Secure PHP Development: Best Practices to Follow

Security should be a top priority in every PHP application. Here are essential best practices to keep your PHP code secure:

1. Input Validation and Sanitization

Always validate and sanitize user input:

$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);
$cleanString = htmlspecialchars($_POST['input'], ENT_QUOTES, 'UTF-8');

2. Password Handling

Use PHP’s built-in password hashing functions:

$hash = password_hash($password, PASSWORD_DEFAULT);
if (password_verify($input, $hash)) {
    // Valid password
}

3. SQL Injection Prevention

Always use prepared statements with PDO or MySQLi:

$stmt = $pdo->prepare('SELECT * FROM users WHERE email = :email');
$stmt->execute(['email' => $email]);

4. Cross-Site Scripting (XSS) Protection

Escape output properly:

echo htmlspecialchars($userContent, ENT_QUOTES, 'UTF-8');

5. CSRF Protection

Implement CSRF tokens for forms:

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

// In form
<input type="hidden" name="csrf_token" value="<?= $_SESSION['csrf_token'] ?>">

// Validate on submission
if (!hash_equals($_SESSION['csrf_token'], $_POST['csrf_token'])) {
    die('CSRF validation failed');
}

6. Secure Session Handling

• Use secure and HttpOnly flags for cookies
• Regenerate session ID after login
• Set proper session timeout

Following these practices will significantly improve your application’s security posture.