digital currency payment was successful.

[0130] The digital currency systems of commercial banks A and B will respectively receive payment completion information fed back by user terminals A and B. After confirmation, they will record and save the payment process. At the same time, the digital currency systems of commercial banks A and B will respectively feedback user payment success confirmation information to the central bank's digital currency system, and the central bank's digital currency system will save the payment records.

[0131] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0132] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A digital currency payment method based on quantum communication, characterized in that: The following steps are involved: (1) Establishing quantum communication links between the user terminals of both parties to the transaction and the corresponding commercial bank digital currency system, and between the commercial bank digital currency system and the central bank digital currency system; (2) Before the transaction, both parties register their identity information in the commercial bank digital currency system and obtain a unique identity code; (3) During the transaction, both parties send their identity codes to the corresponding commercial bank digital currency system through their respective quantum communication links for identity authentication; After identity authentication is passed, the two parties to the transaction establish a session with the corresponding commercial bank digital currency system. The commercial bank digital currency system uses the session key to encrypt the user's identity code as a call identifier; (4) The payee encrypts his / her own identity code with the session key of the corresponding commercial bank digital currency system, and then sends the encrypted identity code and the bank information of his / her commercial bank digital currency system to the payer; (5) The payer sends its own identity information, payment request and digital currency to the corresponding commercial bank digital currency system through the established session, and freezes the digital currency being traded; the payment request contains the payer's identity code encrypted with the payee's current session key, the payee's identity code encrypted with the payee's current session key, and the bank information of the commercial bank digital currency system to which the payee belongs; Digital currency includes a plaintext code and an anti-counterfeiting code. The anti-counterfeiting code is obtained by encrypting the digital currency ownership information and the hash value of the digital currency plaintext code and ownership information using the anti-counterfeiting code key held by the central bank; the ownership information includes the identity information of the digital currency holder; (6) The payer's commercial bank digital currency system verifies whether the digital currency is correct. After verification, the payer's identity information, payment request and digital currency are forwarded to the central bank digital currency system; (7) The central bank’s digital currency system verifies the identity of the payer: decrypts the anti-counterfeiting code in the digital currency, verifies whether the identity information in the ownership information is consistent with the identity information of the payer received, and then calculates the hash value of the plaintext part of the digital currency and verifies whether it is consistent with the hash value obtained after decryption; If they are consistent, the payer's identity authentication is successful; The central bank's digital currency system verifies the payee's identity: the central bank's digital currency system sends the payee's encrypted identity code to the payee's commercial bank digital currency system; After receiving the encrypted identity code of the payee, the payee's commercial bank digital currency system matches the session identifier in the currently valid session. If the session identifier is consistent with the payee's encrypted identity code, the payee's identity code is confirmed and the payee's identity information is sent to the central bank digital currency system via the quantum communication link. After the central bank’s digital currency system authenticates the identities of the payer and payee, it responds to the payment request by generating digital currency for change for the payer and payment for the payee, which are then sent to the commercial bank digital currency systems of both parties. (8) The commercial bank digital currency systems of both parties to the transaction verify the digital currency issued by the central bank digital currency system and send it to the corresponding transaction parties; (9) Both parties to the transaction store the new digital currency, and the payer destroys the frozen original digital currency; The commercial bank digital currency system and the central bank digital currency system are both equipped with QKD equipment, and both parties conduct key negotiation through their respective QKD equipment to achieve confidential communication; Several relay nodes are also set up between the commercial bank digital currency system and the central bank digital currency system; The commercial bank digital currency system and the central bank digital currency system use the following methods for confidential communication: The commercial bank digital currency system / central bank digital currency system is the starting node, and the central bank digital currency system / commercial bank digital currency system is the target node; Divide the n relay nodes between the starting node and the target node into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay nodes of this relay node are regarded as even nodes, and so on, until all relay nodes are divided; Configure each relay node with the quantum key of its neighboring nodes; Before the starting node sends data T to the target node, each odd node XORs the quantum key between itself and the two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and the two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node uses its own quantum key to first XOR the data T to be sent, then XORs the calculation result with all the received key data to obtain the encrypted data, and finally sends the encrypted data to the target node through classical communication. After receiving the key data transmitted by all even nodes, the target node uses its own quantum key to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node.

2. A digital currency payment method based on quantum communication according to claim 1, characterized in that: It also includes the following steps: After the transaction is completed, the payer and the payee respectively feedback the transaction completion information to the corresponding commercial bank digital currency system, and after the commercial bank digital currency system receives the transaction completion information, it saves the transaction record.

3. A digital currency payment method based on quantum communication according to claim 1, characterized in that: In addition to anti-counterfeiting, the digital currency also includes a currency value code, a bank code and a supplementary code. The currency value code is used to indicate the value of the digital currency, the bank code indicates the bank information of the digital currency, and the supplementary code is encoded by the central bank's digital currency system according to demand and is used to expand the information carried by the digital currency.

4. A digital currency payment method based on quantum communication according to claim 1, characterized in that: The user terminal is configured with a QKD device and performs key negotiation with the corresponding commercial bank digital currency system through their respective QKD devices to obtain a shared quantum key.

5. A digital currency payment method based on quantum communication according to claim 4, characterized in that: There are also several relay nodes between the user terminal and the corresponding commercial bank digital currency system. The user terminal and the corresponding commercial bank digital currency system use the following method to conduct confidential communication: The user end / commercial bank digital currency system is the starting node, and the commercial bank digital currency system / user end is the target node; Divide the n relay nodes between the starting node and the target node into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay nodes of this relay node are regarded as even nodes, and so on, until all relay nodes are divided; Configure each relay node with the quantum key of its neighboring nodes; Before the starting node sends data T to the target node, each odd node XORs the quantum key between itself and the two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and the two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node uses its own quantum key to first XOR the data T to be sent, then XORs the calculation result with all the received key data to obtain the encrypted data, and finally sends the encrypted data to the target node through classical communication. After receiving the key data transmitted by all even nodes, the target node uses its own quantum key to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node.

6. A digital currency payment method based on quantum communication according to claim 1, characterized in that: The user terminal does not configure the QKD setting, but instead issues a symmetric key in advance with the corresponding commercial bank digital currency system through a trusted third-party key issuance center, and then the two parties achieve confidential communication based on the shared symmetric key.

7. A digital currency payment method based on quantum communication according to claim 6, characterized in that: Multiple relay nodes are provided between the user terminal and the corresponding commercial bank digital currency system; the user terminal and the corresponding commercial bank digital currency system communicate confidentially in the following manner: When the user sends a message, it encrypts the message T to be sent using the quantum key K shared in advance with the quantum key management center, and then transmits the encrypted message to the commercial bank digital currency system through the classical channel; Taking the quantum key management center as the starting node and the commercial bank digital currency system as the target node, the n relay nodes between the starting node and the target node are divided into odd nodes and even nodes: the relay node directly connected to the target node is regarded as an odd node, and the adjacent relay node of this relay node is regarded as an even node, and so on, until all relay nodes are divided; Configure each relay node with the quantum key of its neighboring nodes; Each odd node XORs the quantum key between itself and its two adjacent nodes and passes it to the starting node. At the same time, each even node XORs the quantum key between itself and its two adjacent nodes and passes it to the target node. After receiving the key data transmitted by all odd nodes, the starting node XORs all the received key data with its own quantum key and the quantum key of the adjacent relay node to obtain the encryption key. It then uses the encryption key to encrypt the shared key K between itself and the user end, and then sends the encrypted data to the target node via classical communication. After receiving the key data transmitted by all even nodes, the target node uses its own quantum key and the quantum key of the adjacent relay node to XOR all the received key data to obtain the decryption key, and uses the decryption key to decrypt the encrypted data from the starting node to obtain the key K; The target node negotiates the quantum key K′ with the commercial bank digital currency system, performs confidential communication based on the negotiated quantum key K′, and transmits the key K to the commercial bank digital currency system; The commercial bank digital currency system uses the key K to decrypt the encrypted data sent by the user end and obtains T; When the commercial bank digital currency system sends a message to the user end, the above steps are followed.

8. A digital currency payment system based on quantum communication, characterized in that: include: The user terminal, the commercial bank digital currency system, the central bank digital currency system, the user terminal, the commercial bank digital currency system and the central bank digital currency system make digital currency payments according to the method described in any one of claims 1 to 7.

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