What are the best practices for securing PHP files and preventing unauthorized access or modifications?

Securing PHP files involves implementing measures to prevent unauthorized access or modifications to sensitive files. One way to achieve this is by using file permissions to restrict access to specific users or groups. Additionally, using encryption techniques to protect sensitive data within PHP files can further enhance security.

// Set restrictive file permissions to prevent unauthorized access
chmod("sensitive_file.php", 0600);

// Encrypt sensitive data within PHP files
$encrypted_data = openssl_encrypt($sensitive_data, 'AES-256-CBC', $encryption_key, 0, $iv);