Adding attributes to access delegation

Access delegation regulates the process that an authorized user transfer part or total of his/her permissions to another user, which is very important in access control system especially in distributed or collaborative environment. Attribute brings salient features to access delegation such as flexibility and effectiveness.The definition of attribute is proposed that attributes selected should accord to the access control target and possess some properties. In access delegation management, the attributes consist of subject attributes, object attributes and permission attributes. As the mechanism of restricting delegation, a delegator delegate the permissions to a delegatee successfully only satisfying the delegator attribute expression, delegatee attribute expression, object attribute expression and permission expression. The definitions of the elements in the expressions are presented.