A blockchain privacy protection method and system based on dynamic threshold homomorphic encryption

Abstract

The application provides a kind of dynamic threshold homomorphic encryption-based blockchain privacy protection method and system, by combining Paillier semi-homomorphic encryption algorithm and dynamic threshold secret sharing mechanism, the efficient encryption and flexible management of private data are realized.The method comprises: generating a public-private key pair and a threshold parameter set based on a large prime number, and grouping and encrypting the private information to be protected, using the additive homomorphic property to directly perform dynamic data update in the ciphertext state, then splitting the decryption key into share ciphertext, and realizing decentralized key distribution and secure recovery through threshold parameter constraints;For participant addition or exit event, dynamically adjust the threshold parameter set and reconstruct the key rule, and update the encrypted data set synchronously to maintain consistency.Thereby, while ensuring the privacy of the account book and the network, the flexibility and scalability of the blockchain system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of blockchain privacy protection, and in particular to a blockchain privacy protection method and system based on dynamic threshold homomorphic encryption. BACKGROUND

[0002] Blockchain technology has been widely applied in the fields of finance, supply chain, and medical treatment due to its decentralization and tamper-proof characteristics. However, traditional blockchain systems have significant drawbacks in terms of privacy protection. All transaction information in the distributed ledger, such as the payer, the receiver, and the transaction amount, is stored publicly by default, and attackers can easily obtain sensitive data, leading to the risk of user privacy leakage. In particular, in the context of cryptocurrencies, the transparency of dynamic data such as account balances and transaction times may expose user behavior patterns, further threatening the security of individuals and institutions. Therefore, how to ensure the openness and verifiability of blockchain while efficiently encrypting and controllably sharing private data has become a core problem that needs to be solved.

[0003] Current mainstream blockchain privacy protection technologies include secure multi-party computation, zero-knowledge proof, homomorphic encryption, coin mixing technology, and ring signature. Secure multi-party computation protects privacy through collaborative computation by multiple parties, but requires high communication and computation costs; zero-knowledge proof verifies the legality of transactions without revealing information, but faces challenges such as low proof generation efficiency and high storage overhead; full homomorphic encryption supports ciphertext operations, but complex calculations lead to performance bottlenecks; coin mixing technology relies on central nodes to obscure transaction paths, posing a risk of trust; ring signature achieves anonymity by obscuring transaction inputs, but is vulnerable to analysis attacks and transaction data is inflated. These technologies have their own advantages, but it is difficult to balance dynamic data update efficiency, flexible key management, and decentralization requirements.

[0004] In summary, the existing technologies have the following problems: first, the dynamic update efficiency is low, specifically, most encryption technologies require decryption, update, and re-encryption, which cannot be directly operated in the ciphertext state (such as adjusting account balances), leading to delays and resource waste; second, the key management is rigid, specifically, fixed threshold secret sharing schemes cannot adapt to the dynamic addition or removal of participants, and require reconfiguration of keys when adding or removing, increasing security risks and operational complexity; third, there is a centralized trust risk, specifically, coin mixing and other schemes rely on central nodes or trusted third parties, which are vulnerable to single-point attacks, violating the decentralization principle of blockchain. SUMMARY

[0005] In view of the above actual situation, the present application proposes a blockchain privacy protection method and system based on dynamic threshold homomorphic encryption to solve the problems of low dynamic update efficiency of private data, rigid key management that cannot adapt to changes in participants, and single-point risk caused by reliance on centralized trust nodes in the existing technology.

[0006] A blockchain privacy protection method based on dynamic threshold homomorphic encryption, the method comprising the following steps:

[0007] S1, initializing the basic parameters required for privacy information encryption and secret sharing, thereby generating public and private keys and a threshold parameter set, the initialization process including generation of Paillier algorithm parameters and setting of secret sharing threshold parameters;

[0008] S2, encrypting and homomorphically transforming the privacy information to be protected, thereby generating a set of additive homomorphic ciphertexts, the encryption and homomorphic transformation process including encryption based on the Paillier public key and multiplication calculation using the additive homomorphic property;

[0009] S3, secret splitting and encryption of the decryption key, thereby generating a set of share ciphertexts, the secret splitting and encryption process including random splitting based on the threshold parameter set and Paillier public key encryption;

[0010] S4, aggregating and decrypting the share ciphertext set provided by participants reaching the threshold number of the threshold parameter set, thereby recovering the original decryption key, the aggregation and decryption process including aggregation operation based on ciphertext product calculation and Paillier private key decryption;

[0011] S5, dynamically adjusting the share ciphertext set and threshold parameter set under participant changes and reconstructing the key rules, thereby generating an updated encrypted data set, the dynamic adjustment and key rule reconstruction process including extraction or splitting of the share ciphertext set, synchronous adjustment of the threshold parameter set, and data update operation in the encrypted state.

[0012] Further, the S1 step includes the following sub-steps:

[0013] S101, initializing the Paillier algorithm parameters required for privacy information encryption, the initialization including randomly selecting two large prime numbers and calculating their product and least common multiple, generating a public key and a private key, the public key being used for encryption operation, the private key being used for decryption operation;

[0014] S102, defining the threshold parameter set for secret sharing, the threshold parameter set including the total number of participants and the minimum number of shares required to recover the secret.

[0015] Further, the S2 step includes the following sub-steps:

[0016] S201, dividing the privacy information to be protected into multiple groups of plaintext data according to grouping rules, encrypting each group of plaintext data using the Paillier public key, generating a set of grouped ciphertexts and storing them to the blockchain ledger;

[0017] S202, based on the additive homomorphism property of the Paillier algorithm, performing multiplication calculation on the ciphertexts in the ciphertext set to generate an additive homomorphism ciphertext set, which is used for dynamic update of private data in the blockchain.

[0018] Further, the S3 step includes the following sub-steps:

[0019] S301, using the decryption key as initial secret data, splitting it into a share plaintext set that satisfies the algebraic sum and equals the original secret by a random function according to the threshold parameter set;

[0020] S302, using the Paillier public key to perform encryption calculation on each component in the share plaintext set to generate a corresponding share ciphertext set, and distributing it to each participant for storage through a secure channel.

[0021] Further, the S4 step includes the following sub-steps:

[0022] S401, collecting share ciphertext sets provided by participants reaching the threshold number of the threshold parameter set, and performing product calculation on the share ciphertext sets to generate a key ciphertext product;

[0023] S402, using the Paillier private key to perform decryption calculation on the key ciphertext product to recover the original decryption key, which is used to decrypt the ciphertext set in the blockchain ledger.

[0024] Further, the S5 step includes the following sub-steps:

[0025] S501, according to the new or exiting participant event triggered by the blockchain transaction, extracting components from the existing share plaintext set to generate a new share ciphertext set, or splitting the exiting participant's share plaintext set to generate a split share ciphertext set, updating the share ciphertext set of the remaining participants, and synchronously adjusting the threshold parameter set based on the change in the number of participants;

[0026] S502, based on the new or split share ciphertext set and the adjusted threshold parameter set, reconstructing the key management rule of private information in the blockchain to ensure that the new participant or the remaining participant can cooperatively recover the decryption key, and at the same time performing operation on the updated data set in the encrypted state through the Paillier additive homomorphism ciphertext set to generate an updated encrypted data set.

[0027] Further, the splitting of the share plaintext set in S301 includes algebraic splitting processing and distribution parameter generation processing. The encryption calculation on each component in the share plaintext set in S302 includes parameter optimization processing and modulus exponent operation simplification processing.

[0028] Further, the decryption calculation of the key ciphertext product in the S402 includes a modular exponentiation operation and a fractional modular operation.

[0029] Further, the threshold parameter set adjustment based on the number of participants in the S501 includes threshold expansion processing for new participants and threshold reduction processing for exiting participants, and the key management rule reconstruction of the privacy information in the S502 includes collaborative verification processing of the updated threshold parameter set and the share ciphertext set.

[0030] In addition, the application also discloses a blockchain privacy protection system based on dynamic threshold homomorphic encryption, characterized in that the system comprises:

[0031] An initialization definition unit is configured to initialize the basic parameters required for privacy information encryption and secret sharing, thereby generating a public key and a private key and a threshold parameter set, and the initialization processing includes

[0032] The blockchain privacy protection method and system based on dynamic threshold homomorphic encryption provided by the application realize real-time synchronization of dynamic threshold parameters and participant changes, efficient homomorphic operation of direct data update in an encrypted state, elimination of single-point trust dependence through decentralized key management, and significant reduction of computing and communication overheads through optimization of the Paillier algorithm and the secret sharing mechanism, thereby improving the flexibility and scalability of the blockchain system while ensuring the privacy of the account book and the network. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A blockchain privacy protection method based on dynamic threshold homomorphic encryption is provided in the application;

[0034] Figure 2 A blockchain privacy protection system based on dynamic threshold homomorphic encryption is provided in the application; DETAILED DESCRIPTION

[0035] The simulation technical route in the embodiments of the application will be described in detail below with reference to the accompanying drawings of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0036] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] The features and performance of the present invention will be further described in detail below with reference to embodiments. Please refer to the appendix. Figure 1 As shown, a blockchain privacy protection method based on dynamic threshold homomorphic encryption is disclosed, the method comprising the following steps:

[0038] S1, Initialize the basic parameters required for encryption and secret sharing of privacy information to generate public and private keys and threshold parameter sets. The initialization process includes generating Paillier algorithm parameters and setting secret sharing threshold parameters.

[0039] Specifically, this step includes the following sub-steps:

[0040] S101, Initialize the Paillier algorithm parameters required for encrypting privacy information. The initialization includes randomly selecting two large prime numbers and calculating their product and least common multiple to generate a public key and a private key. The public key is used for encryption operations, and the private key is used for decryption operations.

[0041] In some implementations, the Paillier algorithm parameter initialization includes randomly selecting two large prime numbers and calculating their product and least common multiple to generate a public key and a private key. In this embodiment, two distinct large prime numbers p and q are randomly selected, and their product is calculated. , where N is used as part of the public key for modulo calculations in encryption operations. Further calculations are performed to find the least common multiple of p−1 and q−1. The The public key is a core parameter of the private key and participates in mathematical operations during the decryption process. In some implementations, the generation of the public key requires obtaining data from a set... Randomly select an integer g from the set, the set Defined as less than And with The set of all coprime integers is used to generate the complete public key pair (N, g). In this embodiment, the private key is generated by directly retaining the original prime numbers p and q, or by calculation. As a parameter of the private key, the mathematical form of the private key is (p, q) or This is used for subsequent decryption operations.

[0042] In some implementations, the security of the parameter initialization depends on the difficulty of factoring large integers. In this embodiment, if an attacker cannot efficiently factorize... Therefore, the private key parameter λ cannot be derived, making it impossible to crack the encrypted data. The public key (N, g) is used in the encryption process, mapping plaintext to ciphertext through modular exponentiation, while the private key is derived through... The decryption formula recovers the original plaintext. In some implementations, the least common multiple... The calculation ensures the mathematical consistency of the decryption formula mod N, where c is the ciphertext, The function is used to map the calculation result of the ciphertext space to the plaintext space, where x is the input value which needs to satisfy x = 1 mod N. In this embodiment, the complete process of parameter initialization covers the key generation phase of the Paillier algorithm, providing a mathematical basis for subsequent encryption, homomorphic operation and decryption.

[0043] S102, define a threshold parameter set of the secret sharing, which contains the total number of participants and a threshold value of the minimum number of shares required to recover the secret.

[0044] In some embodiments, the threshold parameter set of the secret sharing is defined as a set containing the total number of participants and a threshold value of the minimum number of shares required to recover the secret, which is used to constrain the mathematical rules of secret splitting and recovery. In this embodiment, the threshold parameter set adopts the (k, n) threshold structure proposed by Shamir, where n represents the total number of participants, k represents the threshold value of the minimum number of shares required to recover the secret, and satisfies The mathematical basis of the threshold parameter set relies on the principle of polynomial interpolation, by constructing a k−1 order polynomial where is a randomly generated coefficient, ensuring the independence of the shares, The secret share allocated to the ith participant is the point value of the polynomial at x = i, embedding the secret information S as the constant term a0, and assigning a unique polynomial point value to each participant where i is the participant identifier. In this embodiment, when at least k participants provide their shares, the original secret is recovered by the Lagrange interpolation formula ensuring the uniqueness and feasibility of secret recovery, where j is the auxiliary index of iteration in the summation process.

[0045] In some embodiments, another implementation of the threshold parameter set is based on the geometric method of Blakley, which maps the secret information to a point in a high-dimensional space and defines the recovery condition through the intersection of hyperplanes. In this embodiment, n hyperplane equations are constructed, each corresponding to a participant, and the secret information is the unique intersection coordinates of these hyperplanes. When and only when at least k hyperplane equations are provided, the secret point is recovered by solving the linear equation system. The mathematical form of the geometric method can be represented as a linear equation system where the rank of matrix A is k, ensuring the uniqueness of the solution, where x is the point coordinate vector in the high-dimensional space, and its specific components correspond to the secret information S, the hyperplane coefficient matrix, the dimension satisfies the number of rows ≥ k, and b is the hyperplane constant term vector.

[0046] In the present embodiment, the design goal of the threshold parameter set includes preventing internal participants from colluding to disclose secrets and resisting external attacks. By limiting the minimum number of shares required to recover the secret threshold k, any combination of less than k shares cannot derive secret information through polynomial interpolation or hyperplane equation solving. In the Shamir scheme, the polynomial coefficients Generated by random numbers, ensuring the independence between shares; in the Blakley scheme, the coefficient matrix of the hyperplane equation needs to meet certain rank conditions to prevent information leakage.

[0047] In some embodiments, the dynamic adjustment of the threshold parameter set is associated with the changes of participants in the blockchain scenario. In the present embodiment, when new participants are added or existing participants are removed, the threshold parameter set is updated synchronously to And by redistributing the polynomial point values or hyperplane equations, the consistency of the secret recovery rule is ensured. The adjustment process needs to meet mathematical constraint conditions, for example, in the Shamir scheme, the share of the new participant needs to be calculated by the original polynomial, and Always holds true.

[0048] In the present embodiment, the implementation of the threshold parameter set further combines the homomorphic encryption feature of the Paillier algorithm to encrypt the share information into ciphertext form for distribution. The encrypted share Generated by the Paillier public key (N, g) calculation, the specific form is Where r is a random number, is the encrypted secret share, is the plaintext share of the i-th participant, g is the Paillier public key parameter, and N is the public key modulus. Participants can only recover the original secret by collaborative decryption, and a single encrypted share cannot be cracked independently, thereby enhancing the security of the overall scheme.

[0049] S2, the privacy information to be protected is encrypted and homomorphically transformed to generate a set of additive homomorphic ciphertexts, and the encryption and homomorphic transformation process includes encryption based on the Paillier public key and multiplication calculation using the additive homomorphic property;

[0050] Specifically, this step includes the following sub-steps:

[0051] S201, divide the privacy information to be protected into multiple groups of plaintext data according to the grouping rule, encrypt each group of plaintext data using the Paillier public key, generate a set of grouped ciphertexts, and store them in the blockchain ledger;

[0052] In some embodiments, the grouping and encryption process of the privacy information comprises dividing the privacy information to be protected into multiple groups of plaintext data according to a predefined grouping rule, and each group of plaintext data is encrypted to generate corresponding ciphertext data through Paillier public key calculation. In this embodiment, the grouping rule is defined based on data attributes or business requirements, for example, division according to transaction time, account type or data length, to ensure that the size of each group of plaintext data meets the encryption capacity limit of the Paillier algorithm. The Paillier public key (N, g) is generated by S101 step, where N is the product of two large prime numbers, and g is an integer randomly selected to satisfy .

[0053] In some embodiments, the encryption calculation is performed through a trusted execution environment (Trusted Execution Environment, TEE), which ensures that the plaintext data completes the encryption operation in an isolated secure environment. In this embodiment, for each group of plaintext data m, an integer r is randomly selected to satisfy , and the corresponding ciphertext c is generated through the Paillier encryption formula , where g is one of the public key parameters, m is the plaintext data representing the grouped privacy information to be encrypted, r is a randomly selected integer used to introduce randomness to enhance semantic security, N is one of the public key parameters, and mod N 2 is a modulo operation, to realize the mapping from plaintext to ciphertext space, to introduce randomness to enhance semantic security. The generation process of the ciphertext c depends on the public key parameters N and g, which ensures that the encryption result can only be decrypted through the corresponding private key.

[0054] In this embodiment, after the grouping and encryption are completed, the generated group ciphertext set is structured and encoded according to the storage protocol of the blockchain ledger, and is written into the blockchain through a distributed consensus mechanism. The storage protocol includes the generation of a hash digest of the ciphertext data, the marking of a timestamp, and the encapsulation of transaction-related metadata, to ensure the verifiability and tamper resistance of the ciphertext set. In some embodiments, the structured encoding adopts JSON or binary format, which binds each group of ciphertext with its group identifier, encryption parameter (N, g) and hash value of the random number r, to form a complete encryption record unit.

[0055] In some embodiments, the implementation of the trusted execution environment (TEE) is based on a hardware-level security module, such as Intel SGX or ARM TrustZone, to ensure that the plaintext data, random number r, and private key-related calculations in the encryption process are all in an isolated secure memory area. In this embodiment, the TEE verifies its integrity through a remote attestation mechanism to prevent malicious software or external attackers from stealing sensitive information. After the encryption operation is completed, the TEE submits the generated ciphertext set and integrity proof to the blockchain network for node verification and storage in the distributed ledger.

[0056] In this embodiment, the homomorphic property of the grouped ciphertext set supports subsequent dynamic data updates. Through the additive homomorphism of the Paillier algorithm, ciphertext data can be directly added or scalar multiplied in an encrypted state, for example, when updating an account balance, the new ciphertext where Δm is the plaintext increment, is a new random number, is the new ciphertext data generated after dynamic update, is the original ciphertext data already stored in the blockchain ledger, g and N are public key parameters consistent with the definition in the encryption formula. The operation result is still valid ciphertext, and data changes can be completed without decryption, while maintaining the consistency of the encrypted state.

[0057] S202, based on the additive homomorphism property of the Paillier algorithm, performing multiplication calculation on the ciphertexts in the grouped ciphertext set to generate an additive homomorphic ciphertext set, which is used for dynamic update of privacy data in the blockchain.

[0058] In some embodiments, the generation of the additive homomorphic ciphertext set is based on the homomorphic property of the Paillier algorithm, and the plaintext addition equivalent operation is achieved by performing multiplication calculation on the ciphertexts in the grouped ciphertext set. In this embodiment, the grouped ciphertext set is generated by S201 and contains multiple encrypted privacy data units, each corresponding to plaintext data m i in ciphertext form where r i is a random number, and (N, g) is a public key parameter. The additive homomorphic property is that if there are two ciphertexts c1 and c2, corresponding to plaintexts m1 and m2, respectively, then the decryption result of the ciphertext product is , and the mathematical form is: where are two ciphertext units in the grouped ciphertext set, generated by plaintext data m1 and m2 through Paillier encryption, respectively, N is a public key parameter, and Dec is the Paillier decryption function using the private key The decryption calculation is performed, which allows direct addition operation on the data in the encrypted state to generate a new additive homomorphic ciphertext set without decrypting the original ciphertext.

[0059] In some embodiments, the dynamic updating process is implemented through a ciphertext multiplication operation. In this embodiment, when the privacy data in the blockchain needs to be changed (such as an increase or decrease in the account balance), the plaintext increment Δm is encrypted as ciphertext , where Δc is the ciphertext of the plaintext increment Δm, is an integer randomly selected when encrypting Δm, and then multiplied with the original ciphertext to perform a multiplication calculation to generate an updated ciphertext , the decryption result of the updated ciphertext satisfies , ensuring the mathematical consistency of data changes.

[0060] In this embodiment, the scalar multiplication homomorphic property further expands the flexibility of dynamic updating. Given that the ciphertext c corresponds to the plaintext m, and the scalar multiplication of m is required , it is implemented through a ciphertext exponent operation , and after decryption, it satisfies: where c is a single ciphertext unit in the ciphertext set, m is the original plaintext data corresponding to c, is a scalar multiplier (integer), the result of performing an exponent operation on the ciphertext c, this property supports batch data adjustment scenarios, such as batch updating transaction timestamps or adjusting the balance ratio of multiple accounts, and all operations are kept in an encrypted state. It should be noted that Dec() is the core decryption function of the Paillier algorithm, its input is ciphertext, and its output is the original plaintext, its implementation depends on the private key parameters and the auxiliary function L(x).

[0061] In some embodiments, the application of the additive homomorphic ciphertext set is closely related to the data structure of the blockchain ledger. In this embodiment, the updated ciphertext data is written into the distributed ledger after being verified by the blockchain consensus mechanism, and its storage format includes the ciphertext value , the associated transaction hash, and the timestamp metadata. The integrity of the ciphertext data is guaranteed by the hash chain mechanism, ensuring that any tampering can be detected.

[0062] In this embodiment, the security of the homomorphic operation relies on the semantic security of the Paillier algorithm. The introduction of random numbers r i and makes the same plaintext generate different ciphertexts in different encryption operations, preventing frequency analysis attacks. In addition, the decryption key is protected by a secret sharing scheme, and the key can only be recovered when a threshold number of participants collaborate, ensuring the privacy of encrypted data in the public ledger.

[0063] S3, secret split and encryption processing on the decryption key to generate a ciphertext set of shares, the secret split and encryption processing including random split based on a threshold parameter set and Paillier public key encryption;

[0064] Specifically, the step includes the following sub-steps:

[0065] S301, splitting the decryption key as initial secret data into a ciphertext set of shares satisfying an algebraic sum equal to the original secret by a random function according to a threshold parameter set;

[0066] In some embodiments, the splitting into a ciphertext set of shares satisfying an algebraic sum equal to the original secret by a random function according to a threshold parameter set includes an algebraic split processing of secret information and a distribution parameter generation processing. In this embodiment, the algebraic split processing is defined as generating n shares of ciphertexts satisfying an algebraic sum constraint where N is a modulus in the public key parameter of the Paillier algorithm. The random function generates each share of ciphertext with uniform distribution, ensuring that any k−1 shares cannot derive the original secret S through linear combination, meeting the security requirements of the threshold parameter set (k, n).

[0067] In some embodiments, the distribution parameter generation processing includes selecting two equal-length large prime numbers p and q, calculating their product and the parameter and distributing N and g as public parameters to all participants. In this embodiment, the parameter N is used to define the modulus space of the algebraic sum operation, and at the same time as the modulus basis for subsequent Paillier encryption; the parameter g is used to construct the encryption function where r is a randomly selected integer to introduce randomness to enhance semantic security, ensuring the mathematical compatibility of the encryption process and the secret sharing scheme. The parameter generation process needs to meet the secrecy of p and q, only the distributor holds the original prime number, and the participants can only access the public parameters N and g.

[0068] In this embodiment, the mathematical implementation of the algebraic split processing is completed through linear equation constraints. Let the original secret S and n shares of ciphertext satisfy where S is the initial secret data, i.e., the decryption key to be protected, n is the total number of participants defined by the threshold parameter set, which is determined in advance by the secret sharing scheme, is the i-th share of ciphertext, a component generated by a random function, and the distributor generates n−1 independent random numbers and calculates the n-th share , ensuring algebraic and identity to the original secret. The random number generation process employs a cryptographically secure random number generator, preventing prediction or repetition attacks.

[0069] In some embodiments, the distribution parameter generation process further comprises calculating auxiliary parameters for private key recovery in subsequent decryption operations. In this embodiment, the parameters are distributed to trusted participants through a secure channel or retained by the distributor, ensuring that only authorized parties can participate in the secret recovery process. The parameters , in combination with the public key parameter N, support the correct execution of the Paillier decryption formula , where , defined as described above, N as modulus restricts algebraic and operation, while as public parameter of Paillier encryption, λ is distributed to trusted participants through a secure channel, g together with N forms a public key pair (N, g) to support encrypted computation of share plaintext.

[0070] In this embodiment, the generation and distribution process of the share plaintext set is implemented through a trusted execution environment (TEE), ensuring the integrity of the split logic and parameter calculation. The TEE provides full-flow isolation protection for random number generation, algebraic and calculation, and parameter distribution, preventing side-channel attacks or intermediate data leakage. The generated share plaintext set is encrypted to form a share ciphertext set and distributed to each participant based on a secure channel of the blockchain, ensuring the security of the transmission process.

[0071] S302, use the Paillier public key to perform encryption calculation on each component in the share plaintext set, generate the corresponding share ciphertext set, and distribute it to each participant for storage through a secure channel.

[0072] In some embodiments, the encryption calculation of each component in the share plaintext set using the Paillier public key includes parameter optimization processing and modular exponentiation simplification processing. In this embodiment, the parameter optimization processing is defined as selecting a fixed parameter g = N + 1 as part of the Paillier public key, instead of randomly selecting in the original algorithm, where N is the product of two large prime numbers p and q. The parameter selection allows the operation in encryption calculation to be simplified to a linear expression through the binomial theorem, significantly reducing the computational complexity.

[0073] In this embodiment, the modular exponentiation simplification processing is based on the mathematical properties of binomial expansion. For any share plaintext , the calculation expansion is: Where k is the summation index variable, and its value ranges from 0 to m. i integers, The binomial coefficients represent the values ​​from... The number of combinations of selecting k elements from n elements, this expression represents the term index of a binomial expansion, since The existence of modulo operation, when hour, Only the first two items should be retained: The simplification transforms the original exponential operation into a single multiplication and addition operation, mathematically expressed as: This optimization avoids complex calculations involving high powers while ensuring the correctness and security of the encryption results.

[0074] In some implementations, the encryption formula further incorporates random numbers. To enhance semantic security. In this embodiment, the random number r is selected from the set Choose from among them, satisfying that r and N are coprime, and It can be pre-calculated and reused. The specific mathematical expression for the encryption process is: ,in This represents the public key parameter g. The power of, where For the plaintext share to be encrypted, r N Let r be a random number raised to the power of N, where N is the product of two large prime numbers p and q. For the i-th share plaintext The ciphertext of the share generated after encryption, modulo The result of the entire expression is obtained by modulo. The final ciphertext is obtained through the operation. ,Enc(m i ) indicates the plaintext The encryption function, by choosing g=N+1, simplifies the exponentiation operation to a linear expression: This optimization avoids the complex calculations of higher powers. The Nth power of the random number r is used to introduce randomness and prevent the generation of identical ciphertext from the same plaintext. The introduction of the random number r ensures identical plaintext. Different ciphertexts are generated in different encryption operations. To prevent frequency analysis attacks.

[0075] In this embodiment, the encryption computation is performed through a Trusted Execution Environment (TEE) to ensure the integrity and confidentiality of random number generation, parameter optimization, and modular arithmetic. The TEE provides full isolation protection for the encryption process, preventing side-channel attacks or intermediate data leakage. The generated share ciphertext set... The data is distributed to all participants through a secure channel on the blockchain, and the distribution process uses an end-to-end encryption protocol to ensure the security of the transmission path.

[0076] In some implementations, the pre-computation step further reduces real-time computing overhead. In this embodiment, the parameters... The computation is pre-calculated and stored during system initialization, requiring only one multiplication and modulo operation during encryption. This optimization strategy reduces the complexity of the encryption operation from O(m... i The computation time is reduced to O(1), making it suitable for high-concurrency blockchain transaction scenarios.

[0077] In this embodiment, the encrypted share ciphertext set is combined with a threshold parameter set (k, n), where k is the minimum number of shares required to recover the secret, and n is the total number of participants. This ensures that the key ciphertext product can be recovered through a product operation only when at least k participants provide their share ciphertexts, and the original key can then be decrypted. This design enhances the system's flexibility and scalability while maintaining security.

[0078] S4, aggregate and decrypt the share ciphertext set provided by the participants who have reached the threshold parameter set threshold, thereby recovering the original decryption key. The aggregation and decryption process includes aggregation operation based on ciphertext product calculation and Paillier private key decryption.

[0079] Specifically, this step includes the following sub-steps:

[0080] S401, Collect the share ciphertext set provided by the participants who have reached the threshold parameter set threshold, and perform a product calculation on the share ciphertext set to generate the key ciphertext product;

[0081] In some implementations, the key-ciphertext product is defined as the share ciphertext set provided by participants who have reached a threshold parameter set threshold number k. Execution mode The synthesized ciphertext generated by the multiplication operation corresponds to the encrypted form of the original decryption key S. In this embodiment, the share ciphertext... Generated by step S302, satisfying Where m i Let each share be a plaintext of a secret split, and satisfy the algebraic sum. The product calculation is implemented using the additive homomorphism of the Paillier algorithm, and its mathematical form is: , where c is the product of the generated key ciphertext (synthetic ciphertext). The ciphertext of the share provided to the i-th participant, k is the minimum number of shares required to recover the secret from the threshold parameter set, and N and g are Paillier public key parameters. The share plaintext corresponding to the i-th share ciphertext (obtained by splitting the original key S in step S301), r i is encrypted The random number used at this time, since , is consistent with the Paillier encryption formula, indicating that c is the valid ciphertext of the original key S.

[0082] In some embodiments, the threshold constraint of the threshold parameter set (k, n) ensures that the product operation can correctly recover the key ciphertext only when at least k participants provide share ciphertexts. In this embodiment, if less than k share ciphertexts are provided, the algebraic sum , (where t < k), where t represents the actual number of share plaintexts collected, causes the synthetic ciphertext c to be unable to be restored to the original key through the decryption process. The mechanism ensures the uniqueness and security of secret recovery through the mathematical properties of polynomial interpolation or the intersection of geometric hyperplanes.

[0083] In this embodiment, the implementation of the product calculation relies on the distributed consensus protocol in the blockchain network. Participants submit share ciphertexts to the smart contract through the smart contract, and the contract verifies the identity of the submitter and the validity of the share before performing the multiplication operation to generate the key ciphertext product c. The calculation process is completed in a trusted execution environment (TEE), ensuring the confidentiality of the intermediate results and the random number r i , preventing malicious nodes from stealing or tampering with data.

[0084] In some embodiments, the decryption of the synthetic ciphertext c needs to be completed through the private key operation of step S402. In this embodiment, the private key parameter is protected by the secret sharing scheme and can only be recovered when authorized participants cooperate, ensuring the privacy of encrypted data in the public ledger. The design achieves the decentralization and high security of key management by combining homomorphic encryption and threshold secret sharing.

[0085] S402, the key ciphertext product is decrypted using the Paillier private key to recover the original decryption key, which is used to decrypt the set of grouped ciphertexts in the blockchain ledger.

[0086] In some embodiments, the decryption calculation of the key ciphertext product using the Paillier private key includes a modular exponentiation operation and a fractional modulus operation. In this embodiment, the modular exponentiation operation is defined as performing power operations on the key ciphertext product c and then taking the modulus of to generate the intermediate calculation result where is the private key parameter, which satisfies , N is a public key parameter and The mathematical form of the operation is: where g is one of the Paillier public key parameters, R is a composite random number obtained by multiplying k share ciphertexts corresponding random numbers, that is (r i is the encrypted share plaintext The random number used when), since g = N + 1 and , combined with the randomness elimination characteristics of , the intermediate result can be simplified as: where S is the original decryption key, the target secret value to be recovered. In some embodiments, the fractional modulus operation process maps the intermediate result to the plaintext space by applying the function (where x is the input value, and N is the public key modulus), and performs modulus N division operation combined with the pre-computed In this embodiment, the specific calculation of the function L is: At the same time, calculate The final form of the fractional modulus operation is: where is the function L applied to the intermediate result of the key ciphertext product, and the calculation result is , is the function L applied to the power operation result of the public key parameter g, and the calculation result is , S is the final recovered original decryption key, which satisfies The constraint, through this step, the original decryption key S is recovered, which is used to decrypt the grouped ciphertext set in the blockchain ledger.

[0087] In this embodiment, the implementation of the modulus exponent operation process relies on the secure computing capability of the trusted execution environment (TEE), which ensures the confidentiality of the private key parameter and the intermediate result The TEE performs hardware-level isolation of power operations and modulus operations to prevent side-channel attacks or data leakage.

[0088] In some embodiments, the mathematical correctness of the fractional modulus operation process is guaranteed by the homomorphic property of the Paillier algorithm. In this embodiment, the decryption process can correctly recover the original key S only when the key ciphertext product c is generated by at least k valid share ciphertexts. If the number of provided share ciphertexts is insufficient or invalid, the intermediate calculation result cannot satisfy The form, resulting in the fractional modulus operation result deviating from the true value.

[0089] In the present embodiment, the recovered original decryption key S is used to decrypt the set of grouped ciphertexts in the ledger after the blockchain smart contract verifies its validity. The decryption operation is performed on each ciphertext is executed , the corresponding plaintext data is recovered , and reassembled into complete privacy information.

[0090] S5, dynamic adjustment and key rule reconstruction processing of the share ciphertext set and threshold parameter set under the change of participants are performed to generate an updated encrypted data set, the dynamic adjustment and key rule reconstruction processing including extraction or splitting of the share ciphertext set, synchronous adjustment of the threshold parameter set, and data update operation in an encrypted state.

[0091] Specifically, the step includes the following sub-steps:

[0092] S501, according to the new or exit participant event triggered by the blockchain transaction, a new share ciphertext set is generated by extracting components from the existing share plaintext set, or a split share ciphertext set is generated by splitting the exit participant share plaintext set, the share ciphertext set of the remaining participants is updated, and the threshold parameter set is synchronously adjusted based on the change in the number of participants;

[0093] In some embodiments, the synchronous adjustment of the threshold parameter set based on the change in the number of participants includes threshold expansion processing of new participants and threshold reduction processing of exit participants. In the present embodiment, the threshold expansion processing is defined as extracting part of the components from the share plaintext set of the existing (k, n) threshold sharing group when the blockchain transaction triggers a new participant event, generating a new share ciphertext set, and adjusting the threshold parameter to (k+1, n+1). Specifically, k participants are selected from the existing n participants, and components are extracted from their share plaintext , respectively , so that the remaining share plaintext after extraction is , where represents the modulo N operation, ensuring that the result is in the range [0, N), and the algebraic sum of the extracted components is assigned to the share plaintext of the new participant (the nth+1 participant). The new share ciphertext is generated by Paillier public key encryption , while the share ciphertext of the original participant is updated to , ensuring that the algebraic sum still satisfies (n+1 is the total number of participants after the addition). ​​​

[0094] In some implementations, the threshold reduction process is defined as reducing the plaintext set m of the withdrawing participant's share when the participant withdraws. e Split into k−1 parts ,satisfy (where m) e The share of the withdrawing party is explicitly stated. It is m e The split components (k-1 being the new threshold after exiting) are encrypted using Paillier and then distributed to the remaining participants. In this embodiment, the original threshold parameter is adjusted from (k,n) to (k−1,n−1), and the remaining participants... The share ciphertext is updated to ,in Exiter splits components The encryption result, The ciphertext of the original share of the i-th remaining participant. The updated share ciphertext for the i-th remaining participant. The adjustment ensures that the new algebraic sum satisfies... Furthermore, the threshold parameters are updated synchronously with the number of participants.

[0095] In this embodiment, the mathematical basis of the threshold expansion process relies on the polynomial interpolation properties of the Shamir secret-sharing scheme. The original polynomial... For a polynomial of order k-1, a new k-order polynomial needs to be constructed for each new participant. This is achieved by adding a coefficient term to the original polynomial and redistributing the point values. and This ensures the recovery condition of the new threshold k+1. The operation must satisfy interpolation consistency, that is, any k+1 point values ​​can uniquely determine the new polynomial.

[0096] In some implementations, the threshold reduction process employs hyperplane intersection adjustment using the Blakley geometry method. The original secret S is the intersection of n hyperplanes. After exiting, the corresponding hyperplane needs to be removed, and n-1 new hyperplanes are constructed, ensuring that their intersection remains S. Specifically, the hyperplane equation of the exiting participant is decomposed into k-1 linearly independent sub-equations, which are then merged into the hyperplanes of the remaining participants, ensuring that the rank of the new system of equations is k-1, thereby maintaining the uniqueness of the solution.

[0097] In the present embodiment, the dynamic adjustment process is automatically executed by a blockchain smart contract. When a new participant is detected or an existing participant exits, the contract triggers the share extraction or splitting logic, calls a trusted execution environment (TEE) to complete the share plaintext operation and encryption operation, and updates the threshold parameter set to the distributed ledger. The TEE ensures the confidentiality of the share plaintext and random number, preventing intermediate data leakage. The updated threshold parameter set and share ciphertext set take effect after being verified by a consensus mechanism, ensuring that the state of all nodes is synchronized.

[0098] In some embodiments, the update of the threshold parameter set is further associated with the homomorphic operation rule of the Paillier algorithm. The share ciphertext of the new participant participates in subsequent dynamic data updates, such as balance adjustments, together with the original ciphertext. The new ciphertext (where Δc represents the encryption result of the plaintext increment Δm) needs to be compatible with the updated threshold structure. The share splitting of the exiting participant needs to ensure that the remaining ciphertext product can still recover the effective key ciphertext, avoiding data and key disconnection.

[0099] In the present embodiment, the security of the dynamic adjustment is guaranteed by the mathematical constraints of the secret sharing scheme. Any combination of shares that does not reach the threshold number cannot recover the secret through interpolation or hyperplane solving, and the semantic security of Paillier encryption prevents the share ciphertext from being reverse cracked. The mechanism realizes the high scalability and attack resistance of the blockchain privacy protection scheme by combining threshold adjustment and homomorphic encryption.

[0100] S502, based on the updated threshold parameter set and the share ciphertext set after the addition or splitting, reconstruct the key management rule of the privacy information in the blockchain to ensure that the new participant or the remaining participants can cooperatively recover the decryption key, and at the same time, perform operations on the updated data set in the encrypted state through the Paillier additive homomorphic ciphertext set to generate the updated encrypted data set.

[0101] In some embodiments, the reconstruction of the key management rule of the privacy information in the blockchain includes a cooperative verification process of the updated threshold parameter set and the share ciphertext set. In the present embodiment, when a new participant or an exiting participant is added, the threshold parameter set is adjusted from to and the updated share ciphertext set satisfies the algebraic sum constraint , where is the updated share plaintext, S is the original decryption key, is the total number of participants after dynamic adjustment, and N is the Paillier public key parameter. The verification is performed by a blockchain smart contract, which calls a trusted execution environment (TEE) to verify the validity of each share ciphertext and checks the synthesized ciphertext This ensures the consistency of the key recovery logic.

[0102] In some implementations, the operation on dynamically updated data in an encrypted state using a Paillier additive homomorphic ciphertext set includes ciphertext multiplication and random number update processing. In this embodiment, when private data (such as account balance) in the blockchain ledger needs to be updated from blc1 to blc2, the plaintext increment... Encrypted into ciphertext Then, a multiplication operation is performed with the original balance ciphertext blc1 to generate the updated ciphertext: Where blc1 is the ciphertext of the balance before the update, and blc2 is the ciphertext of the balance after the update. For plaintext increment The encryption result, For the plaintext values ​​that need to be added, Here, m1 is the random number used to encrypt Δc, m1 is the original plaintext corresponding to blc1, and r1 is the random number used to encrypt blc1. The result of the operation is still valid ciphertext, and its decryption satisfies the following conditions: This ensures the mathematical correctness of data changes.

[0103] In this embodiment, the random number update process introduces a new random number. To prevent the generation of duplicate ciphertext from the same plaintext increment, semantic security is enhanced. The random number is generated and encrypted through a Trusted Execution Environment (TEE) to ensure its unpredictability and confidentiality. The updated ciphertext blc2 is written to the distributed ledger through the blockchain consensus mechanism. Its storage format includes timestamps, transaction hashes, and homomorphic operation metadata for subsequent verification and auditing.

[0104] In some implementations, the reconstruction of the key management rules is further linked to access control for dynamic data updates. In this embodiment, new participants can only access the adjusted share ciphertext set, and their contributed shares must satisfy a threshold parameter set. Only participants meeting a minimum threshold requirement can participate in subsequent key recovery. The ciphertext of a participant's historical share is marked as invalid in the ledger to prevent malicious nodes from using expired data to tamper with the key recovery process.

[0105] In this embodiment, the security of the homomorphic operation is guaranteed by the mathematical properties of the Paillier algorithm. Any unauthorized modification to the encrypted data will result in the synthesis of ciphertext. Unable to pass decryption verification, thus triggering the blockchain network's anomaly detection mechanism. This mechanism, by combining threshold secret sharing and homomorphic encryption, ensures that privacy data remains encrypted throughout dynamic updates, and that key management rules are strictly synchronized with data change operations.

[0106] In some embodiments, the generation and storage of the updated encrypted dataset is implemented through a hierarchical encryption structure. In this embodiment, each dynamic update operation generates an independent ciphertext increment , which is associated with the original ciphertext blc1 through a hash chain, forming an unforgeable encrypted data history record. The root value of the hash chain is stored in the Merkle tree of the blockchain, ensuring data integrity and traceability.

[0107] In this embodiment, the reconstructed key management rule and dynamic data update process are automatically managed through a smart contract. When a threshold parameter or share ciphertext set change is detected, the contract automatically triggers key rule update and data re-encryption logic to ensure full node state consistency. The design isolates the efficiency and robustness of the blockchain privacy protection scheme through decentralized collaboration and encryption calculation.

[0108] Based on the description of the above-mentioned blockchain privacy protection method based on dynamic threshold homomorphic encryption, the embodiments of the present application also disclose a blockchain privacy protection system based on dynamic threshold homomorphic encryption. The blockchain privacy protection system based on dynamic threshold homomorphic encryption can be a computer program (including program code) running the above-mentioned blockchain privacy protection method based on dynamic threshold homomorphic encryption. Please refer to FIG. 1. Figure 2 The blockchain privacy protection system based on dynamic threshold homomorphic encryption can run the following units:

[0109] The initialization definition unit 110 is used for initialization processing of the basic parameters required for encryption and secret sharing of private information, so as to generate a public key and a private key and a threshold parameter set. The initialization processing includes generation of Paillier algorithm parameters and setting of secret sharing threshold parameters.

[0110] The encryption and homomorphic transformation unit 120 is used for encryption and homomorphic transformation processing of private information to be protected, so as to generate an additive homomorphic ciphertext set. The encryption and homomorphic transformation processing includes encryption based on the Paillier public key and multiplication calculation using the additive homomorphic property.

[0111] The secret splitting and encryption unit 130 is used for secret splitting and encryption processing of the decryption key, so as to generate a share ciphertext set. The secret splitting and encryption processing includes random splitting based on the threshold parameter set and Paillier public key encryption.

[0112] The aggregation and decryption unit 140 is used for aggregation and decryption processing of the share ciphertext set provided by the participants reaching the threshold number of the threshold parameter set, so as to restore the original decryption key. The aggregation and decryption processing includes aggregation operation based on ciphertext product calculation and Paillier private key decryption.

[0113] The dynamic adjustment and key reconstruction unit 150 is configured to perform dynamic adjustment and key rule reconstruction processing on the share ciphertext set and the threshold parameter set under the change of the participant, thereby generating an updated encrypted data set. The dynamic adjustment and key rule reconstruction processing includes extraction or splitting of the share ciphertext set, synchronous adjustment of the threshold parameter set, and data update operation in the encrypted state.

[0114] The above description is only preferred embodiments of the present application. It should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concepts described herein by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A blockchain privacy protection method based on dynamic threshold homomorphic encryption, characterized in that, The method includes the following steps: S1, Initialize the basic parameters required for encryption and secret sharing of privacy information to generate public and private keys and threshold parameter sets. The initialization process includes generating Paillier algorithm parameters and setting secret sharing threshold parameters. S2, perform encryption and homomorphic transformation processing on the privacy information to be protected, thereby generating an additive homomorphic ciphertext set. The encryption and homomorphic transformation processing includes encryption based on the Paillier public key and multiplication calculation using the properties of additive homomorphism. S3, perform secret splitting and encryption processing on the decryption key to generate a share ciphertext set. The secret splitting and encryption processing includes random splitting based on a threshold parameter set and Paillier public key encryption. S4, aggregate and decrypt the share ciphertext set provided by the participants who have reached the threshold parameter set threshold, thereby recovering the original decryption key. The aggregation and decryption process includes aggregation operation based on ciphertext product calculation and Paillier private key decryption. S5, dynamically adjust the share ciphertext set and threshold parameter set under the change of participants and reconstruct the key rules to generate an updated encrypted dataset. The dynamic adjustment and key rule reconstruction process includes the extraction or splitting of the share ciphertext set, the synchronous adjustment of the threshold parameter set and the data update operation under the encrypted state. Step S2 includes the following sub-steps: S201: Divide the privacy information to be protected into multiple groups of plaintext data according to the grouping rules, use the Paillier public key to perform encryption calculation on each group of plaintext data, generate a grouped ciphertext set and store it in the blockchain ledger. S202, Based on the additive homomorphic property of the Paillier algorithm, perform multiplication calculations on the ciphertext in the block ciphertext set to generate an additive homomorphic ciphertext set, which is used for the dynamic updating of privacy data in the blockchain; The S5 step includes the following sub-steps: S501: Based on the events of new or withdrawing participants triggered by blockchain transactions, extract components from the existing plaintext set of shares to generate a new encrypted set of shares, or split the plaintext set of withdrawing participants' shares to generate a split encrypted set of shares, update the encrypted set of shares of the remaining participants, and synchronously adjust the threshold parameter set based on the changes in the number of participants. S502 reconstructs the key management rules for privacy information in the blockchain based on the newly added or split share ciphertext set and the adjusted threshold parameter set, ensuring that new or remaining participants can collaboratively recover the decryption key. At the same time, it performs encrypted operations on the dynamically updated data of the blockchain through the Paillier additive homomorphic ciphertext set to generate the updated encrypted dataset.

2. The blockchain privacy protection method based on dynamic threshold homomorphic encryption according to claim 1, characterized in that, Step S1 includes the following sub-steps: S101, Initialize the Paillier algorithm parameters required for encrypting privacy information. The initialization includes randomly selecting two large prime numbers and calculating their product and least common multiple to generate a public key and a private key. The public key is used for encryption operations, and the private key is used for decryption operations. S102, Define a threshold parameter set for secret sharing, the threshold parameter set including the total number of participants and a threshold for the minimum number of shares required to recover the secret.

3. The blockchain privacy protection method based on dynamic threshold homomorphic encryption according to claim 1, characterized in that, Step S3 includes the following sub-steps: S301, the decryption key is used as the initial secret data, and a random function is used to split it into a set of plaintext shares that satisfy the algebraic sum equal to the original secret according to the threshold parameter set; S302, using the Paillier public key, performs encrypted calculations on each component in the share plaintext set to generate the corresponding share ciphertext set, and distributes it to each participant for storage via a secure channel.

4. A blockchain privacy protection method based on dynamic threshold homomorphic encryption according to any one of claims 1-3, characterized in that, Step S4 includes the following sub-steps: S401, Collect the share ciphertext set provided by the participants who have reached the threshold parameter set threshold, and perform a product calculation on the share ciphertext set to generate the key ciphertext product; S402, use Paillier's private key to perform decryption calculation on the key ciphertext product to recover the original decryption key, which is used to decrypt the block ciphertext set in the blockchain ledger.

5. A blockchain privacy protection method based on dynamic threshold homomorphic encryption according to claim 3, characterized in that, The step S301, which involves splitting the plaintext into share sets according to the threshold parameter set using a random function, includes algebraic splitting of the secret information and generation of distribution parameters. The step S302, which involves using the Paillier public key to perform encrypted calculations on each component in the share plaintext set, includes parameter optimization and modular exponentiation simplification.

6. A blockchain privacy protection method based on dynamic threshold homomorphic encryption according to claim 4, characterized in that, The decryption calculation of the key ciphertext product using the Paillier private key in S402 includes modular exponentiation and fractional modular arithmetic.

7. A blockchain privacy protection method based on dynamic threshold homomorphic encryption according to claim 1, characterized in that, The threshold parameter set adjusted synchronously based on changes in the number of participants in S501 includes threshold expansion processing for new participants and threshold reduction processing for withdrawing participants. The key management rules for reconstructing privacy information in the blockchain in S502 include collaborative verification processing of the updated threshold parameter set and the share ciphertext set.

8. A blockchain privacy protection system based on dynamic threshold homomorphic encryption, characterized in that, The system includes: An initialization definition unit is used to initialize the basic parameters required for encryption and secret sharing of privacy information, thereby generating a public key, a private key, and a threshold parameter set. The initialization process includes generating Paillier algorithm parameters and setting secret sharing threshold parameters. The encryption and homomorphic transformation unit is used to perform encryption and homomorphic transformation processing on the privacy information to be protected, thereby generating an additive homomorphic ciphertext set. The encryption and homomorphic transformation processing includes encryption based on the Paillier public key and multiplication calculation utilizing the properties of additive homomorphism. The secret splitting and encryption unit is used to perform secret splitting and encryption processing on the decryption key to generate a share ciphertext set. The secret splitting and encryption processing includes random splitting based on a threshold parameter set and Paillier public key encryption. The aggregation and decryption unit is used to aggregate and decrypt the share ciphertext set provided by participants that have reached the threshold parameter set threshold, thereby recovering the original decryption key. The aggregation and decryption process includes aggregation operation based on ciphertext product calculation and Paillier private key decryption. The dynamic adjustment and key reconstruction unit is used to dynamically adjust and reconstruct the share ciphertext set and threshold parameter set under the change of participants, thereby generating an updated encrypted dataset. The dynamic adjustment and key rule reconstruction process includes the extraction or splitting of the share ciphertext set, the synchronous adjustment of the threshold parameter set, and the data update operation under the encrypted state. The generation of the additive homomorphic ciphertext set includes the following steps: S201: Divide the privacy information to be protected into multiple groups of plaintext data according to the grouping rules, use the Paillier public key to perform encryption calculation on each group of plaintext data, generate a grouped ciphertext set and store it in the blockchain ledger. S202, Based on the additive homomorphic property of the Paillier algorithm, perform multiplication calculations on the ciphertext in the block ciphertext set to generate an additive homomorphic ciphertext set, which is used for the dynamic updating of privacy data in the blockchain; The process of generating the updated encrypted dataset includes the following steps: S501: Based on the events of new or withdrawing participants triggered by blockchain transactions, extract components from the existing plaintext set of shares to generate a new encrypted set of shares, or split the plaintext set of withdrawing participants' shares to generate a split encrypted set of shares, update the encrypted set of shares of the remaining participants, and synchronously adjust the threshold parameter set based on the changes in the number of participants. S502 reconstructs the key management rules for privacy information in the blockchain based on the newly added or split share ciphertext set and the adjusted threshold parameter set, ensuring that new or remaining participants can collaboratively recover the decryption key. At the same time, it performs encrypted operations on the dynamically updated data of the blockchain through the Paillier additive homomorphic ciphertext set to generate the updated encrypted dataset.

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