Filesystem-level encryption: Difference between revisions

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{{More citations needed|date=October 2024}}

'''Filesystem-level encryption''', often called file or folder encryption, is a form of [[disk encryption]] where individual files or directories are [[encryption|encrypted]] by the [[file system]] itself. This is in contrast to [[full disk encryption]] where the entire partition or disk, in which the file system resides, is encrypted.

'''Filesystem-level encryption''',<ref>{{Cite web |title=File-Level Encryption |url=https://www.pcisecuritystandards.org/glossary/file-level-encryption/ |access-date=2024-10-18 |website=PCI Security Standards Council |language=en-US}}</ref> often called '''file-based encryption''', '''FBE''', or '''file/folder encryption''', is a form of [[disk encryption]] where individual files or directories are [[encryption|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]], so that each file can be and usually is encrypted with a separate encryption key{{citation needed|date=November 2013}}

* 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{{clarify|how it differs from a _non-crypto_ incremental-backup, please... and the purpose (e.g. importance of backing up to another encrypted physical-disk so data remains secure but a lost token, lost disk, etc doesn't make the data irretrievable?)|date=January 2011}}

* [[access control]] can be enforced through the use of [[public-key cryptography]], and

* the fact that [[key (cryptography)|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]], such as the directory structure, file names, sizes or modification timestamps. This can be problematic if the metadata itself needs to be kept confidential. ThisIn alsoother meanswords, thatif thefiles contentare tostored be encrypted can always be discretely identified (its filename and metadata identifies thewith individualidentifying file tonames, anyone includingwho unauthorizedhas users). This makes it impossibleaccess to make the contentphysical undetectabledisk orcan itsknow existencewhich unprovable in ways thatdocuments are possiblestored usingon approachesthe suchdisk, asalthough virtualnot filesystemsthe likecontents aof PGPthe diskdocuments.

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]], 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 &ndash;– 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]], 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 [[file synchronization|synchronized]] with '[[cloud storage]]'. In such cases the cryptographic file system could be 'stacked' on top, to help protect data confidentiality. <!-- Partial sources for this claim include http://members.ferrara.linux.it/freddy77/encfs.html "I use it mostly with Dropbox" and http://geirsdotnet.wordpress.com/2012/04/27/using-encfs4win-for-encrypting-storage-on-cloud-drive/ where the examples are Dropbox and Google Drive. -->

==See also==

{{Portal|Cryptography|Key-crypto-sideways.svg}}

* [[Steganographic file system]]

* [[List of cryptographic file systems]]

* [[Full diskDisk encryption]]

* [[Disk encryption|Full disk encryption]]

==References==

{{Reflist}}

{{crypto-stubFile systems}}

<!-- Categories -->

[[Category:Disk encryption]]

[[Category:Special -purpose file systems]]

[[Category:Cryptographic software]]

[[Category:Utility software types]]