Vertically and horizontally bounded propagation of privileges

A database system permits users to share their data among several users, so it is necessary to have a mechanism, namely an authorization mechanism, to permit data to be accessed only by properly authorized users. In general, most authorization systems give the users who own the resources only some basic control over their resources. In our authorization mechanism we provide the users more direct control over their resources by associating each grant with the vertical and horizontal propagation numbers. Vertically and horizontally bounded propagation of privileges is a way in which the user may exercise some control over privileges after they have been granted to other users, other than revocation of the grant of the privileges and decrement of the propagation numbers of the privileges. Furthermore, the propagation numbers also indicate the grantability and exercisability of the privileges.