Editing Secure Hash Algorithms (section)

{{short description|Family of cryptographic hash functions}}

The '''Secure Hash Algorithms''' are a family of [[cryptographic hash function]]s published by the [[National Institute of Standards and Technology]] (NIST) as a [[United States of America|U.S.]] [[Federal Information Processing Standard]] (FIPS), including:

*'''[[SHA-0]]''': A [[retronym]] applied to the original version of the 160-bit hash function published in 1993 under the name "SHA". It was withdrawn shortly after publication due to an undisclosed "significant flaw" and replaced by the slightly revised version SHA-1.
*'''[[SHA-1]]''': A 160-bit hash function which resembles the earlier [[MD5]] algorithm. This was designed by the [[National Security Agency]] (NSA) to be part of the [[Digital Signature Algorithm]]. Cryptographic weaknesses were discovered in SHA-1, and the standard was no longer approved for most cryptographic uses after 2010.
*'''[[SHA-2]]''': A family of two similar hash functions, with different block sizes, known as ''SHA-256'' and ''SHA-512''. They differ in the word size; SHA-256 uses 32-bit words where SHA-512 uses 64-bit words. There are also truncated versions of each standard, known as ''SHA-224'', ''SHA-384'', ''SHA-512/224'' and ''SHA-512/256''. These were also designed by the NSA.
*'''[[SHA-3]]''': A hash function formerly called ''[[SHA-3|Keccak]]'', chosen in 2012 after a public competition among non-NSA designers. It supports the same hash lengths as SHA-2, and its internal structure differs significantly from the rest of the SHA family.

The corresponding standards are [[Federal Information Processing Standard|FIPS]] PUB 180 (original SHA), FIPS PUB 180-1 (SHA-1), FIPS PUB 180-2 (SHA-1, SHA-256, SHA-384, and SHA-512). NIST has updated Draft FIPS Publication 202, SHA-3 Standard separate from the Secure Hash Standard (SHS).