Security and Trust Boundaries in UMA

Modern software systems have outgrown the infrastructure boundaries that once made trust implicit. For most of software history, the question of whether a component could be trusted was answered by where it ran. Applications deployed inside a controlled network, protected by firewalls and managed by a single organization, inherited trust from their environment. Security teams concentrated their efforts on the perimeter. Services communicating within the same operational domain were treated as implicitly safe. Deployment pipelines, network segmentation, and centralized identity systems reinforced these assumptions, and for a long time, the model held.