Authenticating a subject's identity doesn't help if the subject is a stranger you've never heard of before. In dynamic coalitions, if authorization decisions are based on subject identity, as organizations enter and leave the coalition the rate at which identities must be administered by coalition members can become unmanageably large. By placing those properties in credentials, such as attribute certificates, the approach allows properties to be authenticated off-line. Property-based credentials contain potentially sensitive data and must be protected.
Automation is needed to manage a potentially large number of credentials.
We call the automated or semi-automated exchange of protected credentials Trust Negotiation. While some specification work is planned, the central goal is to provide a clear roadmap for further work in Trust Negotiation and a basis for evaluating its likely impact. It supports role-based access control, mapping a subject to a role based on attributes of the subject other than identity. In a coalition, this means that organizations do not need to maintain databases that associate roles with each subject in each coalition-member organization. Instead, a subject's roles within her home organization are used as the basis for determining her roles and rights in interactions with partner organizations.