What is WS-Trust?

WS-Trust (Web Services Trust Language) is a WS-* specification that defines a framework for requesting and issuing security tokens. It establishes trust relationships between different security domains, enabling secure communication between web services. It is commonly used for federated identity management and single sign-on (SSO) scenarios, allowing a user authenticated in one domain to access resources in another domain without re-authenticating. WS-Trust defines message formats for requesting, issuing, renewing, and validating security tokens, and it integrates with other WS-* specifications like WS-Security and WS-Federation.