## 2 Related Works
In other words, enforcement rules define the security requirements that must be supported by the protection mechanisms in the underlying system (in our case, it is a database management system (DBMS)). Certification rules define the security requirements that the application system should uphold (in this case, these are the proposed solutions within the framework of the DB with UBR schema, taking into account the features and capabilities of the DBMS on the platform on which it is implemented). Figure 2 shows a scheme of the application of these rules to data management. Figure 1: Diagram of the main basic relations \(R^{sh}\) of the DB schema with UBR. Applying the Clark-Wilson Model Recommendations to Ensure the Integrity of Databases with the Universal Basis of Relations  
It is known that access to the data of any modern database is possible only through the DBMS. A traditional DBMS provides authentication, authorization, transaction, data management, logging, etc. Thus, to check whether the subject (user and process) has the necessary authorization to carry out the required operation in traditional DBMS, in the so-called database manager [9], there is a special module for authorization control. Therefore, the implementation of a DB with UBR on the platform of some selected relational DBMSs automatically leads to the fulfillment of the E3 rule requirement of the Clark-Wilson model, which instructs the system to authenticate all users (each subject) trying to perform any \(TP\) procedure. According to the E4 rule, the access rights of subjects (taking into account their functional duties) to DB objects with UBR (processed \(CDI\) elements) can be assigned and changed only by specially authorized subjects (security officers, database administrators, and DB schema owners). For this purpose, the commands (statements) GRANT / REVOKE of the SQL standard are used. In addition, taking into account the peculiarities of the schema and the possibilities of using the DB with UBR [6; 7], an additional mechanism for granting privileges was developed, implemented within the framework of RLS (_Row Level Security_) technology (also known as Fine Grained Access Control (FGAC) and Virtual Private Database (VPD)) [34; 35; 36; 37; 38; 39], which required the introduction of some additional relations to the existing basic schema of the database with UBR:  
_User relation U_:  
\[ \begin{array}{rl}U=&\{(u_{1},u_{2},u_{3})|u_{1}\in U_{1}\wedge u_{2}\in U_{ 2}\wedge u_{3}\in U_{3}\wedge\\ &((\forall u_{1}\forall u_{2}\forall u_{3}(\forall u^{\prime}_{2}\in U_{2})(U_ {pr}(u_{1},u_{2},u_{3})\wedge U_{pr}(u_{1},u^{\prime}_{2},u_{3})\to u_{2}=u^{ \prime}_{2}))\wedge\\ &(\forall u_{1}\forall u_{2}\forall u_{3}(\forall u^{\prime}_{1}\in U_{1})(U_ {pr}(u_{1},u_{2},u_{3})\wedge U_{pr}(u^{\prime},u_{2},u_{3})\to u_{1}=u^{ \prime}_{1})))\},\end{array}  \tag{1}\]  
where \(U_{1}\) is the set of user identifiers (subjects), \(U_{2}\) is the set of user names, \(U_{pr}(\ldots)\) refers to the predicates (predicate symbols) matching the relation \(U\), and \(U_{3}\) is the set of privileges granted to users for performing operations such as deletion, insert, update, select, as well as their combinations;  
_The relation of the access privilege distribution to the data of other users \(G\)_:  
\[G=\{(g_{1},g_{2},g_{3})|g_{1}\in U_{1}\wedge g_{2}\in U_{1}\wedge g_{3}\in U _{3}\}. \tag{2}\]  
The relation extension (2) is a set of tuples, each of which is associated with a specific data user/owner (\(g_{1}\)), which transmits its access privileges (\(g_{3}\)) to another authorized user (\(g_{2}\)). Figure 2: Scheme of applying the rules of the Clark–Wilson model. As a rule, today, in relational DBMSs, individual records (fields and cells) are not specially protected, although there are examples known from practice when this is required.