多层关系数据库的函数依赖推理控制

FUNCTIONAL DEPENDENCY INFERENCE CONTROL IN MULTILEVEL RATIONAL DATABASE

多层关系数据库是解决安全数据库中多实例问题的良好方法。防止未授权的用户从可读取的安全等级较低的数据中推理出安全等级较高的数据是多层关系数据库达到安全的必要保证。由于数据库中元组、属性、元素之间的相互关联性,推理问题成为安全数据库的重要内容。文章以数据库中的函数依赖来检查多层关系数据库的各个属性的安全等级,并在此基础上调整各个属性的安全等级,以保证数据的安全性。

MILD（ Multilevel Relation Database） is a good method for solving the polyinstantiation problem of the security database ,but preventing unauthorized users from inferring higher level data from the authorized lower level data is the necessary assurance of the security of the database. Because of the relations among the tuples ,the attributes and thd elements ,inference becomes an important problem of the security database. It is discussed in the paper how to check and adjust the security level of the attributes of the multilevel relation database in the point of FD.