Filesystem-level encryption, often called file-based encryption, FBE, or file/folder encryption, is a form of

disk encryption Disk encryption is a technology which protects information by converting it into unreadable code that cannot be deciphered easily by unauthorized people. Disk encryption uses disk encryption software or hardware to encrypt every bit of data that ...

where individual files or directories are encrypted by the

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

itself. This is in contrast to the full disk encryption where the entire partition or disk, in which the file system resides, is encrypted. Types of filesystem-level encryption include: * the use of a 'stackable' cryptographic filesystem layered on top of the main file system * a single ''general-purpose'' file system with encryption The advantages of filesystem-level encryption include: * flexible file-based key management, so that each file can be and usually is encrypted with a separate encryption key * individual management of encrypted files e.g. incremental backups of the individual changed files even in encrypted form, rather than backup of the entire encrypted volume *

access control In the fields of physical security and information security, access control (AC) is the selective restriction of access to a place or other resource, while access management describes the process. The act of ''accessing'' may mean consuming ...

can be enforced through the use of

public-key cryptography Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic a ...

, and * the fact that cryptographic keys are only held in memory while the file that is decrypted by them is held open.

General-purpose file systems with encryption

Unlike cryptographic file systems or full disk encryption, general-purpose file systems that include filesystem-level encryption do not typically encrypt file system

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

, such as the directory structure, file names, sizes or modification timestamps. This can be problematic if the metadata itself needs to be kept confidential. In other words, if files are stored with identifying file names, anyone who has access to the physical disk can know which documents are stored on the disk, although not the contents of the documents. One exception to this is the encryption support being added to the ZFS filesystem. Filesystem metadata such as filenames, ownership, ACLs, extended attributes are all stored encrypted on disk. The ZFS metadata relating to the storage pool is stored in

plaintext In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. This usually refers to data that is transmitted or stored unencrypted. Overview With the advent of comp ...

, so it is possible to determine how many filesystems (datasets) are available in the pool, including which ones are encrypted. The content of the stored files and directories remain encrypted. Another exception is CryFS replacement for EncFS.

Cryptographic file systems

Cryptographic file systems are specialized (not general-purpose) file systems that are specifically designed with encryption and security in mind. They usually encrypt all the data they contain – including metadata. Instead of implementing an on-disk format and their own block allocation, these file systems are often layered on top of existing file systems e.g. residing in a directory on a host file system. Many such file systems also offer advanced features, such as

deniable encryption In cryptography and steganography, plausibly deniable encryption describes encryption techniques where the existence of an encrypted file or message is deniable in the sense that an adversary cannot prove that the plaintext data exists. The user ...

, cryptographically secure read-only file system permissions and different views of the directory structure depending on the key or user ... One use for a cryptographic file system is when part of an existing file system is synchronized with '

cloud storage Cloud storage is a model of computer data storage in which the digital data is stored in logical pools, said to be on "the cloud". The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is ty ...

'. In such cases the cryptographic file system could be 'stacked' on top, to help protect data confidentiality.

General-purpose file systems with encryption

Cryptographic file systems

See also