11. Auth - Tokens

In this part, you will explore database-stored tokens as another way of implementing authentication in the Snippets API.

This is mainly for conceptual understanding in class and for extension work in the assignment.

We will:

• Introduce a tokens table.
• Issue random tokens on login.
• Validate tokens on each request.

1. Database: tokens table

Add a tokens table to the Snippets database, for example with columns:

• id (primary key)
• user_id (foreign key to users.id)
• role (string)
• token (string, unique)
• created_at (timestamp)
• expires_at (timestamp, optional)

2. Issue a token on login

Extend login (or create a separate /login-token route) so that:

1. You first verify the username and password using your secure logic.
2. Generate an encoded token value (using Base64 for the further example).
3. Insert a new row into the tokens table with the user ID and token.
4. Return the token to the client (e.g. { "token": "<value>" }).

3. Token auth middleware

Create middleware (e.g. requireTokenAuth) that:

1. Reads the Authorization header, expecting something like Bearer <token>.
2. Looks up the token in the tokens table.
3. (Optionally) checks for expiration.
4. Attaches the corresponding user to req.user, or returns 401 if the token is not valid.

4. Implement role-based routed

Create an /admin rote protected by the role guard, so that:

1. Only the user with 'admin' role can access the route
2. Only the authenticated user can access the route

5. Perform the token forgery

In order to demonstrate why simple encoding is not enough for the token - perform the request forgery

1. Take the token and decode it (examples/token-forgery.js for the full path, CyberChef to go step-by-step)
2. Change the role in the token from user to admin
3. Use the newly 'forged' token to enter /admin route

6. Suggested exercises

• Protect one or more Snippets API endpoints with your token-based middleware.
• Implement a /logout-token endpoint that deletes the token from the database.
• Consider:

  • How many concurrent tokens you allow per user.
  • How you might clean up old or expired tokens.

You will build on this concept further in the assignment.