Access control method based on multi-level security tag for distributed database system

An access control method for distributed database system is discussed in this paper. The method is based on multi-level security tag and mandatory access control policy. This paper designs Multi-level security system structure and defines the security tags of subjects and objects. It also presents definition rule of security tag and security tag table. Mandatory access control is achieved by modifying the user´s query statement and using security tag table in distributed database system.