HIERARCHY REPRESENTATIONS BASED ON ARITHMETIC CODING FOR DYNAMIC INFORMATION PROTECTION SYSTEMS

A hierarchy representation mechanism conceals the hierarchy structure involving the relationships among users in an information protection system. The objective of the mechanism is that the relationships, such as Brother, Father-of, Son-of, and so on, between any two users can be revealed conveniently. This helps in determining whether a file owned by a user may be read, written, or executed by the other users. This paper presents a hierarchy representation mechanism based on the technique of arithmetic coding. To put it briefly, the hierarchy structure is represented by a real number C between 0 and 1. That the computation of a C value is efficient and the relations between any two users can also be obtained easily by conducting simple arithmetic operations on C. Moreover, dynamic operations such as insertion or deletion of a user, or change of relations between users, are also implemented with slight modification on C.