CN107230051A - The method of payment and payment system of digital cash - Google Patents

Abstract

The invention provides a digital currency payment method and payment system to solve various deficiencies in the prior art. The digital currency payment method of the present invention includes: the payer terminal device receives the payment amount input by external operations, the payee ID, and the withdrawal identification code; the payer terminal device selects a number whose total amount is equal to the payment amount in the payer digital currency wallet Currency; the payer's terminal device sends the digital currency and withdrawal identification code to the payee's terminal device corresponding to the payee's identification by near-field communication; the payee's terminal device sends the digital currency and withdrawal identification code to the commercial bank through the network Digital currency system; the commercial bank digital currency system will include digital currency and withdrawal identification codes sent to the central bank digital currency system through the network; the central bank digital currency system will change the owner information of the digital currency from the payer to the payee and note the withdrawal Identifier.

Description

Payment method and payment system of digital currency

technical field

The present invention relates to the technical fields of computer network and computer software, in particular to a digital currency payment method and payment system.

Background technique

Digital currency is a currency that converts cash values into a series of electronically encrypted serial numbers. The security of the currency itself depends on cryptographic algorithms for protection. In terms of cryptographic algorithms, the security of digital currency systems involves symmetric ciphers, asymmetric ciphers, message digest algorithms, and identity-based cryptographic systems. In terms of system implementation, the overall security of cryptographic systems, the selection of cryptographic algorithms, and cryptographic algorithms must be deeply considered. The implementation of algorithms, the design of interactive protocols, the compatibility of international and domestic standards, etc., ensure the security of digital currency transactions.

With the development and popularization of the mobile Internet, the mobile payment industry is rapidly changing and advancing. Business models based on various technologies such as mobile Internet, NFC, HCE, Token, and biometrics are constantly innovating, and the application scenarios are constantly expanding and enriching. Online and offline businesses are integrated. accelerated development. While the new mobile payment technology provides users with diversified and convenient payment services, it also leads the transformation and upgrading of communication, finance, Internet and other industries. The broad development prospect of mobile payment has become a broad consensus of the whole industry, and mobile payment is considered to be an important entry point connecting online and offline. The digital currency transaction system should be designed with mobile payment as the core business model.

In the mobile payment business model, the key storage carrier of digital currency can be provided by hardware SE module (security module), HCE and TEE. Hardware SE has been recognized by the field of financial transactions due to the secure computing environment it provides, and is widely used in current debit cards and electronic cash, and has a wide user base, good acceptance environment and usage habits. With the continuous development of mobile payment technology, many changes have taken place in the form of SE modules, and new solutions are constantly being practiced.

In the data transmission channel between the transaction acceptance terminal (POS machine) and payment tools (such as cards and mobile phones), there are currently multiple transmission methods: RF radio frequency communication, SMS, code scanning, sound waves, photons, and the coexistence of multiple methods Provides convenience for communication between payment carriers.

In terms of authentication methods, it can be divided into password-based authentication, password-based + smart card authentication, and biometric (fingerprint, face)-based authentication. Among them, password and biometric authentication are mostly used for far-field payment, and smart card authentication is mostly used for near-field payment.

Cloud computing is the mainstream direction of the back-end server in the future, and the back-end system of digital currency should adopt a cloud-based solution.

In e-commerce activities, due to different roles, the requirements for digital currency are also different: customers require digital currency to be convenient to use, safe to store and anonymous; merchants require digital currency to be authentic and convertible into real currency; banks It is required that the digital currency cannot be illegally used and counterfeited. Therefore, the digital currency D-RMB should have the following characteristics:

1. Security: It can prevent any party in the business from changing or illegally using digital currency;

2. Non-repeatable spending: digital currency can only be used once, and repeated spending can be easily checked;

3. Controllable anonymity: Banks and merchants cannot track the use of digital currency even if they collude with each other. It is required that the system cannot link the purchase behavior of users of electronic cash together, thereby concealing the purchase history of digital currency users. However, the issuer of digital currency Use of digital currency can be tracked;

4. Unforgeability: Users cannot forge fake digital currency;

5. Fairness: The payment process is fair, ensuring that either the transaction is successful or that both parties have no losses, preventing one transaction party from suffering losses in the transaction;

6. Compatibility: The issuance process and circulation of digital currency in the D-RMB system should refer to the issuance and circulation of physical currency as much as possible.

And for digital currency, it should be able to adapt to various usage scenarios of existing currencies and be freely convertible with existing currencies.

In the current economic life, offline payment technology has been adopted for P2B (Peer to Business) payment scenarios such as bus cards, municipal all-in-one cards, canteen meal cards, etc. Taking the canteen meal card as an example, the individual user first needs to obtain the meal card (that is, a specific offline payment card issued by the catering company), then the individual user recharges the meal card, and finally the user takes the meal card to the cafeteria to order food, and will The meal card is in close contact with the credit card machine in the canteen to exchange transaction information to complete the process of consumption payment. In the above process, there are at least the following disadvantages: (1) The offline payment card is usually a physical card, which consumes materials and is not environmentally friendly. (2) In the process of applying for a card and recharging, individual users and merchants must invest time and energy. (3) When an individual user recharges an offline payment card with paper currency, the merchant needs to put in effort to identify the authenticity of the banknote, and it is still possible to receive counterfeit currency due to financial personnel's mistakes, resulting in economic losses. (4) If the prepaid fee is not fully consumed, the balance cannot be freely circulated in other fields, and the user needs to find a merchant to sell the card for a refund, which is very troublesome. (5) Individual users may have multiple offline payment cards such as bus cards and canteen meal cards at the same time, which is inconvenient to carry.

The offline payment technology in the current person-to-person P2P (Peer to Peer) payment scenario has not been fully popularized, and the application fields are limited due to various limitations of technical details.

Contents of the invention

In view of this, the present invention provides a digital currency payment method and payment system to solve various deficiencies in the prior art. Other purposes, effects and beneficial effects of the present invention can be obtained from the embodiments.

The first aspect of the present invention proposes a digital currency payment method, including: the payer terminal device receives the payment amount input by an external operation, the payee ID, and the withdrawal identification code; the payer terminal device is in the payer digital currency wallet Selecting a digital currency whose total amount is equal to the payment amount; the payer terminal device sends the digital currency and the withdrawal identification code to the payee terminal device corresponding to the payee identifier by means of near-field communication; The terminal device of the payee sends the digital currency and the withdrawal identification code to the digital currency system of the commercial bank through the network; the digital currency system of the commercial bank sends the digital currency and the withdrawal identification code to the central bank digital currency system through the network; The central bank digital currency system changes the owner information of the digital currency from the payer to the payee and notes the withdrawal identification code.

Optionally, it also includes: the central bank digital currency system sending a first transaction success notification to the commercial bank digital currency system; and the commercial bank digital currency system respectively paying to the The terminal device of the payee and the terminal device of the payee send a second transaction success notification.

Optionally, after the central bank digital currency system changes the owner information of the digital currency from the payer to the payee and notes the withdrawal identification code, it also includes: the central bank digital currency system records the transaction running water.

Optionally, before the step of the payee terminal device sending the digital currency and the withdrawal identification code to the digital currency system of the commercial bank through the network, it also includes: the payee terminal device confirms that the digital currency is legal; The payee terminal device confirms that the digital currency is equivalent to the payment amount.

Optionally, before the digital currency system of the commercial bank includes the step of sending the digital currency and the withdrawal identification code to the digital currency system of the central bank through the network, it also includes: the digital currency system of the commercial bank confirms that the digital currency is legal; The digital currency system of the commercial bank confirms that the digital currency is equivalent to the payment amount; the digital currency system of the commercial bank confirms that the payee is a non-registered user of the commercial bank.

Optionally, before the central bank digital currency system changes the owner information of the digital currency from the payer to the payee and notes the withdrawal identification code, it also includes: the central bank digital currency system confirms the The owner of the digital currency is the payer.

Optionally, the digital currency and the withdrawal identification code are signed with the payer's private key based on identity-based cryptographic technology, and encrypted with the payee's identity.

The second aspect of the present invention proposes a digital currency payment system, including: a payer terminal device, a payee terminal device, a commercial bank digital currency system, and a central bank digital currency system, wherein: the payer terminal device is used for: Receive the payment amount, payee ID and withdrawal identification code input by external operations; select a digital currency whose total amount is equal to the payment amount in the payer’s digital currency wallet; send the digital currency and withdrawal identification code by near field communication Give the payee terminal device corresponding to the payee identification; the payee terminal device is used to: send the digital currency and the withdrawal identification code to the commercial bank digital currency system through the network; the commercial bank The bank's digital currency system is used to: send the digital currency and withdrawal identification code to the central bank's digital currency system through the network; the central bank's digital currency system is used to: change the owner information of the digital currency from the payer to the recipient Party and note the withdrawal identification code.

Optionally, the central bank digital currency system is also used to: send a first transaction success notification to the commercial bank digital currency system; the commercial bank digital currency system is also used to: according to the first transaction success notification, Sending a second transaction success notification to the payer terminal device and the payee terminal device respectively.

Optionally, the central bank digital currency system is also used for: recording transaction flow.

Optionally, the payee terminal device is further configured to: confirm that the digital currency is legal; confirm that the digital currency is equivalent to the payment amount.

Optionally, the commercial bank digital currency system is also used to: confirm that the digital currency is legal; confirm that the digital currency is equivalent to the payment amount; confirm that the payee is a non-registered user of the commercial bank.

Optionally, the central bank digital currency system is further configured to: confirm that the owner of the digital currency is the payer.

Optionally, the digital currency and the withdrawal identification code are signed with the payer's private key based on identity-based cryptographic technology, and encrypted with the payee's identity.

According to the technical solution of the present invention, since digital currency is used at the source of currency, the whole process can be virtual and non-substantial, which has the advantages of green environmental protection and completely avoids the disadvantage of inconvenient portability. And because digital currency is adopted at the source of currency, the present invention has the advantages of high anti-counterfeiting performance and anti-money laundering. Compared with the prior art, the technical solution of the present invention can omit the steps of opening a card, recharging, returning the card, or the payee goes to a commercial bank to open an account, saving the time and energy of all parties involved in the transaction. In addition, the payee can be a non-registered user of the bank, and the scope of application is wider.

Description of drawings

The accompanying drawings are used to better understand the present invention, and do not constitute improper limitations to the present invention. in:

Fig. 1 is the schematic diagram of the main flow of the work of the prefabricated card relevant to the embodiment of the present invention;

Fig. 2 is the schematic diagram of the flow chart of the user registration D-RMB account number related to the embodiment of the present invention;

Fig. 3 is a schematic diagram of the D-RMB transaction process related to the embodiment of the present invention;

Fig. 4 is a schematic diagram of a structure of the overall framework when the D-RMB digital currency system according to the embodiment of the present invention provides online services;

5 is a schematic diagram of a computer system included in a commercial bank digital currency system according to an embodiment of the present invention;

Fig. 6 is a schematic diagram of an architecture for interconnecting a commercial bank's digital currency system with an external system according to an embodiment of the present invention;

Fig. 7 is a schematic diagram of the main steps of the digital currency payment method according to the embodiment of the present invention;

Fig. 8 is a schematic diagram of main modules of a digital currency payment system according to an embodiment of the present invention.

detailed description

Exemplary implementations of the present invention are described below in conjunction with the accompanying drawings, which include various details of the implementations of the present invention to facilitate understanding, and they should be regarded as exemplary only. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.

In the embodiment of the present invention, the design scheme of digital currency based on cryptographic mathematics (hereinafter referred to as D-RMB) is described, and the main operation mode is that the central bank and commercial banks build the D-RMB system hierarchically. The central bank here is the issuer of the currency, such as the People's Bank of China. In the following descriptions, central banks are sometimes referred to simply as "central banks," and similarly, commercial banks are sometimes referred to simply as "commercial banks." In addition, the digital currency is represented as "D _coin ".

The D-RMB system is a fund transfer system based on D _currency transactions, which is jointly operated by the central bank and various commercial banks. The D-RMB system includes D _coin issuance, customer login, customer account management, transaction management, fraud detection, and core business modules running on the core server of a specific digital center, as well as mobile phones and laptops on the client side that need to interact with the core server At the same time, it also includes an open form of electronic communication network including the Internet and mobile communication network nationwide on which the D _coin fund transfer system operates. Before discussing the D-RMB system, it is clear that:

1. Compatible with existing physical currency circulation. The issuance process and circulation of digital currency in the D-RMB system refer to the issuance and circulation of physical currency as much as possible. The storage of digital currency in the D-RMB system goes through three links. One is the central bank’s digital currency issuance library (that is, the digital currency fund); The second is the bank library of commercial banks, that is, the inventory digital cash of commercial banks; the third is the customer application program on the client side, that is, in the electronic wallet. During these different links, the registration center of D-RMB will complete the relevant registration operations.

2. D-RMB digital currency does not need blind signature. Limited anonymity protection during use.

3. D-RMB digital currency can be circulated on different networks, and may exist in various electronic equipment terminals such as mobile phones, IC card chips, and laptops in electronic digital form. This article mainly uses mobile phones and IC cards as carriers to store D-RMB numbers Using currency as an example for discussion does not mean that it can only be carried by mobile phones and IC cards.

4. The payment mode designed by the D-RMB system is realized by the transfer of D-RMB digital currency (ie: D _coin transaction).

5. The D-RMB system must obey the relevant system requirements of cash management in my country. The specific requirements are determined by the needs of the business department.

6. In order to avoid homogeneous competition with the existing bookkeeping payment system, the D-RMB system can be designed to limit payment.

For the convenience of subsequent descriptions, the following symbol conventions are used:

Enc: Encryption, here means that after the user downloads the private key from the IBC center, he signs the outgoing message with his own private key and encrypts it with the other party's public key.

Dec: Decryption, here specifically means that the user decrypts the message with his own private key, and uses the mobile phone number of the other party as the corresponding public key (or direct public key) to sign and confirm the information sent by the user.

D _Bank : Refers to the reserve account opened by the bank in the central bank central system for book keeping.

D _currency : refers to the D-RMB digital currency generated by the central bank according to its own encryption mechanism. It is a string of characters representing a certain amount of RMB.

D _{coin 100} : refers to the D-RMB digital currency generated by the central bank according to its own encryption mechanism. It is a series of numbers representing 100 yuan, and so on. The subscript numbers represent the actual amount of RMB.

B _account number: the bank account number of the bank where the user is located.

H(M): The value obtained by performing a hash operation on M. M can be a mobile phone number, an organization code, or a string of characters, numbers, etc.

As a digital currency, D-RMB is established by the People's Bank of China as a legal tender and issued into circulation. The People's Bank of China acts as the ultimate lender to provide guarantees and participate in exchange, exchange and consumption within the national standard framework. It is a string of codes that has the same currency meaning as the "face value" in actual circulation. D-RMB digital currency simulates the issuance and management process of paper currency in the central bank, and generates digital currency at one time in the D-RMB issuance library according to the central bank's digital currency issuance.

In the design of the D-RMB system, D _coins can be generated according to the minimum unit denomination, or according to the specific withdrawal amount of the user, or according to the denomination of the physical currency in circulation. The specific method can be determined through the system parameters in the initial process. set in. In order to be close to reality, the follow-up will take the fixed denomination in circulation as an example to illustrate.

The D-RMB in the issuance library completely simulates the face value in circulation, and "printing" produces digital representations of "one yuan, five yuan, ten yuan, twenty yuan, fifty yuan, one hundred yuan", etc., and an encrypted text represents A face value D-RMB digital currency.

D-RMB is generated according to a fixed face value. If the fifth set of production represents D-RMB (requires production: D _{coin 1} , D _{coin 5} , D _{coin 10} , D _{coin 20} , D _{coin 50} , D _{coin 100} ):

Step 1: Generate six basic encryption passwords from the master password and numbers 1, 5, 10, 20, 50 and 100 respectively.

Step 2: Generate system random numbers by hash algorithm. Random numbers can be understood as prefix numbers.

Step 3: Encrypt with basic encryption passwords representing different currency values and random numbers to generate encrypted passwords.

Step 4: The encrypted password is signed by the private key of the central bank, which represents the generation of new coins. If the withdrawer wants to withdraw D _{coin 100} representing 100 yuan, in the actual withdrawal process, the encrypted ciphertext m can be generated by encrypting the unique random number representing 100 yuan and the corresponding basic encryption password, and then the private key of the central bank will pair m to sign.

In the D-RMB system, there are the digital currency issuance library of the central bank, the digital currency bank library of commercial banks and the electronic wallet of the client (such as mobile phone). The basic content of digital currency transfer includes:

(1) According to the total amount of digital currency issued, the central bank will uniformly generate digital currency (that is, produce digital currency funds) and store it in the central bank's issuance library.

(2) According to the demand application of the commercial bank's digital currency, the digital currency is sent to the database of the corresponding commercial bank to store the digital currency, that is, the digital currency is transferred from the issuing library to the bank library.

For example, according to the total amount of currency issued, the central bank issued 1 billion D-RMB, and these D-RMB were placed in the central bank's issuance library after issuance. Later, 200 million of the 1 billion D-RMB was withdrawn from the 1 billion D-RMB according to the application of a certain bank. In order to reduce the account by 200 million, at the same time, 200 million D-RMB is stored in the bank treasury of the commercial bank, and its bookkeeping operation is equivalent to the withdrawal of existing physical currency). Change to a commercial bank, and record the corresponding operation flow and other information.

(3) When a user applies to withdraw digital currency, the digital currency enters the storage medium of the user client (such as a mobile phone) from the bank warehouse to the circulation link, that is, from the bank warehouse to the user's electronic wallet. In the registration center, the owners of these digital currencies are changed from commercial banks to users, and the corresponding operation flow and other information are recorded.

(4) In the link of circulation, the essence of digital currency is to transfer between the respective electronic wallets of two users to complete the payment. At this time, the payment is divided into online transaction and offline transaction. The specific business process will be analyzed in detail later. In the registration center, the owners corresponding to these digital currencies are changed from user 1 to user 2, and information such as corresponding operation flow is recorded.

During the above digital currency transfer process, the registration center of the D-RMB system needs to verify the legitimacy of the transaction digital currency, record the transaction flow and correct the new owner of the corresponding digital currency, and register other required information (determined by business needs) .

If the IC card is used as the carrier, there is also the work of prefabricated cards. In the work of prefabricated cards, the digital currency system of the central bank and the digital currency system of commercial banks perform a series of operations on the D-RMB chip card containing the storage medium, mainly as follows: : The digital currency system of the central bank generates the personalized data of the D-RMB chip card according to the pre-specified content; the digital currency system of the commercial bank writes the personal information of the user applying for the D-RMB chip card into the D-RMB chip card; the commercial bank The digital currency system applies for the IBC private key from the authentication system with the user's IBC public key, and the user's IBC public key is the identification of the D-RMB chip card or the identification of the user. The main process involved in the above operations is shown in FIG. 1 , which is a schematic diagram of the main process of the prefabricated card work related to the embodiment of the present invention.

As the safe carrier of D _coins , the card base has a certain strengthening effect on ensuring the security of D _coins in all aspects of D _coins circulation (the independent physical carrier IC card is also referred to as "D-RMB chip card").

(1) Production of D-RMB chip cards

The production of D-RMB chip cards must be produced by enterprises with production qualifications certified by the central bank, and the quantity and quality of its production are strictly controlled by the central bank (or other departments authorized by the central bank). The enterprise qualification certification process includes: submission of application, material review, sample card inspection, on-site evaluation, authorization qualification and other links.

(2) Personalization of D-RMB chip card

The personalized data in the D-RMB chip card is generated by the central bank, and the relevant departments are authorized to establish a personalization center to personalize the newly produced D-RMB chip card.

(3) Issuance of D-RMB chip card

The system supports real-name card issuance and anonymous card issuance.

Real-name system card issuance: D-RMB chip card is applied by the user personally, and the real-name system is issued. The central bank authorizes the commercial bank to issue the card on its behalf. The commercial bank conducts real-name verification of the user and registers relevant information. The card is issued for the second time, and the user's personal information is written into the D-RMB chip card.

Anonymous card issuance: The user directly applies for a D-RMB chip card from the commercial bank, and the commercial bank can choose whether to verify the identity information of the applicant according to the actual situation.

The commercial bank chooses to use the unique identification number of the D-RMB chip card or the user's mobile phone number as the user's IBC public key according to the actual situation, and then applies for the private key from the IBC certification center.

The D-RMB system supports computer equipment, mobile phones, POS, ATM, and the Web as carriers, and can choose online or offline transactions. The examples in this article will mainly use mobile phones as carriers for illustration.

With regard to mobile phone terminals, various unlocking settings such as digital passwords and graphic passwords and power-on passwords can effectively protect the security of personal information on mobile phones. With the advent of the era of smart phones, all kinds of biometric-based fingerprint mobile phones have entered the general consumer group. It can adopt different fingerprint encryption for different applications and different specific information. The application of these new technologies can effectively ensure that digital currency on mobile phones, related The storage of transaction information is safe.

In order to ensure the security of the transfer of digital currency between mobile phones, the D-RMB system needs to introduce a security certification system. The central bank and financial institutions use the existing CA certification center, and social users (including individuals and enterprises) can use the IBC (Identity-Based Cryptograph) certification center for identity authentication.

For the private key and central bank public key generated in IBC and PKI, they need to be reliably and safely stored in the secure exclusive area SE (Secure Element) of the mobile phone. The SE area can be controlled by hardware (mobile phone card replacement) or by the host computer simulation card technology HCE ( HostCard Emulation) to achieve. If the user adopts changing the card to protect the key, then download the key to the SE area of the mobile phone during the card changing application process.

In the process of building the certification system, it can be designed according to the traditional PKI certification system, and the PKI system can be established uniformly. The CA can provide a strong digital signature, or it can be designed according to IBC, and the user's mobile phone number is used as the public key to manage, especially for small amounts. Offline payment seems to be more convenient. All business introductions below will be explained with IBC certification. Fig. 2 is a schematic diagram of the flow of a user registering a D-RMB account related to the embodiment of the present invention, and Fig. 3 is a schematic diagram of the D-RMB transaction process related to the embodiment of the present invention.

During user registration, there are mainly the following processes: after receiving the identity information sent by the terminal device used by the user, the central bank digital currency system sends the application software applicable to the terminal device to the terminal device; The system sends the IBC public key and IBC private key to the terminal device running the application software, and then conducts an identity authentication session and session key negotiation with the terminal device; the central bank digital currency system receives the The user account sent by the terminal device, and then send the user password to the terminal device.

Taking user 1 to pay 50 yuan digital currency D _{coin 50} online to user 2 as an example, to illustrate the security protocol when the transfer of D _{coin 50} is involved in the transaction process. User 1 logs in to his own mobile APP, completes the two-party identity authentication with the D-RMB system, and negotiates the session key in SSL mode, then executes the transaction agreement. Taking the mobile phone number as the IBC public key as an example, on the mobile client of user 1: the mobile client automatically selects 50 yuan of digital currency D _{coin 50} , and organizes relevant information M‖m according to the transaction rules, where M can be designed as: M=transaction Code ‖Mobile phone number 1‖D _{coin 50} ‖Payment amount‖Mobile phone number 2, hash the information segment to get message H(M), sign H(M) with the private key corresponding to mobile phone number 1 to get m, and encrypt Send M∥m to the D-RMB system.

D-RMB system side: decrypt the message according to the protocol to get M‖m, verify the validity of the message, that is, verify m and H(M) with the public key, that is, the mobile phone number 1, to prevent the message from being tampered with during transmission; verify D Whether the _{currency 50} is legal, interpret the transaction rules and related information, and perform corresponding operations, mainly including changing the owner of the D _{currency 50} after the business verification, changing the bound mobile phone number 1 to mobile phone number 2, and recording the corresponding transaction. Send D _{coin 50} to mobile phone 2, and prompt both parties that the transaction is successful.

In order to further enhance anonymity, the mobile phone number corresponding to the ownership of the registration center can be changed to the hash of the mobile phone number (that is, referring to the Bitcoin wallet address, which is composed of public key hashes), the specific description is as follows:

The client organization message remains unchanged. On the mobile phone client of user 1: automatically select 50 yuan of digital currency D _{coin 50} , and organize relevant information M‖m according to the transaction rules, where M can be designed as M=transaction code‖mobile phone number 1‖ D _{coin 50} ‖Payment amount‖Mobile phone number 2, hash the information segment to get message H(M), sign H(M) with the private key corresponding to mobile phone number 1 to get m, and send M‖m to D-RMB system.

D-RMB system side: decrypt the message according to the protocol to get M‖m, verify the validity of the message, that is, verify m and H(M) with the public key, that is, the mobile phone number 1, to prevent the message from being tampered with during transmission; verify D Whether the _{currency 50} is legal, interpret the transaction rules and related information, and perform corresponding operations, mainly including changing the owner of the D _{currency 50} after business verification by the registration center, changing the bound H (mobile phone number 1) to H (mobile phone number 2), and Record the corresponding flow. Send D _{coin 50} to mobile phone 2, and prompt both parties that the transaction is successful.

Regarding the design of system convenience, in the embodiment of the present invention, there are various interfaces and entrances for transactions. In the process of scenario example, only one entrance is used as an example. For example, if a registered user handles business at a commercial bank, the user can directly log in to the D-RMB system with a mobile phone, or the commercial bank can log in to the D-RMB system.

Regarding the issue of account passwords, you can flexibly design whether users are required to enter account passwords according to business needs. Since the D-RMB system is a micro-payment system, it is suggested that users can freely choose whether to set a password. In the description of the embodiment of the present invention, it is described as not leaving a password, but in implementation, it can be determined according to the actual situation.

Regarding the client application program, users can download the corresponding client application program on their corresponding terminals (this type of terminal software is equivalent to a "wallet" tool), such as mobile phone users can download the D-RMB mobile phone terminal program (also called for mobile APP). The terminal program can be designed to include the following functions: one is the D _coin management function. (1) The terminal program can automatically count the amount of all D _coins ; (2) It can automatically find the combination of D _coins in the "wallet" according to the amount input by the user, and automatically select the matched D _coins for transaction during the payment process (3) After the transaction is completed, the D _coins involved in the payment will be automatically deleted; (4) It can automatically distinguish between digital currencies that have not been verified online by the central bank in the "wallet" and digital currencies that have been verified and registered. The second is to complete the functions required by the business, such as online registration application, withdrawal, payment, cashing, offline payment request and other business functions, as well as automatically complete public key encryption, private key signature and other operations during the transaction process.

In general, the core elements of the D-RMB system are one currency, two types of libraries, and three centers:

A currency, namely "D-RMB", also known as D _currency , specifically refers to a string of encrypted digital strings signed by the central bank representing a specific amount.

Two types of libraries: D-RMB issue library and bank library. In the issuance library, the digital currency is represented as the digital currency fund of the central bank; in the bank library, the digital currency is represented as the inventory digital cash of commercial banks.

Three centers: one is the registration center (including records of the whole process of currency generation, circulation, inventory verification, and extinction); the other two are certification centers, namely CA certification centers (based on the PKI system, centralized management of organization and user certificates, such as CFCA) and the IBC certification center, that is, the certification center (Identity-Based Cryptograph) established based on identity-based cryptographic technology. Two tables can be designed in the registration center, one is the digital currency ownership registration table, which records the ownership of digital currency, and the other is the transaction flow table.

The identity-based cryptographic system IBC in the embodiment of the present invention can directly use the identity of the user as the public key, and the authentication of the public key no longer depends on the certificate, which simplifies the use and management of the key, and has the advantages of no directory, convenient use, and easy maintenance and other advantages.

For identity identification, individual users can use a mobile phone number, or an E-mail address that matches the mobile phone or other transformed strings, which is convenient for the customer to remember, and others cannot know), so as to achieve the purpose of controllable anonymity. Enterprise users can use the organization code or a custom code as the identity of the IBC center as the public key. In the following examples, only the mobile phone number is used as an example for convenience.

The D-RMB system is a hierarchical system, which is jointly established by the central bank and various commercial banks. The central bank digital currency system is a computer operated and maintained by the central bank or a designated institution of the central bank to process information about digital currency. The main functions of the system include the issuance and verification monitoring of digital currency. Commercial banks are computer systems operated and maintained by commercial banks or institutions designated by commercial banks to process information about digital currencies. Various functions, that is, banking functions, mainly include that after applying for digital currency from the central bank, it is responsible for directly facing the society and meeting the various needs of providing digital currency circulation services.

In the basic structure of the digital currency system according to the embodiment of the present invention, the digital currency system mainly includes a central bank digital currency system, a commercial bank digital currency system (in practice, it may be multiple commercial bank digital currency systems), and an authentication system. Among them, the central bank's digital currency system is used to generate and issue digital currency, and register the ownership of digital currency; the commercial bank's digital currency system is used to perform banking functions for digital currency; the authentication system is used to verify the central bank's digital currency system and digital Authentication is provided for interactions between terminal devices used by currency users, and for interactions between the central bank digital currency system and the commercial bank digital currency system.

Fig. 4 is a schematic diagram of a structure of the overall framework when the D-RMB digital currency system provides online services according to the embodiment of the present invention.

In the overall framework shown in Figure 4, the core of the D-RMB digital currency operation is the commercial bank digital currency system, and the central bank D-RMB system is connected to the commercial bank D-RMB system to be responsible for transaction confirmation. Both the D-RMB system of commercial banks and the D-RMB system of the central bank can make full use of advanced cloud technology for decentralized deployment, and at the same time, the D-RMB system of commercial banks is interconnected with its internal systems.

It can be seen from the figure that the commercial bank digital currency system is at the core and connected to other networks or systems, and can be constructed using "cloud computing" technology. The D-RMB digital currency system supports network data of various protocols, such as: virtual private network VPN, dedicated line, satellite network, public switched telephone network (PSTN), global system for mobile communications (GSM), public land mobile network (PLMN) , each network can be directly or indirectly connected to the central server.

The commercial bank's digital currency system is connected to the central bank's registration center, and it also has four basic functional modules: an electronic wallet function module that automatically tracks how much D-RMB digital currency the account has, and automatically tracks the transfer of D-RMB digital currency between parties and identifies suspicious Transaction supervision function module, electronic banking service function and customer relationship management CRM function module.

The logical layout of the server in the commercial bank digital currency system adopts a three-tier architecture: the presentation layer, which is the front-end application system 200; the back-end application system 202, also called the session layer, application layer, or transaction logic layer; the back-end database 204 is a data layer. Its corresponding physical machine deployment block diagram is shown in Figure 5, which is a schematic diagram of the computer system included in the commercial bank digital currency system according to the embodiment of the present invention.

The front-end application system 200 is used to run applications for direct interaction between users and money transfer service operators, such as web applications, where a cluster of web servers is deployed. Users and money transfer service operators interact with these applications through user interfaces such as personal computing devices 114, mobile devices, and the like. Users can access the electronic wallet function, supervision function, virtual bank function, and CRM function through this entrance. Open source software such as apache can be used on the Web server.

The back-end application system 202 is mainly used to support background functions such as data access and business logic processing of the front-end application system 200 . Application servers are deployed in this area. D-RMB digital currency can use the JBOSS tool under the Red Hat open source system to develop applications.

The background database 204 is mainly a database management system DBMS, including a data warehouse, which stores sales transactions of transferred currency, customer files, and other data required for tracking and adjusting the central bank's digital currency system for D-RMB digital currency transfer. The D-RMB digital currency system can be designed with Oracle's DBMS as the database system.

The above commercial bank digital currency system can be interconnected with external systems. An optional architecture is shown in FIG. 6 , which is a schematic diagram of an architecture for interconnecting a commercial bank digital currency system with external systems according to an embodiment of the present invention.

The figure above demonstrates the physical and logical layout of the commercial bank's digital currency system and various external system adapters including the central bank's central server and other commercial banking systems. There are currency transaction data adapters, mobile service provider SMS gateway adapters, retailer system adapters, ATM data supply system adapters, etc. Through this interconnection, the central server can accept digital currency transfer requests and responses from each type of entity. Figure 6 fully demonstrates the good support of the D-RMB digital currency system for various channels and different protocol networks, which is also a manifestation of the openness of the system.

The following will use the user's mobile phone as the terminal mode, and use the mobile phone number as the identity to explain the various business processes of operating D-RMB, mainly including the processes of client download and login, withdrawal, payment, deposit and cashing, and face-to-face transactions to explain. The user's client login, withdrawal, and redemption processes require that the user must complete it in an online state, and the payment process can be divided into online payment and offline payment, thus forming multiple scene states and their corresponding processes. The purpose of each process is It is realized by a series of operation steps. In addition to mobile phones, other smart terminals that may appear at present and in the future can be used as D-RMB carriers and perform various business processes.

The outline of the process (hereinafter referred to as "process description"), the state of the scene (hereinafter referred to as "scene description") and the steps to realize the process in this scenario (hereinafter referred to as "step description") are described below.

Regarding user client download and login, follow the procedure below:

Process Description: The user downloads the APP installation program provided by the commercial bank through the mobile phone to log in to the D-RMB system.

Scenario description: Qualified commercial banks (such as Industrial and Commercial Bank of China) connect CA certification center, IBC certification center and registration center to provide digital currency services to users. The user downloads the APP installation program provided by the commercial bank to log in to the commercial bank's D-RMB system through the mobile phone.

Step description:

Step 1. The user logs in to the D-RMB system page of a commercial bank (such as Industrial and Commercial Bank of China) with a mobile phone, and downloads the mobile APP installation program provided by the commercial bank. For users who have an existing account (IBC Authentication Center), they can log in directly; for new users Users need to perform account initialization operations first.

Step 2. Initialization: Enter relevant information on the page (such as name, address, e-mail address, mobile phone number, ID card number, registered account or mobile phone number, etc.), and click send.

Step 3. Commercial bank: connect to the IBC authentication center, create a unique account number for the D-RMB digital currency system for the user, and verify its uniqueness at the IBC center. Individual users can use their mobile phone number to generate the user's initial login password and send it to the user's mobile phone; the IBC center generates the user's private key based on the mobile phone number, the public key is the user's mobile phone number, and the public key is used as the account number for transaction circulation.

Step 4. User's mobile phone: After receiving the initial login password, activate the account, download the user's private key and central bank public key to the mobile phone security protection area, and log in to the mobile APP again to modify the login password and complete the initialization.

If the user applies for changing the mobile phone card, the key can be pre-planted in the SE area of the card in advance.

The digital currency payment method and payment system in the embodiments of the present invention will be further described in detail below.

Fig. 7 is a schematic diagram of main steps of a digital currency payment method according to an embodiment of the present invention. As shown in FIG. 7 , the digital currency payment method according to the embodiment of the present invention may include the following steps A1 to A6. In the method of this embodiment, the payee may be a non-registered user of the commercial bank. A non-registered user means that the user has not registered in the digital currency system of the commercial bank, but still downloads the mobile client terminal developed by the commercial bank on the mobile phone. The method in this embodiment is applicable to the digital currency payment system in the embodiment of the present invention.

Step A1: The payer terminal device receives the payment amount, payee ID and withdrawal identification code input by external operations.

Assuming that the payer is user 1, the terminal device of the payer is the mobile client of user 1; the payee is user 3, and the payee is the mobile client of user 3. The identifier of the payee may be the mobile phone number of the user 3 . Withdrawal identification code is the character string used by the payee to verify identity when going to the counter of a commercial bank or self-service withdrawal machine of a commercial bank in the future after the payee successfully collects money.

The specific process of Step A1 is as follows: User 1 logs in to his mobile client, selects the function "offline payment to registered users", and then enters the payment amount (for example, 50 yuan), the payee's identification (for example, user 3's mobile phone number) and withdrawal An identification code (such as a PIN). This means that the terminal device of the payer has received the offline payment instruction including the payment amount and the identification of the payee.

Step A2: The payer's terminal device selects digital currency whose total amount is equal to the payment amount in the payer's digital currency wallet.

If there is a piece of digital currency D _{coin 50} with an amount of 50 yuan in the digital currency wallet of user 1, then select this digital currency.

Step A3: The terminal device of the payer sends the digital currency and the withdrawal identification code to the terminal device of the payee corresponding to the identifier of the payee by means of near field communication.

Specifically, the payer terminal device can organize relevant information according to preset transaction rules, generate the first transaction information including the digital currency D _{coins 50} and the withdrawal identification code PIN, and then send it to the payee terminal corresponding to the payee identification equipment.

It should be noted that the specific form of the NFC (Near Field Communication) mode can be flexibly set. Optionally, in order to enhance confidentiality, the digital currency and withdrawal identification code can be signed with the payer's IBC (Identity-Based Cryptograph) private key and encrypted with the payee's ID.

Optionally, before performing step A4, the payee terminal device performs the following first verification: the payee terminal device verifies the legitimacy of the digital currency; the payee terminal device verifies whether the digital currency is equivalent to the payment amount. It should be noted that the specific content of the first transaction information and the first verification can be flexibly set according to the transaction rules, which are only examples and not limitations of the present invention. The process of the first verification can be completed offline. If the first verification is passed, the payee's terminal device (that is, the mobile phone client of user 2) starts to wait for networking and prepares to upload relevant transaction information, and then executes step A4. If the first verification fails, the flow ends.

Step A4: The terminal device of the payee sends the digital currency and the withdrawal identification code to the digital currency system of the commercial bank through the network.

Specifically: when the terminal device of the payee is successfully connected to the network, the terminal device of the payee organizes relevant information according to the preset transaction rules, and generates the second transaction information including the digital currency D _{coin 50} and the withdrawal identification code PIN, Then send the second transaction information to the digital currency system of the commercial bank through the network.

Optionally, before performing step A5, the commercial bank digital currency system performs the following second verification: the commercial bank digital currency system verifies the legality of the digital currency; the commercial bank digital currency system verifies whether the digital currency is equivalent to the payment amount; the commercial bank digital currency system verifies whether the digital currency is equivalent to the payment amount; The bank's digital currency system verifies whether the payee is a non-registered user of the commercial bank. It should be noted that the specific content of the second transaction information and the second verification can be flexibly set according to the transaction rules, which are only examples and not limitations of the present invention. If the second verification is passed, step A5 is executed. If the second verification fails, the flow ends.

Step A5: The digital currency system of the commercial bank sends the digital currency and the withdrawal identification code to the digital currency system of the central bank through the network.

Specifically: the commercial bank digital currency system organizes relevant information according to the preset transaction specifications, generates the third transaction information including the digital currency D _{coin 50} and the withdrawal identification code PIN, and then sends the third transaction information to the central bank through the network digital currency system.

Optionally, before performing step A6, the central bank digital currency system performs the following third verification: the central bank digital currency system verifies whether the owner of the digital currency is the payer. It should be noted that the specific content of the third transaction information and the third verification can be flexibly set according to the transaction rules, which are just examples and not limitations of the present invention. If the third verification is passed, execute step A6. If the third verification fails, end the process

Step A6: The central bank's digital currency system changes the owner information of the digital currency from the payer to the payee and notes the withdrawal identification code.

Specifically: the central bank digital currency system changes the owner information of the digital currency D _{coin 50} from the payer user 1 to the payee user 3 and notes the withdrawal identification code PIN.

It should be noted that after the central bank's digital currency system changes the owner information of the digital currency and notes the withdrawal identification code, it can also record the transaction flow.

In order for the payer and the payee to get the feedback that the transaction is successful, after step A6, the following step A7 and step A8 may also be included (not shown in FIG. 6 ).

Step A7: The central bank's digital currency system sends the first transaction success notification to the commercial bank's digital currency system.

Step A8: The digital currency system of the commercial bank sends a second transaction success notification to the payer terminal device and the payee terminal device respectively according to the first transaction success notification.

Fig. 8 is a schematic diagram of main modules of a digital currency payment system according to an embodiment of the present invention. As shown in Figure 8, the digital currency payment system B in the embodiment of the present invention may include a payer terminal device B1, a payee terminal device B2, a commercial bank digital currency system B3 and a central bank digital currency system B4. The payee may be a non-registered user of the commercial bank.

The payer's terminal device B1 is used to: receive the payment amount, payee's identification, and withdrawal identification code input by external operations; select digital currency whose total amount is equal to the payment amount in the payer's digital currency wallet; convert the digital currency and withdrawal identification code into a field communication to the payee terminal device B2 corresponding to the payee ID.

The terminal device B2 of the payee is used to: send the digital currency and the withdrawal identification code to the digital currency system B3 of the commercial bank through the network.

The commercial bank digital currency system B3 is used to: send the digital currency and withdrawal identification code to the central bank digital currency system B4 through the network.

The central bank digital currency system B4 is used to: change the owner information of the digital currency from the payer to the payee and note the withdrawal identification code.

Optionally, the central bank digital currency system B4 is also used to: send the first transaction success notification to the commercial bank digital currency system B3; the commercial bank digital currency system B3 is also used to: according to the first transaction success notification, respectively pay The terminal device B1 of the party and the terminal device B2 of the payee send the second transaction success notification.

Optionally, the central bank digital currency system B4 is also used for: recording transaction flow.

Optionally, the payee terminal device B2 is also used to: confirm that the digital currency is legal; confirm that the digital currency is equivalent to the payment amount.

Optionally, the commercial bank digital currency system B3 is also used to: confirm that the digital currency is legal; confirm that the digital currency is equivalent to the payment amount; confirm that the payee is a non-registered user of the commercial bank.

Optionally, the central bank digital currency system B4 is also used to: confirm that the owner of the digital currency is the payer.

Optionally, the digital currency and the withdrawal identification code are signed with the payer's private key based on the identity-based cryptographic technology, and encrypted with the payee's identity.

The following describes the duplicate transaction detection. In the case of online transactions, the D-RMB system prevents repeated transactions through the binding of D _coins and user accounts. The registration center in the D-RMB system has an ownership registration form, and the style of the record form can be designed as shown in Table 1:

Table 1

digital currency name Owner Remark Pbc100adfkl09987766670 138xxxxx001 D _{coin 100} ... ... ... Pbc50cadfkl09987766670 137xxxxx002 D _{coin 50}

When user 1 (mobile phone number 138xxxxx001) pays D _{coin 100} to user 2 (mobile phone number 138xxxxx002), the ownership registration form of the D-RMB system registration center: change the corresponding owner of D _{coin 100} , and replace the owner field with the original mobile phone number 138xxxxx001 Change the wallet address of the mobile phone number 138xxxxx002 to the wallet address of mobile phone number 138xxxxx002. If user 1 still wants to pay other users with D _{coins 100} , the owner is not user 1 at this time, and the payment cannot be completed, so as to prevent repeated payments.

If the ownership registration table of the registration center in the D-RMB system uses the public key hash to represent the owner, the ownership registration table of the registration center can be designed as shown in Table 2:

Table 2

Suppose the value of H(138xxxxx001) is 1Xadcfdgdadg, and the value of H(138xxxxx002) is 2xcfdald3xgdf. When user 1 (mobile phone number 138xxxxx001) pays D _{coin 100} to user 2 (mobile phone number 138xxxxx002), the ownership registration form of D-RMB system registration center : Change the corresponding owner of D _{coin 100} , and change 1Xadcfdgdadg in the owner field to 2xcfdald3xgdf. If user 1 still wants to use D _{coin 100} to pay other users, the owner is no longer user 1 and cannot complete the payment. Prevent double payment.

In the case of offline transactions, it is discovered and held accountable by delaying the double payment check. At present, almost all electronic cash systems perform double payment checks with a lag, that is, the double payment check is performed after the payment process is completed.

At the same time, we set the transaction as a small payment (less than 1,000 yuan), which is an acceptable range for individual users, and adopts an after-the-fact accountability mechanism, and bad records will be entered into the credit investigation system for punishment.

It can be seen from the above that the digital currency payment method and payment system according to the embodiment of the present invention adopts digital currency at the source of the currency, so the whole process can be virtual and non-physical, has the advantages of green environmental protection, and completely avoids carrying Inconvenient downside. And because digital currency is used at the source of currency, the digital currency payment method and payment system in the embodiment of the present invention have the advantages of high anti-counterfeiting performance and anti-money laundering. Compared with the prior art, the technical solution of the embodiment of the present invention can omit the steps of opening a card, recharging, returning the card, or the payee goes to a commercial bank to open an account, saving the time and effort of all parties involved in the transaction. In addition, the payee can be a non-registered user of the bank, and the scope of application is wider.

In terms of convenience, the mobile phone as the terminal carrier solution (hereinafter referred to as the "mobile phone solution") provides more implementation methods and means of use, the system is convenient to deploy, the user operation is convenient, and it is easier to promote.

From the perspective of security, using mobile phones as D-RMB carriers, HCE and TEE solutions can be used to provide larger storage space, not completely dependent on hardware manufacturers, and more convenient to promote.

Compared with other currency systems that replace banknotes in the market, D-RMB initially has the characteristics of good convenience and high security. The convenience is reflected in the following aspects:

In terms of issuance method, D-RMB is the digitization of the currency itself, without relying on any bank account and single network;

In terms of storage methods, the storage medium of D-RMB can be mobile phones, or electronic devices such as cards, disks, and computers, providing users with a variety of options. In particular, the D-RMB based on the mobile phone can make full use of the keyboard, display, positioning, storage, calculation, communication and other functions of the mobile phone, and can also be re-developed to greatly expand the payment scenarios and convenience;

In terms of payment methods, it can not only provide face-to-face payment transactions similar to banknotes, but also provide network remote payment transactions similar to electronic payment systems, which can support online or offline transactions, and the method is convenient and flexible;

In terms of transaction speed, the payment speed is greatly improved compared with the online credit card payment method. Very suitable for small and fast payments;

In terms of usage habits, it is compatible with the original card payment method, and can also provide face-to-face digital currency payment. At the same time, it can also provide electronic transaction records, which is convenient for financial statistics and has high user acceptance.

Safety is manifested in the following aspects:

Compared with other digital currency systems, D-RMB digital currency is a series of electronic encryption serial numbers converted from cash values, and payment transactions are completed through the transfer of these encrypted serial numbers. The security of the currency itself is protected by a cryptographic algorithm, which can effectively guarantee the confidentiality and integrity of the currency information, with high security;

The security of the D-RMB digital currency carrier uses chip technology in the mobile terminal and trusted technology in the background cloud to achieve end-to-end security;

On the one hand, the security of the D-RMB digital currency transaction system relies on the traditional electronic payment system security technology, and at the same time, the powerful D-RMB cloud computing system is used in the background to further guarantee the transaction security;

In terms of user privacy protection, the method of "voluntary at the front desk and real name at the background" not only ensures user privacy, but also avoids the risk of illegal transactions.

The above specific implementation methods do not constitute a limitation to the protection scope of the present invention. It should be apparent to those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (14)

1. A digital currency payment method, characterized in that it comprises: The payer terminal device receives the payment amount, payee ID and withdrawal identification code input by external operations; The payer's terminal device selects a digital currency whose total amount is equal to the payment amount in the payer's digital currency wallet; The payer terminal device sends the digital currency and the withdrawal identification code to the payee terminal device corresponding to the payee identification by means of near field communication; The payee terminal device sends the digital currency and the withdrawal identification code to the commercial bank digital currency system through the network; The digital currency system of the commercial bank will include the digital currency and the withdrawal identification code and send it to the central bank digital currency system through the network; The central bank digital currency system changes the owner information of the digital currency from the payer to the payee and notes the withdrawal identification code. 2. The digital currency payment method according to claim 1, further comprising: The central bank digital currency system sends a first transaction success notification to the commercial bank digital currency system; The commercial bank digital currency system sends a second transaction success notification to the payer terminal device and the payee terminal device respectively according to the first transaction success notification. 3. The payment method of digital currency according to claim 1, characterized in that, in the central bank digital currency system, the owner information of the digital currency is changed from the payer to the payee and the withdrawal identification code is remarked After the steps, also include: The central bank digital currency system records transaction flow. 4. The payment method of digital currency according to claim 1, characterized in that, before the step of the payee terminal device sending the digital currency and withdrawal identification code to the digital currency system of a commercial bank through the network, further comprising: : The payee terminal device confirms that the digital currency is legal; The payee terminal device confirms that the digital currency is equivalent to the payment amount. 5. The payment method of digital currency according to claim 1, wherein the commercial bank digital currency system further includes: The digital currency system of the commercial bank confirms that the digital currency is legal; The digital currency system of the commercial bank confirms that the digital currency is equivalent to the payment amount; The commercial bank digital currency system confirms that the payee is a non-registered user of the commercial bank. 6. The payment method of digital currency according to claim 1, characterized in that, the central bank digital currency system changes the owner information of the digital currency from the payer to the payee and notes the step of withdrawal identification code Previously, also included: The central bank digital currency system confirms that the owner of the digital currency is the payer. 7. The payment method of digital currency according to claim 1, characterized in that, the digital currency and the withdrawal identification code are signed using the private key of the payer's identity-based cryptographic technology, and the payee uses the Identity encryption. 8. A digital currency payment system, characterized in that it includes: a payer terminal device, a payee terminal device, a commercial bank digital currency system and a central bank digital currency system, wherein: The payer's terminal device is used to: receive the payment amount input by external operations, the payee's identification, and the withdrawal identification code; select a digital currency whose total amount is equal to the payment amount in the payer's digital currency wallet; transfer the digital currency and the cash withdrawal identification code are sent to the payee terminal device corresponding to the payee ID by means of near field communication; The payee terminal device is used to: send the digital currency and withdrawal identification code to the commercial bank digital currency system through the network; The commercial bank digital currency system is used to: send the digital currency and withdrawal identification code to the central bank digital currency system through the network; The central bank digital currency system is used to: change the owner information of the digital currency from the payer to the payee and note the withdrawal identification code. 9. The digital currency payment system according to claim 8, characterized in that, The central bank digital currency system is also used to: send a first transaction success notification to the commercial bank digital currency system; The commercial bank digital currency system is further configured to: send a second transaction success notification to the payer terminal device and the payee terminal device respectively according to the first transaction success notification. 10. The digital currency payment system according to claim 8, wherein the central bank digital currency system is also used for: recording transaction flow. 11. The digital currency payment system according to claim 8, wherein the payee terminal device is also used for: confirm that said digital currency is legal; Confirm that said digital currency is equivalent to said payment amount. 12. The digital currency payment system according to claim 8, wherein the commercial bank digital currency system is also used for: confirm that said digital currency is legal; confirm that said digital currency is equivalent to said payment amount; Confirm that the payee is a non-registered user of the commercial bank. 13. The digital currency payment system according to claim 8, wherein the central bank digital currency system is also used for: Confirm that the owner of the digital currency is the payer. 14. The digital currency payment system according to claim 8, wherein the digital currency and the withdrawal identification code are signed using the payer's private key based on identity-based cryptographic technology, and the payee uses the Identity encryption.