PHP Projects · Lesson 5 of 8

Authentication System

Combine secure registration, password verification, sessions, and authorization.

Lesson

An authentication system has several responsibilities: account creation, password hashing, login throttling, secure sessions, logout, and authorization. Keep these flows separate and test them independently. Use established framework features for production rather than building cryptography or session handling from scratch. Never treat a hidden button or client-side flag as an access control. Further guidance Turn the feature into a sequence of small vertical slices: input, validation, domain behavior, persistence, response, and tests. Write acceptance criteria before implementation, protect each operation with authorization, and verify invalid input and failure cases. Document setup and keep deployment secrets out of the repository. Practice task: Create a fresh example for Authentication System. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.

Code examples

PHP

if ($user && password_verify($submittedPassword, $user['password'])) {
    session_regenerate_id(true);
    $_SESSION['user_id'] = $user['id'];
}

Expected output

A fresh session after the stored password hash verifies

Key points

Combine secure registration, password verification, sessions, and authorization.
Build and verify one complete feature at a time.
Test invalid input, permissions, and failure paths before deployment.

Your learning progress

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