- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
As the need of database is increasing, so as the need of securing the data is also increasing. Multilevel secure databases are shared by local databases and users at different sites and the transaction processing takes place at different security levels. So the concurrency requirements include the secure access of data items that are shared by different transactions. These databases are based on the Bell-LaPadula model  and consist of a set of subjects, objects, an access control matrix and security levels. Subjects can be user and processes while the objects are the data items or fields on which the access is required. For the information flow it enforces the following two restrictions: simple security restriction and star property restriction.