Understanding Public-Key Infrastructure: Concepts, Standards, and Deployment Considerations

Trust Models: Hierarchical Versus Distributed

Two fundamental trust models apply in the enterprise context. The first is a strict hierarchy based on superior/subordinate relationships. The second is a distributed mesh based on cross-certification. Although typically not required in an intra-organizational environment, it is also possible to implement a hybrid of the two. Most vendors offer support for one or the other, although a few vendors do support both.

In the enterprise context, it can be argued that the distributed model is more flexible because it allows CAs to come and go with minimal disruption to the other interconnected CA domains. This is true in both an intra- and inter-organizational context. In the case of a strict hierarchy, ...