Generally speaking, information security includes Intrusion Detection, encryption, authentication, access control, and auditing. We will study the access control mechanism in this thesis.

• 一般而言信息安全探讨的内容包括了：入侵检测(Intrusion Detection)、加密(Encryption)、认证(Authentication)、访问控制(Access Control)以及审核(Auditing)等等。