Bracket Capabilities for Distributed Systems Security

The per-method access control lists of standard middleware technologies allow only simple forms of access control to be expressed and enforced. Research systems based on capabilities provide a more secure mechanism but also fail to support more flexible security constraints such as parameter restrictions, logging and state-dependent access. They also fail to enforce a strict need-to-know view of a persistent object for each user. In this paper we present the concept of bracket capabilities as a new, simple security mechanism which fulfils these requirements. We discuss the reasons for integrating bracketing and view types at a fundamental level of the security mechanism. We demonstrate the use of the mechanism in a simple Ecommerce environment to provide secure electronic cheques and describe a prototype implementation of the mechanism in middleware for secure, distributed Java applications.