In the world of computer technology, a disk, sometimes spelled disc, refers to a magnetic or optical medium or device used for the storage of data. A disc can be within a computer, as a hard disk drive is, or outside. If external, it can be more or less permanently connected or it can be made to be easily attached and removed, or the connection may be a wireless one. External disks may be external hard drives or floppy disks, compact discs (CD-Roms), or DVDs (Digital VideoDisc or Digital Versatile Disc). Encryption refers to securing data so that it cannot be interpreted by anyone other than those who are intended to have access, and an encrypted disk is any of the types of disk that has been thus secured.
Hard disk drives and external disks have characteristically been secured by software disk encryption to reduce the cost that lost or stolen computers, drives, or media might cause. In the case of the hard disk drive, disk encryption might be provided by the system software or a software application, In the case of an external disk, encryption has characteristically been provided by software.
The act of creating an encrypted disk drive is referred to by a variety of terms, including disk encryption, hard drive encryption, and full-disk or full disk encryption. Arrangements are made in advance to cover cases of forgetting a password or an employee leaving the company for any reason. Security of an encrypted disk drive is often further secured by the use of a secondary security measure, such as requiring a biometric indicator — like a fingerprint — or using a smartcard keyboard to access the computer. External media in the form of CDs and DVDs is encrypted as the data is burned.
A hard disk encryption standard named the TCG Storage Specification standard was published in 2009. TCG (Trusted Computing Group), the members of which are top manufacturers of computer hard drives agreed to a standard by which encryption will be built into hard disks themselves. There are standard for hard disk drives for individual computers and for enterprise hard drives. Having an industry-wide standard that ensures that there is always an encrypted disk and not depending on the activation of a software program that could be turned off, it is hoped to improve interoperability and consistency of encryption, and save organizations from the damage of lost and stolen data.
