Current computer security systems are based on the premise that once a user presents valid credentials to the authentication system (e.g. valid ID and password), they are granted access permission to all resources assigned to the user that they claim to be. However, numerous studies have shown that most security breaches are done by unauthorized users impersonating as authorized users (e.g. by cracking or stealing passwords) or by circumventing the authentication system altogether (by exploiting security "holes" in the system). Once the authentication system is broken, the system and the information kept in it become wide open to unauthorized access and malicious usage. Moreover, because of the interdependencies among the various (computer and telecommunication) components of a distributed system, a security breach to one component can have repercussions throughout the system. The main objective of this paper is to present new security model that provides additional level of...