Multi-party collaborative certificateless mimicry signature method for digital copyright protection

Abstract

The invention discloses a digital copyright protection-oriented multi-party collaborative certificateless mimicry signature method, which integrates secure multi-party computation (MPC) and a threshold symmetric encryption mechanism, and avoids the key leakage risk and single-point fault problems caused by centralized storage by cooperatively generating and managing a key through a plurality of committee nodes. In the signature generation stage, a mimicry signature structure is utilized, and the copyright identifier is hidden and embedded through a random number redundant space, so that the signature and the copyright identifier are organically fused without influencing the verification correctness. In the copyright traceability stage, the copyright identifier can be reconstructed only by recovering the random number embedded in the signature through multi-party cooperation, and the secret key is not leaked or the signature security is not damaged in the recovery process, so that the safe and reliable traceability of the digital copyright is ensured. The method has signature verifiability, information privacy protection and copyright traceability, and can provide safe and credible technical support in digital work right confirmation, authorization tracking and responsibility tracing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of information security, and particularly relates to a multi-party cooperative certificateless anamorphic signature method for digital copyright protection. BACKGROUND

[0002] With the rapid growth of digital content and the popularity of Internet dissemination, the creation and sharing of digital works such as text, images, audio and video have become extremely convenient. However, digital works are easily copied, tampered with and illegally disseminated in a network environment, resulting in damage to the rights of the original creators and ambiguity in copyright ownership, and the problem of digital copyright protection is increasingly prominent. In order to protect the legitimate rights and interests of the work owners, access control, encryption, digital watermarking, fingerprint identification and digital signature technologies are widely used in the copyright authentication and tracking system. Among them, the digital signature technology can effectively guarantee the integrity, authentication and non-repudiation of data through the private key signature and public key verification mechanism, and is the core means to realize electronic copyright authentication and authorization confirmation. However, the traditional digital signature relies on the public key infrastructure, and the public key authentication and management need to be handled by the certificate authority (CA), which has complex processes such as certificate application, verification and revocation, and the system overhead is large. At the same time, as a centralized trust node, if the CA is attacked or fails, it will lead to a trust crisis in the entire system. In order to reduce the burden of certificate management, the certificateless signature (CLS) mechanism is proposed, which forms a complete user private key by combining the user's own key and the partial key generated by the key generation center (KGC), thereby eliminating the certificate management link and the key escrow problem, and has far-reaching application potential.

[0003] On the other hand, with the increasing demand for digital work authorization and redistribution, copyright authentication no longer requires only to verify the identity of the signer, but also needs to have the ability to trace the authorized party information and control the privacy. The existing copyright protection scheme often uses digital watermarking or fingerprint technology to embed copyright identification and user information, but the watermark is easy to be tampered with or removed, and the embedding and extraction process is inefficient, which is difficult to meet the requirements of security and robustness.

[0004] In recent years, the anamorphic signature technology proposed embeds hidden information in the signature, which provides a new idea for copyright tracking. However, the existing anamorphic signature scheme generally relies on restoring the signature random number in the tracing stage to extract the hidden information, and the random number and the signature private key have a functional dependence in the algorithm. If the random number is completely restored, the signature private key may be leaked, which brings serious system security risks.

[0005] In summary, existing mimetic signature technologies still have shortcomings in preventing private key leakage, protecting authorization privacy, and achieving trusted traceability. Therefore, there is an urgent need to design a signature method that integrates secure multi-party computation (MPC) and mimetic signature structures to achieve multi-party collaborative key generation and secure random number recovery. This method should ensure signature verifiability while preventing private key leakage through inversion, and balance the concealment, traceability, and accountability aspects of copyright protection. Summary of the Invention

[0006] This invention proposes a multi-party collaborative certificateless mimicry signature method for digital copyright protection to address the problems existing in the prior art.

[0007] To achieve the above objectives, this invention provides a multi-party collaborative certificateless pseudo-signature method for digital rights protection, comprising: a system initialization phase, a partial user private key acquisition phase, a user public / private key setting phase, a signature generation phase, a signature verification phase, and a copyright tracing phase. During the system initialization phase, elliptic curves, master key shares, and threshold symmetric encryption keys are generated based on security parameters. The stage of obtaining a portion of the user's private key involves several committee members working together to generate a portion of the user's private key. During the user setting public and private key stage, the user generates a complete user private key and user public key based on the partial user private key and secret value. During the signature generation stage, the committee encrypts the copyright identifier using a threshold symmetric encryption key, and the signer generates a pseudo-signature embedded with the copyright identifier based on the complete user signature private key and the ciphertext of the copyright identifier. The signature verification phase involves the verifier verifying the validity of the signature based on the public key. The copyright tracing phase involves committee members collaboratively restoring the copyright information embedded in the signature.

[0008] Optionally, the system initialization phase includes: committee members collaboratively selecting a master key share and calculating a master public key based on security parameters; generating a threshold symmetric encryption key; and setting public parameters, which include the master public key, threshold encryption parameters, and a cryptographic hash function.

[0009] Optionally, the stage of obtaining a portion of the user's private key includes: each committee member generating a random number and calculating a public value based on the user's identity identifier; calculating a hash value based on the user's identity identifier, the master public key, and the public value; generating a portion of the user's private key share based on the hash value and the master key share, and sending it to the user.

[0010] Optionally, the user setting public and private key stage includes: based on the received partial user private key shares, the user calculates the complete partial user private key and verifies its correctness; the user randomly selects a secret value and calculates the complete user private key and user public key; Optionally, the signature generation stage includes: based on the copyright identifier, the signer requests the committee to generate ciphertext by using threshold encryption for the copyright identifier information; performing a dot product operation between the ciphertext and the elliptic curve base point to obtain an elliptic curve point; calculating the signature value based on the complete user private key, secret value, ciphertext, and hash value; and sending the signature value and the calculated elliptic curve point to the authorized party.

[0011] Optionally, the signature verification stage includes: the verifier calculating a hash value based on the user's public key and publicly available system parameters; and verifying whether the signature equation holds true based on the signature value, the master public key, the user's public key, and the elliptic curve points calculated in the intermediate process, in order to determine the validity of the signature.

[0012] Optionally, the copyright tracing stage includes: committee members collaboratively verifying the correctness of the secret value share based on the secret value share provided by the signer; committee members collaboratively calculating the ciphertext in the signature based on the signature value and their respective shares of user private keys; and committee members collaboratively decrypting the ciphertext and recovering the copyright identifier based on a threshold decryption mechanism.

[0013] Optionally, during the system initialization phase, committee members collaboratively generate master key shares through secure multi-party computation, and the sum of the master key shares constitutes the master key.

[0014] Optionally, in the signature generation stage, the ciphertext is generated using a threshold encryption algorithm, and the elliptic curve points are obtained by multiplying the ciphertext by the base points of the elliptic curve.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention introduces a copyright identifier embedding mechanism during the signing process, achieving deep integration of signature and copyright identifier. It retains the core characteristics of signature integrity and unforgeability while adding copyright traceability functionality. This invention replaces the traditional Key Generation Center (KGC) with a collaborative entity composed of multiple committee nodes. Through a multi-party collaborative key generation and management mechanism, it effectively mitigates the risk of private key leakage and single point of failure. In the signature generation stage, this method utilizes the redundancy space of random numbers to embed the copyright identifier (which may include the copyright holder's copyright identifier, the authorized party's identity identifier, detailed transaction information, etc.). Without affecting the correctness of signature verification, it achieves the covert embedding and verification compatibility of the copyright identifier, thereby improving system scalability while ensuring signature security. In the copyright traceability stage, there is no need to access the original private key; digital copyright traceability can be completed simply by restoring the random number information embedded in the signature. The restoration of the copyright identifier is collaboratively executed by committee members, achieving distributed collaborative restoration based on secure multi-party computation (MPC) and threshold decryption technology. The master key and user private keys are distributed and stored in the form of secret shares, effectively ensuring the confidentiality and anti-leakage capability of the certificateless key pair throughout its entire lifecycle.

[0016] This invention, through an innovative combination of a multi-party collaborative mechanism and a mimicry signature structure, ensures signature verifiability and high system security while achieving secure embedding, distributed protection, and traceable recovery of copyright identifiers. It possesses excellent security, privacy, scalability, and practical application value. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a method according to an embodiment of the present invention, which includes a system initialization stage, a partial user private key acquisition stage, a user public and private key setting stage, a signature generation stage, a signature verification stage, and a copyright tracing stage.

[0018] Figure 2 This is a schematic diagram of a method according to an embodiment of the present invention, including a copyright tracing stage. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0021] The symbols and definitions involved in this invention are as follows: : indicates the first Committee members; Total number of members of the logo committee; : Indicates system initialization security parameters; Indicates the master key; : Indicates the master key share, ; Indicates user identity; Indicates the identity of the authorized person; Threshold key generation, input security parameters Threshold Output Key and public parameters The key Distribute to the i-th participant; A distributed encryption protocol where participants in set s collaborate to encrypt message m. After execution, the protocol outputs ciphertext c (or ⊥, indicating failure).

[0022] A distributed decryption protocol where participants in set s collaborate to decrypt ciphertext c. After the protocol execution is complete, message m (or ⊥, indicating failure) is output.

[0023] like Figure 1 and Figure 2 As shown, this embodiment provides a multi-party collaborative certificateless pseudo-signature method for digital rights protection, including: system initialization stage, partial user private key acquisition stage, user public and private key setting stage, signature generation stage, signature verification stage, and copyright tracing stage; During the system initialization phase, elliptic curves, master key shares, and threshold symmetric encryption keys are generated based on security parameters. During the phase of obtaining partial user private keys, committee members collaborated to generate partial user private keys for each user. During the user's public / private key setup phase, the user generates a complete user private key and user public key based on a portion of the user's private key and secret value. During the signature generation phase, the committee encrypts the copyright identifier, and the signer generates a pseudo-signature with the embedded copyright identifier based on the complete user private key and the ciphertext of the copyright identifier. During the signature verification phase, the verifier verifies the validity of the signature based on the master public key and the user's public key. During the copyright tracing phase, committee members work together to restore the copyright identifier embedded in the signature.

[0024] Furthermore, the system initialization phase includes: based on security parameters, committee members collaboratively select a master key share and calculate the master public key; generate a threshold symmetric encryption key; and set public parameters, including the system master public key, threshold symmetric encryption public parameters, and cryptographic hash function.

[0025] During this system initialization phase, committee members collaboratively generate the master key and threshold symmetric encryption key. Committee members hold a share of the master key and publicly disclose the master public key and threshold encryption parameters. The committee uses security parameters. Perform the following operations: Step 1.1: Step 1.2: Random selection As a share of the master key, and calculate Collaborative computing of the master public key .

[0026] Step 1.3: Construct two hash functions: .

[0027] Step 1.4: Use Generate threshold encryption key and publicly available parameters The key Distribute to ; Step 1.5: Set Public Parameters .

[0028] Furthermore, the stage of obtaining a portion of the user's private key includes: based on the user's identity identifier, each committee member selects a random number and collaboratively calculates a public elliptic curve point; the hash value is calculated based on the user's identity identifier, the master public key, and the public value of the random number; a portion of the user's private key share is generated based on the hash value and the master key share and sent to the user.

[0029] At this stage, the committee provides services to users. Generate partial user private keys The details are as follows: Step 2.1: Random selection ,and private.

[0030] Step 2.2: And it will be announced.

[0031] Step 2.3: calculate , And Send to user .

[0032] Furthermore, the user setting public and private key stage includes: based on the received partial user private key shares, the user calculates the complete partial user private key and verifies its correctness; the user randomly selects a secret value and calculates the complete user private key and user public key; At this stage, users receive After that, the complete user private key can be calculated. And check if it is correct; the user's complete private key is... and a random secret value composition: Step 3.1: calculate and ,verify ; Step 3.2: Random selection As a secret value, calculate .

[0033] Step 3.3: Set up complete user public and private keys .

[0034] Furthermore, the signature generation stage includes: the user requesting committee members to encrypt the copyright identifier to generate ciphertext; calculating elliptic curve points based on the ciphertext and elliptic curve base points; calculating the signature value based on the complete user private key, ciphertext, and hash value; and combining the signature value, elliptic curve points, and public key to form a signature and sending it to the authorized party.

[0035] During the signature generation process, a copyright identifier, such as the authorized person's identity, is embedded using a random number. (Other copyright information can be set according to actual needs), the steps are as follows: Step 4.1: Request the committee to encrypt the copyright notice: ,calculate ,in It indicates the identity of the authorized person.

[0036] Step 4.2: calculate in .

[0037] Step 4.3: Signature Send to the authorized person .

[0038] Furthermore, the signature verification stage includes: calculating the hash value based on the user's public key and the system's public parameters provided in the signature; and verifying whether the signature equation holds true based on the signature value, the master public key, the user's public key, and the elliptic curve points to determine the validity of the signature.

[0039] Obtained from the committee's public announcement ,verify If the verification passes, it indicates copyright. The signature is by Signed by: .

[0040] Furthermore, the copyright tracing phase includes: based on the share of secret value provided by the signer, committee members collaboratively verify the correctness of the share of secret value; based on the signature value and their respective shares of user private keys, committee members collaboratively calculate the ciphertext in the signature; and based on the threshold decryption mechanism, committee members collaboratively decrypt the ciphertext to recover the authorized party's identity.

[0041] When a copyright dispute occurs, the user Will Divided into A random secret value share And sent to respectively Committee members: Step 6.1: calculate Collaborative computation and verification .

[0042] Step 6.2: calculate as well as .

[0043] Step 6.3: Collaborative calculation = .

[0044] Step 6.4: Decrypt This reveals the identity of the authorized person. ; Compared with the prior art, the present invention has the following advantages: This invention proposes a certificateless mimicry signature architecture that integrates a secure multi-party computation (MPC) mechanism. While traditional certificateless signatures avoid the certificate management burden of PKI systems, they still rely on a single key generation center (KGC), posing risks of centralization and private key leakage. This invention, by introducing secure multi-party computation technology, distributes the key generation and management process, with multiple committee nodes collaboratively completing key generation, signing, and verification, thereby achieving key decentralization and leakage resistance. This mechanism combines the privacy protection advantages of MPC with the embeddable nature of mimicry signatures, constructing a secure, verifiable, and scalable certificateless signature system, providing a more robust trust foundation for digital rights protection.

[0045] This invention achieves implicit integration of copyright identification and the signing process based on a random number redundancy embedding method. Unlike traditional methods that treat copyright information as an external tag or watermark, this method utilizes the redundancy space of random number parameters during the signing process to encrypt and encode the copyright identification, embedding it within the signature structure. This method ensures that the correctness and integrity of signature verification are unaffected, while maintaining compatibility with the original signature algorithm. Through this design, the signed file itself carries copyright attribute information, realizing a unified mechanism of signing as authentication and authentication as traceability, significantly enhancing the concealment and tamper-proof capabilities of copyright embedding.

[0046] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A multi-party collaborative certificate-free mimicry signature method for digital copyright protection, characterized in that, include: The system consists of the following phases: system initialization, obtaining partial user private keys, user setting public and private keys, signature generation, signature verification, and copyright tracing. During the system initialization phase, elliptic curves, master key shares, and threshold symmetric encryption keys are generated based on security parameters. The stage of obtaining a portion of the user's private key involves several committee members working together to generate a portion of the user's private key. During the user setting public and private key stage, the user generates a complete user private key and user public key based on the partial user private key and secret value. The signature generation stage involves the signer and the committee generating a pseudo-signature with an embedded copyright identifier based on the complete user private key and copyright identifier; The signature verification phase involves the verifier verifying the validity of the signature based on the user's public key and the master public key. The copyright tracing phase involves committee members collaboratively restoring the copyright identifier embedded in the signature.

2. The method according to claim 1, characterized in that, The system initialization phase includes: committee members collaboratively selecting a master key share and calculating a master public key based on security parameters; generating a threshold symmetric encryption key; and setting public parameters, which include security parameters, the master public key, a cryptographic hash function, elliptic curve parameters, and threshold symmetric encryption parameters.

3. The method according to claim 1, characterized in that, The stage of obtaining a portion of the user's private key includes: each committee member generating a random number and collaboratively calculating the corresponding public value based on the user's identity identifier; calculating a hash value based on the user's identity identifier, master public key, and public value; generating a portion of the user's private key share based on the hash value and master key share, and sending it to the user.

4. The method according to claim 1, characterized in that, The user setting public and private key stage includes: based on the received partial user private key shares, the user calculates the complete partial user private key and verifies its correctness; the user randomly selects a secret value and calculates the complete user private key and user public key.

5. The method according to claim 1, characterized in that, The signature generation stage includes: the committee encrypting the copyright identifier using a threshold symmetric encryption key to generate ciphertext; the user performing an elliptic curve point multiplication operation on the ciphertext and the elliptic curve base point to obtain an elliptic curve point; calculating the signature value based on the user's private key, the ciphertext, and the hash value; and combining the signature value, the elliptic curve point, and the public key to form a signature and sending it to the authorized party.

6. The method according to claim 1, characterized in that, The signature verification stage includes: calculating a hash value based on the user's public key and system public parameters provided in the signature; and verifying whether the signature equation holds true based on the signature value, master public key, user public key, and elliptic curve points to determine the validity of the signature.

7. The method according to claim 1, characterized in that, The copyright tracing phase includes: based on the secret value share provided by the signer, committee members collaboratively verify the correctness of the secret value share; based on the signature value and their respective shares of user private keys, committee members collaboratively calculate the ciphertext in the signature; and based on the threshold decryption mechanism, committee members collaboratively decrypt the ciphertext to recover the copyright identifier.

8. The method according to claim 2, characterized in that, During the system initialization phase, committee members collaboratively generate master key shares through secure multi-party computation, and the sum of these master key shares constitutes the master key.

9. The method according to claim 5, characterized in that, In the signature generation stage, the ciphertext is generated by the threshold pair encryption algorithm, and the elliptic curve points are obtained by performing an elliptic curve point product operation between the ciphertext and the base point.

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