Anonymous payment protocol based on USIM card

Abstract

The invention discloses an anonymous payment protocol based on a USIM card, and relates to the technical field of electronic payment. Comprising the steps of constructing an anonymous transaction environment and executing a payment protocol; the construction of the anonymous transaction environment specifically comprises the following steps: a user terminal initiates an anonymous payment request E to a bank node; a traceable anonymous transaction environment is established after the bank verifies the request; the payment protocol is specifically executed as follows: a payment path is confused by setting a forwarding node and identity replacement; wherein the forwarding node determines message forwarding based on the probability evaluation result until the total communication path meets the preset secret level, and triggers the USIM server to complete payment. The information security of the payer is ensured, and the information of the receiver is held by the USIM instead of the payer, so that the information security of the payee is ensured, and the payment efficiency is improved. And the UISM server records the information of key transaction initiators and receivers, so that the traceability of the information is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic payment, and in particular to an anonymous payment protocol based on a USIM card. BACKGROUND

[0002] In the prior art, the electronic payment method has become the mainstream payment method at present and is a payment means with a wide range of applications. Since the application of the technology, the use scenarios thereof have penetrated into various fields of user life. With the expansion of the use range and the continuous increase of the number of users, the electronic payment method still has the problems of high security and easy exposure of transaction information in some scenarios requiring high security and high privacy.

[0003] Therefore, in the prior art, the anonymous payment method is adopted to hide the information of the payment party and the payee, so that the identity information of the transaction parties can be ensured not to be disclosed after the transaction, thereby achieving the information security of the transaction. SUMMARY

[0004] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the problems in the prior art, the present application is proposed.

[0006] To solve the above technical problems, the present application provides the following technical scheme: an anonymous payment protocol based on a USIM card, comprising: construction of an anonymous transaction environment and execution of a payment protocol. The construction of the anonymous transaction environment specifically comprises: the user terminal initiates an anonymous payment request E to a bank node, the anonymous payment request E containing a user identifier IDu and a random parameter matrix R; the bank generates a virtual anonymous account identifier AID and a corresponding asymmetric key pair (PK AIDi , SK AIDi ) after verifying the request, and distributes a certificate through a USIM server to establish a traceable anonymous transaction environment; The execution of the payment protocol specifically comprises: the user terminal splits a payment amount into multiple parts based on the virtual anonymous account, and sets a forwarding node and an identity replacement to confuse the payment path; wherein the forwarding node determines message forwarding based on a probability evaluation result until the total communication path meets a preset secret level, triggering the USIM server to complete the payment.

[0007] As a preferred scheme of the anonymous payment protocol based on the USIM card, the random parameter matrix R is generated as follows: R=(q, G1, G2, GT, e, g1, g2, h1, h2). Wherein, q is a prime number, G1, G2, GT are three multiplicative bilinear groups G1, G2 and GT of large prime number q, the bilinear pair e: G1×G2→GT, g1∈G1 is the generator of the bilinear group G1, g2∈G2 is the generator of the bilinear group G2, h1, h2 are one-way anti-collision hash functions h1:{0,1}*→G1 and h2:{0,1}*→G2. The expression of the anonymous payment request E is as follows: E(K B,U |SIGN(SKu,IDu||R)); Wherein, KB, U are the pre-generated public keys, SKu is the private key of the user, IDu is the user terminal identifier, and R is the random parameter array used for proving uniqueness.

[0008] As a preferred scheme of the anonymous payment protocol based on the USIM card, the method for generating the virtual anonymous account identifier AID and the corresponding asymmetric key pair (PK AIDi ,SK AIDi ) after the bank verification request is as follows: After receiving the request of the user terminal, the bank uses the public key K B,U to decrypt and verify the request E, and if the bank verification is passed, the bank generates the virtual anonymous payment account identifier AIDi and the random number S for the user terminal; The bank uses the public key K B,U to encrypt IDu, AIDi and the random number S to generate the message E1: E1(ID B ||E(K B,U |IDu|AIDi|S)), and feeds back E1 to the user; After receiving E1, the user uses the private key to decrypt the message, and when the message E1 is successfully decrypted, sends the message E2(IDu|AIDi|S) to the USIM server; After receiving the message E2, the server of the USIM generates the corresponding identifier AIDi of the asymmetric key (PK AIDi, SK AIDi), and stores the key in the USIM server.

[0009] As a preferred scheme of the anonymous payment protocol based on the USIM card, the server of the USIM uses the generated asymmetric key pair to sign the message to be sent, and sends the signed message E3 to the user terminal; the expression of E3 is as follows: E3 (SIGN (SK AIDi , IDu || AIDi || AIDi || S) ) || PK AIDi ) ; After the user terminal receives the message E3, it uses the public key KB,U to encrypt the signature message, and forwards the encrypted signature message E4 to the bank; the expression of E4 is as follows: E4 (IDu || E (K B,U | SIGN (SKu, IDu || AIDi || SIGN (SK AIDi , IDu || AIDi || PK AIDi || S) ; After the bank receives the message E4, it checks PK AIDi , and then creates a certificate CE AIDi opposite to the public key PK ADi . The bank uses the public key PK AIDi to encrypt the message certificate, the expiration time AIDi_ET of AIDi, the transaction limit AIDi_Limit of AIDi, and the certificate CE ADi , and sends the encrypted information to the USIM node using the key K B,U .

[0010] As a preferred scheme of the anonymous payment protocol based on the USIM card, wherein the user terminal splits the payment amount into multiple parts based on the virtual anonymous account comprises: During the payment process of the user terminal, the pre-generated asymmetric key pair (PK AIDi , SK AIDi ) and the channel identifier FL at the time of forwarding are informed to the USIM to create the number of forwarding nodes; Wherein, the user terminal calculates the number of forwarding nodes according to the payment amount, and the more the number of forwarding nodes, the better the anonymity effect. The calculation method of the number of USIM forwarding nodes = payment amount / M, wherein M is a preset value, and the USIM generates the forwarding nodes and informs the communication address shared by each node; Wherein, the channel identifier FL is an identifier known to all forwarding nodes created by the USIM.

[0011] As a preferred scheme of the anonymous payment protocol based on the USIM card, wherein the payment path is confused by setting forwarding nodes and identity replacement (such as the exchange of the user terminal and the node JDO address) comprises: The user terminal generates a key pair (PK AIDi , SK AIDi), and the forwarding information and the identity information FL forwarding identity are combined into a request message Q0, which is forwarded to the first node JD0; After the node JD0 receives the request message, the communication address of the node itself and the communication address of the user terminal are replaced, and the replaced communication address is informed to the USIM node.

[0012] As a preferred scheme of the anonymous payment protocol based on the USIM card, the following steps are further included: The user terminal uses the replaced identity information J0 to generate a key pair (PK AIDi , SK AIDi ) again, and combines the forwarding information and the identity information FL forwarding identity into a request message Q1, which is forwarded to another node J1. After the J1 receives the message Q1, a forwarding probability P is generated by means of coin tossing, and the result TRe is compared with the forwarding probability Pf set by the system, and then the public key PK AIDi is used to encrypt the symmetric key SK1 of the node itself, the signature information of the virtual account pair SK1, and the coin tossing result TRe, to generate a message C, and finally the message C is fed back to the J0. The expression of the message C is C=PK AIDi (SK1|sign(SK1)|TRe). After the J0 receives the message C, the message is parsed by using SK AIDi , and the result of TRe is evaluated, if the result is less than or equal to Pf, the node JD1 is informed to continue forwarding the information, and the message is forwarded to the server of the USIM, and the UISM uses the virtual wallet to send the amount corresponding to HM1 to the payee, otherwise, a node JD2 is randomly selected from the remaining alternative nodes which have not performed message forwarding as the node for forwarding the information, wherein the request forwarding information includes the first part of the payment amount HM1. The J0 sends Q1 to J2 as the message forwarding node, and the user terminal uses SK1 to encrypt the message Q1, wherein the Q1 includes the payment amount information HM2. The Q1 includes the key pair (PK AIDi , SK AIDi ), the forwarding information and the identity information FL forwarding identity, and the payment amount information HM2. After the J2 receives the Q1 message, the above steps are repeated, and the like.

[0013] As a preferred scheme of the anonymous payment protocol based on the USIM card, the following steps are further included: J0 will continuously receive feedback from member Jk. Furthermore, based on member Jk's communication address, it will assess whether the total communication path between the communication terminal and all members meets the communication distance that is consistent with the preset concealment level. Once the total communication distance reaches the preset value, the user terminal will notify the USIM system node that virtual currency in the virtual wallet can be used for payment. The payment process is only completed when the USIM system node receives HM1 and HM2. This involves notifying the bank to convert the virtual currency into electronic money and paying the recipient.

[0014] The beneficial effects of this invention are: 1. This invention constructs an environment capable of anonymous payments by specifying the registration and authentication interaction process between the user terminal, the bank, and the USIM server. 2. This invention splits virtual currency and uses identity replacement to send payment information of the split virtual currency to a virtual wallet through different nodes. Once the virtual wallet receives all the split currency, it notifies the bank that payment can be made to the recipient. At the same time, the transmission process between different transmission nodes is unordered and identity replacement is performed, thus ensuring the information security of the payer. In addition, the recipient's information is held by USIM, not the payer, thus ensuring the information security of the recipient as well. Furthermore, the UISM server records the key information of the transaction initiator and recipient, realizing information traceability. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the overall process of an anonymous payment protocol based on a USIM card proposed in this invention. Figure 2 A flowchart illustrating the process of building an anonymous payment transaction environment. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0018] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0019] Reference Figure 1 As an embodiment of the present invention, an anonymous payment protocol based on a USIM card is provided. This protocol method includes: constructing an anonymous transaction environment and executing a payment protocol. The construction of the anonymous transaction environment specifically involves: the user terminal initiating an anonymous payment request E to the bank node, whereby the anonymous payment request E includes a user identifier IDu and a random parameter matrix R; after verifying the request, the bank generates a virtual anonymous account identifier AID and a corresponding asymmetric key pair (PK). AIDi SK AIDi It distributes certificates through the USIM server to establish a traceable anonymous transaction environment; The payment protocol is executed as follows: the user terminal, based on a virtual anonymous account, splits the payment amount into multiple parts and obfuscates the payment path by setting forwarding nodes and identity replacement (e.g., the user terminal and node JDO addresses are swapped); the forwarding nodes decide to forward messages based on probability assessment results until the total communication path meets the preset concealment level, triggering the USIM server to complete the payment.

[0020] Furthermore, before establishing a transaction environment, to ensure the security and legitimacy of transactions, users need to use a bank account with valid identity information and provide their own public key to the PKU bank. The bank will then provide the user with a Certificate (CE) corresponding to the user's public key (PKU). UB At the same time, the bank generates the user's public key K. B,U The key is transmitted through a separate secure channel and stored on the user's terminal. (See reference...) Figure 2 The specific method for constructing an anonymous payment transaction environment according to the present invention is as follows: S101: The user terminal sends an application to the bank node for the account identifier information BID for anonymous payment. The user writes its user terminal's IDu information and random parameter column matrix R into the anonymous payment request E. The generation process of the random parameter column matrix R is as follows.

[0021] R=(q,G1,G2,GT,e,g1,g2,h1,h2) Let q be a prime number, G1, G2, and GT be three multiplicative bilinear groups G1, G2, and GT of order 3 for a large prime number q, and let e be a bilinear pair: G1 × G2 → GT. Let g1 ∈ G1 be a generator of the bilinear group G1 and g2 ∈ G2 be a generator of the bilinear group G2. Let h1 and h2 be one-way collision-resistant hash functions h1: {0, 1} * → G1 and h2: {0, 1} * → G2.

[0022] Furthermore, the E in this request is expressed as follows: E(K B,U |SIGN(SKu,IDu||R)) Among them, K B,U The public key is pre-generated, SKu is the user's private key, IDu is the user terminal identifier, and R is a random parameter array used to prove uniqueness. S102: After receiving the request from the user terminal, the bank uses the public key K B,U If the decryption and verification request E passes the bank's verification, the bank will generate a virtual anonymous payment account identifier AIDi and a random number S for the user.

[0023] S103: Banks use public key K B,U The encrypted IDu, AIDi, and random number S generate message E1, and E1 is sent back to the user; E1(ID) B ||E(K B,U |IDu|AIDi|S)).

[0024] S104: After receiving E1, the user decrypts the message using the private key. After successfully decrypting message E1, the user sends message E2 (IDu|AIDi|S) to the USIM server.

[0025] S105: After receiving message E2, the USIM server generates an asymmetric key (PK) for the corresponding identifier AIDi based on the message. AIDi SK AIDi ), and store the key in the USIM server.

[0026] S106: The USIM server uses the generated asymmetric key pair to sign the message to be sent and sends the signed message E3 to the user terminal. The format for message E3 is: E3(SIGN(SK) AIDi ,IDu||AIDi||AIDi||S)||PK AIDi ).

[0027] S107: After receiving message E3, the user terminal uses the public key K B,U The encrypted signed message, E4, is forwarded to the bank; message E4 is represented as follows: E4(IDu||E(K B,U |SIGN(SKu,IDu||AIDi||SIGN(SK AIDi ,IDu||AIDi||PK AIDi ||S) S108: After receiving message E4, the bank verifies the PK. AIDi Then create a PK key with the public key. AIDi The corresponding certificate is CE. ADi Banks use public key PK AIDi The message includes the certificate, AIDi expiration time (AIDi_ET), AIDi transaction limit (AIDi_Limit), and certificate CE. ADi Using key K B,U Encrypt the information and send the encrypted message (E5) to the USIM node.

[0028] In summary, by combining S101-S108 above, the user has completed the process of informing the bank and USIM of their identity information, enabling the bank and USIM to identify the transacting parties based on the user's identification information during subsequent transactions.

[0029] Furthermore, after establishing an environment for anonymous payments, to further enhance anonymity, the currency used in anonymous transactions is split. This can be visualized as follows: when a user needs to pay 100 yuan, the user actually makes two or more payment actions. Only when the total amount from both transactions is received can the recipient be considered to have received the complete payment. This prevents the recipient from counterfeiting virtual currency. Simultaneously, the scheme assigns different forwarding probabilities to forwarding nodes. Therefore, forwarding nodes can be understood as router nodes, which assume that any forwarder could be the initiator of the task, i.e., the payer of the currency. This helps to obfuscate the information received by the recipient, preventing them from knowing who made the payment and ensuring the payer's privacy. Specifically: S201: During the payment process at the user terminal, the pre-generated key pair (PK) will be used. AIDi SK AIDiThe system informs the user terminal of the number of forwarding nodes to be created and the channel identifier FL for forwarding. The user terminal calculates the number of nodes to be forwarded based on the payment amount; the more nodes forwarded, the better the anonymity. The calculation method for the number of USIM forwarding nodes is: payment amount / M, where M is a preset value. After generating forwarding nodes, USIM will notify each node of its shared communication address. The channel identifier FL is a unique identifier known to all forwarding nodes created by USIM.

[0030] S202: The user terminal will generate a key pair (PK) AIDi SK AIDi The request forwarding information and the identification information FL forwarding identifier are combined into a request message Q0, which is forwarded to the first node JD0.

[0031] S203: After receiving the request message, node JD0 replaces its own communication address with the communication address of the user terminal and informs the USIM node of the replacement communication address; This step is equivalent to the user terminal and the J0 node exchanging identities. USIM is aware of this identity swap, but other nodes are unaware of it. This ensures that anonymous transactions can be traced later, while also hiding the user terminal's information.

[0032] S204: Further, the user terminal uses the replaced identity information J0 to again transmit the generated key pair (PK). AIDi SK AIDi The request forwarding information and the identification information FL forwarding identifier are combined into a request message Q1, which is forwarded to another node J1.

[0033] S205: After receiving message Q1, J1 generates a forwarding probability P by inserting a coin and compares it with the forwarding probability Pf set by the system, resulting in a result TRe. Then, it uses the public key PK. AIDi Encryption is used to generate message C from the JD1 node's own symmetric key SK1, the virtual account's signature information on SK1, and the coin insertion result TRe. Message C is then sent back to J0 (actually the user terminal); C=PK AIDi (SK1|sign(SK1)|TRe).

[0034] S206: After J0 (actually the user terminal) receives message C, it uses SK AIDiThe message is parsed and the result of TRe is evaluated. If the result is less than or equal to Pf, node JD1 is instructed to continue forwarding the information and forward the message to the USIM server. UISM then uses the virtual wallet to send the corresponding amount HM1 to the recipient. Otherwise, node JD2 is randomly selected from the remaining candidate nodes that have not forwarded the message before as the forwarding node, i.e., the operation in S207 is executed. The request to forward the information includes the amount HM1 paid by the user in the first part.

[0035] S207: J0 (actually the user terminal) sends Q1 to J2 as a message forwarding node. The user terminal uses SK1 to encrypt message Q1, where Q1 contains payment amount information HM2. Q1 includes a key pair (PK). AIDi SK AIDi The system requests forwarding information and identification information FL (forwarding identifier combination) and payment amount information HM2. After receiving message Q1, J2 executes steps S205-S208, and so on.

[0036] S208: J0 (actually the user terminal) will continuously receive information from member Jk. Furthermore, based on member Jk's communication address, it will assess whether the total communication path between the communication terminal and all members meets the communication distance that matches the preset concealment level. Once the total communication distance reaches the preset value, the user terminal will notify the USIM node that virtual currency in the virtual wallet can be used for payment.

[0037] Under these conditions, when the user terminal replaces the communication address of J0, J0 takes over the forwarding function. If the subsequent forwarding meets the communication distance threshold, the user terminal notifies the server that payment for MH1 and MH2 can proceed. Otherwise, the forwarding process executes normally.

[0038] S209: The payment process will only be completed after the USIM system node receives HM1 and HM2. This involves notifying the bank to convert the virtual currency into electronic money and paying the recipient.

[0039] As can be seen from S201-S209 above, because the user terminal replaces the payment information with the J0 node, and at the same time, the virtual currency is divided during the payment process and the payment operation is forwarded using different forwarding nodes and forwarding paths, security is ensured while making it difficult for attackers to trace the path and reverse-engineer the payer's information.

[0040] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An anonymous payment protocol based on a USIM card, characterized in that, include: The construction of anonymous transaction environments and the execution of payment protocols; The construction of the anonymous transaction environment specifically involves: the user terminal initiating an anonymous payment request E to the bank node, wherein the anonymous payment request E includes a user identifier IDu and a random parameter matrix R; after verifying the request, the bank generates a virtual anonymous account identifier AID and a corresponding asymmetric key pair (PK). AIDi SK AIDi It distributes certificates through the USIM server to establish a traceable anonymous transaction environment; The execution of the payment protocol is as follows: the user terminal, based on a virtual anonymous account, splits the payment amount into multiple parts and obfuscates the payment path by setting forwarding nodes and identity replacement; wherein, the forwarding nodes decide to forward messages based on probability assessment results until the total communication path meets the preset concealment level, triggering the USIM server to complete the payment.

2. The anonymous payment protocol based on a USIM card according to claim 1, characterized in that: The random parameter column matrix R is generated as follows: R=(q,G1,G2,GT,e,g1,g2,h1,h2); Where q is a prime number, G1, G2, GT are three multiplicative bilinear groups G1, G2, and GT of order 3 of large prime numbers q, bilinear pair e: G1×G2→GT, g1∈G1 is a generator of bilinear group G1, g2∈G2 is a generator of bilinear group G2, and h1, h2 are one-way collision-resistant hash functions h1:{0,1}*→G1 and h2:{0,1}*→G2. The anonymous payment request E is expressed as: E(K) B,U |SIGN(SKu,IDu||R)); Where KB,U is a pre-generated public key, SKu is the user's private key, IDu is the user terminal identifier, and R is a random parameter array used to prove uniqueness.

3. The anonymous payment protocol based on a USIM card according to claim 1, characterized in that: Upon receiving the bank verification request, a Virtual Anonymous Account Identifier (AID) and a corresponding asymmetric key pair (PK) are generated. AIDi SK AIDi The method is as follows: After receiving the request from the user terminal, the bank uses the public key K. B,U Decrypt and verify request E. If the bank's verification is successful, the bank will generate a virtual anonymous payment account identifier AIDi and a random number S for the user. Banks use public key K B,U Encrypting IDu, AIDi, and a random number S generates message E1: E1(ID) B ||E(K B,U |IDu|AIDi|S)), and will provide E1 feedback to the user; After receiving E1, the user decrypts the message using the private key. Once the message E1 is successfully decrypted, the user sends message E2 (IDu|AIDi|S) to the USIM server. After receiving message E2, the USIM server generates an asymmetric key (PKAIDi, SKAIDi) with the corresponding identifier AIDi based on the message, and stores the key in the USIM server.

4. The anonymous payment protocol based on a USIM card according to claim 3, characterized in that: The USIM server uses the generated asymmetric key pair to sign the message to be sent and sends the signed message (E3) to the user terminal; the E3 is represented as follows: E3(SIGN(SK AIDi ,IDu||AIDi||AIDi||S)||PK AIDi ); After receiving message E3, the user terminal uses the public key KB,U to encrypt and sign the message, and then forwards the encrypted and signed message E4 to the bank; E4 is represented as follows: E4(IDu||E(K B,U |SIGN(SKu,IDu||AIDi||SIGN(SK AIDi ,IDu||AIDi||PK AIDi ||S); After receiving message E4, the bank verifies the PK. AIDi Then create a PK key with the public key. AIDi The corresponding certificate is CE. ADi Banks use public key PK AIDi The message includes the certificate, AIDi expiration time (AIDi_ET), AIDi transaction limit (AIDi_Limit), and certificate CE. ADi Using key K B,U The information is encrypted, and the encrypted information is sent to the USIM node.

5. The anonymous payment protocol based on a USIM card according to claim 1, characterized in that: The user terminal, based on a virtual anonymous account, splits the payment amount into multiple parts, including: During the payment process at the user terminal, the pre-generated asymmetric key pair (PK) will be used. AIDi SK AIDi And inform USIM of the number of forwarding nodes to be created and the channel identifier FL for forwarding; The user terminal calculates the number of nodes that need to be forwarded based on the payment amount. The more nodes that need to be forwarded, the better the anonymity. The calculation method for the number of USIM forwarding nodes is: payment amount / M, where M is a preset value. After USIM generates forwarding nodes, it will notify each node of the communication address shared with it. Among them, the channel identifier FL is an identifier that is known to all forwarding nodes created by USIM.

6. The anonymous payment protocol based on a USIM card according to claim 1, characterized in that: The specific steps of obfuscating the payment path by setting forwarding nodes and identity replacement are as follows: The user terminal will generate a key pair (PK). AIDi SK AIDi The request forwarding information and the identification information FL forwarding identifier are combined into a request message Q0, which is forwarded to the first node JD0; After receiving the request message, node JD0 replaces its own communication address with the communication address of the user terminal and informs the USIM node of the replacement communication address.

7. The anonymous payment protocol based on a USIM card according to claim 6, characterized in that: It also includes the following steps: The user terminal uses the replaced identity information J0 to re-generate the key pair (PK). AIDi SK AIDi The request forwarding information and the identification information FL forwarding identifier are combined into a request message Q1, which is then forwarded to another node J1. After receiving message Q1, J1 generates a forwarding probability P by inserting a coin and compares it with the system-set forwarding probability Pf, resulting in a result TRe. Then, it uses the public key PK. AIDi Encryption is used to generate message C from JD1 node's own symmetric key SK1, the virtual account's signature information on SK1, and the coin insertion result TRe, and finally message C is sent back to J0; The message C is represented as: C=PK AIDi (SK1|sign(SK1)|TRe); After J0 receives message C, it uses SK AIDi The message is parsed and the result of TRe is evaluated. If the result is less than or equal to Pf, node JD1 is instructed to continue forwarding the information and forward the message to the USIM server. UISM then uses the virtual wallet to send the corresponding amount HM1 to the recipient. Otherwise, node JD2 is randomly selected from the remaining candidate nodes that have not forwarded the message before as the forwarding node. The request to forward the message includes the amount HM1 paid by the user in the first part. J0 sends Q1 to J2 as a message forwarding node. The user terminal uses SK1 to encrypt message Q1, which contains payment amount information HM2. Q1 includes a key pair (PK). AIDi SK AIDi ), requesting forwarding information and identification information FL forwarding identification combination, payment amount information HM2; After J2 receives the Q1 message, it repeats the above steps, and so on.

8. The anonymous payment protocol based on a USIM card according to claim 7, characterized in that: The process of triggering the USIM server to complete payment until the total communication path meets the preset confidentiality level includes: J0 will continuously receive feedback from member Jk. Furthermore, based on member Jk's communication address, it will assess whether the total communication path between the communication terminal and all members meets the communication distance that is consistent with the preset concealment level. Once the total communication distance reaches the preset value, the user terminal will notify the USIM system node that virtual currency in the virtual wallet can be used for payment. The payment process is only completed when the USIM system node receives HM1 and HM2. This involves notifying the bank to convert the virtual currency into electronic money and paying the recipient.

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