SECURE DYNAMIC USER HIERARCHY SCHEME BASED ON THE KNAPSACK-PROBLEM

In this paper, a secure dynamic user hierarchy mechanism for information protection systems is proposed The main idea of it is inspired by the concept of trapdoor knapsack. Since the knapsack problem is an NP-complete problem, the security of access control is achieved henceforth. Our scheme maintains a positive integer set S' and assigns each user some key pairs (K, t). Through a simple formula on the key pairs and S', the corresponding relationship between two users can be easily revealed in the protection systems. In addition, whenever a new user is inserted into the user hierarchy system, the corresponding key pair can be determined quickly, without changing any existing key pairs. Furthermore, only some relevant keys are needed to be modified when a user is deleted from the system.