Identity Federation in AWS is a complex yet crucial topic for managing access to AWS resources without creating AWS users for each individual. This explanation aims to demystify the concept and explain how it works with services like SAML and Cognito. Here's a concise breakdown:

Overview of Identity Federation

• Definition: Allows external users to assume temporary roles to access AWS resources, meaning users can access AWS without an AWS-specific user account.
• Mechanism: Users assume an identity provider access role, receiving temporary credentials to access AWS services.

How Federation Works

1. User Authentication: Users authenticate with a third-party server (e.g., company's server), which AWS trusts based on a pre-established trust relationship.
2. Credential Issuance: The third party issues temporary credentials to the user after authentication.
3. AWS Access: Users can access AWS resources directly through the console or API using these credentials.

Third-Party Authentication Methods

• LDAP, Microsoft Active Directory (SAML), Single Sign-On, OpenID, and Cognito can serve as third-party authenticators.
• Key Point: User management is external, eliminating the need for individual IAM users within AWS.

Specific Federation Methods

SAML Federation (for Enterprises)

• Use Case: Ideal for enterprises using Microsoft Active Directory or similar, managing user access without creating IAM users.
• Process: Authentication through an identity provider (IDP) leads to a SAML assertion token, which is exchanged for temporary AWS credentials.

Custom Identity Broker

• Use Case: For entities without SAML 2.0 compliance, requiring a custom program to determine IAM policies.