sha

SHA stands for Secure Hash Algorithm, a family of cryptographic hash functions designed to produce fixed-size digests from arbitrary input data. Hash functions in this family are used for data integrity, digital signatures, and various forms of authentication, as well as in password hashing when combined with appropriate safeguards.

The SHA family has evolved through several generations. SHA-0, the original design published in the early 1990s, was quickly superseded by SHA-1 after a minor flaw was found. SHA-1 generates a 160-bit digest and became widely adopted in security standards and protocols. By the mid-2010s, practical collision attacks against SHA-1 were demonstrated, leading to a broad move away from SHA-1 toward stronger algorithms.

SHA-2 encompasses six hash functions with different output lengths: SHA-224, SHA-256, SHA-384, and SHA-512. Introduced in 2001–2002, SHA-2 remains widely deployed and is currently regarded as secure against known practical attacks. Its design builds on the Merkle–Damgård construction but with substantial updates that improve resistance to cryptanalysis.

SHA-3 is a separate standardization effort that began in the 2010s and was finalized in 2015 as FIPS 202. Based on the Keccak sponge function, SHA-3 provides the same families of digest lengths as SHA-2 (for example, SHA3-256, SHA3-512) but with a different internal structure. SHA-3 offers an independent cryptographic basis and complements SHA-2 rather than replacing it.

In practice, SHA-2 remains the default choice for most security protocols and applications, while SHA-3 provides an alternative path to future-proofing cryptographic diversity. For password storage, using salted, stretched hashes or dedicated password-hashing algorithms is recommended over raw SHA variants.