Verifiable certificate decentralized issuing and security verification scheme in self-sovereignty identity system

Abstract

The invention discloses a verifiable certificate decentralized issuing and security verification scheme in a self-sovereignty identity system, and belongs to the technical field of password protocol design and privacy protection. The method comprises a system initialization stage, a verifiable voucher issuing stage, a selective disclosure and verification stage and a verifiable voucher revocation stage, and is characterized in that decentralized verifiable voucher issuing is realized by using a threshold Point-Sanders signature technology; when the user performs selective disclosure by using the verifiable certificate, pseudo identities are generated based on disclosure attributes and timestamps, and different pseudo identities are generated in each disclosure to resist long-term tracking attacks; and the verifier confirms the legality of the user identity by verifying the false identity and the signature. According to the method, security threats such as long-term tracking, Sybil attacks and replay attacks are effectively resisted while a selective disclosure function is ensured, and the privacy protection capability and practicability of a self-sovereignty identity system are improved.

Description

Technical Field

[0001] This invention relates to the fields of cryptographic protocol design and privacy protection technology, specifically to a decentralized issuance and secure verification scheme for verifiable credentials in a self-sovereign identity system. This scheme features decentralized issuance of verifiable credentials and can resist long-term tracking attacks when selectively disclosed. Background Technology

[0002] As digitalization accelerates, traditional digital identity systems are increasingly revealing the inherent flaws of their centralized architecture. These systems, typically managed by a single institution, face risks such as privacy breaches, data silos, and single points of failure. Self-sovereign identity systems, built on decentralized identifiers (DISTROID) and blockchain technology, are reshaping the digital identity management landscape by empowering individuals and organizations with secure control over their personal data. In a self-sovereign identity system, users apply for verifiable credentials from the credential issuer and, using cryptographic techniques, selectively disclose only the attributes that need to be verified, rather than all information, to the verifier, thereby achieving complete control over their own privacy data.

[0003] However, existing verifiable credentials are typically issued by a single node, neglecting the problem of single-node failure; the verification of verifiable credentials also focuses more on the security of a single disclosure, ignoring the security risks caused by the same credential being disclosed multiple times. Therefore, a solution is needed that can support decentralized credential issuance and resist long-term tracing attacks under multiple selective disclosures. Summary of the Invention

[0004] Objective: To address the technical deficiencies of existing technologies, this invention proposes a verifiable credential issuance and verification scheme for self-sovereign systems, based on threshold Pointcheval-Sanders signatures and pseudo-identity generation technology. This scheme effectively achieves decentralized credential issuance and resists long-term tracking attacks when the same credential is selectively disclosed multiple times. The system includes users, issuers, and verifiers. The pseudo-identity mechanism ensures that each identity disclosure is unrelated, thereby improving security.

[0005] This invention proposes a decentralized issuance and secure verification scheme for verifiable credentials in a self-sovereign identity system, comprising the following steps:

[0006] (1) System initialization phase

[0007] Given a security parameter λ, the system executes the initialization function SetUp(λ) → (PP, SK, PK) to generate common parameters. in:

[0008] E p (a,b) is an elliptic curve, and P is the base point. Let g1 and g2 be a multiplicative cyclic group of order q, and g1 and g2 be generators. It is a bilinear mapping. This is a collision-resistant hash function.

[0009] Suppose there are S credential issuer nodes (VC Issuer, VCI), each holding a share of the private key. The master private key SK is divided using the Shamir secret sharing scheme. PS =(x,y1,y2,…,y m The public key is

[0010] (2) Verifiable credential issuance stage

[0011] The specific steps for a user to request a verifiable credential from a VCI are as follows:

[0012] (2-1) User generates public / private key pair (SK) U PK U Based on attributes (a1, a2, ..., a) n Construct message M = (M1, M2, ..., M n ), and generate commitments. and zero-knowledge proof

[0013] (2-2) The user encrypts the request and sends it to the VCIs.

[0014] (2-3) After each VCI verification request, a partial PS signature is generated. And return it to the user.

[0015] (2-4) The user aggregates at least t partial signatures to obtain the complete signature. The signature is then encrypted and sent to VCIj in VCIs.

[0016] (2-5) VCIj generates complete verifiable credentials VC U ={PK U ,M,σ VC ,t exp The certificate is then sent to the user, and its status is broadcast to the blockchain to complete the issuance.

[0017] (3) Selective Disclosure and Verification Stage

[0018] Users need to selectively disclose a subset of attributes DA = (a1, a2, ..., a...). n When ), perform the following steps:

[0019] (3-1) User generates fake identity Where pt is the timestamp and DI is the set of pseudo-identities corresponding to the disclosure attribute.

[0020] (3-2) User randomly selects Generate a new signature and zero-knowledge proof

[0021]

[0022] (3-3) User constructs a verifiable presentation (VP), VP = (σ′) VC ,{M i} i∈DA ,J,π,hVC,pt), and send {VP,PID,pt} to the verifier.

[0023] (3-4) The verifier checks the signature validity and calculates... And verify the equation:

[0024]

[0025] If the verification passes, the user is allowed access.

[0026] (4) Verifiable credential revocation stage

[0027] Users or VCIs can initiate a credential revocation request:

[0028] (4-1) Construct a revocation request RevokeReq = (STA) VC reason, flag req timestamp, σ Rev ), where reason is the reason for revocation, timestamp is the current timestamp, σ Rev It is the signature of the requester.

[0029] (4-2) After VCIs verify the request, they broadcast the request to the blockchain.

[0030] (4-3) After the blockchain reaches a consensus, the validator adds the credential status value to the local revocation list RList.

[0031] The beneficial effects of this invention are as follows: This invention proposes a decentralized issuance and secure verification scheme for verifiable credentials in a self-sovereign identity system. This scheme achieves decentralized credential issuance through a threshold Pointcheval-Sanders signature, avoiding single points of failure. A pseudo-identity mechanism is used to ensure the uncorrelation of users in different scenarios, and a unique pseudo-identity is generated for each disclosure, preventing the same verifiable credential from being verified multiple times, thus avoiding leakage of user privacy. It also supports resistance to Sybil attacks, forgery, and replay attacks. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the system model of the present invention;

[0033] Figure 2 This is a schematic diagram of the verifiable credential issuance process;

[0034] Figure 3 This is a schematic diagram of the selective disclosure and verification process. Detailed Implementation

[0035] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0036] System model such as Figure 1 As shown, this includes users, validators, and credential issuers. Blockchain, as a decentralized database, provides consensus and data storage services.

[0037] (1) System initialization phase

[0038] (1-1) Select the safety parameter λ = 256 to generate the elliptic curve E. p (a,b):y 2 =x 3 +ax+b mod p, where p is a 256-bit prime number.

[0039] (1-2) Initialize the bilinear group parameters. This is the BN curve group. For extended fields.

[0040] (1-3) Deploy S=5 VCIs and use the Shamir(3,5) thresholding scheme to split the private key.

[0041] (2) Verifiable credential issuance stage

[0042] (2-1) The user attribute set is {name, age, nationality}. Construct message M = (H(name), H(age), H(nationality)).

[0043] (2-2) User generates their own commitment With zero-knowledge proofs, send encrypted requests to VCIs.

[0044] (2-3) Generate a partial signature after each VCI verification request. The user aggregates at least 3 signatures to obtain The signature is encrypted and sent to VCIj.

[0045] (2-4) VCIj generates complete and verifiable credentials VC U ={PK U ,M,σ VC ,t exp =2025-12-31}, send the certificate to the user, and then broadcast the certificate status to the blockchain to complete the issuance.

[0046] (3) Selective Disclosure and Verification Stage

[0047] (3-1) Users need to disclose the attribute {age} to generate a pseudo identity:

[0048] (3-2) User generates new signature With zero-knowledge proof π, construct VP and send it to the verifier.

[0049] (3-4) Verifier Calculation And verify the bilinear mapping equation.

[0050] Whether it is valid or not, access will be authorized after approval.

[0051] (4) Verifiable credential revocation stage

[0052] The user no longer wishes to use their verifiable credentials, and therefore initiates a revocation request:

[0053] (4-1) User constructs a revocation request RevokeReq = (STA VC reason, flag 用户 timestamp, σ 用户 ).

[0054] (4-2) After VCIs verify the request, they broadcast the request to the blockchain.

[0055] (4-3) After the blockchain reaches a consensus, the validator adds the credential status value to the local revocation list RList.

[0056] The above content provides a detailed description of the specific implementation of a decentralized issuance and secure verification scheme for verifiable credentials in a self-sovereign identity system proposed in this invention. The above embodiments are only for helping to understand the proposed method and core ideas of this invention; based on the ideas of this invention, there may be some differences in specific implementation methods. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A verifiable credential decentralized issuance and secure verification scheme in a self-sovereign identity system, characterized in that, Comprising the following steps: (1) System initialization phase: given the security parameters, the system executes the initialization function to generate public parameters, set up the bilinear group, elliptic curve, hash function, and initialize multiple credential issuing nodes, each node holding a share of the master private key through a threshold secret sharing scheme and generating a corresponding public key; (2) Verifiable credential issuing phase: the user generates a user public-private key pair, attribute message, identity commitment, and zero-knowledge proof, encrypts and sends them to the credential issuing node, applies for a verifiable credential from the credential issuing node; after the credential issuing node verifies the user's identity and request, it generates a partial signature and returns it to the user; The user aggregates at least a threshold number of partial signatures to obtain a complete verifiable credential signature and returns it to the credential issuing node to generate a final verifiable credential, and broadcasts the credential status to the blockchain, and after the blockchain consensus, the credential takes effect; (3) Selective disclosure and verification phase: when the user discloses part of the attributes, generate a pseudo-identity based on the current timestamp and the disclosed attributes, generate a new signature and zero-knowledge proof, and construct a VP to send to the verifier; The verifier verifies the validity of the signature, pseudo-identity and attributes, and performs cryptographic verification through a bilinear mapping equation to obtain access rights after verification; (4) Verifiable credential revocation phase: the user or the credential issuing node initiates a revocation request and constructs a signed revocation request message; the credential issuing node verifies the legality of the request and broadcasts the revocation transaction to the blockchain; after the blockchain consensus, each verifier updates the local revocation list to realize the update of the credential status.

2. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the public parameters generated by the scheme for decentralized issuance and security verification are characterized by: In step (1), the public parameters specifically include: a large prime number p, an elliptic curve E p (a, b) and its base point P, a multiplicative cyclic group of order q and its generators g1, g2, a bilinear mapping e: and an anti-collision hash function H: The use of these public parameters ensures the security and efficiency of the system, supports the bilinear mapping and hash function, and provides protection for subsequent signature and verification.

3. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the key splitting is achieved using the Shamir secret sharing scheme, characterized by: In step (1), the threshold secret sharing scheme is Shamir secret sharing, the master private key SK PS = (x, y1, y2, …, y m ) is divided into S shares, and the corresponding public key is This scheme uses the implementation of Shamir secret sharing to realize key splitting and decentralized issuance, prevent single node failure, and improve the security of the system.

4. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the user uses commitment and zero-knowledge proof to prove true identity, characterized by: In step (2), the specific way for the user to generate the identity commitment is: where DID_{U} is the user decentralized identifier, h is an element in the group , and r is a random number; a zero-knowledge proof is generated based on the commitment This scheme protects user privacy using identity commitment and zero-knowledge proof, ensuring the authenticity of the user's identity without revealing sensitive information.

5. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the VCIs use threshold Pointcheval-Sanders signature technology for signature, characterized by: In step (2), the partial signature generated by the credential issuing node is in the form of: each node randomly selects Computing the signature where (x j ,y i,j ) is the private key share of the node, M_i is the attribute message, and VCs is implemented using a threshold Pointcheval-Sanders signature technology to realize decentralized signature, ensuring that only when a threshold number of partial signatures are reached can a final valid signature be generated, thereby enhancing the security and reliability of the signature.

6. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the user uses Lagrange interpolation to aggregate the signatures of t VCI, characterized by: In step (2), the user aggregates the signatures in the following way: using Lagrange interpolation to aggregate at least t partial signatures to obtain a complete verifiable credential signature The user aggregates the signatures of the t VCIs using Lagrange interpolation to generate a complete signature and verifiable credential, reducing communication overhead and improving system efficiency.

7. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the user generates a pseudo-identity based on the disclosed attributes and the current time, characterized by: In step (3), the pseudo-identity is generated in the following manner: wherein pt is the current timestamp, DI is the pseudo-identity set corresponding to the attribute of this disclosure, Y i is a component of the system public key, PID i is the original pseudo-identity corresponding to the attribute, the user effectively resists long-term tracking attacks using the pseudo-identity, generates a unique pseudo-identity through the binding of the timestamp and the attribute, and ensures the security of the user under multiple disclosures.

8. The verifiable credential decentralized issuance and security verification scheme in a self-sovereign identity system according to claim 1, wherein the user generates a new signature for this disclosure using the pseudo-identity, characterized by: In step (3), the user randomizes the credential signature by randomly selecting Generating a new randomized signature This scheme using randomized signature processing enhances privacy protection, prevents signatures from being linked, and ensures independence and anonymity each time it is disclosed.

9. A verifiable credential decentralized issuance and secure verification scheme in a self-sovereign identity system according to claim 1, verifier computes J ′ and verifies whether the equation holds to decide whether the verification passes or not, characterized in that: In step (3), the specific process of the verifier performing the cryptographic verification is to calculate and verify whether the equation holds, where J is a component in the zero-knowledge proof, X is a part of the system public key, and DA is the disclosed attribute set.

10. The self-sovereign identity system verifiable credential decentralized issuance and secure verification scheme of claim 1, wherein: the scheme uses secret sharing and Pointcheval-Sanders signature to achieve decentralized issuance of credentials, and by generating a unique pseudo-identity bound to time and attributes each time the disclosure is made, the user's unlinkability in different disclosure processes is achieved, thereby resisting long-term tracking attacks.

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