How to implement OAuth 2.0 authorization code flow

· Category: Cybersecurity

Short answer

The authorization code flow redirects the user to an identity provider, which returns an authorization code exchanged for tokens server-side. PKCE protects public clients. For understanding identity concepts, see authentication vs authorization. For hashing, see how does hashing work.

Steps

  1. Register your application with the identity provider
  2. Generate a PKCE code verifier and challenge
  3. Redirect the user to the authorization endpoint
  4. Receive the authorization code at your redirect URI
  5. Exchange the code for tokens server-side

Tips

  • Always use PKCE even for confidential clients
  • Validate the state parameter to prevent CSRF attacks
  • Store tokens securely and handle refresh logic properly