More practical application of Trust management credentials

Trust management is an approach to access control in distributed open systems, where access control decisions are based on policy statements made by multiple principals. The family of Role-based Trust management languages (RT) is an effective means for representing security policies and credentials in decentralized, distributed, large scale access control systems. It provides a set of role assignment credentials. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities. The main purpose of this paper is to show how extensions can make the RT family languages more useful in practice. It shows how security policies can be made more realistic by including timing information, maintaining the procedure or parameterizing the validity of credentials.