Systems, devices and automated processes provide robust, computationally-efficient and secure protection of media content or other electronic data stored on a user-supplied storage device through the use of efficient file system encryption. Only certain portions of the content are encrypted by the host device, thereby reducing the computational demand in comparison to encrypting all of the content. By selecting the particular portions to encrypt, the formatting and structure of the stored data can be concealed, thereby making the use of the unencrypted content very difficult, if not impossible. In implementations based upon the XFS file system, for example, the superblocks that store header information about the files stored on the drive can be encrypted, thereby rendering the unencrypted content