Amazon S3's Query String Authentication is the only way to secure your files, while allowing you to make them available to those customers who should have access via your web site. If you run a membership site based on WordPress, this plugin is a must-have. If you care about the security of your content and want to prevent link sharing and hot-linking to your files on S3, do NOT make your content security settings (ACL) Readable by Everyone like many tutorials out there teach. Use Query String Authentication instead. Visit out site to learn more.