Credentials for privacy and interoperation

We consider the problem of providing secure, private access to applications and data in a world-wide distributed client-server environment such as the Internet of the future. In such a system, the set of potential users of a service may extend far beyond the local community knowable to the application providing the service. Applications will not generally have prior knowledge of the individual making a request upon which an access control decision can be based and furthermore, knowledge of an individual´s identity may not be directly useful. We frame our discussion in the context of supporting credentials which are submitted with a request, and propose a list of desiderata for such credentials. We evaluate several well-known proposals for credentials, focusing on issues related to privacy and scalability, and then point out the research issues that remain before such schemes can be deployed in a world-wide environment with strong privacy guarantees