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 code that cannot be deciphered easily by unauthorized people or processes. Disk encryption uses disk encryption software or disk encryption hardware, hardware to encry ...

where individual files or directories are encrypted by the file system 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 Key management refers to management of Key (cryptography), cryptographic keys in a cryptosystem. This includes dealing with the generation, exchange, storage, use, crypto-shredding (destruction) and replacement of keys. It includes cryptographic ...

, 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 physical security and information security, access control (AC) is the action of deciding whether a subject should be granted or denied access to an object (for example, a place or a resource). 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 alg ...

, 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 (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * 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 ZFS (previously Zettabyte File System) is a file system with Volume manager, volume management capabilities. It began as part of the Sun Microsystems Solaris (operating system), Solaris operating system in 2001. Large parts of Solaris, includin ...

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 use ...

, cryptographically secure read-only

file system permissions Typically, a file system maintains permission settings for each stored item commonly files and directories that either grant or deny the ability to manipulate file system items. Often the settings allow controlling access based on function s ...

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 data, said to be on "the cloud", is stored remotely in logical pools and is accessible to users over a network, typically the Internet. The physical storage spans multiple servers (so ...

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

References

{{File systems Disk encryption Special-purpose file systems Cryptographic software Utility software types

General-purpose file systems with encryption

Cryptographic file systems

See also

References