Editing Block cipher (section)

===Blowfish===
{{Main|Blowfish (cipher)}}
''[[Blowfish (cipher)|Blowfish]]'' is a block cipher, designed in 1993 by [[Bruce Schneier]] and included in a large number of cipher suites and encryption products. Blowfish has a 64-bit block size and a variable [[key length]] from 1 bit up to 448 bits.<ref name=blowfish-paper>{{cite journal |author=Bruce Schneier |author-link=Bruce Schneier |year=1994 |title=Description of a New Variable-Length Key, 64-Bit Block Cipher (Blowfish) |url=http://www.schneier.com/paper-blowfish-fse.html |journal=Dr. Dobb's Journal |volume=19 |issue=4 |pages=38–40}}</ref> It is a 16-round [[Feistel cipher]] and uses large key-dependent [[Substitution box|S-boxes]]. Notable features of the design include the key-dependent [[S-box]]es and a highly complex [[key schedule]].

It was designed as a general-purpose algorithm, intended as an alternative to the aging DES and free of the problems and constraints associated with other algorithms. At the time Blowfish was released, many other designs were proprietary, encumbered by [[patent]]s, or were commercial/government secrets. Schneier has stated that "Blowfish is unpatented, and will remain so in all countries. The algorithm is hereby placed in the [[public domain]], and can be freely used by anyone." The same applies to [[Twofish]], a successor algorithm from Schneier.