Building Secure Authentication in Core PHP

Introduction

Authentication is one of the most critical components of any web application. A poorly implemented login system can expose sensitive user data and compromise the entire system. In this article, we explore how to build a secure authentication system using Core PHP.

1. Password Hashing

Never store plain text passwords. Use secure hashing algorithms such as:

$password = password_hash($userInput, PASSWORD_BCRYPT);

This ensures that even if your database is compromised, raw passwords are not exposed.

2. Session Handling

Sessions must be regenerated after login to prevent session fixation attacks.

session_start();
session_regenerate_id(true);
$_SESSION['user_id'] = $user['id'];

3. CSRF Protection

Always generate CSRF tokens and verify them during form submission. This prevents cross-site request forgery attacks.

$_SESSION['csrf_token'] = bin2hex(random_bytes(32));

Conclusion

Secure authentication requires careful handling of sessions, hashing, validation, and request protection. Even without a framework, implementing best practices ensures your application remains safe and production-ready.