At its core, identity federation is the process of linking a user’s identity across multiple independent systems. It allows users to authenticate once with their primary IdP (e.g., their corporate directory) and then access various applications and services (SPs) without needing to re-authenticate.
Think of it like a digital passport. Just as a passport allows you to travel to different countries without needing separate visas for each, identity federation provides a unified way to access diverse digital realms using a single set of credentials.
Identity federation is useful because it provides a:
- Better user experience
- Better security
- Easier access management
Common Identity Federation Protocols
Several protocols are commonly used for implementing identity federation:
- Security Assertion Markup Language (SAML): A widely adopted standard for exchanging authentication and authorization data between IdPs and SPs.
- OpenID Connect (OIDC): An identity layer on top of the OAuth 2.0 authorization framework, providing a simple and standardized way to verify user identity.
- WS-Federation: A Microsoft-specific protocol similar to SAML, often used in conjunction with Active Directory Federation Services (ADFS).