Double-certificate DID management method and system based on blind signature and chameleon hash

Abstract

The invention discloses a blind signature and chameleon Hash-based dual-certificate DID management method and system, and the method comprises a registration stage, a verification stage and an updating stage: the registration stage: a user terminal sends a registration message, a blind message and an original identity Hash value as identity Hash, a registration mechanism generates a blind signature after verification, issues a registration certificate, and sends the registration certificate to a user terminal; the user terminal locally generates a verifiable certificate after blind verification; in the verification stage, the server calls the smart contract, and verifiable certificate validity is verified based on a chameleon hash function; in the updating stage, the user terminal generates a new verifiable certificate by using the chameleon Hash controllable collision characteristic, and chain identification updating is completed after verification of the intelligent contract. According to the method, authority is split through a double-certificate architecture, blind signature and chameleon hash technologies are fused, autonomous control of user identities, privacy protection and flexible updating are realized, and verification security and efficiency are improved.

Description

A dual-credential DID management method and system based on blind signatures and chameleon hashing Technical Field

[0001] This invention relates to the field of digital identity management technology, specifically to a dual-credential DID management method and system based on blind signatures and chameleon hashing. Background Technology

[0002] In today's era of widespread digital technology application, identity authentication has become a core foundation for online business operations, and users' demands for autonomy over their digital identities and privacy protection continue to rise. In the traditional centralized identity management model, user identity data is centrally stored and managed by a single institution, which not only poses a high risk of data leakage and identity theft, but also causes users to lose control over their own identity data, making it difficult to meet the security requirements of digital identity management.

[0003] To address these issues, decentralized identity (DID) technology has gradually emerged. Leveraging the distributed nature of blockchain to build a trust network, and combining verifiable credentials (VCs) to achieve self-control and verifiability of identity, it has become an important development direction in the field of identity management. However, existing DID schemes still have significant technical flaws: most schemes adopt a single VC architecture, where the registration authority is responsible for both identity registration and VC issuance, resulting in excessive centralization of authority. This allows the registration authority to potentially possess users' core privacy information, and poses the risk of unauthorized tampering and misuse of credentials, failing to achieve true user identity sovereignty.

[0004] At the application level of cryptographic technology, while chameleon hash functions possess controllable collision characteristics and can be used for updating and verifying identity credentials, current technologies still require users to rely on issuing authorities to synchronously verify key parameters such as random numbers. Users cannot independently update credentials, limiting the flexibility of identity management. Blind signature technology can achieve privacy protection during the signing process, but it has not yet been effectively integrated with chameleon hash technology. Solutions for applying it to the DID architecture to split registration authority permissions and strengthen user sovereignty remain lacking.

[0005] Furthermore, existing DID schemes suffer from vulnerabilities in verification information and cumbersome credential update processes during identity verification, severely impacting user experience and system security. In summary, the DID field urgently needs an identity management solution that can decentralize registration authority permissions, safeguard user identity sovereignty, and balance privacy protection with operational flexibility. This would address issues such as centralized permissions, privacy leaks, and inconvenience in existing technologies, thereby promoting the practical application and large-scale deployment of decentralized identity technology. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a dual-credential DID management method and system based on blind signatures and chameleon hashing. This invention discloses a dual-credential DID management method based on blind signatures and chameleon hashing, comprising a registration phase and a verification phase: The registration phase includes: a user terminal sending a registration request to a registration authority, the registration request including at least a registration message, a blinded message after blinding the user's privacy information, and an original identity hash value, the original identity hash value being calculated from the blind message, a random number generated by the user terminal, and the user terminal's public key; the registration authority verifies the registration message, and upon successful verification, signs the blind message to generate a blind signature, and issues a registration credential containing the blind signature to the relevant authority. The user terminal records identity information, including at least the original identity hash value, on the blockchain. The user terminal performs deblinding verification on the blind signature. After successful verification, it generates a verifiable credential locally based on the registration credential. The verifiable credential includes the user terminal's public key, the blind message, and the random number. The verification stage includes: the user terminal presenting the verifiable credential to the server. The server calls a smart contract deployed on the blockchain and uses the original identity hash value stored on the blockchain to verify the validity of the verifiable credential based on the Chameleon hash function to confirm the user's identity.

[0007] As a further improvement of the present invention, the blind message of the user privacy message The generation process is as follows: In the formula, m represents privacy information. As a blinding factor, , These are the registry's RSA algorithm public key and the registry's publicly disclosed RSA modulus, respectively; the original identity hash value. The generation process is as follows: In the formula, For the user terminal's RSA public key, Blind messages for privacy information The random number is generated for the user terminal, and g is the Chameleon Hash Modulus published by the registry.

[0008] As a further improvement of the present invention, the blind signature The generation process is as follows: In the formula, Blind messages for privacy information , These are the RSA algorithm private key of the registry and the RSA modulus published by the registry, respectively.

[0009] As a further improvement of the present invention, the user terminal performs deblinding verification on the blind signature, the specific process of which includes: the user terminal using a deblinding formula... Blind signature in the registration certificate Unblinding was performed to obtain the unblinding results. In the formula, Blind signatures generated for registration authorities The blinding factor generated for the user terminal. The modulus of the RSA algorithm for the registration authority; the user terminal verifies the formula. For the unblinding results Verification is performed; if the verification result matches the original privacy information, the registration certificate is confirmed to be authentic and valid; where, For privacy information, , These are the public key of the registry's RSA algorithm and the RSA modulus published by the registry, respectively.

[0010] As a further improvement of the present invention, the identity information also includes a registration credential identifier and a DID identifier.

[0011] As a further improvement of the present invention, the verification stage further includes: the user terminal generating a verification token and performing blinding processing using the server's public key, and sending the blinded verification token and the verifiable credential together to the server; after the server verifies the validity of the verifiable credential through a smart contract, it records the hash value of the verification token in the blockchain; the user terminal uses the verification token to request subsequent online services; the verification token contains a unique identifier of the user device and a timestamp.

[0012] As a further improvement of the present invention, the specific process of verifying the validity of the verifiable credential based on the chameleon hash function is as follows: the server extracts the blind message contained in the verifiable credential, calls the pre-deployed chameleon hash algorithm through a smart contract, and calculates the verification hash value using the hash operation formula. The hash operation formula is: In the formula, For the user terminal's RSA public key, Blind messages for privacy information A random number is generated for the user terminal, and g is the Chameleon Hash Modulus published by the registry; the smart contract will calculate the verification hash value. Compared to the original identity hash value stored on the blockchain Perform a comparison and verify the logic: The determination process is as follows: If res is true, it confirms that the verifiable credential has not been tampered with and its source is legitimate. At the same time, the smart contract verifies whether the registration credential information in the verifiable credential is consistent with the registration credential identifier and DID identifier stored on the blockchain. If they are consistent, the verification is successful. If this is the first verification after user registration, the smart contract will also record the signed verifiable credential identifier on the blockchain. In subsequent verifications, the smart contract needs to verify the legality of the verifiable credential identifier. If the verification is successful, the verification result is confirmed to be valid.

[0013] As a further improvement of the present invention, an update phase is also included, which includes: the user terminal, based on the controllable collision characteristics of the Chameleon hash function, uses its own RSA private key as a trapdoor to generate a new verifiable credential containing new user privacy information, a new blind message, a new random number, and a corresponding new signature; the user terminal submits the new verifiable credential and the verifiable credential to be updated to the server; the server calls a smart contract deployed on the blockchain to verify the validity of the verifiable credential and the consistency between the new verifiable credential and the identity information stored on the blockchain; if the verification is successful, the smart contract updates the corresponding verifiable credential identifier on the blockchain to the identifier of the new verifiable credential and enables the new verifiable credential.

[0014] As a further improvement of the present invention, the specific implementation process of the update stage includes: the user terminal generating a new blind message formula. New blind message calculated In the formula, For new privacy messages, The new blinding factor regenerated for the user terminal, , These are the RSA algorithm public key of the registry and the RSA modulus published by the registry, respectively; the user terminal uses the new random number generation formula. Calculate the new random number In the formula, For the user terminal's RSA private key, This is a new privacy message; the user terminal uses the new privacy information as a basis. New blind messages and the new random number The new verifiable credential is constructed, and both the new verifiable credential and the existing verifiable credential are submitted to the server. The server invokes the smart contract, which calculates and verifies the hash value of the new verifiable credential. and the hash value of the verifiable credential. and compared with the original identity hash value stored on the blockchain. The consistency of two verifiable credentials is verified by comparison; where pk is the RSA public key of the user terminal. Blind messages for privacy information Blind messages for new privacy information Random numbers generated for user terminals The random number regenerated for the user terminal. The hash modulus is the chameleon hash value. If the verification passes, the smart contract replaces the corresponding verifiable credential identifier on the blockchain with the new verifiable credential identifier and enables the new verifiable credential.

[0015] This invention discloses a dual-credential DID management system based on blind signatures and chameleon hashes, applied to the aforementioned dual-credential DID management method. It is characterized by comprising: a user terminal, used to initiate the registration request, perform deblinding verification on the blind signature, generate a verifiable credential locally based on the registration credential after successful verification, and initiate a verifiable credential update request and generate a verification token; a registration authority, used to receive the registration request, sign the blind message to generate a blind signature, issue registration credentials, and record identity information, including at least the original identity hash value as an identity hash, on the blockchain; a server, used to receive the verifiable credential and verification token sent by the user terminal, call a smart contract on the blockchain for verification, and forward the verifiable credential update request; and a blockchain, used to store identity information and execute verifiable credential validity verification and verifiable credential update logic through smart contracts.

[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention achieves dual protection of user identity autonomy and privacy by integrating the technologies of "dual credential architecture + blind signature + chameleon hash + blockchain". The innovative design of the "registration credential + verifiable credential (VC)" dual architecture separates the permissions of the registration institution. The registration institution is only responsible for initial identity verification and blind signature issuance. The generation, updating, and management of VC are controlled by the user terminal. The DID identifier, as a unique identity index, is written into the blockchain and is completely under the user's control. This completely breaks the platform monopoly of the traditional centralized identity system, truly returning identity sovereignty to the user, and enabling cross-scenario identity verification without relying on a third party.

[0017] In terms of privacy protection and security, this invention utilizes blind signature technology to achieve the blinding of privacy information. Registration institutions only sign the blinded data, unable to access the user's original privacy. The verification phase only verifies legitimacy through hash comparison and identifier verification, achieving "minimal information disclosure" and reducing the risk of data leakage and identity theft at its source. Simultaneously, the distributed storage of blockchain ensures the immutability of core identity information, the fusion of RSA and Chameleon hash algorithms guarantees the security of cryptographic operations, automated smart contract execution reduces the risk of human intervention, and all operations are fully traceable on the blockchain, while also meeting the requirements of decentralization.

[0018] This invention significantly improves the flexibility and operational efficiency of identity management. Leveraging the controllable collision characteristics of chameleon hashes, users can autonomously generate new VCs using their private keys, dynamically updating identity information without altering the core on-chain verification criteria. This overcomes the editing challenges posed by the "immutability" of traditional blockchain data. In the verification process, the server rapidly completes automated verification via smart contracts, eliminating the need for real-time interaction with registration institutions. Furthermore, the standardized design based on DID identifiers supports cross-platform and cross-chain interoperability, breaking the "island effect" of identity systems. Attached Figure Description

[0019] Figure 1 is a flowchart of a dual-credential DID management method based on blind signature and chameleon hash disclosed in an embodiment of the present invention; Figure 2 is a framework diagram of a dual-credential DID management system based on blind signature and chameleon hash disclosed in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The invention will now be described in further detail with reference to the accompanying drawings: As shown in Figure 1, the present invention provides a dual-credential DID management method based on blind signatures and chameleon hashing. It adopts a dual-credential architecture (i.e., the DID contains two types of credentials during its lifecycle: a registration credential and a verifiable credential (VC)). Combining blockchain, blind signature technology, and the chameleon hash function, the dual-credential architecture is designed as follows: Registration credential: Issued by a registration authority, it mainly includes a registration credential identifier (used to uniquely identify a registration credential), a decentralized identity identifier (DID identifier, serving as the unique identifier for the DID), the credential source, and a blind signature. This assists users in generating verifiable credentials (VC), linking the registration credential, verifiable credential (VC), and DID, and storing some information (such as the registration credential identifier and credential source) in the blockchain as one of the verification conditions. Registration credentials effectively hide user privacy information from the registration authority. Because the registration authority does not possess the verifiable credential (VC), it cannot obtain the user's ID (DID) during the registration process. The verifiable credential (VC) is used to prove user identity and is constructed by the user based on the registration credentials. It includes a VC identifier (used to uniquely identify a VC), a DID identifier, registration credentials information, identity claims, registration information, and a signature (different from the signature on the registration credentials; this signature is used to verify identity). The generation, storage, and updating of the verifiable credential (VC) are all performed on the user's terminal, ensuring a high degree of user control. During use, blockchain and smart contracts automate and decentralize the process, avoiding excessive server-side involvement.

[0022] Blockchain: DID information is stored on the blockchain, and the main business logic of identity verification and updates is executed on the blockchain through smart contracts. After successful user registration, the registration authority records information such as the DID identifier, the signed registration credential identifier, and the identity hash on the blockchain. The identity hash and registration credential information are used to verify the validity of the verifiable credential (VC). Storing information and executing business logic on the blockchain ensures traceability and avoids the server failure problems of centralized institutions.

[0023] The dual-credential DID management method includes a registration phase, a verification phase, and an update phase. The following is a detailed description of each phase.

[0024] I. Registration Phase: 1.1 The user terminal sends a registration request to the registration authority. The registration request includes at least a registration message, a blinded message containing the user's privacy information (after blinding), and the original identity hash value calculated based on the blinded message, a random number generated by the user terminal, and the user terminal's public key; the blinded message containing the user terminal's privacy information. The generation process is as follows: In the formula, m represents privacy information. As a blinding factor, , These are the RSA algorithm public key of the registration authority and the RSA modulus published by the registration authority, respectively.

[0025] The original identity hash value of the user terminal The generation process is as follows: In the formula, For the user terminal's RSA public key, Blind messages for privacy information The random number is generated for the user terminal, and g is the Chameleon Hash Modulus published by the registry.

[0026] That is, before a user applies for registration, privacy information must be determined, and a blinding factor, a blind message for the privacy information, and the original identity hash value must be generated on the user's terminal. And will carry blind messages containing registration information, privacy information, and original identity hash values. The registration request is sent to the registration authority.

[0027] 1.2 The registration authority verifies the registration message. Upon successful verification, it signs the blind message to generate a blind signature. The generation process is as follows: In the formula, , These are the registry's RSA algorithm private key and the registry's publicly available RSA modulus, respectively. For privacy messages, the following steps are taken: 1.3 The registration authority issues a registration certificate containing a blind signature to the user terminal, and simultaneously records identity information, including at least the original identity hash value as an identity hash, on the blockchain; this identity message also includes a registration certificate identifier and a DID identifier; 1.4 The user terminal performs deblinding verification on the blind signature. After successful verification, a verifiable certificate is generated locally based on the registration certificate. The specific process of deblinding verification includes: the user terminal uses a deblinding formula... Blind signatures in registration certificates Unblinding was performed to obtain the unblinding results. In the formula, Blind signatures generated for registration authorities The blinding factor generated for the user terminal. The modulus of the RSA algorithm for the registration authority; the user terminal verifies the formula. For the unblinding results Verification is performed. If the verification result matches the original privacy information, the registration certificate is confirmed to be authentic and valid. In the formula, For privacy information, , These are the registration authority's RSA algorithm public key and the RSA modulus published by the registration authority, respectively. 1.5. After successful verification, a verifiable credential is generated locally based on the registration credential. The verifiable credential includes the user terminal's public key, blind message, and random number. That is, based on the verified registration credential, the user terminal associates and integrates its own RSA public key, blind message, and random number with the registration credential identifier and DID identifier in the registration credential, and adds its own private key signature to form a complete verifiable credential VC, which is stored locally.

[0028] In this process, blind signing hides the user terminal's privacy information from the registration authority, enabling the registration authority to generate a signature for the registration credential without knowing the specific privacy information. Subsequently, the user terminal generates a new blind message based on the chameleon hash collision algorithm, which serves as the signature for the verifiable credential (VC). Blind signing achieves both user privacy hiding from the registration authority and credential verification, and also associates both types of credentials (registration credential and verifiable credential) with the DID.

[0029] At this stage, the registration credential verification scheme based on blind signatures uses a "blinding-signing-deblinding" process to re-establish the connection between the two credentials with separate permissions, ensuring the authenticity of the registration credential and the validity of the VC.

[0030] II. Verification Phase: The Chameleon Hash Function is a hash function that allows for the manual discovery of collisions. To enable users to control the entire lifecycle of the VC (Verification Token), this invention uses Chameleon Hash as a method to verify user identity and employs a scheme where the user terminal generates a verification token, providing a flexible verification and expansion mechanism. To ensure information security and prevent server-side attacks from tampering with verification results, the server is primarily responsible for verifying legality and information integrity during this process. The core logic is implemented on the blockchain and the user terminal. Specifically, the user terminal presents a verifiable credential to the server. The server, by calling a smart contract deployed on the blockchain, uses the identity information stored on the blockchain and verifies the validity of the verifiable credential based on the Chameleon Hash Function to confirm the user's identity. The specific process includes: 2.1 The user terminal presents a verifiable credential VC to the server. This verifiable credential VC contains a blind message for identity verification. The server processes this blind message, verifies the integrity of the verifiable credential VC, and then calls the smart contract; 2.2 The server calls the pre-deployed Chameleon Hash algorithm through the smart contract and calculates the verification hash value using the hash operation formula. The hash operation formula is: In the formula, For the user terminal's RSA public key, Blind messages for privacy information 2.3 The smart contract will use the calculated verification hash value to generate a random number for the user terminal, where g is the Chameleon Hash Modulus published by the registration authority; Compared to the original identity hash value stored on the blockchain Perform a comparison and verify the logic: The determination process is as follows: if res is true, it confirms that the verifiable credential has not been tampered with and its source is legitimate; at the same time, the smart contract verifies whether the registration credential information in the verifiable credential is consistent with the registration credential identifier and DID identifier stored on the blockchain. If they are consistent, the verification is successful; the algorithm used is a custom chameleon hash algorithm based on RSA algorithm, modular arithmetic and large number arithmetic, and controlled collision is achieved based on the trapdoor one-way property of RSA. `res` represents the original identity hash value on the blockchain, and `res` represents the verification result of the chameleon hash. Is it equal to That is, the verification hash value obtained by calculation. Compared to the original identity hash value stored on the blockchain Whether they match. In addition, it is necessary to compare whether the registration certificate information in the verifiable credential VC corresponds to the registration certificate information recorded on the blockchain.

[0031] 2.4 If the verification result is correct, it proves that the user is the DID holder, and the verification is successful. Afterwards, the user terminal initiates a business request to the server. If this is the user's first verification after registration, the smart contract will also record the signed verifiable credential identifier on the blockchain; in subsequent verifications, the smart contract needs to verify the legality of the verifiable credential identifier, and confirm the validity of the verification result after successful verification.

[0032] The verification phase also includes: the user terminal generating a verification token and performing blinding processing using the server's public key (the blinding algorithm is described in the blind message calculation formula above), and sending the blinded verification token and verifiable credentials to the server; after the server verifies the validity of the verifiable credentials through a smart contract, it records the hash value of the verification token (based on a general SHA-256) to the blockchain. The response to the user only needs to include the request status and does not need to carry the verification token; the user terminal uses the verification token to request subsequent online services, and the server can calculate the hash for comparison; the verification token contains a unique identifier for the user device and a timestamp. In this embodiment, the format of the verification token is: CPU serial number: timestamp.

[0033] At this stage, the local generation and updating of verifiable credentials (VC) and the local generation of verification tokens (tokens) not only enhance users' self-sovereignty over DIDs but also avoid verification failures caused by hackers intercepting responses, which is beneficial for sharing tokens among cluster servers. The automation of the identity verification process by smart contracts reduces the risk of single points of failure and improves traceability.

[0034] III. Update Phase: Based on the controllable collision characteristics of the Chameleon Hash Function, the user terminal uses its own RSA private key as a trapdoor to generate a new verifiable credential containing new user privacy information, a new blind message, a new random number, and a corresponding new signature. The user terminal submits the new verifiable credential and the verifiable credential to be updated to the server. The server calls the smart contract deployed on the blockchain to verify the validity of the verifiable credential and the consistency between the new verifiable credential and the identity information stored on the blockchain. If the verification passes, the smart contract updates the corresponding verifiable credential identifier on the blockchain to the identifier of the new verifiable credential and enables the new verifiable credential. The specific implementation process of the update phase includes: 3.1, the user terminal generates a new blind message using the formula... New blind message calculated In the formula, For new privacy messages, The new blinding factor regenerated for the user terminal, , These are the RSA algorithm public key of the registration authority and the RSA modulus published by the registration authority, respectively; 3.2, the user terminal uses the new random number generation formula. Calculate the new random number In the formula, For the user terminal's RSA private key, For new privacy messages; the collision calculation steps are as follows: 1. Obtain the original identity hash value stored on the blockchain based on the DID identifier. 2. Enter new privacy information Original identity hash value And extract the trapdoor private key sk; 3. Based on the modular inverse property of RSA (the private key sk is the modular inverse of the public key pk), through Calculate new random numbers In the formula, 3.3 The Chameleon Hash Modulus publicly available from the registration authority; The user terminal is based on new privacy information. New blind messages and new random numbers 3.4 Construct a new verifiable credential and submit it along with the existing verifiable credential to the server; the server then calls a smart contract, which calculates and verifies the hash value of the new verifiable credential. and the hash value of the verifiable credential. and compared with the original identity hash value stored on the blockchain. The consistency of two verifiable credentials is verified by comparison; where pk is the RSA public key of the user terminal. Blind messages for privacy information Blind messages for new privacy information Random numbers generated for user terminals The random number regenerated for the user terminal. 3.5. If the verification passes, the smart contract will replace the corresponding verifiable credential identifier on the blockchain with the new verifiable credential identifier and enable the new verifiable credential.

[0035] At this stage, on-chain data consistency is ensured while granting users complete control over their identities. Furthermore, this solution only involves the user terminal and the blockchain; the server only performs integrity and validity checks, with core processes occurring on the user terminal and the blockchain. The business logic on the user terminal guarantees user sovereignty over their identity, while the business logic on the blockchain ensures decentralization and business traceability, avoiding data storage on a central server.

[0036] As shown in Figure 2, this invention also discloses a dual-credential DID management system based on blind signatures and chameleon hashes, which is applied to the aforementioned dual-credential DID management method. The system includes: a user terminal, used to initiate a registration request, perform deblinding verification on the blind signature, generate a verifiable credential locally based on the registration credential after successful verification, and initiate a verifiable credential update request and generate a verification token; a registration authority, used to receive the registration request, sign the blind message to generate a blind signature, issue a registration credential, and record identity information, including at least the original identity hash value as an identity hash, on the blockchain; a server, used to receive the verifiable credential and verification token sent by the user terminal, call the smart contract on the blockchain for verification, and forward the verifiable credential update request; and a blockchain, used to receive the verifiable credential and verification token sent by the user terminal, call the smart contract on the blockchain for verification, and forward the verifiable credential update request.

[0037] The beneficial effects of this invention are as follows: By integrating the technologies of "dual credential architecture + blind signature + chameleon hash + blockchain", this invention achieves dual protection of user identity autonomy and privacy security. The innovative design of the "registration credential + verifiable credential (VC)" dual architecture separates the permissions of the registration institution. The registration institution is only responsible for initial identity verification and blind signature issuance. The generation, updating, and management of VC are controlled by the user terminal. The DID identifier, as a unique identity index, is written into the blockchain and is completely under the user's control. This completely breaks the platform monopoly of the traditional centralized identity system, truly returning identity sovereignty to the user, and enabling cross-scenario identity verification without relying on a third party.

[0038] In terms of privacy protection and security, this invention utilizes blind signature technology to achieve the blinding of privacy information. Registration institutions only sign the blinded data, unable to access the user's original privacy. The verification phase only verifies legitimacy through hash comparison and identifier verification, achieving "minimal information disclosure" and reducing the risk of data leakage and identity theft at its source. Simultaneously, the distributed storage of blockchain ensures the immutability of core identity information, the fusion of RSA and Chameleon hash algorithms guarantees the security of cryptographic operations, automated smart contract execution reduces the risk of human intervention, and all operations are fully traceable on the blockchain, while also meeting the requirements of decentralization.

[0039] This invention significantly improves the flexibility and operational efficiency of identity management. Leveraging the controllable collision characteristics of chameleon hashes, users can autonomously generate new VCs using their private keys, dynamically updating identity information without altering the core on-chain verification criteria. This overcomes the editing challenges posed by the "immutability" of traditional blockchain data. In the verification process, the server rapidly completes automated verification via smart contracts, eliminating the need for real-time interaction with registration institutions. Furthermore, the standardized design based on DID identifiers supports cross-platform and cross-chain interoperability, breaking the "island effect" of identity systems.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dual-credential DID management method based on blind signature and chameleon hash, characterized in that, The system includes a registration phase and a verification phase. The registration phase includes: a user terminal sending a registration request to a registration authority, the registration request including at least a registration message, a blinded message (after processing user privacy information), and an original identity hash value. The original identity hash value is calculated from the blind message, a random number generated by the user terminal, and the user terminal's public key. The registration authority verifies the registration message; upon successful verification, it signs the blind message to generate a blind signature and issues a registration credential containing the blind signature to the user terminal, while simultaneously recording identity information containing at least the original identity hash value on the blockchain. The user terminal deblinds and verifies the blind signature; upon successful verification, it generates a verifiable credential locally based on the registration credential. The verifiable credential includes the user terminal's public key, the blind message, and the random number. The verification phase includes: the user terminal presenting the verifiable credential to a server; the server, by calling a smart contract deployed on the blockchain, verifies the validity of the verifiable credential using the original identity hash value stored on the blockchain and a chameleon hash function to confirm the user's identity.

2. The dual-credential DID management method according to claim 1, characterized in that, The blind message of the user privacy message The generation process is as follows: In the formula, m represents privacy information. As a blinding factor, 、 These are the registry's RSA algorithm public key and the registry's publicly disclosed RSA modulus, respectively; the original identity hash value. The generation process is as follows: In the formula, For the user terminal's RSA public key, Blind messages for privacy information The random number is generated for the user terminal, and g is the Chameleon Hash Modulus published by the registration authority.

3. The dual-credential DID management method according to claim 1, characterized in that, blind signature The generation process is as follows: In the formula, Blind messages for privacy information 、 These are the RSA algorithm private key of the registry and the RSA modulus published by the registry, respectively.

4. The dual-credential DID management method according to claim 1, characterized in that, The user terminal performs deblinding verification on the blind signature, specifically including: the user terminal using a deblinding formula... Blind signature in the registration certificate Unblinding was performed to obtain the unblinding results. In the formula, Blind signatures generated for registration authorities The blinding factor generated for the user terminal. The modulus of the RSA algorithm for the registration authority; the user terminal verifies the formula. For the unblinding results Verification is performed; if the verification result matches the original privacy information, the registration certificate is confirmed to be authentic and valid; where, For privacy information, 、 These are the public key of the registry's RSA algorithm and the RSA modulus published by the registry, respectively.

5. The dual-credential DID management method according to claim 1, characterized in that, The identity information also includes registration credential identifier and DID identifier.

6. The dual-credential DID management method according to claim 1, characterized in that, The verification phase further includes: the user terminal generating a verification token and performing blinding processing using the server's public key, sending the blinded verification token and the verifiable credential together to the server; after the server verifies the validity of the verifiable credential through a smart contract, recording the hash value of the verification token in the blockchain; the user terminal using the verification token to request subsequent online services; the verification token contains a unique identifier for the user device and a timestamp.

7. The dual-credential DID management method according to claim 1, characterized in that, The specific process of verifying the validity of the verifiable credential based on the chameleon hash function is as follows: The server extracts the blind message contained in the verifiable credential, calls the pre-deployed chameleon hash algorithm through a smart contract, and calculates the verification hash value using the hash operation formula. The hash operation formula is: In the formula, For the user terminal's RSA public key, Blind messages for privacy information A random number is generated for the user terminal, and g is the Chameleon Hash Modulus published by the registration authority; the smart contract will calculate the verification hash value. Compared to the original identity hash value stored on the blockchain Perform a comparison and verify the logic: The determination process is as follows: If res is true, it confirms that the verifiable credential has not been tampered with and its source is legitimate. At the same time, the smart contract verifies whether the registration credential information in the verifiable credential is consistent with the registration credential identifier and DID identifier stored on the blockchain. If they are consistent, the verification is successful. If this is the first verification after user registration, the smart contract will also record the signed verifiable credential identifier on the blockchain. In subsequent verifications, the smart contract needs to verify the legality of the verifiable credential identifier. If the verification is successful, the verification result is confirmed to be valid.

8. The dual-credential DID management method according to claim 1, characterized in that, It also includes an update phase, which includes: the user terminal, based on the controllable collision characteristics of the Chameleon hash function, uses its own RSA private key as a trapdoor to generate a new verifiable credential containing new user privacy information, a new blind message, a new random number, and a corresponding new signature; the user terminal submits the new verifiable credential and the verifiable credential to be updated to the server; the server calls a smart contract deployed on the blockchain to verify the validity of the verifiable credential and the consistency between the new verifiable credential and the identity information stored on the blockchain; if the verification passes, the smart contract updates the corresponding verifiable credential identifier on the blockchain to the identifier of the new verifiable credential and enables the new verifiable credential.

9. The dual-credential DID management method according to claim 8, characterized in that, The specific implementation process of the update phase includes: the user terminal generating a formula through the new blind message. New blind message calculated In the formula, For new privacy messages, The new blinding factor regenerated for the user terminal, 、 These are the RSA algorithm public key of the registry and the RSA modulus published by the registry, respectively; the user terminal uses the new random number generation formula. Calculate the new random number In the formula, For the user terminal's RSA private key, This is a new privacy message; the user terminal uses the new privacy information as a basis. New blind messages and the new random number The new verifiable credential is constructed, and both the new verifiable credential and the existing verifiable credential are submitted to the server. The server invokes the smart contract, which calculates and verifies the hash value of the new verifiable credential. and the hash value of the verifiable credential. and compared with the original identity hash value stored on the blockchain. The consistency of two verifiable credentials is verified by comparison; where pk is the RSA public key of the user terminal. Blind messages for privacy information Blind messages for new privacy information Random numbers generated for user terminals The random number regenerated for the user terminal. The hash modulus is the chameleon hash value. If the verification passes, the smart contract replaces the corresponding verifiable credential identifier on the blockchain with the new verifiable credential identifier and enables the new verifiable credential.

10. A dual-credential DID management system based on blind signature and chameleon hashing, applied to the dual-credential DID management method according to any one of claims 1-9, characterized in that, include: The user terminal is used to initiate the registration request, perform deblinding verification on the blind signature, generate a verifiable credential locally based on the registration credential after successful verification, and initiate a verifiable credential update request and generate a verification token. The registration authority is used to receive registration requests, sign blind messages to generate blind signatures, issue registration certificates, and record identity information, including at least the original identity hash value as an identity hash, on the blockchain; the server is used to receive verifiable certificates and verification tokens sent by user terminals, call smart contracts on the blockchain for verification, and forward verifiable certificate update requests; the blockchain is used to store identity information and execute verifiable certificate validity verification and verifiable certificate update logic through smart contracts.

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