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Federated Identity

Federated identity is a method of linking a user’s identity across multiple systems and organizations, enabling authentication and access without requiring multiple accounts.

What is federated identity?How it typically works?Common techniquesImpactFurther reading

What is federated identity?

**Federated identity** enables users to authenticate once and then use the same credentials to access services across different organizations or domains. Unlike Single Sign-On, which usually works within one organization, federated identity extends trust relationships across multiple entities. This approach relies on protocols and standards that allow identity providers (IdPs) to share authentication information securely with service providers (SPs). For example, a university student may use the same account to log into academic resources hosted by external research institutions. Federated identity plays a critical role in cloud adoption, collaboration platforms, and partnerships where seamless access across organizational boundaries is required.

How it typically works?

  1. Identity provider authentication: the user authenticates with their home organization’s IdP.
  2. Assertion generation: the IdP creates a secure assertion that confirms the user’s identity.
  3. Trust exchange: the assertion is shared with the service provider through a standardized protocol.
  4. Access granted: the service provider accepts the assertion and grants the user access without requiring new credentials.
  5. Session management: the trust remains valid for the session, and reauthentication may be required if policies dictate.

Trust relationships between IdPs and SPs are established in advance, often using metadata and cryptographic keys.

Common techniques

  • SAML (Security Assertion Markup Language): a widely used XML-based protocol for exchanging authentication data between IdPs and SPs.
  • OAuth 2.0: a framework for delegated access, commonly used for authorizing third-party applications.
  • OpenID Connect (OIDC): an authentication layer built on OAuth 2.0 that allows identity federation in modern applications.
  • Cross-domain federation: enabling employees of one organization to access applications hosted by another.
  • Cloud federation: extending identities to SaaS and cloud platforms through IdPs such as Azure AD or Okta.
  • EduGAIN and InCommon: examples of federated identity systems in higher education.

Impact

Federated identity has transformed the way organizations manage access and collaboration.

For users, it:

  • Reduces the number of accounts and passwords they need to manage.
  • Provides seamless access across organizational boundaries.
  • Improves productivity by minimizing login friction.

For organizations, it:

  • Simplifies identity management across multiple domains.
  • Strengthens security by centralizing authentication policies.
  • Facilitates partnerships, mergers, and cross-company collaboration.
  • Supports regulatory compliance by ensuring consistent access control and auditing.

Challenges include ensuring interoperability between different protocols and managing trust relationships securely. Poorly configured federations may expose organizations to unauthorized access or account compromise.

Further reading

Related topics

Single Sign-On (SSO)Passwordless AuthenticationIdentity and Access Management (IAM)Multi-Factor Authentication (MFA)