A data encryption method and system based on enterprise data element security management

Abstract

The application discloses a data encryption method and system based on enterprise data element security management, relates to the technical field of data security, and comprises the following steps: verifying zero-knowledge proof information carried by a data calling request, verifying a one-time password, verifying the effective state of a request subject certificate, performing consistency comparison on a business-related certificate, and initiating signature authorization confirmation on a request that fails to pass the consistency comparison to obtain an authorized context; and positioning a key data unit according to the authorized context and compiling an access control strategy, converting the access control strategy into an access tree and a linear secret sharing structure access matrix to obtain an encryption description result. The application utilizes ciphertext policy attribute-based proxy re-encryption based on the linear secret sharing structure, and significantly reduces the calculation and management overhead of dynamic authorization update.

Description

Technical Field

[0001] This invention relates to the field of data security technology, and in particular to a data encryption method and system based on enterprise data element security management. Background Technology

[0002] With the continuous advancement of market-based allocation of data elements and the assetization of enterprise data, data encryption technologies for enterprise data element security management have gradually evolved from traditional boundary isolation protection to an endogenous security protection mechanism covering the entire data lifecycle. Existing related technologies typically employ a combination of digital certificate authentication, password verification, and symmetric encryption combined with asymmetric key encapsulation to protect sensitive fields in structured data objects. Simultaneously, to support cross-entity sharing, role-based access, and usage constraint management, some solutions further introduce technologies such as attribute-based encryption, access control policy modeling, proxy re-encryption, and on-chain auditing, aiming to achieve the security governance goals of data being "usable but not visible," authorization being verifiable, and the flow process being recordable.

[0003] However, existing technologies still generally have the following shortcomings in enterprise data element circulation scenarios: On the one hand, existing solutions mostly focus on static identity authentication or coarse-grained access control, making it difficult to uniformly link and verify the identity of the requesting subject, usage restrictions, business relationships, and authorization validity status. This results in insufficient coupling between the authorization basis and the actual business relationship, making it difficult to meet the requirements of highly reliable and fine-grained data use control. On the other hand, when there are situations such as changes in subject, usage, adjustment of the scope of re-sharing, or authorization failure, many solutions still need to re-encrypt the original ciphertext or the entire data object. The update cost is high, and it is easy to cause complex policy migration, increased key management burden, and broken audit chain, which is not conducive to the secure, continuous, and traceable use of enterprise data elements in dynamic circulation environments. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a data encryption method based on enterprise data element security management to solve the problems of difficulty in dynamically updating fine-grained authorization encryption and insufficient audit traceability during the circulation of enterprise data elements.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a data encryption method based on enterprise data element security management, comprising, The system verifies the zero-knowledge proof information carried in the data call request, verifies the one-time password, verifies the validity status of the request subject certificate, performs a consistency comparison on the business-related credentials, and initiates signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context. Based on the authorization context, key data units are located and access control policies are compiled. The access control policies are then converted into access trees and linear secret-sharing structure access matrices to obtain encrypted description results. The key data units in the encrypted description result are processed by numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategy, and key field replacement and digital signature are performed to obtain signed data packets. When the signed data packet experiences one of the following situations: change of subject, change of purpose, reduction of re-sharing scope, authorization expiration, or failure of business association, the access tree and linear secret sharing structure access matrix are reconstructed, and the field key encapsulation layer and policy index transformation are performed using the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to obtain the policy update data packet; The policy update data packet is signed and verified, the attribute private key is unsealed, the key data unit is restored, the numerical precision is restored, and the hash chain is audited and solidified to obtain the controlled decryption audit result of the target data object.

[0007] As a preferred embodiment of the data encryption method based on enterprise data element security management according to the present invention, the step of obtaining the authorization context specifically includes: The system receives the request subject certificate, zero-knowledge proof information, one-time password, purpose description, target dataset identifier, and business-related credentials submitted by the data user. It performs verification on the zero-knowledge proof information, verifies the one-time password, and verifies the validity period, revocation status, and issuance status of the request subject certificate to form an identity authentication result. Perform a consistency comparison between the business-related credential summary, historical agreement summary, authorization form summary, and business transaction summary and the request subject identifier to form an association verification result; For requests that fail to pass, confirm the result by sending and receiving a signed authorization confirmation form from the data controller; The authorization context integrates the identity authentication result, the association verification result, and the signature confirmation result.

[0008] As a preferred embodiment of the data encryption method based on enterprise data element security management described in this invention, the location of key data units refers to determining key data units from the corresponding data directory, field dictionary, and field tag list based on the subject identity information, usage restriction information, authorization validity information, and target dataset identifier in the authorization context, forming a key data unit location result that includes field identifier, field location, field type, precision identifier, and field group identifier.

[0009] As a preferred embodiment of the data encryption method based on enterprise data element security management according to the present invention, the step of obtaining the encryption description result specifically includes: Extract the subject identity information, usage restriction information, authorization validity information, and field identifiers, field positions, and precision identifiers from the authorization context, and configure them as access control policies that include subject attributes, usage descriptions, retention periods, decryption time limits, re-sharing restrictions, and access scope. Parse the attribute conditions and logical relationships in the access control policy, construct the access tree, expand the nodes and map the relationships in the access tree, configure the row identifiers and attribute identifiers of the access matrix, form a linear secret sharing structure access matrix, assign policy indexes to the access control policy and extract policy digests as policy verification information; The key data unit location results, access tree, linear secret sharing structure access matrix, policy index, and policy verification information are organized into an encrypted description result.

[0010] As a preferred embodiment of the data encryption method based on enterprise data element security management according to the present invention, the step of performing numerical fixed-point processing, data key generation, and symmetric encryption on key data units in the encryption description result specifically includes: Read the list of key data units in the encrypted description result, detect the decimal places of the numerical key data units and convert them into fixed-point integers to form numerical processing results; The key data units are grouped according to the field group identifiers in the key data unit location results to generate data key groups; Using the data key in the data key group, symmetric encryption is performed on each key data unit in the numerical processing result to form the field ciphertext. Organize the ciphertext of the fields, the decimal places in the numerical processing results, the field positions, the policy indexes, and the key versions into a data packet to be encapsulated.

[0011] As a preferred embodiment of the data encryption method based on enterprise data element security management described in this invention, the step of replacing key fields and digital signature specifically includes: Retrieve the access tree and linear secret sharing structure access matrix from the encryption description result, encapsulate the data keys in the data key group with the ciphertext policy attribute base key of the hiding policy, and form the field key encapsulation result; The field replacement result is generated by replacing the plaintext value of a key field in the target data object with the ciphertext value of the field. The field key encapsulation result, field ciphertext, decimal information, field position, policy index, and key version are organized into a data packet to be signed and digital signature is performed to form a signed data packet.

[0012] As a preferred embodiment of the data encryption method based on enterprise data element security management described in this invention, the reconstructing of the access tree and the linear secret sharing structure access matrix specifically includes: Continuously detect changes in the subject, purpose, scope of sharing reduction, authorization expiration, and business association failure of signed data packets to generate update trigger results; Extract the request subject identifier, purpose description, and target dataset identifier corresponding to the update trigger result, re-initiate signature authorization confirmation, and form the latest authorization context; Extract the subject attributes, purpose description, authorization validity information, and access scope from the latest authorization context, and reconfigure them to update the access control policy; The system parses the attribute conditions and logical relationships in the access control policy, reconstructs the access tree, expands the nodes and maps the relationships in the reconstructed access tree, reconstructs the linear secret sharing structure access matrix, and uses the existing access tree and linear secret sharing structure access matrix in the signed data packet as the old access tree and the old linear secret sharing structure access matrix, respectively.

[0013] As a preferred embodiment of the data encryption method based on enterprise data element security management described in this invention, the field key encapsulation layer and policy index conversion specifically include: Extract the field key encapsulation layer, field ciphertext body, field position, decimal information, old policy index, and old linear secret sharing structure access matrix from the signed data packet, and retrieve the reconstructed linear secret sharing structure access matrix; Attribute item comparison and access relationship comparison are performed on the old linear secret sharing structure access matrix and the reconstructed linear secret sharing structure access matrix to distinguish between retained attribute items, removed attribute items and added attribute items, and form a strategy transformation relationship; According to the policy transformation relationship, the ciphertext policy attribute base proxy re-encryption process based on the linear secret sharing structure is performed. The transformation is performed on the encapsulation components corresponding to the retained attribute items in the field key encapsulation layer, the revocation is performed on the encapsulation components corresponding to the removed attribute items, and the supplementation is performed on the encapsulation components corresponding to the newly added attribute items, forming the encapsulation layer transformation result. Adjust the policy identifier and access relationship identifier corresponding to the old policy index to form an updated policy index, and replace the encapsulation layer transformation result and the updated policy index in the signature data packet, record the update time identifier, and form a policy update data packet.

[0014] As a preferred embodiment of the data encryption method based on enterprise data element security management described in this invention, the step of obtaining the controlled decryption audit result of the target data object specifically includes: The public key of the data provider is invoked to perform signature verification on the policy update data packet, resulting in a signature verification result. When the signature verification result is successful, the private key of the attribute held by the receiver is used to deseal the field key encapsulation layer in the policy update data packet to obtain the data key; The data key is used to decrypt the encrypted body of each field in the policy update data packet, and the key data units are recovered according to the field positions. For the recovered numerical key data units, the decimal information in the data packet is updated according to the strategy to restore the numerical precision and then filled back into the corresponding field position of the target data object. Extract the subject identity digest, business-related credential digest, policy index, key version, update time identifier, and decryption result digest, construct a hash chain audit record in chronological order, and solidify the audit digest to the consortium blockchain to form a controlled decryption audit result for the target data object.

[0015] Secondly, this invention provides a data encryption system based on enterprise data element security management, comprising: The authentication module verifies the zero-knowledge proof information carried in the data call request, verifies the one-time password, verifies the validity status of the request subject certificate, performs a consistency comparison on the business-related credentials, and initiates signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context. The policy conversion module locates key data units based on the authorization context and compiles access control policies, converting the access control policies into access trees and linear secret sharing structure access matrices to obtain encrypted description results. The layered encryption module performs numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategies on key data units in the encryption description result, and performs key field replacement and digital signature to obtain a signed data packet. The policy update module reconstructs the access tree and the linear secret sharing structure access matrix when the signed data packet experiences one of the following: subject change, purpose change, reduction of re-sharing scope, authorization expiration, or business association failure. It then uses the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to perform field key encapsulation layer and policy index transformation to obtain the policy update data packet. The decryption audit module performs signature verification, attribute private key decryption, key data unit recovery, numerical precision restoration, and hash chain auditing and solidification on the policy update data packet to obtain the controlled decryption audit result of the target data object.

[0016] The beneficial effects of this invention are as follows: By jointly verifying the consistency of zero-knowledge proof information, one-time passwords, request subject certificate status, and business-related credentials, and introducing a signature authorization confirmation mechanism when necessary, the authenticity of identity, the authenticity of business association, and the legality of authorization can be integrated and bound together, thereby improving the credibility of the authorization context from the source. Based on the authorization context, key data units are precisely located, and access control policies are converted into access trees and linear secret sharing structure access matrices, thereby achieving fine-grained encryption control oriented towards subject attributes, uses, durations, and re-sharing restrictions. Simultaneously, the risk of policy content leakage is reduced by encapsulating the ciphertext policy attribute base of the hidden policy. By performing numerical fixed-pointing, block key generation, and symmetric encryption on key fields, the encryption efficiency and numerical recovery accuracy of structured data can be balanced. Utilizing the ciphertext policy attribute base based on the linear secret sharing structure for proxy re-encryption, only the field key encapsulation layer and policy index are converted, eliminating the need for repeated processing of the original field plaintext or the entire ciphertext, significantly reducing the computational and management overhead of dynamic authorization updates. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a data encryption method based on enterprise data element security management.

[0019] Figure 2 A diagram illustrating the construction of the authorization context and the location of key data.

[0020] Figure 3 This is a flowchart of the hybrid encryption process based on the LSSS matrix.

[0021] Figure 4 This is a diagram illustrating the dynamic update of the strategy based on proxy re-encryption. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Reference Figures 1-4 This is one embodiment of the present invention, which provides a data encryption method based on enterprise data element security management, including the following steps: S1. Verify the zero-knowledge proof information carried in the data call request, verify the one-time password, verify the validity status of the request subject certificate, perform a consistency comparison on the business-related credentials, and initiate signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context.

[0026] S1.1. Receive the request subject certificate, zero-knowledge proof information, one-time password, purpose description, target dataset identifier and business-related credentials submitted by the data user.

[0027] Among them, the requesting entity certificate is the digital identity credential of the data user, which includes the requesting entity identifier and the certificate validity period; the zero-knowledge proof information is used to prove to the data provider that the data user holds a legitimate credential without disclosing the specific identity credential content; the one-time password is a dynamic verification code that is valid only once; the purpose description records the specific business purpose of this data call; the target dataset identifier points to the data resource requested for access; and the business association credential is a credential file or credential summary of a data usage agreement, authorization form or business transaction document signed between the data user and the data controller.

[0028] After receiving the request, the data provider performs verification on the zero-knowledge proof information.

[0029] The verification of zero-knowledge proof information employs a non-interactive zero-knowledge proof verification algorithm. The data provider calls the zero-knowledge proof verification function, inputting the zero-knowledge proof information and publicly available verification parameters. If the verification passes, it indicates that the data user indeed possesses a legitimate credential and has not disclosed the credential content itself. If the zero-knowledge proof information verification fails, the data call request is terminated, and an authentication failure message is returned.

[0030] S1.2. After the zero-knowledge proof information verification passes, the one-time password is verified. The data provider queries the trusted one-time password generation service for the current one-time password value and compares it with the one-time password submitted by the data user. If the one-time password verification fails, the current data call request is terminated and a dynamic password error message is returned.

[0031] After the one-time password verification is successful, the validity status of the requesting entity's certificate is verified. Validity status verification includes validity period verification, revocation status verification, and issuance status verification.

[0032] The validity period verification compares the current time with the validity period field in the request subject certificate to determine whether the request subject certificate is within its validity period; the revocation status verification checks the certificate revocation list with the certificate issuing authority to confirm that the request subject certificate has not been revoked; and the issuance status verification verifies the issuance chain of the request subject certificate to confirm that the request subject certificate was issued by a trusted certificate issuing authority.

[0033] If any of the verifications for the validity period, revocation status, or issuance status of the requesting entity's certificate fails, the data retrieval request will be terminated and an invalid certificate message will be returned.

[0034] Once all verifications are successful, the requesting entity's identifier, the timestamp of successful verification, and the verification method will be recorded together to form the identity authentication result.

[0035] S1.3. Perform a consistency comparison between the request subject identifier in the identity authentication result and the business-related credential summary, historical protocol summary, authorization form summary, and business transaction summary.

[0036] The business-related credential summary is the hash value obtained by hashing the business-related credential submitted by the data user; the historical protocol summary is the hash value obtained by hashing the effective data usage protocol stored locally by the data provider; the authorization form summary is the hash value obtained by hashing the authorization form issued by the data controller; and the business transaction summary is the hash value obtained by hashing the transaction record of the completed data call business.

[0037] The specific method for consistency comparison is as follows: Using the request subject identifier from the authentication result as the query condition, the system retrieves the business-related credential summary, historical agreement summary, authorization form summary, or business transaction summary associated with the request subject identifier from the data provider's business-related credential repository. Upon successful retrieval, each summary value is compared item by item with the summary value calculated from the business-related credential submitted by the data user. If any summary value matches the retrieved corresponding summary value, it indicates that the current data call request has a corresponding business-related basis. The consistency comparison result is recorded as the association verification result, which includes an identifier indicating whether the comparison passed or failed.

[0038] When the association verification result is a successful comparison, the identity authentication result is directly used as the authorization context.

[0039] If the verification result indicates a failed comparison, an authorization confirmation form is constructed and sent to the data controller. The authorization confirmation form includes the requesting entity identifier from the authentication result, the purpose description submitted by the data user, and the target dataset identifier. Upon receiving the authorization confirmation form, the data controller automatically reviews the requesting entity identifier, purpose description, and target dataset identifier according to preset authorization rules. If the review is successful, the data controller uses its private key to digitally sign the authorization confirmation form, generating a signature confirmation result which is then returned to the data provider.

[0040] Authorization rules are a set of pre-configured authorization rules by the data controller, used to determine whether to grant permission for this data access based on the requesting entity identifier, purpose description, and target dataset identifier.

[0041] After receiving the signature confirmation result returned by the data controller, the data provider uses the data controller's public key to verify the signature confirmation result. Once the verification is successful, the signature confirmation result is merged with the identity authentication result into an authorization context.

[0042] The authorization context includes subject identity information, usage restriction information, and authorization validity information. The subject identity information comes from the requesting subject identifier in the identity authentication result, the usage restriction information comes from the usage description submitted by the data user, and the authorization validity information comes from the authorization timestamp and authorization validity period in the signature confirmation result.

[0043] S2. Locate the key data units based on the authorization context and compile the access control policy. Convert the access control policy into an access tree and a linear secret sharing structure access matrix to obtain the encrypted description result.

[0044] S2.1. The data provider uses the target dataset identifier in the authorization context as an index to retrieve the data directory, field dictionary, and field label list corresponding to the target dataset identifier.

[0045] The data catalog describes the organizational structure of each data table in the target dataset, including the table name, table description, and field list; the field dictionary describes the metadata information of each field in each data table, including the field name, field type, length rules, format rules, code table identifier, and whether it can be null; the field label list describes the sensitivity level label of each field, including the field name and sensitivity label, with sensitivity labels including four levels: non-sensitive, internal, sensitive, and highly sensitive.

[0046] Based on the subject identity information, usage restriction information, and authorization validity information in the authorization context, and in conjunction with the target dataset identifier, the data provider filters the accessibility range of each field in the field dictionary, and determines the fields that meet the access permission range corresponding to the subject identity information, the business usage range corresponding to the usage restriction information, and are within the validity period of the authorization validity information as candidate fields.

[0047] The scope of access permissions is determined by the role corresponding to the requesting subject identifier contained in the subject identity information. The scope of business use is determined by the usage description contained in the usage restriction information.

[0048] Each field in the candidate fields is matched against rules, and the field that meets any one of the following conditions is identified as the key data unit: field name matching condition, field type matching condition, length rule matching condition, format rule matching condition, code table identifier matching condition, and sensitive tag matching condition.

[0049] Among them, the field name matching condition is that the field name belongs to the list of highly sensitive field names, such as fields with the field name "ID number", "bank account number", or "mobile phone number"; the field type matching condition is that the field type belongs to the list of sensitive field types, such as fields with the field type being string and marked as encrypted storage; the length rule matching condition is that the field length meets the encryption length requirements; the format rule matching condition is that the field format meets the regular expression validation rules; the code table identifier matching condition is that the code table identifier corresponding to the field belongs to the code table identifier in the sensitive code table list; and the sensitive label matching condition is that the field's sensitive label is sensitive or highly sensitive.

[0050] Each selected key data unit is recorded, and a field identifier, field location, field type, precision identifier, and field group identifier are configured for each key data unit. The field identifier is a unique number for the key data unit in the field dictionary; the field location is the starting offset and length of the key data unit within the target data object; the field type is the data type of the key data unit, including numeric, string, and date types; the precision identifier is only valid when the field type is numeric and is used to record the decimal places of the numeric key data unit; the field group identifier is the group identifier of the field group to which the key data unit belongs. Field groups divide key data units into different groups according to business relevance, and key data units within the same field group share the same data key. All configuration information is then compiled into the key data unit location result.

[0051] It should be noted that by encrypting only key data units rather than encrypting the entire enterprise data, the overhead of encryption operations is reduced, while ensuring targeted protection for sensitive data units, thereby guaranteeing data security.

[0052] S2.2. Extract the subject identity information, usage restriction information, authorization validity information, and field identifiers, field positions, and precision identifiers from the authorization context, and use these six extracted information items as policy compilation items. Map the subject identity information in the policy compilation items to the subject attributes in the access control policy; map the usage restriction information in the policy compilation items to the usage description in the access control policy; determine the authorization timestamp in the authorization validity information in the policy compilation items as the start time of the retention period in the access control policy; determine the authorization validity period in the authorization validity information in the policy compilation items as the decryption time limit in the access control policy; use the pre-configured re-sharing restriction boolean value as the re-sharing restriction in the access control policy; and determine the field identifier list in the policy compilation items as the accessible scope in the access control policy. Fill each item of information in the policy compilation items into the corresponding field positions of the access control policy through the mapping relationship, forming an access control policy containing subject attributes, usage description, retention period, decryption time limit, re-sharing restriction, and accessible scope.

[0053] Among them, the subject attribute is mapped from the request subject identifier in the subject identity information, including the department, role and permission level of the request subject; the purpose description directly references the purpose restriction information in the authorization context; the retention period specifies the maximum storage time of the ciphertext generated in this encryption on the data provider's side; the decryption time limit specifies the deadline that the data user is allowed to decrypt after obtaining the ciphertext; the re-sharing restriction is a boolean value, indicating whether the data user is allowed to share the decrypted data with other subjects again; the accessible scope is a list of field identifiers, specifying the range of key data units that are allowed to be accessed in this authorization.

[0054] S2.3. Parse the attribute conditions and logical relationships in the access control policy and construct the access tree. An access tree is a tree-like data structure used to represent the logical relationships between the attribute conditions in an access control policy. The leaf nodes of the access tree correspond to a single attribute condition, storing the attribute name and value. The non-leaf nodes correspond to logic gates, including AND and OR gates. An AND gate indicates that all child node conditions must be satisfied, while an OR gate indicates that only one child node condition needs to be satisfied. The root node of the access tree represents the final logical judgment result of the entire access control policy.

[0055] The specific process of constructing the access tree is as follows: The subject attributes, purpose description, retention period, decryption time limit, re-sharing restrictions, and access scope conditions in the access control policy are taken as atomic conditions. These are then organized into logical expressions according to the implicit logical relationships in the access control policy (e.g., the department in the subject attributes is the finance department and the role is auditor, the purpose description is financial audit, and the decryption time limit is before the current time). The logical expressions are then parsed into a syntax tree, where the leaf nodes are the atomic conditions, the internal nodes are AND or OR operations, and the syntax tree is output as the access tree.

[0056] S2.4. Expand the nodes and map the relationships in the access tree, configure the row identifiers and attribute identifiers of the access matrix, and form a linear secret sharing structure access matrix. The linear secret sharing structure access matrix is ​​a matrix representation based on a linear secret sharing scheme, used to bind the access policy to the ciphertext in ciphertext policy attribute-based encryption.

[0057] The original form of the linear secret sharing scheme is: a secret value is shared as a set of shares under an access policy, and the secret value can be reconstructed by a linear combination of shares if and only if the attribute sets of the participants satisfy the access policy.

[0058] In this embodiment, the specific method for combining the secret sharing process of the linear secret sharing scheme with the access tree structure to obtain the access matrix of the linear secret sharing structure is as follows: Starting from the root node of the access tree, assign a secret shared polynomial to each node from top to bottom. Assign a randomly selected secret value to the root node. ,in For model finite field, Let be a large prime number. For each non-leaf node in the access tree, allocate shares to its child nodes according to the logic gate type corresponding to the non-leaf node: if the non-leaf node corresponds to an AND gate, then distribute the secret value of the non-leaf node to each child node through addition secret sharing, so that the sum of the shares of each child node equals the secret value of the non-leaf node; if the non-leaf node corresponds to an OR gate, then directly copy the secret value of the non-leaf node to each child node, so that each child node obtains the same secret value as the non-leaf node. This allocation is recursively executed according to the above method until each leaf node obtains a share value. ,in This is the number of the leaf node. .

[0059] After the share allocation is completed, each leaf node in the access tree is mapped to a row of the access matrix of the linear secret sharing structure to be constructed. Let the total number of leaf nodes in the access tree be... Then the linear secret shared structure access matrix for Matrix, where The value is the highest number of random polynomials used to visit non-leaf nodes in the tree plus one. The specific value is determined by the structure of the access tree and the distribution of logic gates.

[0060] For the access matrix of the linear secret sharing structure For each row in the configuration, the corresponding access matrix row identifier is set to the corresponding leaf node number. Configure the attribute identifier corresponding to this row as the attribute condition bound to this leaf node. The attribute condition comes from the atomic conditions such as the main attribute, purpose description, or accessible scope corresponding to each leaf node when the access tree is constructed.

[0061] The linear secret-sharing structure access matrix constructed in the manner described above The core property of a linear secret-sharing scheme is: for any set of attributes that satisfy the access control policy... There exists a reconstruction coefficient vector , making , This indicates the transpose operation.

[0062] Based on its core nature, during the decryption phase, if the receiver possesses a set of attributes... If the access control policy in the ciphertext is satisfied, then the coefficient vector is reconstructed. The root node secret value used during encryption is recovered by linearly combining the secret share values ​​corresponding to each leaf node. The expression for the recovery process is: ; in, For attribute collection The set of leaf node numbers corresponding to each attribute in the access tree. ; For the number The secret share value obtained from the leaf node. ; To reconstruct the coefficient vector The middle corresponds to the number The components of the leaf nodes, , The specific values ​​are determined by the linear secret sharing structure access matrix. In attribute collection The linear combination relationship is determined when the access strategy is satisfied; The secret value assigned to the root node. .

[0063] S2.5. Assign a policy index to the access control policy and extract the policy summary of the access control policy as policy verification information. The policy index is a unique identifier for the access control policy in the policy library, using a globally unique identifier format.

[0064] The policy digest is extracted as follows: The main attributes, purpose description, retention period, decryption time limit, re-sharing restrictions, and access scope fields of the access control policy are concatenated into a policy string. The SHA-256 hash algorithm is then applied to the policy string, and the first 8 bytes of the hash value are used as the policy digest. Since the policy digest only stores a fragment of the hash value, it is impossible to deduce the complete access control policy content from it. The access control policy itself is not written into the ciphertext header, thus preventing attackers from directly identifying the policy content from the ciphertext structure and enhancing data security.

[0065] The key data unit location results, access tree, linear secret sharing structure access matrix, policy index, and policy verification information are organized into an encrypted description result.

[0066] S3. Perform numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategy on key data units in the encryption description result, and perform key field replacement and digital signature to obtain a signed data packet.

[0067] S3.1. The data provider extracts the key data unit location results from the encrypted description results. The key data unit location results include field identifier, field location, field type, precision identifier, and field group identifier.

[0068] The data provider iterates through each key data unit in the key data unit location results, performing fixed-point conversion on key data units with numeric field types. The specific method of fixed-point conversion is as follows: The number of decimal places corresponding to the numeric key data unit is detected, and the decimal places are recorded as the precision identifier corresponding to the numeric key data unit; the original value of the numeric key data unit is multiplied by 10 raised to the power of the precision identifier to obtain a fixed-point integer representation. The fixed-point integer representations of all key data units after fixed-point conversion, along with the original values ​​of non-numeric key data units, are used as the numerical processing result. By converting numeric key data units to fixed-point integers, numerical precision is preserved, and numeric key data units can be directly used as input to symmetric encryption algorithms, while avoiding inconsistencies in encryption and decryption caused by differences in floating-point representations, thus ensuring data security.

[0069] S3.2. The data provider groups the key data units according to the field group identifiers in the key data unit location results. Key data units with the same field group identifier are grouped into the same field group. A random bit string is generated for each field group as the field group data key, and the data keys of all field groups constitute a data key group. The length of each data key in the data key group is determined according to the key length requirement of the symmetric encryption algorithm used. For example, when using the AES-256 symmetric encryption algorithm, each data key is a 256-bit random bit string.

[0070] The specific method for generating the data key group is as follows: call the root key identifier based on the target dataset identifier, and obtain the root key by indexing the root key identifier; apply the key derivation function to the combination of the root key and the field group identifier to derive the data key of the corresponding field group.

[0071] The key derivation function uses the HMAC-SHA256 algorithm, and the expression for the derivation process is as follows: ; in, The data key for the derived field group. The root key is used to identify the corresponding root key. For field group identifiers, For a pre-configured random salt value, the symbol This indicates bit string concatenation. HMAC-SHA256 is a hash-based message authentication code algorithm.

[0072] S3.3. The data provider uses the data key corresponding to the field group in the data key group to perform symmetric encryption on each key data unit belonging to the same field group in the numerical processing result, forming the field ciphertext. The symmetric encryption uses the AES-256 algorithm, and the encryption mode is GCM mode. In GCM mode, an authentication tag is generated during encryption to verify the integrity of the ciphertext.

[0073] For those belonging to the field group identifier as Each key data unit in the field group is identified sequentially using the field group identifier in the data key group. Corresponding data key AES-256-GCM encryption is performed, generating a random initialization vector (IV) during encryption. The output of each key data unit after encryption includes the IV, a ciphertext block, and an authentication tag; these three parts together constitute the field ciphertext. The field ciphertext, along with decimal information from the numerical processing result, field positions from the encryption description result, policy indexes, and key versions, are then organized into a data packet to be encapsulated.

[0074] Among them, the decimal information is a list of precision identifiers recorded during the numerical fixed-point processing, which is used to restore the numerical precision after decryption; the field position is the starting offset and length of the key data unit in the target data object, which is used to fill the recovered plaintext back into the correct position after decryption; the policy index is the unique identifier of the assigned access control policy; and the key version is the key rotation version number corresponding to the root key identifier, which is used to support key update scenarios.

[0075] S3.4. The data provider retrieves the access tree and linear secret-sharing structure access matrix from the encrypted description result, and uses ciphertext policy attribute-based encryption with a hidden strategy to encapsulate the data keys in the data key group. Ciphertext policy attribute-based encryption with a hidden strategy means binding the access control policy to the ciphertext, but the access control policy itself is not directly attached to the ciphertext in plaintext form; the ciphertext only carries the generated linear secret-sharing structure access matrix. The recipient must hold an access matrix that satisfies the linear secret sharing structure. Only the private key can decrypt the data key, and the specific access control policy content cannot be directly identified from the ciphertext.

[0076] The key encapsulation process is as follows: For each data key in the data key group, perform a ciphertext policy attribute-based encryption encapsulation operation. The ciphertext policy attribute-based encryption encapsulation algorithm takes a linear secret-sharing structure access matrix as input. The data key and the output field key encapsulation result are then used. The field key encapsulation result contains an access matrix related to the linear secret sharing structure. The encapsulation components corresponding to each leaf node.

[0077] S3.5. The data provider replaces the plaintext values ​​of critical fields in the target data object with ciphertext. The target data object is the original data file or data table corresponding to the target dataset identifier. For each critical data unit, based on the field position in the critical data unit location result, the starting offset and length of the critical data unit in the target data object are located, and the original plaintext value within the location range is replaced with the corresponding ciphertext. For non-critical fields, the original plaintext value and its structure in the target data object remain unchanged, and the field replacement result is formed after the replacement is completed. Since only critical data units are ciphertext replaced, and the plaintext of non-critical fields is retained, the encryption computation overhead is reduced, and the target data object can be directly parsed and transmitted, ensuring the practicality of data security.

[0078] S3.6. The data provider organizes the field key encapsulation result, field ciphertext, decimal information, field position, policy index, and key version into a data packet to be signed. The data packet to be signed is packaged according to a preset binary serialization format, with the fields in the following order: length of field key encapsulation result, content of field key encapsulation result, length of field ciphertext list, length and content of each field ciphertext, list of decimal information, list of field positions, policy index, and key version. A digital signature is performed on the data packet to be signed, using a combination of the ECDSA algorithm and SHA-256 hash. The data provider's private key is used to sign the serialized data packet to generate a signature value, which is then appended to the end of the data packet to form the signed data packet.

[0079] The signed data packet contains a field ciphertext body and a field key encapsulation layer. The field ciphertext body stores the key data unit after symmetric encryption, and the field key encapsulation layer stores the data key after being encrypted and encapsulated by the hidden policy ciphertext policy attribute base.

[0080] S4. When the signed data packet experiences one of the following situations: subject change, purpose change, reduction of re-sharing scope, authorization expiration, or business association failure, the access tree and linear secret sharing structure access matrix are reconstructed, and the field key encapsulation layer and policy index transformation are performed using the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to obtain the policy update data packet.

[0081] S4.1. The data provider continuously performs status checks on the signed data packets, including entity change detection, purpose change detection, re-sharing scope reduction detection, authorization expiration detection, and business association failure detection.

[0082] Subject change detection refers to detecting whether the requesting subject identifier of the data retrieval request is inconsistent with the subject identity information recorded in the authorization context of the original signed data packet; Purpose change detection refers to detecting whether the purpose description of the current data retrieval is inconsistent with the purpose restriction information recorded in the authorization context of the original signed data packet; Re-sharing scope reduction detection refers to detecting whether the re-sharing permission of the data user has been revoked or reduced by the data controller; Authorization expiration detection refers to comparing the current time with the authorization validity period in the authorization validity information to determine whether the authorization has expired; Business association failure detection refers to detecting whether the data usage agreement, authorization form or business transaction corresponding to the original business association voucher has been revoked or terminated.

[0083] When any one of the five situations mentioned above is detected, an update trigger result is generated. The update trigger result includes the type of change that triggered this update, the identifier of the requesting subject involved in the change, a description of the purpose of the change, and the identifier of the target dataset involved in the change.

[0084] S4.2. The data provider extracts the request subject identifier, purpose description, and target dataset identifier from the update trigger result, re-executes identity authentication and business-related credential consistency comparison, and re-initiates signature authorization confirmation to form the latest authorization context.

[0085] The data provider extracts the subject identity information, usage restriction information, and authorization validity information from the latest authorization context. It maps the extracted subject identity information to subject attributes, the usage restriction information to usage descriptions, determines the authorization timestamp in the authorization validity information as the start time of the retention period, determines the authorization validity period in the authorization validity information as the decryption time limit, and combines it with the pre-configured re-sharing restriction boolean value and the range of key data units allowed to be accessed in the latest authorization context to reconfigure and form an updated access control policy.

[0086] S4.3. The data provider parses and updates the attribute conditions and logical relationships in the access control policy, constructs a new access tree, and calls the new access tree the reconstructed access tree. The reconstructed access tree is then expanded and its relationships mapped to reconstruct the linear secret sharing structure access matrix, which is called the reconstructed linear secret sharing structure access matrix. Simultaneously, the original access tree and the original linear secret sharing structure access matrix already included in the signed data packet are respectively identified as the old access tree and the old linear secret sharing structure access matrix.

[0087] The data provider extracts the field key encapsulation layer, field ciphertext body, field position, decimal place information, old policy index, and old linear secret sharing structure access matrix from the signed data packet. Simultaneously, it retrieves and reconstructs the linear secret sharing structure access matrix.

[0088] The data provider performs a row-by-row comparison of the old linear secret sharing structure access matrix and the reconstructed linear secret sharing structure access matrix. The comparison includes attribute item comparison and access relationship comparison. Attribute item comparison involves matching the attribute identifiers of each row in the old linear secret sharing structure access matrix with the attribute identifiers of each row in the reconstructed linear secret sharing structure access matrix. Attribute items that exist in both matrices are retained; attribute items that exist only in the old linear secret sharing structure access matrix but not in the reconstructed linear secret sharing structure access matrix are removed; and attribute items that exist only in the reconstructed linear secret sharing structure access matrix but not in the old linear secret sharing structure access matrix are added. Access relationship comparison involves comparing whether the linear relationship between the corresponding rows of the access matrix for retained attribute items has changed in both matrices. The results of the attribute item comparison and access relationship comparison are summarized into a policy transformation relationship.

[0089] S4.4. The data provider performs ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure according to the policy transformation relationship. Ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure refers to converting the field key encapsulation layer encapsulated under the old linear secret sharing structure access matrix into a new field key encapsulation layer bound to the reconstructed linear secret sharing structure access matrix without exposing the original data key plaintext. According to the policy transformation relationship, a transformation operation is performed on the encapsulation components in the field key encapsulation layer corresponding to the retained attribute items, ensuring they simultaneously satisfy the constraints of both the old and reconstructed linear secret sharing structure access matrices; a reversal operation is performed on the encapsulation components in the field key encapsulation layer corresponding to the removed attribute items, marking these encapsulation components as invalid; and a supplement operation is performed on the encapsulation components in the field key encapsulation layer corresponding to the added attribute items, generating a new encapsulation component bound to the added attribute item. After completing the transformation, reversal, and supplement operations, the encapsulation layer transformation result is formed.

[0090] During the proxy re-encryption process, only the field key encapsulation layer is transformed, without touching the field ciphertext body, modifying the field position and decimal information, or making any changes to non-critical fields in the original target data object. This minimizes the policy update overhead while ensuring data security.

[0091] S4.5. The data provider adjusts the policy identifier and access relationship identifier corresponding to the old policy index. The policy identifier in the old policy index is replaced with the policy index corresponding to the updated access control policy, and the access relationship identifier in the old policy index is replaced with the access matrix identifier corresponding to the reconstructed linear secret sharing structure access matrix, forming the updated policy index. The encapsulation layer transformation result and the updated policy index are then replaced with the corresponding positions in the original field key encapsulation layer and the original policy index in the signed data packet, maintaining the ciphertext body, field position, decimal information, and non-critical field structure unchanged. Simultaneously, the current time is recorded as the update time identifier, forming the policy update data packet.

[0092] S5. Perform signature verification, attribute private key decryption, key data unit recovery, numerical precision restoration, and hash chain auditing and solidification on the policy update data packet to obtain the controlled decryption audit result of the target data object.

[0093] S5.1. After the receiver obtains the policy update data packet, it calls the public key of the data provider to verify the signature of the policy update data packet.

[0094] The specific method of signature verification is as follows: extract the signature value from the policy update data packet, use the data provider's public key and the ECDSA signature verification algorithm to perform signature verification on the content to be signed in the policy update data packet except for the signature value. If the verification is successful, the signature verification result is successful; if the verification fails, the signature verification result is unsuccessful and the decryption process is terminated.

[0095] When the signature verification result is successful, the recipient uses the attribute private key held by the recipient to deseal the field key encapsulation layer in the policy update data packet. The attribute private key is a private key that the recipient has obtained in advance from an attribute authority and is bound to the recipient's attribute set. The attribute set in the attribute private key contains attribute items such as the recipient's subject identity information and department role.

[0096] The decryption process follows the decryption algorithm based on the ciphertext policy attribute base encryption. The algorithm takes the recipient's attribute private key and the field key encapsulation layer as input. If the attribute set corresponding to the recipient's attribute private key satisfies the reconstructed linear secret sharing structure access matrix bound in the field key encapsulation layer, decryption succeeds and the data keys corresponding to each field group in the data key group are output. If the attribute set corresponding to the recipient's attribute private key does not satisfy the reconstructed linear secret sharing structure access matrix, decryption fails and the decryption process terminates. By matching and verifying the attribute private key with the reconstructed linear secret sharing structure access matrix, it ensures that only authorized recipients can obtain the data keys, guaranteeing secure data access control.

[0097] S5.2. The receiver uses the decrypted data key set to decrypt each field in the policy update data packet's ciphertext body. For each field in the ciphertext body, the initialization vector IV, ciphertext block, and authentication tag are extracted. AES-256-GCM decryption is then performed using the data key set corresponding to the ciphertext field. The decrypted value yields either a fixed-point integer representation or the original non-numeric value of the key data unit. According to the field positions recorded in the policy update data packet, the decrypted key data unit values ​​are sequentially filled into the corresponding positions to form the key data recovery result.

[0098] The receiver restores the numerical precision of key data units in the key data recovery results. Based on the policy update, it updates the decimal information recorded in the data packet, finds the precision identifier corresponding to each numerical key data unit, and divides the fixed-point integer representation of the numerical key data unit by 10 raised to the power of the precision identifier value to restore the original value with the original decimal places. The numerically precision-restored key data units and non-numerical key data units are then backfilled into the corresponding field positions of the target data object according to their field positions, restoring the target data object to a directly usable enterprise data result. Through numerical precision restoration, the original precision of the numerical data is maintained, while a balance is achieved between encryption processing and business availability, ensuring data security and business continuity.

[0099] S5.3. After completing the decryption and recovery, the data provider and receiver jointly perform a hash chain audit solidification operation. This involves extracting the subject identity digest, business-related credential digest, policy index, key version, update time identifier, and decryption result digest related to this data call. The subject identity digest is obtained by applying the SHA-256 hash algorithm to the requesting subject identifier and taking the first 8 bytes; the business-related credential digest is the digest value calculated in step S1.3; the policy index is the update policy index formed in step S4.5; the key version is the key version recorded in the policy update data packet; the update time identifier is the update time identifier recorded in the policy update data packet; and the decryption result digest is obtained by taking the first 8 bytes of the hash value of the decrypted and recovered target data object. All digest information is concatenated in chronological order, and the SHA-256 hash algorithm is applied to the concatenation result to generate the audit record hash value for this decryption operation. The audit record hash value is then hashed together with the hash value of the previous audit record to form a hash chain audit record. The final audit digest value of the hash chain audit record is submitted to the consortium blockchain node through a consortium blockchain transaction. The consortium blockchain node then writes the audit digest value into the consortium blockchain block for solidification and storage.

[0100] This embodiment also provides a data encryption system based on enterprise data element security management, including: The authentication module verifies the zero-knowledge proof information carried in the data call request, verifies the one-time password, verifies the validity status of the request subject certificate, performs a consistency comparison on the business-related credentials, and initiates signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context. The policy conversion module locates key data units based on the authorization context and compiles access control policies, converting the access control policies into access trees and linear secret sharing structure access matrices to obtain encrypted description results. The layered encryption module performs numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategies on key data units in the encryption description result, and performs key field replacement and digital signature to obtain a signed data packet. The policy update module reconstructs the access tree and the linear secret sharing structure access matrix when the signed data packet experiences one of the following: subject change, purpose change, reduction of re-sharing scope, authorization expiration, or business association failure. It then uses the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to perform field key encapsulation layer and policy index transformation to obtain the policy update data packet. The decryption audit module performs signature verification, attribute private key decryption, key data unit recovery, numerical precision restoration, and hash chain auditing and solidification on the policy update data packet to obtain the controlled decryption audit result of the target data object.

[0101] In summary, this invention, by jointly verifying the consistency of zero-knowledge proof information, one-time passwords, request subject certificate status, and business-related credentials, and introducing a signature authorization confirmation mechanism when necessary, integrates identity authenticity, business-related authenticity, and authorization legitimacy, thereby enhancing the credibility of the authorization context from the source. It precisely locates key data units based on the authorization context and transforms access control policies into access trees and linear secret-sharing structure access matrices, achieving fine-grained encryption control oriented towards subject attributes, uses, durations, and re-sharing restrictions. Simultaneously, it reduces the risk of policy content leakage by encapsulating the ciphertext policy attribute base of the hidden policy. By performing numerical fixed-pointing, block key generation, and symmetric encryption on key fields, it balances the encryption efficiency and numerical recovery accuracy of structured data. Utilizing the ciphertext policy attribute base based on the linear secret-sharing structure for proxy re-encryption, only the field key encapsulation layer and policy index are transformed, eliminating the need for repeated processing of the original field plaintext or the entire ciphertext, significantly reducing the computational and management overhead of dynamic authorization updates.

[0102] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A data encryption method based on enterprise data element security management, characterized in that: include, The system verifies the zero-knowledge proof information carried in the data call request, verifies the one-time password, verifies the validity status of the request subject certificate, performs a consistency comparison on the business-related credentials, and initiates signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context. Based on the authorization context, key data units are located and access control policies are compiled. The access control policies are then converted into access trees and linear secret-sharing structure access matrices to obtain encrypted description results. The key data units in the encrypted description result are processed by numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategy, and key field replacement and digital signature are performed to obtain signed data packets. When the signed data packet experiences one of the following situations: change of subject, change of purpose, reduction of re-sharing scope, authorization expiration, or failure of business association, the access tree and linear secret sharing structure access matrix are reconstructed, and the field key encapsulation layer and policy index transformation are performed using the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to obtain the policy update data packet; The policy update data packet is signed and verified, the attribute private key is unsealed, the key data unit is restored, the numerical precision is restored, and the hash chain is audited and solidified to obtain the controlled decryption audit result of the target data object.

2. The data encryption method based on enterprise data element security management as described in claim 1, characterized in that: The obtained authorization context specifically includes: The system receives the request subject certificate, zero-knowledge proof information, one-time password, purpose description, target dataset identifier, and business-related credentials submitted by the data user. It performs verification on the zero-knowledge proof information, verifies the one-time password, and verifies the validity period, revocation status, and issuance status of the request subject certificate to form an identity authentication result. Perform a consistency comparison between the business-related credential summary, historical agreement summary, authorization form summary, and business transaction summary and the request subject identifier to form an association verification result; For requests that fail to pass, the signature confirmation result is sent to and received from the data controller. The authorization context integrates the identity authentication result, the association verification result, and the signature confirmation result.

3. The data encryption method based on enterprise data element security management as described in claim 2, characterized in that: The location of key data units refers to determining key data units from the corresponding data directory, field dictionary, and field tag list based on the subject identity information, usage restriction information, authorization validity information, and target dataset identifier in the authorization context, forming a key data unit location result that includes field identifier, field location, field type, precision identifier, and field group identifier.

4. The data encryption method based on enterprise data element security management as described in claim 3, characterized in that: The obtained encrypted description result specifically includes: Extract the subject identity information, usage restriction information, authorization validity information, and field identifiers, field positions, and precision identifiers from the authorization context, and configure them as access control policies that include subject attributes, usage descriptions, retention periods, decryption time limits, re-sharing restrictions, and access scope. Parse the attribute conditions and logical relationships in the access control policy, construct the access tree, expand the nodes and map the relationships in the access tree, configure the row identifiers and attribute identifiers of the access matrix, form a linear secret sharing structure access matrix, assign policy indexes to the access control policy and extract policy digests as policy verification information; The key data unit location results, access tree, linear secret sharing structure access matrix, policy index, and policy verification information are organized into an encrypted description result.

5. The data encryption method based on enterprise data element security management as described in claim 4, characterized in that: The process of numerical fixed-point normalization, data key generation, and symmetric encryption of key data units in the encrypted description result specifically includes: Read the list of key data units in the encrypted description result, detect the decimal places of the numerical key data units and convert them into fixed-point integers to form numerical processing results; The key data units are grouped according to the field group identifiers in the key data unit location results to generate data key groups; Using the data key in the data key group, symmetric encryption is performed on each key data unit in the numerical processing result to form the field ciphertext. Organize the ciphertext of the fields, the decimal places in the numerical processing results, the field positions, the policy indexes, and the key versions into a data packet to be encapsulated.

6. The data encryption method based on enterprise data element security management as described in claim 5, characterized in that: The key field replacement and digital signature process specifically includes: Retrieve the access tree and linear secret sharing structure access matrix from the encryption description result, encapsulate the data keys in the data key group with the ciphertext policy attribute base key of the hiding policy, and form the field key encapsulation result; The field replacement result is generated by replacing the plaintext value of a key field in the target data object with the ciphertext of the field. The field key encapsulation result, field ciphertext, decimal information, field position, policy index, and key version are organized into a data packet to be signed and digital signature is performed to form a signed data packet.

7. The data encryption method based on enterprise data element security management as described in claim 6, characterized in that: The reconstructed access tree and linear secret-sharing structure access matrix specifically include: Continuously detect changes in the subject, purpose, scope of sharing reduction, authorization expiration, and business association failure of signed data packets to generate update trigger results; Extract the request subject identifier, purpose description, and target dataset identifier corresponding to the update trigger result, re-initiate signature authorization confirmation, and form the latest authorization context; Extract the subject attributes, purpose description, authorization validity information, and access scope from the latest authorization context, and reconfigure them to update the access control policy; The system parses the attribute conditions and logical relationships in the access control policy, reconstructs the access tree, expands the nodes and maps the relationships in the reconstructed access tree, reconstructs the linear secret sharing structure access matrix, and uses the existing access tree and linear secret sharing structure access matrix in the signed data packet as the old access tree and the old linear secret sharing structure access matrix, respectively.

8. The data encryption method based on enterprise data element security management as described in claim 7, characterized in that: The field key encapsulation layer and strategy index transformation specifically include: Extract the field key encapsulation layer, field ciphertext body, field position, decimal information, old policy index, and old linear secret sharing structure access matrix from the signed data packet, and retrieve the reconstructed linear secret sharing structure access matrix; Attribute item comparison and access relationship comparison are performed on the old linear secret sharing structure access matrix and the reconstructed linear secret sharing structure access matrix to distinguish between retained attribute items, removed attribute items and added attribute items, and form a strategy transformation relationship; According to the policy transformation relationship, the ciphertext policy attribute base proxy re-encryption process based on the linear secret sharing structure is performed. The transformation is performed on the encapsulation components corresponding to the retained attribute items in the field key encapsulation layer, the revocation is performed on the encapsulation components corresponding to the removed attribute items, and the supplementation is performed on the encapsulation components corresponding to the newly added attribute items, forming the encapsulation layer transformation result. Adjust the policy identifier and access relationship identifier corresponding to the old policy index to form an updated policy index, and replace the encapsulation layer transformation result and the updated policy index in the signature data packet, record the update time identifier, and form a policy update data packet.

9. The data encryption method based on enterprise data element security management as described in claim 8, characterized in that: The obtained controlled decryption audit results of the target data object specifically include: The public key of the data provider is invoked to perform signature verification on the policy update data packet, resulting in a signature verification result. When the signature verification result is successful, the private key of the attribute held by the receiver is used to deseal the field key encapsulation layer in the policy update data packet to obtain the data key; The data key is used to decrypt the encrypted body of each field in the policy update data packet, and the key data units are recovered according to the field positions. For the recovered numerical key data units, the decimal information in the data packet is updated according to the strategy to restore the numerical precision and then filled back into the corresponding field position of the target data object. Extract the subject identity digest, business-related credential digest, policy index, key version, update time identifier, and decryption result digest, construct a hash chain audit record in chronological order, and solidify the audit digest to the consortium blockchain to form a controlled decryption audit result for the target data object.

10. A data encryption system based on enterprise data element security management, based on the data encryption method based on enterprise data element security management according to any one of claims 1 to 9, characterized in that: include, The authentication module verifies the zero-knowledge proof information carried in the data call request, verifies the one-time password, verifies the validity status of the request subject certificate, performs a consistency comparison on the business-related credentials, and initiates signature authorization confirmation for requests that fail the consistency comparison to obtain the authorization context. The policy conversion module locates key data units based on the authorization context and compiles access control policies, converting the access control policies into access trees and linear secret sharing structure access matrices to obtain encrypted description results. The layered encryption module performs numerical fixed-point processing, data key generation, ciphertext policy attribute base key encapsulation of symmetric encryption and hiding strategies on key data units in the encryption description result, and performs key field replacement and digital signature to obtain a signed data packet. The policy update module reconstructs the access tree and the linear secret sharing structure access matrix when the signed data packet experiences one of the following: subject change, purpose change, reduction of re-sharing scope, authorization expiration, or business association failure. It then uses the ciphertext policy attribute base proxy re-encryption based on the linear secret sharing structure to perform field key encapsulation layer and policy index transformation to obtain the policy update data packet. The decryption audit module performs signature verification, attribute private key decryption, key data unit recovery, numerical precision restoration, and hash chain auditing and solidification on the policy update data packet to obtain the controlled decryption audit result of the target data object.

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