What model relies on organizations certifying each other within a federation?

The model that relies on organizations certifying each other within a federation is known as Cross-Certification. In this framework, different organizations create a trust relationship by mutually recognizing and validating each other's security certificates. This allows users from one organization to access resources and services from another organization without having to independently verify credentials every time.

Cross-Certification is particularly useful in federated identity management, where multiple organizations wish to collaborate and share access to their respective systems while maintaining security and trust. By certifying each other's public key infrastructures, the organizations establish a level of trust that facilitates seamless interactions across their networks.

While Transitive Trust involves situations where if A trusts B and B trusts C, then A trusts C, it does not specifically describe the mutual certification aspect seen in Cross-Certification. The Trusted Third Party (Bridge) model uses an external entity to establish trust among disparate organizations, which is different from self-certification. OpenID is an authentication protocol that allows users to log in to various services using a single identity but does not directly involve organizations certifying each other.