A Quantum-Computing-Resistant Anonymous Double-Offline Transaction Method and System for Digital Currency

Abstract

The present invention discloses a quantum computing-resistant anonymous dual offline transaction method and system for digital currency. The method comprises: a central bank digital currency system issuing quantum computing-resistant digital currency and quantum computing-resistant digital certificates based on ID cryptography to a payment terminal and a payment terminal, respectively; and a key management server issuing private keys based on ID cryptography to the payment terminal and the payment terminal, respectively; conducting a dual offline transaction between the payment terminal and the payment terminal via a trusted intermediary; and confirming the transaction using the central bank digital currency system. Beneficial Effects: The present invention designs digital currency equipped with private keys and a trusted intermediary for transactions, which can implement a quantum computing-resistant anonymous dual offline transaction method for digital currency, so that the two parties in the dual offline transaction do not know each other's information, thereby protecting the identity information of the traders.

Description

Technical Field

[0001] The present invention relates to the field of digital currency, and in particular to a quantum computing-resistant anonymous dual-offline transaction method and system for digital currency. Background Art

[0002] The core elements of the People's Bank of China's digital currency (D-RMB) system are one currency, two repositories, and three centers. The currency, "D-RMB" (DC / EP), or D-coin for short, refers to an encrypted digital string representing a specific amount signed by the central bank. The two repositories are the D-RMB issuing repository and the bank repositories (the central bank's digital currency database and the commercial bank's digital currency database). The digital currency in the issuing repository represents the central bank's digital currency fund; the digital currency in the bank repositories represents the commercial bank's digital cash reserves. The three centers are: a registration center (which records the entire process of currency generation, circulation, inventory verification, and expiration); and certification centers: a CA certification center (based on the PKI system, centrally managing institution and user certificates, such as CFCA) and an IBC certification center (an identity-based cryptography certification center). The registration center can maintain two tables: a digital currency ownership registration table, which records digital currency ownership, and a transaction flow table.

[0003] The D-RMB system is a hierarchical system, jointly built by the central bank and commercial banks. The central bank digital currency system is a computer system operated and maintained by the central bank or an institution designated by the central bank to process information about digital currency. Its main functions include being responsible for the issuance and verification monitoring of digital currency. The commercial bank digital currency system is a computer system operated and maintained by commercial banks or institutions designated by commercial banks to process information about digital currency. It performs various currency-related functions of existing banks, namely banking functions, which mainly include being directly facing the society and meeting various needs of providing digital currency circulation services after applying for digital currency from the central bank.

[0004] Patent CN201911053809 discloses an anonymous transaction method and system based on digital currency, but this method and system have some problems: only online transactions can be carried out, and the user's temporary identity can only be used to carry out subsequent transaction processes if it is recognized by its own server. When the user cannot communicate with its own server, the payee of this method cannot use the user's temporary identity to verify its digital signature for the transaction (in a mathematical signature based on a digital certificate, since the user needs to hide his true identity, he cannot provide a digital certificate containing his true identity, and cannot prove the association between his temporary identity and his digital certificate, so he cannot use his digital certificate to verify his digital signature for the transaction; in a mathematical signature based on ID cryptography, since the user needs to hide his true identity, he cannot provide his true identity, and cannot prove the association between his temporary identity and his true identity, so he cannot use his true identity to verify his digital signature for the transaction). Therefore, the payee cannot recognize the legitimacy of the transaction and complete the entire transaction process without receiving any identity credentials from the sender.

[0005] Based on the above analysis, the existing technology of digital currency communication system has the following defects:

[0006] 1. Most existing digital currency transaction methods based on digital certificates or user IDs expose user identities;

[0007] 2. Existing digital currency anonymous transaction methods based on digital certificates or user IDs can guarantee user anonymity, but cannot perform anonymous transactions when both the sender and the recipient are offline (i.e., dual offline).

[0008] 3. Existing digital currency transaction methods are not resistant to quantum computing. Summary of the Invention

[0009] In response to the problems in the related technology, the present invention proposes a quantum computing-resistant anonymous dual offline transaction method and system for digital currency to overcome the above-mentioned technical problems existing in the existing related technology.

[0010] To this end, the specific technical solutions adopted in the present invention are as follows:

[0011] According to one aspect of the present invention, a method for quantum computing-resistant anonymous dual offline transaction of digital currency is provided, the method comprising the following steps:

[0012] S1. Preparation stage: The central bank digital currency system issues quantum computing-resistant digital currency and quantum computing-resistant digital certificates based on ID cryptography to the issuing terminal and the receiving terminal respectively, and issues private keys based on ID cryptography to the issuing terminal and the receiving terminal respectively through the key management server;

[0013] S2, dual offline transaction stage: the sending terminal and the receiving terminal conduct dual offline transactions through a trusted intermediary;

[0014] S3. Online transaction stage: Use the central bank digital currency system to confirm the transaction;

[0015] The S1 central bank digital currency system issues quantum computing-resistant digital currencies based on ID cryptography to the payment terminal and the payment terminal respectively, which specifically includes the following steps:

[0016] The payment terminal / payment terminal generates a set of public-private key pairs based on the RSA or ECC cryptographic system, and sends the public key to the corresponding commercial bank. The corresponding commercial bank sends the public key to the central bank digital currency system. The central bank digital currency system generates quantum computing-resistant digital currencies of corresponding various currency values and ID cryptography-based private keys corresponding to the ID of the digital currency based on the public key and currency value, and sends the digital currency and the ID cryptography-based private key to the corresponding commercial bank. The corresponding commercial bank then sends the digital currency and the ID cryptography-based private key to the corresponding user terminal.

[0017] Furthermore, the dual offline transaction between the payment sending terminal and the payment receiving terminal in S2 through a trusted intermediary includes the following steps:

[0018] S21. The trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal, and the payment terminal verifies the digital certificate.

[0019] S22. The payment terminal sends the first combination information to the trusted intermediary, and the trusted intermediary verifies the first combination information;

[0020] S23. The trusted intermediary sends the second combination information to the payment terminal, and the payment terminal verifies the second combination information;

[0021] S24. The payment terminal sends the transaction to the payment terminal;

[0022] S25. The payment terminal confirms the transaction.

[0023] Furthermore, in S21, the trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal, and the payment terminal verifies the digital certificate, specifically including the following steps:

[0024] S211. The trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal;

[0025] S212. After receiving the certificate, the payment terminal uses the public key of the central bank's digital currency system to decrypt the encrypted signature in the trusted intermediary's anti-quantum computing digital certificate and verifies the decrypted signature. If the verification is successful, the payment terminal recognizes the trusted intermediary as the owner of the trusted intermediary's anti-quantum computing digital certificate and proceeds to subsequent steps.

[0026] Furthermore, in S22, the payment terminal sends the first combination information to the trusted intermediary, and the trusted intermediary verifies the first combination information, specifically including the following steps:

[0027] S221. The payment terminal generates a temporary public-private key pair based on the RSA or ECC cryptographic system and calculates the first symmetric key between the terminal and the trusted intermediary;

[0028] S222. Use the payment terminal private key to sign the temporary public key of the payment terminal and the first timestamp based on ID cryptography to obtain first signature information. Use the first symmetric key to encrypt the temporary public key of the payment terminal and the first signature information to obtain first encrypted information. Combine the encrypted information with the first timestamp and the quantum computing resistant digital certificate of the payment terminal to form first combined information. Send the first combined information to the trusted intermediary.

[0029] S223. After receiving the first combined information, the trusted intermediary confirms that the first timestamp is the current time, decrypts the encrypted signature in the quantum computing resistant digital certificate of the payment terminal using the central bank digital currency system public key, and verifies the decrypted signature. After verification, it confirms that the quantum computing resistant digital certificate of the payment terminal is legitimate and the payment terminal ID contained therein is valid.

[0030] S224. Calculate a second symmetric key between the trusted intermediary and the payment terminal;

[0031] S225. Decrypt the first encrypted information using the second symmetric key to obtain the temporary public key of the payment terminal and the first signature information, and verify the signature information using the public key of the payment terminal. If the verification is successful, the trusted intermediary recognizes the identity of the payment terminal.

[0032] The calculation of the first symmetric key between the party and the trusted intermediary in S221 specifically includes the following steps: the payment terminal obtains the first timestamp, calculates the public key of the trusted intermediary, and simultaneously takes out the payment terminal private key based on ID cryptography, and calculates the first symmetric key.

[0033] Furthermore, in S23, the trusted intermediary sends the second combination information to the payment terminal, and the payment terminal verifies the second combination information, specifically including the following steps:

[0034] S231. Calculate the third symmetric key between the trusted intermediary and the payment terminal;

[0035] S232. Sign the temporary public key of the payment terminal and the second timestamp using the trusted intermediary private key to obtain second signature information, encrypt the temporary public key of the payment terminal and the second signature information using the third symmetric key to obtain second encrypted information, and combine the second encrypted information with the second timestamp and the trusted intermediary quantum computing-resistant digital certificate to form second combined information, which is then sent to the payment terminal.

[0036] S233. After receiving the second combined information, the payment terminal confirms that the second timestamp is the current time, decrypts the encrypted signature in the trusted intermediary quantum computing-resistant digital certificate using the central bank digital currency system public key, and verifies the decrypted signature.

[0037] S234. Calculate the fourth symmetric key between the payment terminal and the trusted intermediary;

[0038] S235. Use the fourth symmetric key to decrypt the second encrypted information to obtain the temporary public key of the payment terminal and the second signature information, and verify the signature information with the public key of the trusted intermediary. If the verification is successful, the payment terminal recognizes the trusted intermediary as the owner of the trusted intermediary quantum computing-resistant digital certificate and recognizes the temporary public key of the payment terminal as the payee ID and public key.

[0039] Furthermore, in S24, the sending terminal sends the transaction to the receiving terminal, specifically including the following steps:

[0040] S241. The payment terminal takes out a quantum computing-resistant digital currency, obtains a third timestamp, and combines the third timestamp, the payment party's commercial bank ID, the second combination information, and the quantum computing-resistant digital currency into a transaction;

[0041] S242. Sign the transaction using the RSA or ECC private key corresponding to the digital currency to obtain third signature information, and calculate the fifth symmetric key between the quantum computing-resistant digital currency and the payment terminal;

[0042] S243. Use the fifth symmetric key to encrypt the transaction and the third signature information to obtain third encrypted information, and send the third timestamp, the third encrypted information and the quantum computing resistant digital currency ID together to the payment terminal.

[0043] Furthermore, the payment terminal confirming the transaction in S25 specifically includes the following steps:

[0044] S251. After receiving the third timestamp, the third encrypted information, and the quantum computing-resistant digital currency ID, the payment terminal calculates a sixth symmetric key between the payment terminal and the quantum computing-resistant digital currency;

[0045] S252. The third encrypted information is decrypted using the sixth symmetric key to obtain the transaction and third signature information. The payment terminal extracts the encrypted public key in the quantum computing-resistant digital currency and decrypts it using the central bank digital currency system public key to obtain the RSA or ECC public key therein. The third signature information is then verified using the public key. If the verification is successful, the quantum computing-resistant digital currency is then verified. If the verification is successful, the transaction is trusted, the quantum computing-resistant digital currency in the transaction is extracted and stored, and marked as unconfirmed by the central bank.

[0046] S253. The payment terminal signs the transaction confirmation message using the temporary private key of the payment terminal to obtain fourth signature information, encrypts the transaction confirmation message and the fourth signature information using the sixth symmetric key, and sends the encrypted information to the payment terminal.

[0047] S254. After receiving the transaction confirmation message and the fourth signature information encrypted with the sixth symmetric key, the payment terminal decrypts them with the fifth symmetric key to obtain the transaction confirmation message and the fourth signature information, and uses the temporary public key of the payment terminal to verify the fourth signature information. If the verification is successful and the transaction confirmation message is successful, the quantum computing-resistant digital currency and its private key are deleted.

[0048] Furthermore, the use of the central bank digital currency system to confirm transactions in S3 specifically includes the following steps:

[0049] S31. The payment terminal sends the third combination of information to the beneficiary commercial bank, and the beneficiary commercial bank sends the payment terminal ID, transaction, and temporary public key of the payment terminal to the central bank digital currency system;

[0050] S32. After receiving the payment terminal ID, transaction and payment terminal temporary public keys, the central bank digital currency system stores the payment terminal ID, transaction and payment terminal temporary public keys locally, and encrypts the transaction and payment terminal temporary public keys with the public key of the payee's commercial bank and sends the encrypted data to the payee's commercial bank.

[0051] S33. After receiving the transaction and the temporary public key of the receiving terminal encrypted with the public key of the issuing commercial bank, the issuing commercial bank decrypts the encrypted transaction and the temporary public key of the receiving terminal with its own private key, locates the issuing terminal based on the quantum computing-resistant digital currency in the transaction, and obtains the issuing terminal ID. The issuing commercial bank stores the issuing terminal ID, the temporary public key of the receiving terminal, and the transaction as a complete transaction entry locally.

[0052] S34. The issuing commercial bank encrypts the issuing terminal ID and transaction results using the central bank digital currency system public key and sends them to the central bank digital currency system;

[0053] S35. The central bank digital currency system receives the payment terminal ID and transaction result encrypted with the central bank digital currency system public key and decrypts them to obtain the payment terminal ID and transaction result. If the transaction result is successful, the central bank digital currency system stores the payment terminal ID, payment terminal ID, and transaction as a complete transaction entry locally, and the central bank digital currency system encrypts the transaction result with the public key of the payee commercial bank and sends it to the payee commercial bank.

[0054] S36. The payee commercial bank receives the transaction result encrypted with the payee commercial bank's public key and decrypts it to obtain the transaction result. If the transaction result is successful, the payee commercial bank ID, the payee terminal ID, and the transaction are stored locally as a complete transaction entry. The transaction result is encrypted with the payee terminal's public key and sent to the payee terminal.

[0055] S37. The payment terminal receives the transaction result encrypted with the public key of the payment terminal and decrypts it to obtain the transaction result. If the transaction result is successful, the payment terminal marks the quantum computing-resistant digital currency as confirmed by the central bank.

[0056] Furthermore, in S31, the payment terminal sends the third combination of information to the payee commercial bank, and the payee commercial bank sends the payment terminal ID, transaction and temporary public key of the payment terminal to the central bank digital currency system, specifically including the following steps:

[0057] S311. The payment terminal obtains the fourth timestamp and extracts the transaction. It uses the payment terminal private key to sign the transaction, the payment terminal temporary public key, and the fourth timestamp to obtain fifth signature information. The fifth signature information, the payment terminal temporary public key, the fourth timestamp, the payment terminal quantum computing resistant digital certificate, and the transaction form a third combination of information, which is sent to the payment recipient commercial bank.

[0058] S312. After receiving the third combination information, the payee commercial bank confirms the fourth timestamp, decrypts the encrypted signature in the quantum computing resistant digital certificate of the payee terminal with the public key of the central bank digital currency system, and verifies the decrypted signature. If the verification is successful, the fifth signature information is verified with the public key of the payee terminal. If the verification is successful, the payee commercial bank obtains the payee terminal ID from the quantum computing resistant digital certificate of the payee terminal, confirms that the temporary public key of the payee terminal is the payee ID and public key in this transaction, and the payee commercial bank sends the payee terminal ID, transaction and temporary public key of the payee terminal to the central bank digital currency system.

[0059] According to another aspect of the present invention, a quantum computing-resistant anonymous dual offline transaction system for digital currency is provided, which includes a central bank digital currency system, a trusted intermediary, a payee commercial bank, a payee commercial bank, a payee terminal and a payee terminal. The payee commercial bank corresponds to the payee terminal, and the payee commercial bank corresponds to the payee terminal. A quantum computing-resistant communication system is deployed between the central bank digital currency system and the commercial banks, and between the commercial banks and the user terminals. The central bank digital currency system has a pair of public and private key pairs based on the RSA cryptographic system, and the private key is stored in the central bank. The public key is issued to all commercial banks and user terminals and stored in the corresponding hardware wallets; the central bank digital currency system is also equipped with a key management server based on ID cryptography, and the key management server is used to issue system private keys for the central bank digital currency system, and is also used to issue private keys based on ID cryptography for all objects with IDs; each member has a quantum computing-resistant digital certificate, which contains the member's true identity, and the trusted intermediary stores the quantum computing-resistant digital certificates of each commercial bank.

[0060] The beneficial effects of the present invention are:

[0061] 1. The present invention designs a digital currency equipped with a private key and a trusted intermediary for transactions, which can implement a quantum computing-resistant anonymous dual offline transaction method for digital currency. In this method, the two parties in the dual offline transaction do not know each other's information, thereby protecting the identity information of the traders. The method of the present invention can also be used for various types of transactions between digital currencies, including dual offline transactions, to achieve the same effect of protecting the identity information of traders. It can also achieve quantum computing resistance.

[0062] 2. In addition to supporting dual offline transactions, the transaction process in the present invention also supports transactions where the sender is online and the payee is offline, transactions where the sender is offline and the payee is online, and transactions where the sender is online and the payee is online. That is, the process supports all types of transactions and can achieve the same anonymity for both parties to the transaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0064] Figure 1 This is a flowchart of the steps for quantum computing-resistant anonymous dual offline transactions of digital currencies involved in an embodiment of the present invention;

[0065] Figure 2This is a data structure diagram of quantum computing-resistant digital currency in an embodiment of the present invention;

[0066] Figure 3 This is a basic structural diagram of the central bank digital currency system in an embodiment of the present invention. DETAILED DESCRIPTION

[0067] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. By referring to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0068] According to an embodiment of the present invention, a quantum computing-resistant anonymous dual-offline transaction method and system for digital currency are provided.

[0069] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. Figure 1-2 As shown, according to one embodiment of the present invention, a quantum computing-resistant anonymous dual offline transaction method for digital currency is provided, and the method includes the following steps:.

[0070] S1. Preparation stage: The central bank digital currency system issues quantum computing-resistant digital currency and quantum computing-resistant digital certificates based on ID cryptography to the issuing terminal and the receiving terminal respectively, and issues private keys based on ID cryptography to the issuing terminal and the receiving terminal respectively through the key management server;

[0071] Specifically, SS has a pair of public and private key pairs PK based on the RSA cryptographic system SS / SK SS , where the private key SK SS Saved by SS, public key PK SS Issued to all commercial banks and user terminals and stored in their hardware wallets, and never made public. SS also maintains a key management server KMS based on ID cryptography, which issues system private keys SKMS to SS and issues private keys based on ID cryptography to all objects with IDs (including commercial banks, user terminals, trusted intermediaries and digital currencies), such as issuing SK for the payee terminal CT. CT , issue SK to the sender terminal PT PT There is a public-private key correspondence SK CT =SKMS*PK CT and SK PT =SKMS*PK PT , and PK CT =H1(IDCT) and PK PT=H1(IDPT).

[0072] The S1 central bank digital currency system issues quantum computing-resistant digital currencies based on ID cryptography to the payment terminal and the payment terminal respectively, which specifically includes the following steps:

[0073] The process by which the central bank (SS) issues quantum-resistant digital currency to user terminals is as follows: the payment terminal (PT) generates a public-private key pair based on the RSA or ECC cryptography system and sends the public key to the corresponding commercial bank (PS). The PS then sends the public key to the central bank (SS). Based on the public key and the currency value, the SS generates quantum-resistant digital currency corresponding to various denominations and a private key based on ID cryptography corresponding to the digital currency's ID. The SS then sends the digital currency and ID cryptography-based private key to the PS, which then sends the digital currency and ID cryptography-based private key to the PT. The central bank also uses this method to issue quantum-resistant digital currency and the corresponding ID cryptography-based private key to the payment terminal (CT).

[0074] The data structure of the quantum computing-resistant digital currency issued by SS is as follows Figure 2 As shown, it includes ID, currency value, encrypted public key and encrypted signature. The public key carried by the digital currency (that is, the public key involved in generating the digital currency mentioned above) is encrypted using the true random number parameter RPK to obtain the {public key} RPK, and then the private key SK of SS is used to encrypt the digital currency. SS Encrypt the parameter RPK to get {RPK}SK SS , combine the two to get {public key}RPK||{RPK}SK SS , which is the encrypted public key in the digital currency data structure. To obtain the public key, use PK SS Decrypt {RPK}SK SS Get RPK, and then use RPK to decrypt {public key}RPK to get the public key. Use the true random number parameter RS to encrypt the digital currency signature to get {signature}RS, and then use SS's private key SK SS Encrypt parameter RS to get {RS}SK SS , combining the two to get {signature}RS||{RS}SK SS , which is the encrypted signature in the digital currency data structure. To get the signature, use PK SS Decrypting {RS}SK SS Get RS, and then use RS to decrypt {signature} RS to get the signature. After the public key and signature are symmetrically encrypted, they can resist quantum computing.

[0075] S2, dual offline transaction stage (dual offline transaction between the sending terminal and the receiving terminal through a trusted intermediary)

[0076] S21. MT (Trusted Intermediary) sends a message, and CT (Cash Terminal) verifies it (the Trusted Intermediary sends a Trusted Intermediary Quantum Computing-Resistant Digital Certificate to the Cash Terminal, and the Cash Terminal verifies the digital certificate)

[0077] MT will be resistant to quantum computing digital certificate CERT MT Send to CT.

[0078] After receiving CT, use SS's public key PK SS Decrypted CERT MT The encrypted signature in the CT is obtained and the decrypted signature is verified. If the verification is successful, the CT recognizes the MT as the CERT. MT The owner of the CT is a trusted intermediary and proceeds with the subsequent steps. Otherwise, CT confirms that the transaction has failed and does not proceed with the subsequent steps.

[0079] S22. CT sends a message, and MT verifies (the payment terminal sends the first combination information to the trusted intermediary, and the trusted intermediary verifies the first combination information)

[0080] CT generates a temporary public-private key pair PK based on the RSA or ECC cryptographic system CT(TEMP) / SK CT(TEMP) , calculate the symmetric key K between oneself and MT CT-MT (First symmetric key): Get the current timestamp T1 (first timestamp), according to the formula PK MT =H1(IDMT) calculate PK MT , take out CT's private key SK based on ID cryptography CT , calculate the symmetric key K between the two CT-MT =FTX(T1,e(SK CT , PK MT )), where FTX(T,K) is any function, such as a message authentication function or a concatenation function. CT PK CT(TEMP) ||T1 performs a signature based on ID cryptography to obtain SIGN(PK CT(TEMP) ||T1,SK CT )(first signature information), use K CT-MT PK CT(TEMP) ||SIGN(PK CT(TEMP) ||T1,SK CT ) is encrypted and used with T1 and CT's quantum computing-resistant digital certificate CERT CT Composition message {PK CT(TEMP) ||SIGN(PK CT(TEMP) ||T1,SK CT )}K CT-MT ||T1||CERT CT(The first set of combined information) and sends the message to MT. After the public key and signature are symmetrically encrypted, they can resist quantum computing.

[0081] After receiving the message, MT confirms that the timestamp T1 is the current time and uses SS's public key PK SS Decrypted CERT CT The encrypted signature in the CERT is verified and the signature is confirmed after verification. CT Legal and CERT CT The IDCT in is valid. Calculate the symmetric key K between the self and CT MT-CT (Second symmetric key): According to the formula PK CT =H1(IDCT) calculates PK CT , take out your own private key SK based on ID cryptography MT , calculate the symmetric key K between the two MT-CT =FTX(T1,e(SK MT , PK CT )). According to ID cryptography, we can get: e(SK MT , PK CT )=e(SKMS*PK MT , PK CT )=e(SKMS*PK CT , PK MT )=e(SK CT , PK MT ), so K MT-CT =K CT-MT So we can use K MT-CT Decryption {PK CT(TEMP) ||SIGN(PK CT(TEMP) ||T1,SK CT )}K CT-MT Get PK CT(TEMP) (first encrypted information) and signature SIGN(PK CT(TEMP) ||T1,SK CT ), and use the public key PK CT The signature is verified. If all verifications are successful, the MT recognizes the identity of the CT.

[0082] S23. MT sends a message, and PT (payment terminal) verifies it (the trusted intermediary sends the second combination information to the payment terminal, and the payment terminal verifies the second combination information)

[0083] MT calculates the symmetric key K between itself and PT MT-PT (Third symmetric key): Get the current timestamp T2 (second timestamp), according to the formula PK PT =H1(IDPT) calculates PK PT, take out MT's private key SK based on ID cryptography MT , calculate the symmetric key K between the two MT-PT =FTX(T2,e(SK MT , PK PT )). Use SK MT PK CT(TEMP) ||T2 signs and obtains SIGN(PK CT(TEMP) ||T2,SK MT )(Second signature information), use K MT-PT PK CT(TEMP) ||SIGN(PK CT(TEMP) ||T2,SK MT ) is encrypted and CERT is used to verify the quantum computing resistance of T2 and MT. MT Composing a message

[0084] {PK CT(TEMP) ||SIGN(PK CT(TEMP) ||T2,SK MT )}K MT-PT ||T2||CERT MT (Second combined information), this message is called MPC and is sent to PT.

[0085] After PT receives the message MPC, it confirms that the timestamp T2 is the current time and uses the public key PK of SS SS Decrypted CERT MT Calculate the symmetric key K between the user and MT PT-MT (Fourth symmetric key): According to the formula PK MT =H1(IDMT) calculate PK MT , take out your own private key SK based on ID cryptography PT , calculate the symmetric key K between the two PT-MT =FTX(T2,e(SK PT , PK MT )). According to ID cryptography, we can get: e(SK PT , PK MT )=e(SKMS*PK PT , PK MT )=e(SKMS*PK MT , PK PT )=e(SK MT , PK PT ), so K PT-MT =K MT-PT So we can use K PT-MT Decryption

[0086] {PKCT(TEMP) ||SIGN(PK CT(TEMP) ||T2,SK MT )}K MT-PT (Second encrypted information) gets PK CT(TEMP) and signature SIGN(PK CT(TEMP) ||T2,SK MT ), and use the public key PK MT Verify the signature. If all verifications are successful, PT recognizes MT as CERT. MT The owner is a trusted intermediary and recognizes PK CT(TEMP) It is the beneficiary ID and public key, otherwise PT confirmation transaction fails.

[0087] S24, PT sends transaction (the sending terminal sends the transaction to the receiving terminal)

[0088] PT takes out a quantum computing-resistant digital currency PM, obtains the current timestamp T3 (the third timestamp), and combines T3, the sender information IDPS, the recipient information MPC, and PM to form a transaction TX, that is, TX=

[0089] {T3||IDPS||MPC||PM}. Since the sender's information is represented by IDPS, the payee only knows the commercial bank to which the sender belongs and is not aware of the sender's specific identity; and the payee's information is represented by MPC, so the sender is also not aware of the payee's specific identity. Use the RSA or ECC private key corresponding to the digital currency to sign TX to obtain TXS (the third signature information), and then calculate the symmetric key K between PM and CT PM-CT (Fifth symmetric key): According to the formula PK CT =H1(IDCT) calculates PK CT , take out PM's ID cryptography-based private key SK PM , calculate the symmetric key TXK between the two = FTX(T3,e(SK PM , PK CT )). Use K PM-CT Encrypt TX||TXS to get {TX||TXS}K PM-CT (Third encrypted information), and T3||{TX||TXS}K PM-CT Sent to CT together with IDPM.

[0090] S25, CT confirms the transaction (payment terminal confirms the transaction)

[0091] After receiving the message, CT gets T3||{TX||TXS}K PM-CT and IDPM. CT calculates the symmetric key K between itself and PM CT-PM (Sixth symmetric key): According to the formula PKPM =H1(IDPM) calculate PK PM , take out CT's private key SK based on ID cryptography CT , calculate the symmetric key K between the two CT-PM =FTX(T3,e(SK CT , PK PM )). According to ID cryptography, we can get: e(SK CT , PK PM )=e(SKMS*PK CT , PK PM )=

[0092] e(SKMS*PK PM , PK CT )=e(SK PM , PK CT ), so K CT-PM =K PM-CT . Use K CT-PM Decrypt {TX||TXS}K PM-CT Get TX||TXS. CT takes out the encrypted public key in the digital currency PM and uses PK SS Decrypt the TXS to get the RSA or ECC public key, and then use the public key to verify the signature TXS. After successful verification, verify the digital currency PM, such as verifying the currency value and the central bank signature. If the verification is successful, the transaction is trusted, the PM in TX is taken out and stored, and marked as unconfirmed by the central bank. CT will confirm the transaction message RET CT Use the temporary private key SK CT(TEMP) Sign and get SIG CT (Fourth signature information), then RET CT ||SIG CT Use K CT-PM Encrypted and sent to PT.

[0093] After receiving the message, PT uses K PM-CT Decrypted to get RET CT and SIG CT , use PK CT(TEMP) Verify the signature SIG CT If the verification is successful, check RET CT After a successful transaction, the digital currency PM and its private key are deleted. Since the private key corresponds to the digital currency one-to-one, the private key must also be destroyed after the digital currency is issued. After the digital currency is received by the recipient, it becomes ordinary digital currency without the private key.

[0094] S3. Online transaction stage (Online transaction stage: using the central bank digital currency system to confirm the transaction)

[0095] CT sends a message:

[0096] CT obtains the current timestamp T4 and takes out the previously confirmed transaction TX, using its own private key SK CT TX||PK CT(TEMP) ||T4 signs and obtains SIGN(TX||PK CT(TEMP) ||T4,SK CT )(fifth signature information), forming the message PK CT(TEMP) ||T4||CERT CT ||TX||SIGN(TX||PK CT(TEMP) ||T4,SK CT The third combined message is sent to the corresponding commercial bank CS. The message is encrypted by a quantum computing-resistant secure communication mechanism between the two parties.

[0097] After receiving the message, CS confirms T4 and uses SS's public key PK SS Decrypted CERT CT The encrypted signature in the , and verify the signature. If the verification is successful, use the CT's public key PK CT Signature SIGN(TX||PK CT(TEMP) ||T4,SK CT ) for verification. If the verification is successful, CS will receive a CT Get the owner's real identity IDCT and confirm PK CT(TEMP) It is the payee ID and public key in this transaction.

[0098] CS will send the message IDCT||TX||PK CT(TEMP) Sent to the central bank SS.

[0099] SS forwarding transaction:

[0100] After receiving the message, SS stores IDCT||TX||PK locally CT(TEMP) , TX||PK CT(TEMP) The message is encrypted using the public key corresponding to the sender's commercial bank, PS, and sent to PS. The message is encrypted by a quantum-resistant secure communication mechanism between the two parties.

[0101] PS sends transaction results:

[0102] After receiving the message, PS uses its own private key to decrypt and obtain TX||PK CT(TEMP) According to the digital currency PM in TX, the owner is found to be PT, and the sender’s real identity IDPT is known. PS will IDPT||PK CT(TEMP) ||TX is stored locally as a complete transaction entry, where PK CT(TEMP) It represents the identity of the payee, so the PS does not know the real identity of the payee.

[0103] PS uses the transaction success or failure result as RET, encrypts IDPT||RET with SS's public key, and sends it to SS. The message is encrypted by a quantum-resistant secure communication mechanism between the two parties.

[0104] SS forwarding transaction results:

[0105] After receiving the message, SS decrypts it to obtain IDPT||RET. If RET contains a successful transaction message, SS stores IDPT||IDCT||TX as a complete transaction entry locally. SS knows the true identity of the payee, IDCT.

[0106] SS encrypts RET with CS's public key and sends it to CS. The message is encrypted by the quantum computing-resistant secure communication mechanism between the two parties.

[0107] CS forwards transaction results:

[0108] After receiving the message, the CS decrypts it to obtain RET. If the RET contains a successful transaction message, the CS stores IDPS||IDCT||TX as a complete transaction entry locally. IDPS represents the identity of the sender, so the CS does not know the sender's true identity.

[0109] CS encrypts RET with CT's public key and sends it to CT. The message is encrypted by a quantum computing-resistant secure communication mechanism between the two parties.

[0110] CT confirms the transaction result:

[0111] After receiving the message, CT decrypts it to obtain RET. If the RET contains a successful transaction message, CT marks the digital currency PM stored in step S25 as confirmed by the central bank and can be used normally in the future.

[0112] According to another aspect of the present invention, taking the operation example of the central bank digital currency as an example, Figure 3As shown, the basic structure of the digital currency system primarily includes a central bank digital currency system, a commercial bank digital currency system (which may, in practice, be multiple commercial bank digital currency systems), and users. The central bank digital currency system is used to generate and issue digital currency and register ownership of digital currency; the commercial bank digital currency system is used to perform banking functions for digital currency; and users are the primary users of digital currency. In this invention, users hold terminals to conduct digital currency transactions. In this invention, quantum-resistant communication systems are deployed between the central bank digital currency system and the commercial bank digital currency system, and between the commercial bank digital currency system and user terminals, ensuring quantum-resistant communication between them. For example, a quantum secure communication system based on QKD key distribution is deployed between the central bank digital currency system and the commercial bank digital currency system, and a key card system based on a symmetric or asymmetric key pool is deployed between the commercial bank digital currency system and the user terminal.

[0113] Assume that the present invention has a central bank (i.e., a central bank digital currency system) SS, an issuing commercial bank (i.e., a commercial bank digital currency system) PS and its corresponding issuing terminal PT, a receiving commercial bank CS and its corresponding receiving terminal CT. Their corresponding IDs are IDSS, IDPS, IDPT, IDCS, and IDCT, respectively. The issuing terminal corresponds to the user. If the issuing terminal ID is exposed, the user's identity and transaction behavior will be exposed.

[0114] In the present invention, the central bank SS also issues a quantum computing-resistant digital certificate based on ID cryptography to the user terminal. The data structure corresponding to the digital certificate is different from that of an ordinary digital certificate in the following ways: the certificate owner field contains the ID of the digital certificate owner, the certificate public key field is empty, the public key algorithm field is based on ID cryptography, and the certificate signature field is an encrypted signature. The structure of the encrypted signature is as described above.

[0115] The present invention also includes a trusted intermediary (MT), which represents trusted infrastructure, such as digital currency ATMs, digital currency POS terminals, and digital currency transaction devices held by trusted merchants. MTs lack networking capabilities and do not store received certificates, preventing user information leakage. In this invention, each member carries a quantum-resistant digital certificate containing their true identity. The MT stores the quantum-resistant digital certificates of various commercial banks. PTs, CTs, and MTs utilize short-range communication (e.g., NFC), preventing third-party access to any communication between them.

[0116] In summary, the present invention designs a digital currency equipped with a private key and a trusted intermediary for transactions, which can implement a quantum computing-resistant anonymous dual offline transaction method for digital currency. This method prevents the parties in the dual offline transaction from knowing each other's information, thereby protecting the identity information of the transactors. The method of the present invention can also conduct various types of transactions between digital currencies, including dual offline transactions, to achieve the same effect of protecting the identity information of the transactors, and can also achieve quantum computing resistance. In addition to supporting dual offline transactions, the transaction process of the present invention also supports transactions where the sender is online and the payee is offline, transactions where the sender is offline and the payee is online, and transactions where the sender is online and the payee is online. That is, the process supports all types of transactions and can achieve the same anonymity effect for both parties.

[0117] 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.

[0118] 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 quantum computing-resistant anonymous dual offline transaction method for digital currency, characterized by: The method comprises the following steps: S1. Preparation stage: The central bank digital currency system issues quantum computing-resistant digital currency and quantum computing-resistant digital certificates based on ID cryptography to the issuing terminal and the receiving terminal respectively, and issues private keys based on ID cryptography to the issuing terminal and the receiving terminal respectively through the key management server; S2, dual offline transaction stage: the sending terminal and the receiving terminal conduct dual offline transactions through a trusted intermediary; S3. Online transaction stage: Use the central bank digital currency system to confirm the transaction; The S1 central bank digital currency system issues quantum computing-resistant digital currencies based on ID cryptography to the payment terminal and the payment terminal respectively, which specifically includes the following steps: The payment terminal / payment terminal generates a public-private key pair based on the RSA or ECC cryptographic system and sends the public key to the corresponding commercial bank. The corresponding commercial bank sends the public key to the central bank digital currency system. The central bank digital currency system generates quantum computing-resistant digital currency of corresponding values and a private key based on ID cryptography corresponding to the ID of the digital currency based on the public key and currency value. The central bank digital currency system then sends the digital currency and the private key based on ID cryptography to the corresponding commercial bank. The corresponding commercial bank then sends the digital currency and the private key based on ID cryptography to the corresponding user terminal. Among them, the trusted intermediary is the trusted infrastructure; The dual offline transaction between the payment sending terminal and the payment receiving terminal in S2 through a trusted intermediary includes the following steps: S21. The trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal, and the payment terminal verifies the digital certificate. S22. The payment terminal sends the first combination information to the trusted intermediary, and the trusted intermediary verifies the first combination information; S23. The trusted intermediary sends the second combination information to the payment terminal, and the payment terminal verifies the second combination information; S24. The payment terminal sends the transaction to the payment terminal; S25. The payment terminal confirms the transaction; In S21, the trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal. The payment terminal verifies the digital certificate in the following steps: S211. The trusted intermediary sends the trusted intermediary quantum computing-resistant digital certificate to the payment terminal; S212. After receiving the digital currency, the payment terminal uses the public key of the central bank's digital currency system to decrypt the encrypted signature in the trusted intermediary's quantum-resistant digital certificate and verifies the decrypted signature. If the verification is successful, the payment terminal recognizes the trusted intermediary as the owner of the quantum-resistant digital certificate and proceeds to the subsequent steps. In step S22, the payment terminal sends the first combination information to the trusted intermediary, and the trusted intermediary verifies the first combination information, which specifically includes the following steps: S221. The payment terminal generates a temporary public-private key pair based on the RSA or ECC cryptographic system and calculates the first symmetric key between the terminal and the trusted intermediary; S222. Use the payment terminal private key to sign the temporary public key of the payment terminal and the first timestamp based on ID cryptography to obtain first signature information. Use the first symmetric key to encrypt the temporary public key of the payment terminal and the first signature information to obtain first encrypted information. Combine the encrypted information with the first timestamp and the quantum computing resistant digital certificate of the payment terminal to form first combined information. Send the first combined information to the trusted intermediary. S223. After receiving the first combined information, the trusted intermediary confirms that the first timestamp is the current time, decrypts the encrypted signature in the quantum computing resistant digital certificate of the payment terminal using the central bank digital currency system public key, and verifies the decrypted signature. After verification, it confirms that the quantum computing resistant digital certificate of the payment terminal is legitimate and the payment terminal ID contained therein is valid. S224. Calculate a second symmetric key between the trusted intermediary and the payment terminal; S225. Decrypt the first encrypted information using the second symmetric key to obtain the temporary public key of the payment terminal and the first signature information, and verify the signature information using the public key of the payment terminal. If the verification is successful, the trusted intermediary recognizes the identity of the payment terminal. The calculation of the first symmetric key between the user and the trusted intermediary in S221 specifically includes the following steps: the payment terminal obtains the first timestamp, calculates the public key of the trusted intermediary, and simultaneously extracts the payment terminal private key based on ID cryptography and calculates the first symmetric key; In step S23, the trusted intermediary sends the second combination information to the payment terminal, and the payment terminal verifies the second combination information, which specifically includes the following steps: S231. Calculate the third symmetric key between the trusted intermediary and the payment terminal; S232. Sign the temporary public key of the payment terminal and the second timestamp using the trusted intermediary private key to obtain second signature information, encrypt the temporary public key of the payment terminal and the second signature information using the third symmetric key to obtain second encrypted information, and combine the second encrypted information with the second timestamp and the trusted intermediary quantum computing-resistant digital certificate to form second combined information, which is then sent to the payment terminal. S233. After receiving the second combined information, the payment terminal confirms that the second timestamp is the current time, decrypts the encrypted signature in the trusted intermediary quantum computing-resistant digital certificate using the central bank digital currency system public key, and verifies the decrypted signature. S234. Calculate the fourth symmetric key between the payment terminal and the trusted intermediary; S235. Use the fourth symmetric key to decrypt the second encrypted information to obtain the temporary public key of the payment terminal and the second signature information, and verify the signature information with the public key of the trusted intermediary. If the verification is successful, the payment terminal recognizes the trusted intermediary as the owner of the trusted intermediary quantum computing-resistant digital certificate and recognizes the temporary public key of the payment terminal as the payee ID and public key.

2. A quantum computing-resistant anonymous dual offline transaction method for digital currency according to claim 1, characterized in that: In step S24, the sending terminal sends the transaction to the receiving terminal, which specifically includes the following steps: S241. The payment terminal takes out a quantum computing-resistant digital currency, obtains a third timestamp, and combines the third timestamp, the payment party's commercial bank ID, the second combination information, and the quantum computing-resistant digital currency into a transaction; S242. Sign the transaction using the RSA or ECC private key corresponding to the digital currency to obtain third signature information, and calculate the fifth symmetric key between the quantum computing-resistant digital currency and the payment terminal; S243. Use the fifth symmetric key to encrypt the transaction and the third signature information to obtain third encrypted information, and send the third timestamp, the third encrypted information and the quantum computing resistant digital currency ID together to the payment terminal.

3. A quantum computing-resistant anonymous dual offline transaction method for digital currency according to claim 2, characterized in that: The payment terminal confirming the transaction in S25 specifically includes the following steps: S251. After receiving the third timestamp, the third encrypted information, and the quantum computing-resistant digital currency ID, the payment terminal calculates a sixth symmetric key between the payment terminal and the quantum computing-resistant digital currency; S252. The third encrypted information is decrypted using the sixth symmetric key to obtain the transaction and third signature information. The payment terminal extracts the encrypted public key in the quantum computing-resistant digital currency and decrypts it using the central bank digital currency system public key to obtain the RSA or ECC public key therein. The third signature information is then verified using the public key. If the verification is successful, the quantum computing-resistant digital currency is then verified. If the verification is successful, the transaction is trusted, the quantum computing-resistant digital currency in the transaction is extracted and stored, and marked as unconfirmed by the central bank. S253. The payment terminal signs the transaction confirmation message using the temporary private key of the payment terminal to obtain fourth signature information, encrypts the transaction confirmation message and the fourth signature information using the sixth symmetric key, and sends the encrypted information to the payment terminal. S254. After receiving the transaction confirmation message and the fourth signature information encrypted with the sixth symmetric key, the payment terminal decrypts them with the fifth symmetric key to obtain the transaction confirmation message and the fourth signature information, and uses the temporary public key of the payment terminal to verify the fourth signature information. If the verification is successful and the transaction confirmation message is successful, the quantum computing-resistant digital currency and its private key are deleted.

4. The quantum computing-resistant anonymous dual offline transaction method for digital currency according to claim 1 is characterized in that: The use of the central bank digital currency system in S3 to confirm transactions specifically includes the following steps: S31. The payment terminal sends the third combination of information to the beneficiary commercial bank, and the beneficiary commercial bank sends the payment terminal ID, transaction, and temporary public key of the payment terminal to the central bank digital currency system; S32. After receiving the payment terminal ID, transaction and payment terminal temporary public keys, the central bank digital currency system stores the payment terminal ID, transaction and payment terminal temporary public keys locally, and encrypts the transaction and payment terminal temporary public keys with the public key of the payee's commercial bank and sends the encrypted data to the payee's commercial bank. S33. After receiving the transaction and the temporary public key of the receiving terminal encrypted with the public key of the issuing commercial bank, the issuing commercial bank decrypts the encrypted transaction and the temporary public key of the receiving terminal with its own private key, locates the issuing terminal based on the quantum computing-resistant digital currency in the transaction, and obtains the issuing terminal ID. The issuing commercial bank stores the issuing terminal ID, the temporary public key of the receiving terminal, and the transaction as a complete transaction entry locally. S34. The issuing commercial bank encrypts the issuing terminal ID and transaction results using the central bank digital currency system public key and sends them to the central bank digital currency system; S35. The central bank digital currency system receives the payment terminal ID and transaction result encrypted with the central bank digital currency system public key and decrypts them to obtain the payment terminal ID and transaction result. If the transaction result is successful, the central bank digital currency system stores the payment terminal ID, payment terminal ID, and transaction as a complete transaction entry locally, and the central bank digital currency system encrypts the transaction result with the public key of the payee commercial bank and sends it to the payee commercial bank. S36. The payee commercial bank receives the transaction result encrypted with the payee commercial bank's public key and decrypts it to obtain the transaction result. If the transaction result is successful, the payee commercial bank ID, the payee terminal ID, and the transaction are stored locally as a complete transaction entry. The transaction result is encrypted with the payee terminal's public key and sent to the payee terminal. S37. The payment terminal receives the transaction result encrypted with the public key of the payment terminal and decrypts it to obtain the transaction result. If the transaction result is successful, the payment terminal marks the quantum computing-resistant digital currency as confirmed by the central bank.

5. The quantum computing-resistant anonymous dual offline transaction method for digital currency according to claim 4 is characterized in that: In step S31, the payment terminal sends the third combination of information to the payee commercial bank, and the payee commercial bank sends the payment terminal ID, transaction and temporary public key of the payment terminal to the central bank digital currency system, which specifically includes the following steps: S311. The payment terminal obtains the fourth timestamp and extracts the transaction. It uses the payment terminal private key to sign the transaction, the payment terminal temporary public key, and the fourth timestamp to obtain fifth signature information. The fifth signature information, the payment terminal temporary public key, the fourth timestamp, the payment terminal quantum computing resistant digital certificate, and the transaction form a third combination of information, which is sent to the payment recipient commercial bank. S312. After receiving the third combination information, the payee commercial bank confirms the fourth timestamp, decrypts the encrypted signature in the quantum computing resistant digital certificate of the payee terminal with the public key of the central bank digital currency system, and verifies the decrypted signature. If the verification is successful, the fifth signature information is verified with the public key of the payee terminal. If the verification is successful, the payee commercial bank obtains the payee terminal ID from the quantum computing resistant digital certificate of the payee terminal, confirms that the temporary public key of the payee terminal is the payee ID and public key in this transaction, and the payee commercial bank sends the payee terminal ID, transaction and temporary public key of the payee terminal to the central bank digital currency system.

6. A quantum computing-resistant anonymous dual offline transaction system for digital currency, used to implement the steps of the quantum computing-resistant digital currency communication method based on ID cryptography according to any one of claims 1 to 5, characterized in that: The system includes a central bank digital currency system, a trusted intermediary, a payee commercial bank, a payee commercial bank, a payee terminal and a payee terminal. The payee commercial bank corresponds to the payee terminal, and the payee commercial bank corresponds to the payee terminal. Anti-quantum computing communication systems are deployed between the central bank digital currency system and the commercial banks, and between the commercial banks and the user terminals. Among them, the central bank digital currency system has a pair of public and private key pairs based on the RSA cryptographic system, and the private key is stored in the central bank. The public key is issued to all commercial banks and user terminals and stored in the corresponding hardware wallets; the central bank digital currency system is also equipped with a key management server based on ID cryptography, and the key management server is used to issue system private keys for the central bank digital currency system, and is also used to issue private keys based on ID cryptography for all objects with IDs; each member has an anti-quantum computing digital certificate, which contains the member's true identity, and the trusted intermediary stores the anti-quantum computing digital certificates of each commercial bank.

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