Jonathan Zdziarski, writing on his website, discusses some problems with Apple's FileVault. FileVault is a system built into Mac OS X that lets a user encrypt their entire home folder. As Zdziarski points out, however, "Encrypted volumes preserve much of the data that is deleted from the volume." Even using Apple's Disk Utility to erase free space does not affect a FileVault volume: "Because a file vault is treated as a separate file system, a free space wipe does virtually nothing to destroy deleted data stored inside a vault." For this reason, it is possible, if a FileVault volume is cracked, to access not only existing files, but also to use data recovery software and access files that a user has "deleted".