Apples iCloud service lets users sync a staggering amount of data between Macs, Windows PCs, iPhones, and iPads. Though Apple says it stores this data securely in an encrypted format, just how safe is it? An Ars reader wrote in to ask us this question, so we decided to investigate.The simple answer is that your data is at least as safe as it is when stored on any remote server, if not more so. All data is transferred to computers and mobile devices using secure sockets layer via WebDAV, IMAP, or HTTP. All data except e-mail and notes—more on that later—are stored and encrypted on disk on Apples servers. And secure authentication tokens are created on mobile devices to retrieve information without constantly transmitting a password.