Disk encryption software
Disk encryption generally refers to wholesale encryption that operates on an entire volume mostly transparently to the user, the system, and applications. This is generally distinguished from file-level encryption that operates by user invocation on a single file or group of files, and which requires the user to decide which specific files should be encrypted. Disk encryption usually includes all aspects of the disk, including directories, so that an adversary cannot determine content, name or size of any file. It is well suited to portable devices such as laptop computers and thumb drives which are particularly susceptible to being lost or stolen. If used properly, someone finding a lost device cannot penetrate actual data, or even know what files might be present.
Encryption
Conventional methods for deleting data permanently from a storage device involve overwriting its whole content with zeros, ones or other patterns – a process which can take a significant amount of time, depending on the capacity and the type of the medium. Cryptography offers a way of making the erasure almost instantaneous. This method is called crypto-shredding. An example implementation of this method can be found on iOS devices, where the cryptographic key is kept in a dedicated 'Effaceable Storage'. Because the key is stored on the same device, this setup on its own does not offer full confidentiality protection in case an unauthorised person gains physical access to the device.