WS-Federation

WS-Federation (Web Services Federation) is a protocol used for exchanging identity, authentication, and authorization information between different realms or security domains. It is part of the larger WS-Security framework and is commonly used in scenarios involving federated identity management.

WS-Federation allows different security realms (e.g., different organizations or different security systems within an organization) to share identity information. This is particularly useful in single sign-on (SSO) implementations where users can access resources across multiple domains with one set of credentials.

The protocol typically involves the exchange of security tokens containing claims about a user. These claims can include user identity, roles, group memberships, and other attributes relevant to authentication and authorization. WS-Federation is designed to work across different platforms and technologies, fostering interoperability between various web services and applications.

Although WS-Federation is a distinct protocol, it often operates in conjunction with SAML, a standard for exchanging authentication and authorization data between parties.

WS-Federation is commonly used to enable SSO across different web applications and services, allowing users to authenticate once and gain access to multiple applications. In enterprise settings, WS-Federation facilitates integration and cooperation between different identity management systems, streamlining access control and user management across organizational boundaries.

It enables businesses to integrate their on-premises identity management systems with cloud services, providing seamless access to cloud-based applications.

Imagine a company, "Company A," that uses Microsoft's Active Directory for internal user management and wants its employees to access services provided by "Company B" without creating new accounts. Company B also has its own user management system. Using WS-Federation, Company A and Company B establish trust, and Company A’s users can use their existing credentials to access services at Company B with SSO, reducing the need for multiple usernames and passwords.