A cross-chain identity privacy protection method based on oblivious transfer

Abstract

The present invention discloses a cross-chain identity privacy protection method based on oblivious transmission, which is characterized in that it includes the following steps: S1: adopting a negotiated key designed based on a peninsula group permutable rational function to ensure that both the regulatory agency and the local enterprise can securely negotiate the key; S2: when the regulatory agency performs identity attribute compliance inspection on the local enterprise on the local chain, a cross-chain communication scheme based on oblivious transmission technology is adopted to achieve cross-chain identity authentication. The present invention relates to the field of identity privacy protection technology, and specifically, to a cross-chain identity privacy protection method based on oblivious transmission. The technical problem to be solved by the present invention is to provide a cross-chain identity privacy protection method based on oblivious transmission, ensuring that the regulatory agency in the regional stock exchange market can perform cross-chain security authentication and compliance inspection of identity information of local enterprises on the local chain under the premise of safety. It has higher security and is suitable for multiple fields such as finance.

Description

Technical Field

[0001] The present invention relates to the technical field of identity privacy protection, and in particular to a cross-chain identity privacy protection method based on oblivious transmission. Background Art

[0002] With the continuous development of blockchain technology, numerous blockchain systems have emerged and are being developed. However, this rapid growth has brought about a major challenge known as the "island" problem, which hinders the information interaction between different blockchains. Therefore, achieving information transfer and integration across different blockchain networks has become a prominent research area in the blockchain field. One of the key solutions to this challenge is cross-chain technology, which aims to solve the interoperability problem between different blockchain platforms. However, while cross-chain technology is promising, most existing implementations have privacy vulnerabilities. Given the huge differences between the various chains, cross-chain operations are still particularly vulnerable to privacy leaks.

[0003] The two-layer "regulatory chain-local chain" architecture in the regional equity market achieves distributed management and efficient transmission of data by establishing a two-layer chain between the regulatory agency and local enterprises. However, in the cross-chain communication process between the regulatory agency and local enterprises, how to ensure the security of identity information transmission and efficient compliance verification of identity attributes has become an urgent problem to be solved.

[0004] In terms of identity management, in order to solve the problem of trusted authentication of user identities, a lightweight distributed mobile producer authentication protocol based on blockchain is proposed. This protocol effectively solves the problem of insecure interaction between producers and network forwarding information management systems, but does not take into account the privacy of producers and lacks privacy protection for information stored on the chain. An implementable heterogeneous identity management system architecture, which implements trusted access to heterogeneous identity management systems based on blockchain, can support entity cross-domain and secure identity authentication, but does not implement cross-blockchain identity management. A new key management protocol that combines implicit certificates with standard elliptic curve Diffie-Hellman exchange and performs identity authentication and key derivation. A lightweight two-way authentication and dynamic session key scheme for batch devices uses a decentralized authentication method to solve the problem of single-point identity authentication failure to a certain extent, but there are problems such as key distribution and leakage.

[0005] At present, the research on privacy protection of blockchain is relatively mature. The Coinjoin scheme uses a mixed coin method to hide the mapping of input and output addresses, ensuring that suppliers cannot obtain accurate information and protecting user privacy. A blinding factor is added to homomorphic encryption, and a confidential transaction technology is proposed. The multi-KGC group signature scheme based on identity authentication uses an improved SM9 identification password scheme to verify identities between nodes while protecting node privacy. Combining the concept of group in group signature and consortium chain, homomorphic encryption is added to achieve blockchain transaction and identity privacy protection.

[0006] Traditional cross-heterogeneous chain communication solutions usually rely on the public key infrastructure (PKI) system in identity authentication. A trusted third party acts as a certificate authority (CA) to provide a trust root for all PKI certificates. However, cross-chain networks need to frequently communicate across chains. The certificate-based authentication method is highly complex to operate and requires large amounts of data storage, which is not conducive to users in the cross-chain network quickly passing authentication and obtaining cross-chain resources. In addition, during cross-chain communication, traditional data transmission methods may expose too much information, exposing sensitive identity information to risks such as leakage and man-in-the-middle attacks. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a cross-chain identity privacy protection method based on inadvertent transmission, which ensures that the regulatory authorities in the regional stock exchange market can perform cross-chain security authentication and compliance inspection of the identity information of local enterprises on the local chain under the premise of safety. It has higher security and is applicable to multiple fields such as finance.

[0008] The present invention adopts the following technical solutions to achieve the invention objectives:

[0009] A cross-chain identity privacy protection method based on oblivious transfer, characterized by comprising the following steps:

[0010] S1: Use negotiation keys designed based on the Peninsula Group permutable rational function to ensure that both regulators and local enterprises can negotiate keys securely;

[0011] The local enterprise encrypts the identity attribute information according to the key pre-negotiated by both parties and uploads it to the relay chain smart contract in the cross-chain network for storage;

[0012] S2: When the regulatory authorities conduct identity attribute compliance checks on local enterprises on the local chain, a cross-chain communication solution based on oblivious transfer technology is adopted to achieve cross-chain identity authentication. Local enterprises group identity attributes according to risk levels and upload each group’s identity attributes in the cross-chain request. The cross-chain network receives the cross-chain request from the local chain and parses and verifies the request, and forwards the request to the supervision chain.

[0013] The regulator is based on 1 out of The oblivious transfer property selects one identity attribute in each identity attribute group for verification, and cannot obtain other attributes other than the selected identity attribute, thus avoiding excessive exposure of all identity attributes of local enterprises. In addition, local enterprises cannot know which identity attribute the regulator wants to obtain, thereby ensuring the privacy of local enterprises and the content selected by the regulator;

[0014] S3: The regulator uses the previously generated negotiated key to encrypt the obtained identity attributes and compares them with the identity attribute ciphertext stored in the relay chain smart contract in the cross-chain network to ensure that the identity attributes are not tampered with during transmission.

[0015] As a further limitation of the present technical solution, in S1, the peninsula group structure replaces the classical cyclic group structure, ensuring that it has a more complex algebraic structure and cannot be cracked simply by relying on exponential operations; permutable rational functions can replace exponential operations and transform the elements of the peninsula group to achieve a more complex key generation method.

[0016] As a further limitation of the present technical solution, in S1, the key negotiation process is described from the perspectives of the regulatory agency and the local enterprise, and both parties predefine the permutable rational function to be used. and , and choose a large prime number and a generator , making the group The order is ,satisfy , and has the property of permutable rational functions. The specific negotiation steps of the two parties are:

[0017] S11: The regulator randomly selects an integer , and choose a random number ,according to Generate regulatory public key parameters , and the supervisory public key parameters Sent to local enterprises and receive local public key parameters from local enterprises ;

[0018] in, Representation model q The set of integers under q A valid integer in the sense of ;

[0019] The regulator randomly selects an integer , and meet and Coprime and not 2 and Divisibility relation: ,symbol Indicates that the values ​​on both sides are not divisible, calculate the intermediate key factor and Regulatory Safety Summary Parameters , will supervise the intermediate key factor and Regulatory Safety Summary Parameters sent to local businesses;

[0020] in, The function is used to generate a secure digest by combining it with the key factors using the mapping of the function;

[0021] At the same time, the local intermediate key factor generated by the local enterprise is received and local security summary parameters After that, place security summary parameters Decrypt to get , regulators first verify Are they equal? ​​Verify that they are equal. Calculate the local negotiated key. ;

[0022] S12: Local enterprises randomly select an integer , and choose a random number ,according to Generate local public key parameters , and place the public key parameter Sent to local enterprises and receive regulatory public key parameters from regulatory agencies ;

[0023] Local enterprises randomly select an integer , and meet and Coprime and not 2 and Divisibility relation: Correct, calculate the local intermediate key factor and local security summary parameters , the local intermediate key factor with local security summary parameters sent to regulatory authorities;

[0024] At the same time, the supervisory intermediate key factor generated by the supervisory authority is received and Regulatory Safety Summary Parameters After that, the supervisory safety summary parameters Decrypt it to get , local enterprises first verify Whether they are equal, the verification is established, and the supervision negotiation key is calculated ;

[0025] S13: Local enterprises and regulatory agencies will negotiate the regulatory negotiation key Negotiate key with local The negotiated key is used for later encryption of identity attributes.

[0026] As a further limitation of this technical solution, the cross-chain identity authentication process based on oblivious transfer technology is as follows:

[0027] S21: Local enterprises on the local chain have multiple identity attributes. Multiple identity attributes are divided into multiple identity attribute groups according to the degree of risk. Local enterprises generate Public-private key ;

[0028] S22: Local enterprises on the local chain will all their public keys Disclosed to regulators in the chain of custody;

[0029] S23: The supervisor in the chain of custody generates a random large integer , and the first Identity attribute public key To encrypt large integers , get the ciphertext ;

[0030] S24: The supervisor in the chain of custody will Pass it on to local enterprises in the local chain;

[0031] S25: Local companies try to use all private keys Decrypt the ciphertext separately , after decryption, we get Symmetric Key , , , ;

[0032] S26: Local enterprises based on the decryption Symmetric Key , all identity attribute contents in this identity attribute group Encryption , , , , the encrypted identity attribute set is ;

[0033] S27: The local enterprise will encrypt all the ciphertext of the identity attribute group , and sent back to the regulator;

[0034] S28: The supervisor receives the encrypted identity attribute group Then, using the random large integer generated previously , for the first The decryption result is .

[0035] Compared with the prior art, the advantages and positive effects of the present invention are:

[0036] The present invention proposes a cross-chain identity privacy protection scheme based on the oblivious transfer protocol. The proposed scheme ensures that local enterprises and regulators can securely negotiate shared keys through the designed peninsula group permutable rational function mechanism, thereby encrypting identity attributes and uploading them to the relay chain smart contract in the cross-chain network for storage, in preparation for subsequent identity information authenticity verification. In terms of cross-chain communication, the present invention designs an oblivious transfer technology based on which the regulator randomly extracts one of the multiple identity attributes of the local enterprise for verification each time. The local chain cannot know which identity attribute is specifically selected, and the regulatory chain cannot obtain other attributes other than the selected one, which effectively avoids excessive exposure of the identity attributes of local enterprises and protects their privacy. Finally, the regulatory agency uses the negotiated key to encrypt the acquired identity attributes, and compares the encrypted identity attributes with the ciphertext stored in the relay chain smart contract in the cross-chain network to ensure that the identity attributes are not tampered with during the transmission process and to ensure the security of the content. In addition, after completing the compliance check of the selected identity attributes, the regulatory agency can conduct random inspections on other identity attribute groups through multiple oblivious transfers to fully ensure the compliance of the identity information of local enterprises. The proposed scheme has significant advantages in security and practicality, especially in privacy protection and data security. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the process of the present invention.

[0038] Figure 2 A negotiation key flow chart is designed for the present invention based on the Peninsula Group permutable rational function.

[0039] Figure 3 This is the cross-chain communication process based on oblivious transfer of the present invention. DETAILED DESCRIPTION

[0040] A specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation.

[0041] The present invention comprises the following steps:

[0042] S1: Use negotiation keys designed based on the Peninsula Group permutable rational function to ensure that both regulators and local enterprises can negotiate keys securely;

[0043] Local enterprises encrypt the identity attribute information according to the key pre-negotiated by both parties and upload it to the relay chain smart contract in the cross-chain network for storage; this process ensures the security of identity attributes stored on the cross-chain network and prepares for the subsequent verification of the authenticity of identity information by regulatory agencies;

[0044] The negotiated key is used to encrypt the identity attributes and upload them to the relay chain smart contract in the cross-chain network in preparation for subsequent regulatory authorities to verify the authenticity of the user's identity information;

[0045] In S1, the peninsula group structure replaces the classic cyclic group structure, which can ensure that it has a more complex algebraic structure and cannot be cracked simply by exponential operations; permutable rational functions can replace exponential operations and transform the elements of the peninsula group to achieve a more complex key generation method. In the present invention, the regulatory agency and local enterprises conduct key negotiation off-chain, and the two parties can build a common negotiated key without disclosing their respective secret information. The negotiated key is used to encrypt identity attribute information, and the encrypted identity attributes are stored on the chain. In addition, during cross-chain communication transmission, the regulatory agency uses the negotiated key to decrypt and verify the encrypted identity attributes sent by local enterprises. The specific process is as follows. Figure 2 shown.

[0046] In S1, the key negotiation process is described from the perspectives of the regulatory agency and the local enterprise. Both parties predefine the permutable rational function to be used. and , and choose a large prime number and a generator , making the group The order is ,satisfy , and has the property of permutable rational functions. The specific negotiation steps of the two parties are:

[0047] S11: The regulator randomly selects an integer , and choose a random number ,according to Generate regulatory public key parameters , and the supervisory public key parameters Sent to local enterprises and receive local public key parameters from local enterprises ;

[0048] in, Representation model q The set of integers under q A valid integer in the sense of ;

[0049] The regulator randomly selects an integer , and meet and Coprime and not 2 and Divisibility relation: ,symbol Indicates that the values ​​on both sides are not divisible, calculate the intermediate key factor and Regulatory Safety Summary Parameters , will supervise the intermediate key factor and Regulatory Safety Summary Parameters sent to local businesses;

[0050] in, The function is used to generate a secure digest by combining it with the key factors using the mapping of the function;

[0051] At the same time, the local intermediate key factor generated by the local enterprise is received and local security summary parameters After that, place security summary parameters Decrypt it to get , regulators first verify Are they equal? ​​Verify that they are equal. Calculate the local negotiated key. ;

[0052] S12: Local enterprises randomly select an integer , and choose a random number ,according to Generate local public key parameters , and place the public key parameter Sent to local enterprises and receive regulatory public key parameters from regulatory agencies ;

[0053] Local enterprises randomly select an integer , and meet and Coprime and not 2 and Divisibility relation: Correct, calculate the local intermediate key factor and local security summary parameters , the local intermediate key factor with local security summary parameters sent to regulatory authorities;

[0054] At the same time, the supervisory intermediate key factor generated by the supervisory authority is received and Regulatory Safety Summary Parameters After that, the supervisory safety summary parameters Decrypt it to get , local enterprises first verify Whether they are equal, the verification is established, and the supervision negotiation key is calculated ;

[0055] S13: Local enterprises and regulatory agencies will negotiate the regulatory negotiation key Negotiate key with local The negotiated key is used for later encryption of identity attributes, etc.

[0056] S2: When the regulatory authorities conduct identity attribute compliance checks on local enterprises on the local chain, a cross-chain communication solution based on oblivious transfer technology is adopted to achieve cross-chain identity authentication. Local enterprises group identity attributes according to risk levels and upload each group’s identity attributes in the cross-chain request. The cross-chain network receives the cross-chain request from the local chain and parses and verifies the request, and forwards the request to the supervision chain.

[0057] The regulator is based on 1 out of The oblivious transfer property selects one identity attribute in each identity attribute group for verification, and cannot obtain other attributes other than the selected identity attribute, thus avoiding excessive exposure of all identity attributes of local enterprises. In addition, local enterprises cannot know which identity attribute the regulator wants to obtain, thereby ensuring the privacy of local enterprises and the content selected by the regulator;

[0058] Through this technology, local enterprises on the local chain cannot know which identity attribute information the regulator wants to verify, and the regulator cannot obtain other attribute information other than the identity attribute selected by it. This design effectively avoids excessive exposure of all identity attributes of local enterprises, thereby protecting their privacy;

[0059] The present invention proposes to perform cross-chain communication based on oblivious transfer technology. Oblivious transfer technology is a special data transmission protocol in which the sender has a set of data, and the receiver selects one or more data from it to receive. The key is that the sender does not know which data the receiver has selected, and the receiver cannot know the full data content of the sender. The use of oblivious transfer technology for cross-chain communication can ensure that the regulator can perform compliance verification on key identity attribute information without directly accessing all identity attribute information. At the same time, it can ensure that unselected attribute information remains private, avoiding exposure of all identity attribute information of local enterprises. It not only protects the privacy of users, but also reduces the risk of sensitive information being leaked. The specific process is as follows: Figure 3 As shown:

[0060] The cross-chain identity authentication process based on oblivious transfer technology is as follows:

[0061] S21: Local enterprises on the local chain have multiple identity attributes. Multiple identity attributes are divided into multiple identity attribute groups according to the degree of risk. Local enterprises generate Public-private key ;

[0062] S22: Local enterprises on the local chain will all their public keys Disclosed to regulators in the chain of custody;

[0063] S23: The supervisor in the chain of custody generates a random large integer , and the first Identity attribute public key To encrypt large integers , get the ciphertext ;

[0064] S24: The supervisor in the chain of custody will Pass it on to local enterprises in the local chain;

[0065] S25: Local companies try to use all private keys Decrypt the ciphertext separately , after decryption, we get Symmetric Key , , , ;

[0066] S26: Local enterprises based on the decryption Symmetric Key , all identity attribute contents in this identity attribute group Encryption , , , , the encrypted identity attribute set is ;

[0067] S27: The local enterprise will encrypt all the ciphertext of the identity attribute group , and sent back to the regulator;

[0068] S28: The supervisor receives the encrypted identity attribute group Then, using the random large integer generated previously , for the first The decryption result is .

[0069] in: for Encryption function, through The public key encrypts the message, expressed as , is to select a random large integer, is the public key, is the encrypted ciphertext;

[0070] for Decryption function, through The private key decrypts the ciphertext to restore the message, expressed as , is ciphertext, is the private key, is the decrypted large integer;

[0071] for The encryption function is a symmetric encryption algorithm used to encrypt data. Given the identity attribute information plaintext and through Decrypted large integer ,pass The encryption algorithm converts plaintext into ciphertext M . Expressed as ;

[0072] for The decryption function is a symmetric decryption algorithm used to decrypt data. Given the identity attribute ciphertext M and the previously randomly selected large integer key ,pass The decryption algorithm converts the ciphertext into plaintext with identity attributes. It is represented as ;

[0073] for The public key is generated by the key generation algorithm and is used to encrypt messages. The public key is usually made public and is used by others to encrypt messages;

[0074] for The private key is also generated by the key generation algorithm and is used to decrypt messages. The private key needs to be kept secret and is only used by the holder for decryption;

[0075] It is the plain text of identity attribute information;

[0076] is the ciphertext of identity attribute information;

[0077] is a randomly selected large integer;

[0078] To adopt The large integer value obtained after asymmetric decryption, decrypted indivual There is one value with same.

[0079] The supervisors on the supervision chain subsequently conduct multiple inadvertent transmission spot checks on each identity attribute group of local enterprises on the local chain to complete the compliance check on the identity attributes of local enterprises on the local chain.

[0080] S3: The regulator uses the previously generated negotiated key to encrypt the acquired identity attributes and compares them with the identity attribute ciphertext stored in the relay chain smart contract in the cross-chain network to ensure that the identity attributes are not tampered with during transmission. After analysis, compared with other methods, this scheme has higher security and is suitable for multiple fields such as finance.

[0081] If there is a matching ciphertext, it proves that the identity attribute has not been tampered with during the transmission process, ensuring the authenticity of the identity attribute information. In addition, after the regulatory agency has checked the identity attributes of the group, it will conduct multiple 1 out of Inadvertently transmit and sample the remaining identity attribute groups to complete the regulatory agency's identity information compliance inspection of local enterprises. The process framework structure is as follows Figure 1 shown.

[0082] The local chain is the blockchain where each local enterprise is located. Blockchain technology helps local enterprises establish their own local chains to improve data ownership and privacy security. The local chain allows enterprises to process and execute transactions in the local environment; enterprises can initiate, verify and confirm transactions on the local chain, including contract execution. When the local chain of an enterprise interacts with the cross-chain relay network, the transaction and status information on the local chain can be transmitted to the relay chain through specific cross-chain protocols and mechanisms, and the cross-chain transaction results can be obtained on the relay chain. The local chain ledger records identity attribute storage information, processing records and cross-chain transactions.

[0083] The supervision chain is the blockchain where the regulatory agency is located. The supervision chain is responsible for storing and recording the enterprise data submitted by local enterprises to the regulatory agency, such as identity attribute information. When the regulatory agency needs to conduct compliance inspections on the identity attribute information of local enterprises, it can apply for compliance inspection permits from various local chains through the cross-chain relay network. The regulatory agency in the supervision chain is responsible for supervising and maintaining the enterprise data of each local chain, providing reliable guarantees for the compliance and healthy development of the equity trading market.

[0084] The above disclosure is only a specific embodiment of the present invention, but the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A cross-chain identity privacy protection method based on oblivious transfer, characterized in that: The following steps are involved: S1: Use negotiation keys designed based on the Peninsula Group permutable rational function to ensure that both regulators and local enterprises can negotiate keys securely; The local enterprise encrypts the identity attribute information according to the key pre-negotiated by both parties and uploads it to the relay chain smart contract in the cross-chain network for storage; In S1, the key negotiation process is described from the perspectives of the regulatory agency and the local enterprise. Both parties predefine the permutable rational function to be used. and , and choose a large prime number and a generator , making the group The order is ,satisfy , and has the property of permutable rational functions. The specific negotiation steps of the two parties are: S11: The regulator randomly selects an integer , and choose a random number ,according to Generate regulatory public key parameters , and the supervisory public key parameters Sent to local enterprises and receive local public key parameters from local enterprises ; in, Representation model q The set of integers under q A valid integer in the sense of ; The regulator randomly selects an integer , and meet and Coprime and not 2 and Divisibility relation: ,symbol Indicates that the values ​​on both sides are not divisible, calculate the intermediate key factor and Regulatory Safety Summary Parameters , will supervise the intermediate key factor and Regulatory Safety Summary Parameters sent to local businesses; in, The function is used to generate a secure digest by combining it with the key factors using the mapping of the function; At the same time, the local intermediate key factor generated by the local enterprise is received and local security summary parameters After that, place security summary parameters Decrypt to get , regulators first verify Whether they are equal, the verification is established, and the local negotiation key is calculated ; S12: Local enterprises randomly select an integer , and choose a random number ,according to Generate local public key parameters , and place the public key parameter Sent to local enterprises and receive regulatory public key parameters from regulatory agencies ; Local enterprises randomly select an integer , and meet and Coprime and not 2 and Divisibility relation: Correct, calculate the local intermediate key factor and local security summary parameters , the local intermediate key factor with local security summary parameters sent to regulatory authorities; At the same time, the supervisory intermediate key factor generated by the supervisory authority is received and Regulatory Safety Summary Parameters After that, the supervisory safety summary parameters Decrypt to get , local enterprises first verify Whether they are equal, the verification is established, and the supervision negotiation key is calculated ; S13: Local enterprises and regulatory agencies will negotiate the regulatory negotiation key Negotiate key with local The negotiated key is stored on the chain and used for later encryption of identity attributes. S2: When the regulatory authorities conduct identity attribute compliance checks on local enterprises on the local chain, a cross-chain communication solution based on oblivious transfer technology is adopted to achieve cross-chain identity authentication. Local enterprises group identity attributes according to risk levels and upload each group’s identity attributes in the cross-chain request. The cross-chain network receives the cross-chain request from the local chain and parses and verifies the request, and forwards the request to the supervision chain. The regulator is based on 1 out of The oblivious transfer property selects one identity attribute in each identity attribute group for verification, and cannot obtain other attributes other than the selected identity attribute, thus avoiding excessive exposure of all identity attributes of local enterprises. In addition, local enterprises cannot know which identity attribute the regulator wants to obtain, thereby ensuring the privacy of local enterprises and the content selected by the regulator; S3: The regulator uses the previously generated negotiated key to encrypt the obtained identity attributes and compares them with the identity attribute ciphertext stored in the relay chain smart contract in the cross-chain network to ensure that the identity attributes are not tampered with during transmission.

2. The cross-chain identity privacy protection method based on oblivious transfer according to claim 1 is characterized in that: In S1, the peninsula group structure replaces the classic cyclic group structure, ensuring that it has a more complex algebraic structure and cannot be cracked simply by relying on exponential operations; permutable rational functions can replace exponential operations and transform the elements of the peninsula group to achieve a more complex key generation method.

3. The cross-chain identity privacy protection method based on oblivious transfer according to claim 1 is characterized in that: The cross-chain identity authentication process based on oblivious transfer technology is as follows: S21: Local enterprises on the local chain have multiple identity attributes. Multiple identity attributes are divided into multiple identity attribute groups according to the degree of risk. Local enterprises generate Public-private key ; S22: Local enterprises on the local chain will all their public keys Disclosed to regulators in the chain of custody; S23: The supervisor in the chain of custody generates a random large integer , and the first Identity attribute public key To encrypt large integers , get the ciphertext ; S24: The supervisor in the chain of custody will Pass it on to local enterprises in the local chain; S25: Local companies try to use all private keys Decrypt the ciphertext separately , after decryption, we get Symmetric Key , , , ; S26: Local enterprises based on the decryption Symmetric Key , all identity attribute contents in this identity attribute group Encryption , , , , the encrypted identity attribute set is ; S27: The local enterprise will encrypt all the ciphertext of the identity attribute group , and sent back to the regulator; S28: The supervisor receives the encrypted identity attribute group Then, using the random large integer generated previously , for the first The decryption result is .

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