OAuth vs OIDC

Introduction

In the realm of Identity and Access Management (IAM), understanding the differences between OAuth and OpenID Connect (OIDC) is crucial for implementing secure authentication and authorization mechanisms.

Definitions

OAuth

OAuth enables a user to grant a third-party application access to their resources without sharing credentials. It involves multiple roles:

• Resource Owner
• Client Application
• Authorization Server
• Resource Server

OAuth Workflow

        1. User initiates authentication.
        2. User is redirected to the Authorization Server.
        3. User grants permission to the Client Application.
        4. Authorization Server redirects back to the Client with authorization code.
        5. Client exchanges authorization code for an access token.
        6. Client uses access token to access resources on Resource Server.
    

OpenID Connect (OIDC)

OIDC extends OAuth 2.0 to provide user authentication. The key component is the ID Token, which is a JWT (JSON Web Token) that contains user information.

OIDC Workflow

        1. User initiates authentication.
        2. User is redirected to the OIDC Provider.
        3. User logs in and grants permission.
        4. OIDC Provider redirects back to the Client with an ID Token.
        5. Client verifies the ID Token and obtains user information.
        6. Client can now authenticate the user.
    

Key Differences

• OAuth is for authorization; OIDC is for authentication.
• OIDC uses ID tokens; OAuth does not.
• OIDC provides user information directly; OAuth requires additional API calls.

Best Practices

When implementing OAuth and OIDC, consider the following:

• Always use HTTPS to protect tokens.
• Implement token expiration and rotation policies.
• Use scopes to limit access to user data.
• Validate ID Tokens to ensure authenticity.

FAQ