A data security access control method, system and storage medium based on dynamic trust evaluation

Abstract

The present invention discloses a data security access control method, system and storage medium based on dynamic trust assessment. The method includes the following steps: Step 1. The user initiates an access application. If there is no corresponding user access record table in the access control system, an access record table is generated; Step 2. The access control system collects access subject and object information and generates access record information; Step 4. The access control system determines whether this access belongs to a whitelist access; Step 5. Based on the information in the access record table, the user access risk security baseline value is calculated and the user access risk is dynamically assessed; Step 6. If the risk assessment value is higher than or equal to the access risk security baseline value, the access is denied and the process is terminated. If the risk assessment value is lower than the security baseline value, the user is authorized. The present invention uses a whitelist access method to establish a user risk security baseline, which effectively reduces the difficulty of system transformation and can be combined with existing technologies such as UEBA for internal access control.

Description

Technical Field

[0001] The invention relates to a network data security access control method, belonging to the technical field of enterprise network data security. Background Art

[0002] Zero Trust Architecture is an enterprise network security architecture built on the principle of zero trust. It follows the principle of "never trust, always authenticate". All devices, users and traffic in the network should be authenticated and authorized. It aims to prevent internal data leakage in the enterprise and limit the lateral movement and damage of internal attackers. The essence of Zero Trust Architecture is to build a dynamic access control system between the access subject (user) and the object (data), encrypt, authenticate and force authorization for all data access requests that are untrusted by default, conduct continuous trust evaluation on the access subject, and dynamically adjust the access rights based on the trust evaluation results, and finally establish a dynamic trust relationship between the access subject and the access object. Figure 1 As shown in Figure 1, the policy engine component is responsible for the final decision on granting a given subject access to an object. The policy engine uses enterprise policy and external input data as input to the trust algorithm to grant, deny, or revoke a subject's access to an object. This mainly includes the following types of data:

[0003] 1) Subject information: Indicates who is requesting access to the resource. This includes basic user information, activity information, permissions, historical user behavior, and device usage information such as frequent locations and number of failed login attempts.

[0004] 2) Access Request: The actual request initiated by the access subject. It contains information about the request subject and the requested information.

[0005] 3) Asset Status: This record compares the location and status of the existing asset (requested location, patch level, etc.) with the asset status of the database to determine whether access to the resource is granted or denied.

[0006] 4) Resource access requirements: Define the minimum requirements of the policy, including resource sensitivity level, visitor level, IP blacklist and whitelist, etc., to quickly exclude visitors who do not meet the requirements.

[0007] 5) Risk Threats: Refers to information about possible threats and malware in the current system, such as malicious information sources or malware commands.

[0008] Dynamic access control is the functional core of the policy engine, which implements hierarchical business access based on continuous trust assessment. In the zero-trust architecture, the trust assessment of the access subject is a dynamic adjustment of the identity trust in the current access context, which is related to authentication strength, risk status and environmental factors. When there are risks in the access context and environment, real-time intervention in access rights is required. The trust assessment module continuously receives enterprise asset status information and activity log information from the CDM system. Combined with identity and permission data, it continuously profiles users based on technologies such as user behavior trees and neural networks, continuously analyzes access behavior, and continuously evaluates trust. It ultimately generates trust assessment results to provide a decision-making basis for dynamic access control.

[0009] As mentioned above, zero-trust dynamic access control solutions require the collection of a large amount of relevant data as a factor in trust assessment. The accuracy of trust assessment results depends largely on the ability to collect, analyze, and process relevant data, relying on information such as subject activity logs, asset status, and threat intelligence. Due to the fragmented data sources, the accuracy, completeness, and timeliness of assessment data have become major issues in the practical application of zero trust. In particular, the centralized deployment of zero-trust policy engines is prone to data migration delays, placing very high demands on the policy engine's algorithms and performance. Existing technical solutions lack the ability to quickly and effectively conduct trust assessments.

[0010] For objects requiring secure data access, data must be classified and graded based on security indicators such as importance, sensitivity, and risk. This allows for the identification of sensitive data, the organization of business processes, and the analysis of potential risks throughout the data lifecycle. Existing data classification schemes typically categorize data into general, important, and core data, setting fixed data security levels through methods such as data tagging. These schemes are unable to adapt to fine-grained dynamic access control and lack real-time awareness of the security status of data assets.

[0011] Existing trust assessment solutions often use static trust value calculation methods. Trust value updates lag behind changes in subject behavior, making it difficult to promptly respond to threats posed by compromised endpoints due to sudden behavioral changes. Existing trust value calculation methods are primarily based on information system risk assessment and UEBA technologies. Access control is primarily based on rigid role or attribute matching, and no quantitative correlation rules are established between subject trust assessment and object security classification. Summary of the Invention

[0012] The technical problem to be solved by the present invention is: in the process of secure access to network data,

[0013] The technical solution adopted in the present invention is:

[0014] A data security access control method based on dynamic trust evaluation includes the following steps:

[0015] Step 1. The user initiates an access request. If there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information;

[0016] Step 2. The access control system collects access subject and object information and generates access record information. The subject and object information includes key information such as user risk value, data asset ID, data level, whitelist access, risk coefficient, etc.;

[0017] Step 3. Generate data level based on access record information;

[0018] Step 4. The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization. Otherwise, it performs dynamic risk assessment operation;

[0019] Step 5. Calculate the user access risk security baseline value based on the information in the access record table, dynamically assess the user access risk, and determine whether the user risk assessment value exceeds the security baseline value;

[0020] Step 6. If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends. If the risk assessment value is lower than the security baseline value, the user is authorized.

[0021] The aforementioned data security access control method based on dynamic trust evaluation further includes:

[0022] Step 7. Access the object resource and update the access record table.

[0023] In the aforementioned data security access control method based on dynamic trust evaluation, in step 1, the access record table structure includes: session ID: a globally unique ID of the business system access session;

[0024] Start time TS: access start time;

[0025] Visit interval: the time interval between this visit and the last visit;

[0026] User ID: The globally unique ID of the user who is accessing the site.

[0027] User risk value R: The risk measurement value of the user who is accessing the site. The initial value is R0. It is recalculated each time an access request is made and locked before the access operation ends.

[0028] Data asset ID: The globally unique ID of the data asset being accessed.

[0029] Data level S: The data level of the object being accessed. The initial value is 1. It is recalculated after each access and locked before the access operation ends.

[0030] Whitelist access: Checks whether the accessed object belongs to the subject whitelist. This is a sample list of assets that users can access legally and compliantly. It is used only to establish a reference security baseline for user access. When the user's risk assessment is lower than the security baseline, the user's access is considered to have a low security risk and is dynamically authorized. If the user has previously requested access above the security baseline or unauthorized access, the user's access is considered to have a high security risk, dynamic authorization is denied, and an alert is issued.

[0031] Risk Factor: The risk factor of unauthorized access to the object being accessed, set according to the corresponding sensitivity level;

[0032] Data operation: A description of the specific data operation performed by the access subject on the object.

[0033] In the aforementioned data security access control method based on dynamic trust evaluation, in step 3, the data self-information formula is used to estimate the data level

[0034]

[0035] S(data) represents the data level. If the set of user entities accessing data assets is U={u1,u2,...,u n}, R i represents the risk measure of the i-th access subject, T i represents the average access time interval of the i-th access subject, T all represents the average access time interval of all access subjects, c i Indicates the number of accesses by the i-th access subject. If there is no access record, the data level is set to 1 by default. n indicates that there are n users accessing the data asset.

[0036] In the aforementioned data security access control method based on dynamic trust assessment, in step 5, the user access risk security baseline value is calculated as follows:

[0037] 1) Use the access record table to calculate the user trust limit, and create a whitelist of data assets that users can access in compliance with the principle of least privilege. If the whitelist contains a data asset set WD = {wd1, wd2, ..., wd m}, m represents the number of data assets in the whitelist, ws i Indicates the data level corresponding to the whitelist data that meets the user's access rights, and sets the data asset wd per unit time. i The probability of the number of visits and the probability of the number of visits to all data assets both satisfy the Poisson distribution:

[0038]

[0039] Where P(X=k) is the probability that the number of times a random event X occurs is exactly k in n independent experiments, λ is the mathematical expectation of P, and ! represents the factorial;

[0040] 2) Get the data asset wd by querying the actual access records i Number of visits value x i ={x1,x2,...,x n}, then the maximum likelihood function of λ is:

[0041]

[0042] The maximum likelihood estimate of λ is the X mean, then the data asset wd i Access probability P i for:

[0043]

[0044] Referring to the Poisson distribution formula, E(X i )=λ i For data assets wd i The mathematical expectation of the number of visits, E(X all )=λ all is the mathematical expectation of the number of visits to all assets;

[0045] 3) Calculate the user access risk security baseline value R0 using formula (5):

[0046]

[0047] When the user risk assessment value is lower than the access risk security baseline value, the system allows access.

[0048] In the aforementioned data security access control method based on dynamic trust evaluation, in step 5, any user accessing data assets that are not in the user's whitelist represents an increase in the risk of system data leakage. If the data asset set in the access record is D = {d1, d2, ..., d m}, S j Represents data assets d j Data level, w j d j The unauthorized access risk coefficient is set according to the data sensitivity classification and business system security requirements. The user dynamic access risk value R(user) is:

[0049]

[0050] If the user's dynamic risk assessment value is higher than or equal to the security baseline value, it means that the user's access is a high-risk operation, access is denied, the user is listed as a monitoring object, and the access record table is updated; if it is lower than the security baseline value, dynamic authorization operations are performed.

[0051] In the aforementioned data security access control method based on dynamic trust assessment, in step seven, a dynamic risk value R is assigned to the network access subject and a level value S is assigned to the data. If a subject accesses the data normally and in compliance with regulations, the R value remains unchanged; if there are multiple attempts to unauthorized access, the dynamic risk value R increases continuously according to the level of the target data being accessed. At this time, the corresponding subject will be listed as a priority monitoring subject by the access control system and the access rights will be restricted; after a certain time interval, if no other dangerous operations occur, the user's dynamic risk value R returns to the security baseline state, and the data level is dynamically updated according to the number of user accesses and the user's risk value, that is, the level of target data frequently accessed by high-risk users will also increase accordingly.

[0052] A data security access control system based on dynamic trust evaluation, including the following modules:

[0053] Access record table generation module: When a user initiates an access request, if there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information;

[0054] Access record information generation module: The access control system collects access subject and object information and generates access record information. The subject and object information includes key information such as user risk value, data asset ID, data level, whitelist access, risk coefficient, etc.

[0055] Data level generation module: generates data level according to access record information;

[0056] Whitelist access identification module: The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization; otherwise, it performs dynamic risk assessment operations;

[0057] Risk Assessment Module: Calculates the user access risk security baseline value based on the information in the access record table, dynamically assesses the user access risk, and determines whether the user risk assessment value exceeds the security baseline value;

[0058] Authorization module: If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends. If the risk assessment value is lower than the security baseline value, the user is authorized.

[0059] In the aforementioned data security access control system based on dynamic trust evaluation, in the access record table generation module, the access record table structure includes:

[0060] Session ID: The globally unique ID of the business system access session;

[0061] Start time TS: access start time;

[0062] Visit interval: the time interval between this visit and the last visit;

[0063] User ID: The globally unique ID of the user who is accessing the site.

[0064] User risk value R: The risk measurement value of the user who is accessing the site. The initial value is R0. It is recalculated each time an access request is made and locked before the access operation ends.

[0065] Data asset ID: The globally unique ID of the data asset being accessed.

[0066] Data level S: The data level of the object being accessed. The initial value is 1. It is recalculated after each access and locked before the access operation ends.

[0067] Whitelist access: Checks whether the accessed object belongs to the subject whitelist. This is a sample list of assets that users can access legally and compliantly. It is used only to establish a reference security baseline for user access. When the user's risk assessment is lower than the security baseline, the user's access is considered to have a low security risk and is dynamically authorized. If the user has previously requested access above the security baseline or unauthorized access, the user's access is considered to have a high security risk, dynamic authorization is denied, and an alert is issued.

[0068] Risk factor: The risk factor of unauthorized access to the object of this access, set according to the corresponding sensitivity level; Data operation: A description of the specific data operation performed by the access subject on the object of this access.

[0069] The aforementioned data security access control system based on dynamic trust evaluation uses the data self-information formula to estimate the data level in the data level generation module.

[0070]

[0071] S(data) represents the data level. If the set of user entities accessing data assets is U={u1,u2,...,u n}, R i represents the risk measure of the i-th access subject, T i represents the average access time interval of the i-th access subject, T all represents the average access time interval of all access subjects, c i Indicates the number of accesses by the i-th access subject. If there is no access record, the data level is set to 1 by default. n indicates that there are n users accessing the data asset.

[0072] A computer-readable storage medium is used to store the module of the data security access control system based on dynamic trust evaluation.

[0073] The beneficial effects achieved by the present invention: The present invention utilizes access record tables, data levels and user dynamic risk metrics to achieve data security risk control, which can be used as an optimized implementation plan for data security access control. The data self-information formula is used to estimate the importance level of the actual data flow and use process. At the same time, the data level is estimated in real time based on security factors such as high-risk users, high-frequency access and multiple unauthorized access, avoiding rigid provisions on sensitivity levels, which causes data security protection to be disconnected from actual work. The user dynamic risk measurement algorithm can achieve real-time tracking of user unauthorized access risks. The algorithm only relies on access record table data, avoiding the performance bottleneck of the access control policy engine, and can achieve fast and effective risk assessment. The established quantitative association rules between risk assessment and data level, high-risk user access, unauthorized access, and high-frequency access all have real-time impacts on data levels; at the same time, unauthorized access to highly sensitive data will significantly increase user risks. The present invention utilizes whitelist access to establish a user risk security baseline, which effectively reduces the difficulty of system transformation and can be conveniently combined with existing technologies such as UEBA for internal access control. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a flow chart of the data security access control method of the present invention. DETAILED DESCRIPTION

[0075] The present invention will be further described in detail below with reference to the accompanying drawings.

[0076] A data security access control method based on dynamic trust evaluation includes the following steps:

[0077] Step 1. The user initiates an access request. If there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information;

[0078] Step 2. The access control system collects access subject and object information and generates access record information. The subject and object information includes key information such as user risk value, data asset ID, data level, whitelist access, risk coefficient, etc.;

[0079] Step 3. The policy engine module generates data levels based on the access record information;

[0080] Step 4. The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization. Otherwise, it performs dynamic risk assessment operation;

[0081] Step 5. Calculate the user access risk security baseline value based on the information in the access record table, dynamically assess the user access risk, and determine whether the user risk assessment value exceeds the security baseline value;

[0082] Step 6. If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends. If the risk assessment value is lower than the security baseline value, the user is authorized;

[0083] Step 7. Access the object resource and update the access record table.

[0084] In step 1, the access record table structure is as follows:

[0085] Table 1 Access record table structure

[0086]

[0087] Session ID: The globally unique ID of the business system access session;

[0088] Start time TS: access start time;

[0089] Visit interval I: the time interval between this visit and the last visit;

[0090] User ID: The globally unique ID of the user who is accessing the site.

[0091] User risk value R: The risk measurement value of the user who is accessing the site. The initial value is R0, which is the user access risk security baseline value. It is recalculated each time an access request is made and locked before the access operation is completed.

[0092] Data asset ID: The globally unique ID of the data asset being accessed.

[0093] Data level S: The data level of the object being accessed. The initial value is 1. It is recalculated after each access and locked before the access operation ends.

[0094] Whitelist access: Checks whether the accessed object belongs to the subject whitelist. The whitelist is unrelated to user permissions and is a sample list of assets that users can access legally and compliantly. It is only used to establish a reference security baseline for user access. When the user risk assessment is lower than the security baseline, the user's access is considered to have a low security risk and is dynamically authorized. If the user has previously requested access above the security baseline or unauthorized access, the user's access is considered to have a high security risk, dynamic authorization is denied, and an alert is issued.

[0095] Risk Factor: The risk factor of unauthorized access to the object being accessed, set according to the corresponding sensitivity level;

[0096] Data operation: A description of the specific data operations performed by the access subject on the object, used for user behavior analysis, etc.

[0097] In step 3, the data level is estimated using the data self-information formula

[0098]

[0099] S(data) represents the data level. If the set of user entities accessing data assets is U={u1,u2,...,u n}, R i represents the risk measure of the i-th access subject, T i represents the average access time interval of the i-th access subject, T all represents the average access time interval of all access subjects, c i Indicates the number of accesses by the i-th access subject. The data level is set to 1 by default when there is no access record, or is set according to the enterprise security policy. n indicates that there are n users accessing the data asset.

[0100] In step 5, the user access risk security baseline value is calculated as follows:

[0101] 1) Use the access record table to calculate the user trust limit, and create a whitelist of data assets that users can access in compliance with the principle of least privilege. If the whitelist contains a data asset set WD = {wd1, wd2, ..., wd m}, m represents the number of data assets in the whitelist, ws i Indicates the data level corresponding to the whitelist data that meets the user's access rights, and sets the data asset wd per unit time. i The probability of the number of visits and the probability of the number of visits to all data assets both satisfy the Poisson distribution:

[0102]

[0103] The above formula P(X=k) is the probability that the number of times X of a random event occurs is exactly k in n independent experiments. λ is the mathematical expectation of P, and ! represents the factorial.

[0104] 2) Get the data asset wd by querying the actual access records i Number of visits value x i ={x1,x2,...,x n}, then the maximum likelihood function of λ is:

[0105]

[0106] The maximum likelihood estimate of λ is the X mean, then the data asset wd i Access probability P i for:

[0107]

[0108] Referring to the Poisson distribution formula, E(X i )=λ i For data assets wd i The mathematical expectation of the number of visits, E(X all )=λ all is the mathematical expectation of the number of visits to all assets;

[0109] 3) Calculate the user access risk security baseline value R0 using formula (5):

[0110]

[0111] When the user risk assessment value is lower than the access risk security baseline value, the system allows access.

[0112] In step 5, any user accessing data assets that are not in the user's whitelist represents an increase in the risk of system data leakage. If the data asset set in the access record is D = {d1, d2, ..., d m}, S j Represents data assets d j Data level, w j d j The unauthorized access risk coefficient is set according to the data sensitivity classification and business system security requirements. The user dynamic access risk value R(user) is:

[0113]

[0114] If the user's dynamic risk assessment value is higher than or equal to the security baseline value, it means that the user's access is a high-risk operation, access is denied, the user is listed as a monitoring object, and the access record table is updated; if it is lower than the security baseline value, dynamic authorization operations are performed.

[0115] In step seven, a dynamic risk value R is assigned to the network access subject, and a level value S is assigned to the data. If a subject accesses the data normally and in compliance with regulations, the R value remains unchanged. If there are multiple attempts to unauthorized access, the dynamic risk value R will continue to increase according to the level of the target data being accessed. At this time, the corresponding subject will be listed as a priority monitoring subject by the access control system, and access rights will be restricted. After a certain time interval, if no other dangerous operations occur, the user's dynamic risk value R will be restored to the security baseline state, and the data level will be dynamically updated according to the number of user accesses and the user's risk value. That is, the level of target data frequently accessed by high-risk users will also increase accordingly.

[0116] A data security access control system based on dynamic trust evaluation, including the following modules:

[0117] Access record table generation module: When a user initiates an access request, if there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information;

[0118] Access record information generation module: The access control system collects access subject and object information and generates access record information. The subject and object information includes key information such as user risk value, data asset ID, data level, whitelist access, risk coefficient, etc.

[0119] Data level generation module: generates data level according to access record information;

[0120] Whitelist access identification module: The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization; otherwise, it performs dynamic risk assessment operations;

[0121] Risk Assessment Module: Calculates the user access risk security baseline value based on the information in the access record table, dynamically assesses the user access risk, and determines whether the user risk assessment value exceeds the security baseline value;

[0122] Authorization module: If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends. If the risk assessment value is lower than the security baseline value, the user is authorized.

[0123] Data update module: access object resources and update the access record table.

[0124] A computer-readable storage medium is used to store the module of the data security access control system based on dynamic trust evaluation.

[0125] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0126] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0127] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0129] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A data security access control method based on dynamic trust evaluation, characterized in that: The following steps are involved: Step 1. The user initiates an access request. If there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information; Step 2. The access control system collects access subject and object information and generates access record information. The subject and object information includes user risk value, data asset ID, data level, whitelist access, and key risk factor information; Step 3. Estimate the data level based on the access record information and the data self-information formula: （1）； Indicates the data level. If the user subject set accessing the data asset is , Indicates the Risk measurement of access subjects, Indicates the The average access time interval of the access subjects, Indicates the average access time interval of all access subjects. Indicates the The default value of the data level is 1 when there is no access record. Indicates shared Individual users access data assets; Step 4. The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization. Otherwise, it performs dynamic risk assessment operation; Step 5. Calculate the user access risk security baseline value based on the information in the access record table, dynamically assess the user access risk, and determine whether the user risk assessment value exceeds the security baseline value; Step 6. If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends. If the risk assessment value is lower than the security baseline value, the user is authorized; Step 7. Access the object resource and update the access record table, including: A dynamic risk value R is assigned to the network access subject, and a level value S is assigned to the data. If a subject accesses the data normally and in compliance with regulations, the R value remains unchanged. If there are multiple attempts to unauthorized access, the dynamic risk value R will continue to increase according to the level of the target data being accessed. At this time, the corresponding subject will be listed as a priority monitoring subject by the access control system, and access rights will be restricted. After a certain time interval, if no other dangerous operations occur, the user's dynamic risk value R will be restored to the security baseline state, and the data level will be dynamically updated according to the number of user accesses and the user's risk value. That is, the level of target data frequently accessed by high-risk users will also increase accordingly.

2. A data security access control method based on dynamic trust evaluation according to claim 1, characterized in that: In step 1, the structure of the access record table includes: Session ID: the globally unique ID of the business system access session; Start time TS: access start time; Visit interval: the time interval between this visit and the last visit; User ID: The globally unique ID of the user who is accessing the site. User risk value R: The risk measurement value of the user who is accessing the site. The initial value is R0. It is recalculated each time an access request is made and locked before the access operation ends. Data asset ID: The globally unique ID of the data asset being accessed. Data level S: The data level of the object being accessed. The initial value is 1. It is recalculated after each access and locked before the access operation ends. Whitelist access: Checks whether the accessed object belongs to the subject whitelist. This is a sample list of assets that users can access legally and compliantly. It is used only to establish a reference security baseline for user access. When the user's risk assessment is lower than the security baseline, the user's access is considered to have a low security risk and is dynamically authorized. If the user has previously requested access above the security baseline or unauthorized access, the user's access is considered to have a high security risk, dynamic authorization is denied, and an alert is issued. Risk Factor: The risk factor of unauthorized access to the object being accessed, set according to the corresponding sensitivity level; Data operation: A description of the specific data operation performed by the access subject on the object.

3. According to the data security access control method based on dynamic trust assessment in claim 1, in step 5, the user access risk security baseline value is calculated as follows: 1) Use the access record table to calculate the user trust limit and create a whitelist of data assets that users can access in compliance with the principle of least privilege. If the whitelist contains a data asset collection of , Indicates the number of data assets in the whitelist. Indicates the data level corresponding to the whitelist data that meets the user's access rights, and sets the data assets per unit time. The probability of the number of visits and the probability of the number of visits to all data assets both satisfy the Poisson distribution: （2）； in, For The number of random events that occur in independent experiments Exactly The probability of is the mathematical expectation of P, ! represents factorial; 2) Obtain data assets by querying actual access records Visits value ,but The maximum likelihood function is: （3）； The maximum likelihood estimate is Mean, then data assets Access probability for: （4）； Referring to the Poisson distribution formula, = For data assets The mathematical expectation of the number of visits, = is the mathematical expectation of the number of visits to all assets; 3) Calculate the user access risk security baseline value using formula (5) : （5）； When the user risk assessment value is lower than the access risk security baseline value, the system allows access.

4. The data security access control method based on dynamic trust evaluation according to claim 3 is characterized in that: In step 5, any user accessing data assets that are not in the user's whitelist represents an increase in the risk of system data leakage. If the data asset set in the access record is , Representing data assets Data level, for Unauthorized access risk coefficient is set according to data sensitivity classification and business system security requirements, and the user dynamic access risk value for: （6）； If the user's dynamic risk assessment value is higher than or equal to the security baseline value, it means that the user's access is a high-risk operation. Access is denied and the user is listed as a monitoring target. The access record table is updated. If the value is lower than the security baseline, dynamic authorization is performed.

5. A data security access control system based on dynamic trust evaluation, characterized in that: Includes the following modules: Access record table generation module: When a user initiates an access request, if there is no corresponding user access record table in the access control system, an access record table is generated and initialized according to the identity management system and pre-defined whitelist information; Access record information generation module: The access control system collects access subject and object information and generates access record information. The subject and object information includes user risk value, data asset ID, data level, whitelist access, and risk coefficient key information; Data level generation module: Estimates data level based on access record information and the data self-information formula: （1）； Indicates the data level. If the user subject set accessing the data asset is , Indicates the Risk measurement of access subjects, Indicates the The average access time interval of the access subjects, Indicates the average access time interval of all access subjects. Indicates the The default value of the data level is 1 when there is no access record. Indicates shared Individual users access data assets; Whitelist access identification module: The access control system determines whether the access belongs to the whitelist access. If it is a whitelist access, it directly performs dynamic access authorization; otherwise, it performs dynamic risk assessment operations; Risk Assessment Module: Calculates the user access risk security baseline value based on the information in the access record table, dynamically assesses the user access risk, and determines whether the user risk assessment value exceeds the security baseline value; Authorization module: If the risk assessment value is higher than or equal to the access risk security baseline value, access is denied and the process ends; if the risk assessment value is lower than the security baseline value, the user is authorized; Update access module: access object resources and update the access record table, including: assigning a dynamic risk value R to the network access subject and assigning a level value S to the data. If a subject accesses normally and in compliance, the R value remains unchanged; if there are multiple attempts to unauthorized access, the dynamic risk value R will continue to increase according to the level of the access target data. At this time, the corresponding subject will be listed as a priority monitoring subject by the access control system and the access rights will be restricted; after a certain time interval, if no other dangerous operations occur, the user's dynamic risk value R will be restored to the security baseline state, and the data level will be dynamically updated according to the number of user accesses and the user's risk value. That is, the target data level frequently accessed by high-risk users will also increase accordingly.

6. The data security access control system based on dynamic trust evaluation according to claim 5, wherein in the access record table generation module, the access record table structure includes: Session ID: The globally unique ID of the business system access session; Start time TS: access start time; Visit interval: the time interval between this visit and the last visit; User ID: The globally unique ID of the user who is accessing the site. User risk value R: The risk measurement value of the user who is accessing the site. The initial value is R0. It is recalculated each time an access request is made and locked before the access operation ends. Data asset ID: The globally unique ID of the data asset being accessed. Data level S: The data level of the object being accessed. The initial value is 1. It is recalculated after each access and locked before the access operation ends. Whitelist access: Checks whether the accessed object belongs to the subject whitelist. This is a sample list of assets that users can access legally and compliantly. It is used only to establish a reference security baseline for user access. When the user's risk assessment is lower than the security baseline, the user's access is considered to have a low security risk and is dynamically authorized. If the user has previously requested access above the security baseline or unauthorized access, the user's access is considered to have a high security risk, dynamic authorization is denied, and an alert is issued. Risk Factor: The risk factor of unauthorized access to the object being accessed, set according to the corresponding sensitivity level; Data operation: A description of the specific data operation performed by the access subject on the object.

7. A computer-readable storage medium for storing a module of the data security access control system based on dynamic trust assessment according to any one of claims 5-6.

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