Disk encryption software is computer security software that protects the confidentiality of data stored on computer media (e.g., a hard disk, floppy disk, or USB device) by using disk encryption.Compared to access controls commonly enforced by an operating system (OS), encryption passively protects data confidentiality even when the OS is not active, for example, if data is read directly from the hardware or by a different OS.Disk encryption generally refers to wholesale encryption that operates on an entire volume mostly transparently to the user, the system, and applications.