AN ACCESS-CONTROL SCHEME BASED ON CHINESE REMAINDER THEOREM AND TIME STAMP CONCEPT

In this paper we propose a new dynamic access control method for the c omputer system with frequently inserted, deleted and updated users/fil es. Our method, based on the concepts of the access control matrix, ke y-lock-pair, time stamp and Chinese remainder theorem, associates each user with a user key and a user lock and each tile with a file key an d a file lock Our method can achieve the following four goals. (1) By a simple module operation on the keys and locks of the user and the fi le, we can reveal the access right of a user to a file. (2) When a use r/file is added to the computer system, we only assign a key and a loc k to the user/file without affecting the keys and locks of the other u sers/files in the system. (3) When a user/file is deleted from the com puter system, we simply erase the entry of the user/file in the comput er system. (4) When the access right of a user to a file is updated, w e merely modify the key and lock of the user or the file without affec ting the keys and locks of the other users/ files in the system. The m ain contribution of our method is that the action of inserting, deleti ng a user/file, or updating the access right of a user to a file can b e done by modifying only one key and one lock, which could not be achi eved simultaneously before.