Federated Identity Architect

What Is Federated Identity

Federated identity is an authentication architecture that allows users to access multiple independent systems and organizations using a single set of credentials managed by a trusted identity provider (IdP). Instead of each application maintaining its own user database, federated identity delegates authentication to a central authority and establishes trust through cryptographic tokens.

This approach is the foundation of enterprise Single Sign-On (SSO), cross-organization collaboration, and consumer identity services like "Sign in with Google." Federated identity reduces password fatigue, centralizes security policy enforcement, and simplifies user provisioning across complex multi-application environments.

How Federation Works

Federated identity relies on trust relationships between three parties:

1. Identity Provider (IdP) — Authenticates users and issues security tokens (e.g., Okta, Azure AD, Auth0)
2. Service Provider (SP) — The application or system the user wants to access
3. User — The person authenticating

Federation Protocols

Protocol	Token Format	Primary Use Case	Typical Environment
SAML 2.0	XML assertion	Enterprise SSO	Corporate applications, legacy systems
OpenID Connect	JWT (id_token)	Web and mobile SSO	Modern web apps, consumer services
OAuth 2.0	Access token (JWT or opaque)	API authorization	API access, third-party integrations
WS-Federation	XML assertion	Microsoft ecosystem	SharePoint, ADFS, legacy Microsoft apps
SCIM	JSON	User provisioning	Automated account creation/deprovisioning

Typical SAML Flow

1. User navigates to the Service Provider (application)
2. SP redirects the user to the Identity Provider with a SAML AuthnRequest
3. IdP authenticates the user (password, MFA, certificate, etc.)
4. IdP returns a signed SAML Assertion containing user attributes and group memberships
5. SP validates the assertion signature, extracts attributes, and creates a local session

Common Use Cases

• Enterprise SSO architecture: Design federated identity systems that connect corporate applications to a central IdP
• Multi-organization collaboration: Enable employees from partner organizations to access shared resources without creating separate accounts
• Cloud migration planning: Map existing LDAP/Active Directory authentication to cloud-based federation with Azure AD, Okta, or Ping Identity
• Zero Trust implementation: Federation is a building block of Zero Trust architecture, ensuring every access request is authenticated by a trusted identity provider
• Protocol selection: Compare SAML, OIDC, and OAuth 2.0 to determine which federation protocol fits your application requirements

Best Practices

1. Implement MFA at the IdP — Federated identity centralizes authentication, which means the IdP is a high-value target. Require multi-factor authentication for all federated logins.
2. Enforce session lifetime limits — Set maximum session durations and idle timeouts. Long-lived sessions negate the security benefits of centralized authentication.
3. Automate deprovisioning with SCIM — When employees leave or change roles, SCIM-based provisioning ensures their access is revoked across all federated service providers within minutes.
4. Validate token signatures rigorously — Never accept unsigned or self-signed SAML assertions. Always verify the IdP's signing certificate and check assertion expiration timestamps.
5. Use OIDC for new applications — Unless you need SAML for legacy compatibility, OpenID Connect is simpler, uses JSON instead of XML, and has better library support in modern frameworks.