Authentication and Authorization

Authentication and authorization are essential aspects of building secure web applications. They ensure that users have the appropriate access rights to resources and help protect sensitive information. Here's an overview of authentication and authorization, along with some common practices in Node.js:

Authentication:

Authentication is the process of verifying the identity of a user, device, or system attempting to access a resource. It ensures that users are who they claim to be.

Common Authentication Practices in Node.js:

Users provide a username and password, which are compared against stored credentials in a database.

Users receive a token upon successful login, which is included in subsequent requests to authenticate their identity.

Used for delegating authorization to third-party services. It's commonly used in applications that allow users to log in with social media accounts.

Authorization:

Authorization determines what actions an authenticated user is allowed to perform within the application. It defines the level of access and permissions associated with a user's identity.

Common Authorization Practices in Node.js:

Users are assigned roles, and each role has specific permissions. This is common in applications with different user roles (e.g., admin, regular user). 

const authenticate = (req, res, next) => {
  // Check if user is authenticated (e.g., check for valid token)
  // If authenticated, set user information in request object (req.user)
  req.user = { id: 123, role: 'admin' };
  next();
};

const authorizeAdmin = (req, res, next) => {
  const user = req.user;
  if (user && user.role === 'admin') {
    next(); // User is authorized, continue to the next middleware/route
  } else {
    res.status(403).send('Access denied'); // User is not authorized
  }
};

app.get('/admin/dashboard', authenticate, authorizeAdmin, (req, res) => {
  // This route is only accessible to authenticated admins
  res.send('Admin Dashboard');
});

Security Considerations:

Encrypt data in transit to protect against man-in-the-middle attacks.