Integrating OAuth

1. Introduction

OAuth (Open Authorization) is a widely used open standard for access delegation, commonly used as a way to grant websites or applications limited access to users' information without exposing passwords. This lesson will guide you through integrating OAuth in your back-end applications.

2. Key Concepts

• **Authorization**: Process of granting access to a user or application.
• **OAuth Provider**: Service that authenticates users and provides access tokens.
• **Access Token**: A token that is issued to access protected resources.
• **Refresh Token**: A token used to obtain a new access token without re-authentication.
• **Scopes**: Define the permissions granted by the user to the application.

3. Step-by-Step Implementation

Integrating OAuth can vary based on the provider but generally follows these steps:

1. **Register Your Application**: Go to the OAuth provider's developer portal and register your application. Obtain Client ID and Client Secret.
2. **Set Up Redirect URI**: Specify a redirect URI where the OAuth provider will send users after they authorize your app.
3. **Initiate OAuth Flow**: Direct users to the OAuth provider's authorization endpoint.

   GET https://oauth-provider.com/auth?response_type=code&client_id=YOUR_CLIENT_ID&redirect_uri=YOUR_REDIRECT_URI&scope=YOUR_SCOPES
                           

4. **Handle Authorization Code**: Once the user authorizes, the provider redirects back with an authorization code. Capture this code.
5. **Exchange Code for Token**: Send a request to the token endpoint to exchange the authorization code for an access token.

   POST https://oauth-provider.com/token
                           Content-Type: application/x-www-form-urlencoded
   
                           grant_type=authorization_code&code=AUTHORIZATION_CODE&redirect_uri=YOUR_REDIRECT_URI&client_id=YOUR_CLIENT_ID&client_secret=YOUR_CLIENT_SECRET
                           

6. **Access Protected Resources**: Use the access token to make authenticated requests on behalf of the user.

   GET https://api.oauth-provider.com/resource
                           Authorization: Bearer ACCESS_TOKEN
                           

4. Best Practices

• **Use HTTPS**: Always ensure your application uses HTTPS to protect the token from interception.
• **Store Tokens Securely**: Use secure storage mechanisms, avoid exposing tokens in client-side code.
• **Implement Token Expiration**: Handle token expiration gracefully with refresh tokens.
• **Limit Scopes**: Only request the scopes necessary for your application to minimize security risks.

5. FAQ