CN114519574A - Anonymous double-off-line transaction method and system for digital currency - Google Patents

Anonymous double-off-line transaction method and system for digital currency Download PDF

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Publication number
CN114519574A
CN114519574A CN202011304842.8A CN202011304842A CN114519574A CN 114519574 A CN114519574 A CN 114519574A CN 202011304842 A CN202011304842 A CN 202011304842A CN 114519574 A CN114519574 A CN 114519574A
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China
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terminal
transaction
digital currency
digital
information
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富尧
钟一民
汪仲祥
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Ruban Quantum Technology Co Ltd
Nanjing Ruban Quantum Technology Co Ltd
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Ruban Quantum Technology Co Ltd
Nanjing Ruban Quantum Technology Co Ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00—Payment architectures, schemes or protocols
    • G06Q20/04—Payment circuits
    • G06Q20/06—Private payment circuits, e.g. involving electronic currency used among participants of a common payment scheme
    • G06Q20/065—Private payment circuits, e.g. involving electronic currency used among participants of a common payment scheme using e-cash
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00—Payment architectures, schemes or protocols
    • G06Q20/08—Payment architectures
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00—Payment architectures, schemes or protocols
    • G06Q20/38—Payment protocols; Details thereof
    • G06Q20/382—Payment protocols; Details thereof insuring higher security of transaction
    • G06Q20/3823—Payment protocols; Details thereof insuring higher security of transaction combining multiple encryption tools for a transaction
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q40/00—Finance; Insurance; Tax strategies; Processing of corporate or income taxes
    • G06Q40/02—Banking, e.g. interest calculation or account maintenance
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L63/00—Network architectures or network communication protocols for network security
    • H04L63/04—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks
    • H04L63/0428—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks wherein the data content is protected, e.g. by encrypting or encapsulating the payload
    • H04L63/045—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks wherein the data content is protected, e.g. by encrypting or encapsulating the payload wherein the sending and receiving network entities apply hybrid encryption, i.e. combination of symmetric and asymmetric encryption
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L63/00—Network architectures or network communication protocols for network security
    • H04L63/08—Network architectures or network communication protocols for network security for authentication of entities
    • H04L63/0823—Network architectures or network communication protocols for network security for authentication of entities using certificates

Abstract

The invention discloses an anonymous double-off-line transaction method and system for digital currency, wherein the method comprises the following steps: the central bank digital currency system respectively issues digital currencies for the payment terminal and the collection terminal; the payment terminal and the collection terminal carry out double off-line transaction through a trusted intermediary; the transaction is confirmed using a central bank digital currency system. Has the advantages that: the invention designs the digital currency with the private key and the credible medium of the transaction, and can realize an anonymous double-off-line transaction method of the digital currency, so that two transaction parties in the double-off-line transaction can not know the information of the other party, thereby protecting the identity information of a transactor.

Description

Anonymous double-off-line transaction method and system for digital currency
Technical Field
The invention relates to the field of digital currency, in particular to an anonymous double-off-line transaction method and system of digital currency.
Background
The core elements of the digital currency D-RMB system of the Chinese people's bank are a currency, two types of banks and three centers. One currency, D-RMB (DC/EP), abbreviated as D currency, refers in particular to a series of encrypted digital strings representing a specific amount signed by the central row. Two types of libraries: respectively an issuing bank and a banking bank (central bank digital currency database, commercial bank digital currency database) of the D-RMB. The digital currency is expressed as digital currency fund at the central row in the issuing bank; the digital currency is presented in the bank vault as digital cash in stock by the commercial bank. Three centers: the first is a registration center (recording the whole processes of currency generation, circulation, counting, checking and death); the other two are the certification centers, namely the CA certification center (Based on the PKI system, centralized management of the authority and user certificates, such as CFCA) and the IBC certification center [ namely, the certification-Based cryptography built Based on the identified cryptography ]. Two tables can be designed in the registration center, one is a digital currency ownership registration table for recording the ownership of digital currency, and the other is a transaction flow meter.
The D-RMB system is a hierarchical system, namely, a central bank and each commercial bank are built together, the central bank digital currency system is a computer system which is operated and maintained by the central bank or a central bank appointed organization and is used for processing information about digital currency, the main functions of the central bank digital currency system comprise the issuing and verification monitoring of the digital currency, the commercial bank digital currency system is a computer system which is operated and maintained by the commercial bank or the commercial bank appointed organization and is used for processing the information about the digital currency, the commercial bank digital currency system executes various functions about the currency of the existing bank, namely, bank functions, and the D-RMB system mainly comprises the functions of being directly oriented to the society after applying for the digital currency from the central bank and meets various requirements for providing digital currency circulation services.
Patent CN201911053809 discloses an anonymous transaction method and system based on digital currency, but there are some problems with the method and system: only online transaction can be carried out, the temporary identity of the user can only be approved by the self-service end to carry out subsequent transaction flow, when the user can not communicate with the self-service end, the payee of the method can not verify the digital signature of the transaction by using the temporary identity of the user (in the mathematical signature based on the digital certificate, the user can not provide the digital certificate containing the real identity because the user needs to hide the real identity, and can not prove the association between the temporary identity and the digital certificate, and can not verify the digital signature of the transaction by using the digital certificate, in the mathematical signature based on ID cryptography, the user can not provide the real identity because the user needs to hide the real identity, and can not prove the association relationship between the temporary identity and the real identity, and can not verify the digital signature of the transaction by using the real identity), therefore, the payee cannot acknowledge the validity of the transaction and complete the whole transaction flow without receiving any identity certificate of the sender.
Based on the above analysis, the prior art of digital currency communication systems has the following drawbacks:
1. most existing digital currency transaction methods based on digital certificates or user IDs expose the user identity;
2. the existing digital currency anonymous transaction method based on a digital certificate or user ID can ensure the anonymous identity of a user but cannot perform anonymous transaction of off-line (namely double off-line) of both a sender and a receiver.
Disclosure of Invention
The present invention is directed to solving the above-mentioned problems of the related art.
Therefore, the invention adopts the following specific technical scheme:
according to one aspect of the invention, there is provided a method of anonymous double offline transactions of digital currency, the method comprising the steps of:
s1, preparation stage: the central bank digital currency system issues digital currencies for the payment terminal and the collection terminal respectively;
s2, double off-line transaction stage: the payment terminal and the collection terminal carry out double off-line transaction through a trusted intermediary;
s3, online transaction stage: validating the transaction using a central bank digital currency system;
wherein, the central bank digital currency system in S1 respectively issuing digital currency for the issuing terminal and the receiving terminal comprises the following steps:
s11, the central bank digital currency system issues digital currency for the payment terminal;
s12, the central bank digital currency system issues digital currency for the collection terminal;
the step of issuing digital currency for the issuing terminal by the central bank digital currency system in the step S11 specifically includes the following steps:
the payment terminal generates a group of public and private key pairs and sends the public key to the corresponding payment party commercial bank, the payment party commercial bank sends the public key to the central bank digital currency system, the central bank digital currency system generates digital currencies with various corresponding currency values according to the public key and the currency values and sends the digital currencies to the payment party commercial bank, and the payment party commercial bank sends the digital currencies to the payment terminal;
the step of issuing digital currency for the collection terminal by the central bank digital currency system in the step S12 specifically includes the following steps:
the collection terminal generates a public and private key pair and sends the public key to the corresponding collection commercial bank, the collection commercial bank sends the public key to the central bank digital currency system, the central bank digital currency system generates digital currencies of various corresponding currency values according to the public key and the currency values and sends the digital currencies to the collection commercial bank, and the collection commercial bank sends the digital currencies to the collection terminal.
Further, the step of performing a dual offline transaction between the payment terminal and the payment receiving terminal through a trusted intermediary in S2 includes the following steps:
s21, the trusted intermediary sends the second combination information to the collection terminal, and the collection terminal verifies the second combination information;
s22, the collection terminal sends the third combination information to the trusted intermediary, and the trusted intermediary verifies the third combination information;
s23, the trusted intermediary sends the fifth combined information to the payment terminal, and the payment terminal verifies the fifth combined information;
s24, the payment terminal sends the transaction to the payment terminal;
s25, the receiving terminal confirms the transaction.
Further, the step of sending, by the trusted intermediary, the second combination information to the receiving terminal in S21, where the step of verifying the second combination information by the receiving terminal specifically includes:
s211, the trusted intermediary acquires a first time stamp, the first time stamp and the ID of the trusted intermediary form first combined information, the first combined information is signed by the private key of the trusted intermediary to obtain first signature information, then a digital certificate of the trusted intermediary is taken out, the ID of the trusted intermediary, the first time stamp and the first signature information form second combined information, and the second combined information is sent to the collection terminal;
and S212, after receiving the second combined information, the collection terminal confirms that the first time stamp is the current time, verifies the first signature information by using the trusted intermediary public key and verifies the trusted intermediary digital certificate, if the verification is successful, the collection terminal approves the trusted intermediary as the owner of the trusted intermediary digital certificate and carries out subsequent steps, otherwise, the collection terminal confirms that the transaction is failed and does not carry out subsequent steps.
Further, the step of sending, by the payee terminal in S22, the third combination information to the trusted intermediary, where the step of verifying the third combination information by the trusted intermediary specifically includes the following steps:
s221, the collection terminal generates a collection terminal temporary public and private key pair, a collection terminal private key is used for signing a collection terminal temporary public key and a first timestamp to obtain second signature information, meanwhile, a collection terminal digital certificate is taken out and encrypted by a trusted intermediary public key to obtain first encryption information, the collection terminal temporary public key, the first timestamp, the second signature information and the first encryption information form third combined information, and the third combined information is sent to a trusted intermediary;
s222, after the trusted intermediary receives the third combined information, the first timestamp is confirmed, the first encrypted information is decrypted by using a private key of the trusted intermediary to obtain a collection terminal digital certificate, meanwhile, a collection terminal public key in the collection terminal digital certificate is used for verifying the second signature information, and if the verification is successful, the identity of the collection terminal can be confirmed.
Further, the step of the trusted intermediary sending the fifth combination information to the terminal for sending payment in S23, where the step of the terminal for sending payment verifying the fifth combination information specifically includes the following steps:
s231, the trusted intermediary acquires the second timestamp, forms fourth combined information with the temporary public key of the collection terminal received in the step S222, signs the fourth combined information by using the private key of the trusted intermediary to obtain third signature information, forms fifth combined information by using the fourth combined information, the third signature information and the digital certificate of the trusted intermediary, and sends the fifth combined information to the payment sending terminal;
and S232, after receiving the fifth combined message, the money issuing terminal confirms that the second timestamp is the current time, verifies the third signature information by using the trusted intermediary public key and verifies the trusted intermediary digital certificate, if the verification is successful, the money issuing terminal approves the trusted intermediary as the owner of the trusted intermediary digital certificate and approves the collection terminal temporary public key as the collection party ID and public key, and otherwise, the money issuing terminal confirms that the transaction is failed.
Further, the step of sending the transaction to the payment terminal by the payment terminal in S24 specifically includes the following steps:
and the payment terminal takes out a digital currency, acquires a third time stamp, forms a transaction by the third time stamp, the ID of the commercial bank of the payment party, the fifth combination information and the digital currency, signs the transaction by a private key corresponding to the digital currency to obtain fourth signature information, and sends the transaction and the fourth signature information to the collection terminal.
Further, in S24, the manner of sending the transaction and the fourth signature information to the receiving terminal is sending in plaintext or sending after encrypting with a public key of the receiving terminal, and if the transaction and the fourth signature information are sent in encrypted form, the receiving terminal receives the transaction and decrypts with a corresponding private key.
Further, the step of confirming the transaction by the receiving terminal in S25 specifically includes the following steps:
s251, after receiving the transaction and the fourth signature information, the cash receiving terminal takes out a public key corresponding to the digital currency, verifies the fourth signature information, verifies the digital currency if the verification is successful, trusts the transaction if the verification is successful, takes out the digital currency in the transaction and stores the digital currency at the same time, marks the digital currency as not confirmed in the central bank, signs a message for confirming the transaction by using a temporary private key of the cash receiving terminal to obtain fifth signature information, and then sends the message for confirming the transaction and the fifth signature information to the payment sending terminal;
and S252, after receiving the transaction confirmation message and the fifth signature information, the payment terminal verifies the fifth signature information, and if the verification is successful, deletes the digital currency and the private key corresponding to the digital currency.
Further, the step of confirming the transaction with the central bank digital currency system in S3 specifically includes the following steps:
s301, the collection terminal acquires a fourth timestamp, signs the transaction, the collection terminal temporary public key and the fourth timestamp by using a collection terminal private key to obtain sixth signature information, encrypts a collection terminal digital certificate and a transaction combination by using a public key of a collection party commercial bank to obtain second encryption information, forms sixth combination information by using the collection terminal temporary public key, the fourth timestamp, the sixth signature information and the second encryption information, and sends the sixth combination information to the collection party commercial bank;
s302, after receiving the sixth combined information, the commercial bank of the payee confirms the fourth timestamp, decrypts the second encrypted information by using a private key of the commercial bank of the payee to obtain a digital certificate of the payee terminal and a transaction, verifies the digital certificate of the payee terminal, verifies the sixth signature information by using a public key of the payee terminal in the digital certificate of the payee terminal, and if the verification is successful, the commercial bank of the payee terminal acquires the ID of the payee terminal from the digital certificate of the payee terminal and confirms that the temporary public key of the payee terminal is the ID and the public key of the payee terminal, and meanwhile, the commercial bank of the payee terminal sends the ID of the payee terminal and the transaction to a digital money system of a central bank;
s303, after receiving the message, the digital money system of the central bank locally stores the ID and the transaction of the money receiving terminal, encrypts the transaction by using a public key corresponding to the commercial bank of the money sender and sends the encrypted transaction to the commercial bank of the money sender;
s304, after receiving the message, the commercial bank of the sender decrypts the message by using a private key of the commercial bank of the sender to obtain a transaction, finds the sender terminal according to the digital currency in the transaction, acquires the ID of the sender terminal, takes out the fifth combined information from the transaction, simultaneously takes out the temporary public key of the collection terminal from the fifth combined information, stores the ID of the sender terminal, the temporary public key of the collection terminal and the transaction as a complete transaction item in the local, and encrypts the ID of the sender terminal and the transaction result by using the public key of the digital currency system of the central bank and sends the encrypted ID and transaction result to the digital currency system of the central bank;
s305, the central bank digital currency system receives the message and then decrypts the message to obtain the ID of the payment terminal and the transaction result, if the transaction result is a successful transaction message, the central bank digital currency system stores the ID of the payment terminal, the ID of the collection terminal and the transaction as a complete transaction item in the local, and the central bank digital currency system encrypts the transaction result by using the public key of the commercial bank of the collection party and sends the encrypted transaction result to the commercial bank of the collection party;
s306, the commercial bank of the payee decrypts the received message to obtain a transaction result, if the transaction result is a successful transaction message, the commercial bank of the payee stores the ID of the commercial bank of the sender, the ID of the payee terminal and the transaction as a complete transaction item in the local, and the commercial bank of the payee encrypts the transaction result by using the public key of the payee terminal and sends the encrypted transaction result to the payee terminal;
and S307, the receiving terminal receives the message and then decrypts the message to obtain a transaction result, and if the transaction result is a successful transaction message, the receiving terminal marks the digital money stored in the step S25 as the confirmation of the central row and the digital money can be normally used subsequently.
According to another aspect of the present invention, there is provided an anonymous double offline transaction system for digital currency, the system comprising a central bank digital currency system, a commercial bank digital currency system, a trusted intermediary and a user, and the user holds a corresponding user terminal;
the user terminal comprises a money sending terminal and a money receiving terminal, the commercial bank digital currency system comprises a money sending commercial bank and a money receiving commercial bank, the money sending commercial bank corresponds to the money sending terminal, and the money receiving commercial bank corresponds to the money receiving terminal;
the central bank digital currency system is used for generating and issuing digital currency and performing ownership registration on the digital currency; a commercial bank digital currency system for performing banking functions on digital currency; the user is the main body for using the digital currency, and the user holds the terminal to carry out the transaction of the digital currency; the trusted intermediary is a trusted infrastructure that has no networking capability and does not store received certificates, including but not limited to digital currency ATM machines, digital currency POS machines, digital currency transaction devices held by trusted merchants.
The invention has the beneficial effects that:
1. the invention designs the digital currency with the private key and the credible medium of the transaction, and can realize an anonymous double-off-line transaction method of the digital currency, so that two transaction parties in the double-off-line transaction can not know the information of the other party, thereby protecting the identity information of a transactor.
2. The transaction flow in the invention not only supports double off-line transaction, but also supports transaction with online sender and offline receiver, transaction with offline sender and online receiver, and transaction with online sender and online receiver, i.e. the flow supports all types of transaction, and can realize the same anonymous effect of both parties of the transaction.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a flow diagram of anonymous double offline transaction steps involving digital currency in an embodiment of the invention;
fig. 2 is a basic configuration diagram of a central bank digital currency system in an embodiment of the present invention.
Detailed Description
For further explanation of the various embodiments, the drawings which form a part of the disclosure and which are incorporated in and constitute a part of this specification, illustrate embodiments and, together with the description, serve to explain the principles of operation of the embodiments, and to enable others of ordinary skill in the art to understand the various embodiments and advantages of the invention, and, by reference to these figures, reference is made to the accompanying drawings, which are not to scale and wherein like reference numerals generally refer to like elements.
According to the embodiment of the invention, the anonymous double offline transaction method and system of the digital currency are provided
Referring now to the drawings and the detailed description, the invention will be further described, as shown in fig. 1, according to one embodiment of the invention, there is provided an anonymous double offline transaction method for digital currency, the method comprising the steps of:
s1, preparation stage: the central bank digital currency system respectively issues digital currencies for the payment terminal and the collection terminal;
wherein, the central bank digital currency system in S1 respectively issuing digital currency for the issuing terminal and the receiving terminal comprises the following steps:
s11, the central bank digital currency system issues digital currency for the payment terminal;
the process of issuing digital money for a dispensing terminal by a central bank SS (central bank digital money system) is as follows: the terminal PT (terminal) of the payment side generates a group of public and private key pairs and sends the public key to the corresponding PS (commercial bank of the payment side), the PS sends the public key to the SS of the central bank, the SS generates digital currencies of various corresponding currency values according to the public key and the currency values and sends the digital currencies to the PS, and the PS sends the digital currencies to the PT.
S12, the central bank digital currency system issues digital currency for the collection terminal;
the process for the central row SS to issue digital currency for the collection terminal is as follows: the CT (collection terminal) of collection side generates a group of public and private key pairs and sends the public key to the corresponding commercial bank CS (collection side commercial bank), CS sends the public key to the CCW SS, SS generates digital currency with various corresponding currency values according to the public key and the currency values and sends the digital currency to CS, and CS sends the digital currency to PT.
S2, double off-line transaction stage (double off-line transaction stage: double off-line transaction is carried out between the payment terminal and the collection terminal through a trusted intermediary):
s21, MT (trusted intermediary) sends message, CT verifies (trusted intermediary sends second combination information to payee terminal, payee terminal verifies second combination information):
MT acquires current timestamp T1(first timestamp) and forms IDMT T with the identity of the own party IDMT (ID of trusted intermediary)1(first Combined information), with own private Key SKMTSigning the signature (by a trusted intermediary private key) to obtain SIGN (IDMT | | | T)1,SKMT) (first signature information), and then take out own digital certificate CERTMT(trusted intermediary digital certificate) and compose the message IDMT | | T1||SIGN(IDMT||T1,SKMT)||CERTMT(second combined information) and sends the message to the CT.
CT receives message IDMT | | T1||SIGN(IDMT||T1,SKMT)||CERTMTThereafter, the timestamp T is confirmed1For the current time, use the public key PK of MTMTSignature SIGN (IDMT | | T) pair (trusted intermediary public key)1,SKMT) Performs authentication and CERTs on the digital certificateMTAnd (6) carrying out verification. If the verification is successful, CT recognizes the MT as CERTMTIf the CT is a trusted intermediary, the subsequent steps are performed, otherwise the CT confirms that the transaction fails and does not perform the subsequent steps.
S22, the CT sends a message, MT verifies (the payee terminal sends the third combination information to the trusted intermediary, and the trusted intermediary verifies the third combination information):
CT generates temporary public and private key pair PKCT(TEMP)/SKCT(TEMP)Using own private key SKCTFor PKCT(TEMP)||T1Signing to obtain SIGN (PK)CT(TEMP)||T1,SKCT) (second signature information), and extracting own digital certificate CERTCTPublic key PK of MTMTEncrypting to obtain Ciphertext ENC (CERT)CT,PKMT) (first encryption information) constituting a message PKCT(TEMP)||T1||SIGN(PKCT(TEMP)||T1,SKCT)||ENC(CERTCT,PKMT) (third combined information) and transmitted to the MT.
MT receives message PKCT(TEMP)||T1||SIGN(PKCT(TEMP)||T1,SKCT)||ENC(CERTCT,PKMT) Then, for T1Making confirmation by using own private key SKMTDecrypting ENC (CERT)CT,PKMT) Obtaining CERTCTBy CERTCTPublic key PK of CT in (1)CTPair signature SIGN (PK)CT(TEMP)||T1,SKCT) And (6) carrying out verification. If the verification is successful, the identity of the CT may be confirmed.
S23, MT sends message, PT verification (trusted intermediary sends fifth combination information to terminal for payment, terminal for payment verifies fifth combination information):
MT acquires current timestamp T2(second time stamp) and the PK received in the previous stepCT(TEMP)Composition PKCT(TEMP)||T2(fourth combination information) with own private key SKMTSigning it to obtain SIGN (PK)CT(TEMP)||T2,SKMT) (third signature information), and own digital certificate CERTMTTogether forming a message PKCT(TEMP)||T2||SIGN(PKCT(TEMP)||T2,SKMT)||CERTMT(fifth combined information), which is called MPC, and then sends the message MPC to the PT.
After PT receives message MPC, it confirms time stamp T2For the current time, use the public key PK of MTMTPair signature SIGN (PK)CT(TEMP)||T2,SKMT) Performing authentication and verifying the digital certificate CERTMTAnd (7) performing verification. If the verification is successful, the PT recognizes the MT as CERTMTIs a trusted intermediary, and recognizes PKCT(TEMP)The ID of the payee is also used as the public key, otherwise, the PT confirms that the transaction fails.
S24, PT send transaction (send transaction to send terminal to receive terminal):
PT takes out a digital currency PM, acquires the current time stamp T3(third time stamp), and will T3The sender information IDPS, the receiver information MPC and the PM form a transaction TX, namely TX is { T }3I IDPS MPC PM }. Because the information of the sender is represented by IDPS, the payee only knows the commercial bank to which the sender belongs, and does not know the specific identity of the sender; and the payee information is represented by MPC, the sender is not aware of the specific identity of the payee. And signing TX by using a private key corresponding to digital currency to obtain TXS (fourth signature information), and sending the TX | | TXS to the CT (sending in a clear text or sending after encrypting by using a public key of the CT, and if the TX is encrypted, decrypting by using a corresponding private key after receiving by the CT).
S25, CT confirmation transaction (transaction confirmation by the receiving terminal):
the CT receives the message to obtain TX | | TXs. The CT takes out the public key in the digital currency, verifies the signature TXS, and verifies the digital currency PM after the verification is successful, such as the verification of the currency value, the central line signature and the like. The transaction is trusted if the verification is successful, and the PM in the TX is taken out and stored, marked as not acknowledged at the central row. Message RET that CT will confirm transactionCTUsing a temporary private key SKCT(TEMP)Signing to obtain SIGCT(fifth signature information), RETCT||SIGCTSent to the PT.
PT receiving RETCT||SIGCTThen, to SIGCTAnd verifying, and deleting the digital currency PM and the private key thereof after the verification is successful. Because the private key corresponds to the digital currency one to one, the private key also needs to be destroyed after the digital currency is sent out. The digital currency is received by the payee as ordinary digital currency without the private key.
S3, online transaction phase (online transaction phase: transaction is confirmed using central bank digital currency system):
s301, CT sends a message:
CT acquires the current timestamp T4(fourth timestamp), with own private key SKCTFor TX | | PKCT(TEMP)||T4Signing to obtain SIGN (TX | | | PK)CT(TEMP)||T4,SKCT) (sixth signature information) using the public key PK of the CSCSTo own digital certificate CERTCTCombined CERT with transaction TXCTI TX is encrypted to obtain Ciphertext ENC (CERT)CT||TX,PKCS) (second encryption information) constituting a message PKCT(TEMP)||T4||SIGN(TX||PKCT(TEMP)||T4,SKCT)||ENC(CERTCT||TX,PKCS) (sixth combination information) and to the corresponding commercial bank CS.
S302, CS receives message
PKCT(TEMP)||T4||SIGN(TX||PKCT(TEMP)||T4,SKCT)||ENC(CERTCT||TX,PKCS) Then, for T4Make confirmation by private key SK of own partyCSDecrypting ENC (CERT)CT||TX,PKCS) Obtaining CERTCTAnd TX and CERTCTPerforming verification by CERTCTPublic key PK of middle CTCTPair signature SIGN (TX | | | PKCT(TEMP)||T4,SKCT) And (6) carrying out verification. If the verification is successful, the CS slave CERTCTObtaining the true identity IDCT of the owner and confirming the PKCT(TEMP)Is payee ID and public key.
The CS sends a message IDCT | | | TX to the central row SS.
S303, the SS forwards the transaction:
and the SS stores IDCT (inverse discrete cosine transform) TX locally after receiving the message, encrypts the TX by using a public key corresponding to the PS of the commercial bank of the sender and sends the encrypted TX to the PS.
S304, the PS sends a trading result:
and the PS receives the message and then decrypts the message by using the private key of the own party to obtain the transaction TX, finds out the owner of the transaction TX as PT according to the digital currency PM in the TX, and acquires the real identity IDPT of the sender. PS takes MPC from TX and PK from MPCCT(TEMPThe IDPT | | | PKCT(TEMP)I TX is stored locally as a complete transaction entry, where PKCT(TEMP)The identity of the payee is represented, so the PS does not know the true identity of the payee.
And the PS takes the successful or failed transaction result as RET, encrypts IDPT with the public key of the SS and sends the encrypted IDPT to the SS.
S305, the SS forwards the transaction result:
and the SS decrypts the received message to obtain IDPT (inverse transform). If the RET carries a message that the transaction is successful, the SS stores IDPT | | | | IDCT | | TX as a complete transaction entry locally, and the SS knows the true identity IDCT of the payee.
The SS encrypts the RET with the public key of the CS and sends it to the CS.
S306, the CS forwards the transaction result:
and the CS decrypts the received message to obtain the RET. If the RET carries a successful transaction message, the CS stores IDPS | | | IDCT | | | TX locally as a complete transaction entry, where IDPS represents the identity of the issuer and thus the CS does not know the true identity of the issuer.
The CS encrypts the RET with the CT's public key and sends it to the CT.
S307, CT confirms the transaction result:
and the CT receives the message and decrypts the message to obtain the RET. If the RET carries a message that the transaction was successful, the CT marks the digital currency PM stored in the step CT confirmation transaction as a central row confirmed and may be used normally subsequently.
According to another aspect of the present invention, there is provided an anonymous double offline transaction system for digital currency, as shown in fig. 2, in terms of an example of operation of central bank digital currency, the digital currency system infrastructure mainly includes a central bank digital currency system, a commercial bank digital currency system (which may be a plurality of commercial bank digital currency systems in practice), and a user. The central bank digital currency system is used for generating and issuing digital currency and performing ownership registration on the digital currency; a commercial bank digital currency system for performing banking functions on digital currency; the user is the main body for using the digital currency, and the user holds the terminal to carry out the transaction of the digital currency.
Suppose that there are a central bank (i.e. a central bank digital currency system) SS, a sender commercial bank (i.e. a commercial bank digital currency system) PS and its corresponding sender terminal PT, a receiver commercial bank CS and its corresponding receiver terminal CT, whose corresponding IDs are IDSS, IDPS, IDPT, IDCS and IDCT, respectively.
The invention also comprises a trusted intermediary MT which is a trusted infrastructure, such as a digital currency ATM, a digital currency POS machine, a digital currency transaction device held by a trusted merchant and the like, has no networking function, does not store received certificates and prevents user information from being leaked. In the invention, each member has a digital certificate, the real identity of the member is stored in the certificate, and the MT stores the digital certificate of each commercial bank. The PT, the CT and the MT are in near field communication (such as NFC), and the communication content cannot be acquired by a third party when any two are in communication.
In conclusion, the invention designs the digital currency with the private key and the credible medium of the transaction, and can realize the anonymous double-off-line transaction method of the digital currency, so that the two transaction parties in the double-off-line transaction can not know the information of the other party, thereby protecting the identity information of the transactor. The transaction flow in the invention not only supports double off-line transaction, but also supports transaction with online sender and offline receiver, transaction with offline sender and online receiver, and transaction with online sender and online receiver, i.e. the flow supports all types of transaction, and can realize the same anonymous effect of both parties of the transaction.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. An anonymous double offline transaction method for digital currency, characterized by comprising the steps of:
s1, preparation stage: the central bank digital currency system issues digital currencies for the payment terminal and the collection terminal respectively;
s2, double off-line transaction stage: the payment terminal and the collection terminal carry out double off-line transaction through a trusted intermediary;
s3, online transaction stage: validating the transaction using a central bank digital currency system;
wherein the step of respectively issuing digital currency for the issuing terminal and the receiving terminal by the central bank digital currency system in the step S1 includes the following steps:
s11, the central bank digital currency system issues digital currency for the payment terminal;
s12, the central bank digital currency system issues digital currency for the collection terminal;
the step of issuing digital currency for the issuing terminal by the central bank digital currency system in the step S11 specifically includes the following steps:
the payment terminal generates a group of public and private key pairs and sends the public key to the corresponding payment party commercial bank, the payment party commercial bank sends the public key to the central bank digital currency system, the central bank digital currency system generates digital currencies with various corresponding currency values according to the public key and the currency values and sends the digital currencies to the payment party commercial bank, and the payment party commercial bank sends the digital currencies to the payment terminal;
the step of issuing digital currency for the collection terminal by the central bank digital currency system in the step S12 specifically includes the following steps:
the collection terminal generates a group of public and private key pairs and sends the public key to the corresponding collection commercial bank, the collection commercial bank sends the public key to the central bank digital currency system, the central bank digital currency system generates digital currencies with various currency values according to the public key and the currency values and sends the digital currencies to the collection commercial bank, and the collection commercial bank sends the digital currencies to the collection terminal.
2. The anonymous double offline transaction method of digital currency according to claim 1, wherein said double offline transaction between said terminal for issuing and said terminal for receiving at S2 via a trusted intermediary comprises the steps of:
s21, the trusted intermediary sends the second combination information to the collection terminal, and the collection terminal verifies the second combination information;
s22, the collection terminal sends the third combination information to the trusted intermediary, and the trusted intermediary verifies the third combination information;
s23, the trusted intermediary sends the fifth combined information to the payment terminal, and the payment terminal verifies the fifth combined information;
s24, the payment terminal sends the transaction to the payment terminal;
s25, the receiving terminal confirms the transaction.
3. The anonymous double offline transaction method of digital currency according to claim 2, wherein said trusted intermediary sends the second combination information to the receiving terminal in S21, and the receiving terminal verifies the second combination information specifically includes the following steps:
s211, the trusted intermediary acquires a first time stamp, the first time stamp and the ID of the trusted intermediary form first combined information, the first combined information is signed by the private key of the trusted intermediary to obtain first signature information, then a digital certificate of the trusted intermediary is taken out, the ID of the trusted intermediary, the first time stamp and the first signature information form second combined information, and the second combined information is sent to the collection terminal;
and S212, after receiving the second combined information, the collection terminal confirms that the first time stamp is the current time, verifies the first signature information by using the trusted intermediary public key and verifies the trusted intermediary digital certificate, if the verification is successful, the collection terminal approves the trusted intermediary as the owner of the trusted intermediary digital certificate and carries out subsequent steps, otherwise, the collection terminal confirms that the transaction is failed and does not carry out subsequent steps.
4. The anonymous double offline transaction method of digital currency according to claim 3, wherein said receiving terminal sends a third combination of information to said trusted intermediary at S22, and said step of verifying said third combination of information by said trusted intermediary comprises the steps of:
s221, the collection terminal generates a collection terminal temporary public and private key pair, a collection terminal private key is used for signing a collection terminal temporary public key and a first timestamp to obtain second signature information, meanwhile, a collection terminal digital certificate is taken out and encrypted by a trusted intermediary public key to obtain first encryption information, the collection terminal temporary public key, the first timestamp, the second signature information and the first encryption information form third combined information, and the third combined information is sent to a trusted intermediary;
s222, after the trusted intermediary receives the third combined information, the first timestamp is confirmed, the first encrypted information is decrypted by using a private key of the trusted intermediary to obtain a collection terminal digital certificate, meanwhile, a collection terminal public key in the collection terminal digital certificate is used for verifying the second signature information, and if the verification is successful, the identity of the collection terminal can be confirmed.
5. The anonymous double offline transaction method for digital currency according to claim 4, wherein said trusted intermediary sends the fifth combination information to the terminal in S23, and the terminal for issuing verification of the fifth combination information specifically comprises the following steps:
s231, the trusted intermediary acquires the second timestamp, forms fourth combined information with the temporary public key of the collection terminal received in the step S222, signs the fourth combined information by using the private key of the trusted intermediary to obtain third signature information, forms fifth combined information by using the fourth combined information, the third signature information and the digital certificate of the trusted intermediary, and sends the fifth combined information to the payment sending terminal;
and S232, after receiving the fifth combined message, the money issuing terminal confirms that the second timestamp is the current time, verifies the third signature information by using the trusted intermediary public key and verifies the trusted intermediary digital certificate, if the verification is successful, the money issuing terminal approves the trusted intermediary as the owner of the trusted intermediary digital certificate and approves the collection terminal temporary public key as the collection party ID and public key, and otherwise, the money issuing terminal confirms that the transaction is failed.
6. The anonymous double offline transaction method of digital currency according to claim 5, wherein said step of sending the transaction from the payment terminal to the payment terminal in S24 comprises the following steps:
and the payment terminal takes out a digital currency, acquires a third time stamp, forms a transaction by the third time stamp, the ID of the commercial bank of the payment party, the fifth combination information and the digital currency, signs the transaction by a private key corresponding to the digital currency to obtain fourth signature information, and sends the transaction and the fourth signature information to the collection terminal.
7. The anonymous double offline transaction method of digital money according to claim 6, wherein in said step S24, the transaction and the fourth signature information are sent to the receiving terminal in a clear text or encrypted by a public key of the receiving terminal, and if the transaction and the fourth signature information are sent in an encrypted manner, the receiving terminal receives the transaction and decrypts the transaction by a corresponding private key.
8. The anonymous double offline transaction method of digital currency according to claim 6, wherein said confirmation by said receiving terminal at S25 comprises the following steps:
s251, after receiving the transaction and the fourth signature information, the cash receiving terminal takes out a public key corresponding to the digital currency, verifies the fourth signature information, verifies the digital currency if the verification is successful, trusts the transaction if the verification is successful, takes out the digital currency in the transaction and stores the digital currency at the same time, marks the digital currency as not confirmed in the central bank, signs a message for confirming the transaction by using a temporary private key of the cash receiving terminal to obtain fifth signature information, and then sends the message for confirming the transaction and the fifth signature information to the payment sending terminal;
and S252, after receiving the transaction confirmation message and the fifth signature information, the payment terminal verifies the fifth signature information, and if the verification is successful, deletes the digital currency and the private key corresponding to the digital currency.
9. The anonymous double offline transaction method of digital currency according to claim 1, wherein said step of validating the transaction using the central bank digital currency system in S3 comprises the steps of:
s301, the collection terminal acquires a fourth timestamp, signs the transaction, the collection terminal temporary public key and the fourth timestamp by using a collection terminal private key to obtain sixth signature information, encrypts a collection terminal digital certificate and a transaction combination by using a public key of a collection party commercial bank to obtain second encryption information, forms sixth combination information by using the collection terminal temporary public key, the fourth timestamp, the sixth signature information and the second encryption information, and sends the sixth combination information to the collection party commercial bank;
s302, after receiving the sixth combined information, the commercial bank of the payee confirms the fourth timestamp, decrypts the second encrypted information by using a private key of the commercial bank of the payee to obtain a digital certificate of the payee terminal and a transaction, verifies the digital certificate of the payee terminal, verifies the sixth signature information by using a public key of the payee terminal in the digital certificate of the payee terminal, and if the verification is successful, the commercial bank of the payee terminal acquires the ID of the payee terminal from the digital certificate of the payee terminal and confirms that the temporary public key of the payee terminal is the ID and the public key of the payee terminal, and meanwhile, the commercial bank of the payee terminal sends the ID of the payee terminal and the transaction to a digital money system of a central bank;
s303, after receiving the message, the digital money system of the central bank locally stores the ID and the transaction of the money receiving terminal, encrypts the transaction by using a public key corresponding to the commercial bank of the money sender and sends the encrypted transaction to the commercial bank of the money sender;
s304, after receiving the message, the commercial bank of the sender decrypts the message by using a private key of the commercial bank of the sender to obtain a transaction, finds the sender terminal according to the digital currency in the transaction, acquires the ID of the sender terminal, takes out the fifth combined information from the transaction, simultaneously takes out the temporary public key of the collection terminal from the fifth combined information, stores the ID of the sender terminal, the temporary public key of the collection terminal and the transaction as a complete transaction item in the local, and encrypts the ID of the sender terminal and the transaction result by using the public key of the digital currency system of the central bank and sends the encrypted ID and transaction result to the digital currency system of the central bank;
s305, the central bank digital currency system receives the message and then decrypts the message to obtain the ID of the payment terminal and the transaction result, if the transaction result is a successful transaction message, the central bank digital currency system stores the ID of the payment terminal, the ID of the collection terminal and the transaction as a complete transaction item in the local, and the central bank digital currency system encrypts the transaction result by using the public key of the commercial bank of the collection party and sends the encrypted transaction result to the commercial bank of the collection party;
s306, the commercial bank of the payee decrypts the received message to obtain a transaction result, if the transaction result is a successful transaction message, the commercial bank of the payee stores the ID of the commercial bank of the sender, the ID of the payee terminal and the transaction as a complete transaction item in the local, and the commercial bank of the payee encrypts the transaction result by using the public key of the payee terminal and sends the encrypted transaction result to the payee terminal;
and S307, the receiving terminal receives the message and then decrypts the message to obtain a transaction result, and if the transaction result is a successful transaction message, the receiving terminal marks the digital money stored in the step S25 as the confirmation of the central row and the digital money can be normally used subsequently.
10. An anonymous double offline transaction system for digital currency, for implementing the steps of the anonymous double offline transaction method for digital currency according to any one of claims 1 to 9, wherein the system comprises a central bank digital currency system, a commercial bank digital currency system, a trusted intermediary and a user, and the user holds a corresponding user terminal;
the user terminal comprises a money sending terminal and a money receiving terminal, the commercial bank digital currency system comprises a money sending commercial bank and a money receiving commercial bank, the money sending commercial bank corresponds to the money sending terminal, and the money receiving commercial bank corresponds to the money receiving terminal;
the central bank digital currency system is used for generating and issuing digital currency and performing ownership registration on the digital currency; a commercial bank digital currency system for performing banking functions on digital currency; the user is the main body for using the digital currency, and the user holds the terminal to carry out the transaction of the digital currency; the trusted intermediary is a trusted infrastructure that has no networking capability and does not store received certificates, including but not limited to digital currency ATM machines, digital currency POS machines, digital currency transaction devices held by trusted merchants.
CN202011304842.8A 2020-11-19 2020-11-19 Anonymous double-off-line transaction method and system for digital currency Pending CN114519574A (en)

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