OAuth 2.0 and OpenID Connect

Introduction

OAuth 2.0 and OpenID Connect are protocols used for authorization and authentication, respectively. These protocols are essential in securing APIs and managing user identities in modern applications.

What is OAuth 2.0?

OAuth 2.0 is an authorization framework that allows third-party applications to obtain limited access to HTTP services on behalf of a user.

Key Concepts

• Resource Owner: The user who owns the data.
• Client: The application requesting access to the resource.
• Authorization Server: The server that issues access tokens.
• Resource Server: The server that hosts the resource.
• Access Token: A token that grants access to the user's resources.

OAuth 2.0 Grant Types

1. Authorization Code Grant
2. Implicit Grant
3. Resource Owner Password Credentials Grant
4. Client Credentials Grant

What is OpenID Connect?

OpenID Connect is an identity layer built on top of the OAuth 2.0 protocol, allowing clients to verify the identity of the end-user based on the authentication performed by an authorization server.

Key Concepts

• ID Token: A token that contains user identity information.
• UserInfo Endpoint: An endpoint that returns user profile information.
• Scopes: Permissions requested by the client.

OAuth 2.0 Workflow

graph TD;
    A[User] -->|Requests Access| B[Client];
    B -->|Redirect to Authorization Server| C[Authorization Server];
    C -->|User Authenticates| D[Resource Owner];
    D -->|Returns Authorization Code| C;
    C -->|Redirect to Client with Code| B;
    B -->|Requests Access Token| E[Token Endpoint];
    E -->|Returns Access Token| B;
    B -->|Access Resource| F[Resource Server];
            

Best Practices

• Use short-lived access tokens and refresh tokens.
• Implement scopes to limit access.
• Validate tokens on the resource server.
• Keep client secrets confidential.

FAQ