SHA-2
Sign in to saveSHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher.
Key facts
- Cryptographic hash function.name
- SHA-2
- Cryptographic hash function.image
- SHA-2.svg
- Cryptographic hash function.designers
- National Security Agency
- Cryptographic hash function.series
- (SHA-0), SHA-1, SHA-2, SHA-3
- Cryptographic hash function.certification
- FIPS PUB 180-4, CRYPTREC, NESSIE
- Cryptographic hash function.digest size
- 224, 256, 384, or 512 bits
- Cryptographic hash function.structure
- Merkle–Damgård construction with Davies–Meyer compression function
- Cryptographic hash function.rounds
- 64 or 80
- Cryptographic hash function.cryptanalysis
- A 2011 attack breaks preimage resistance for 57 out of 80 rounds of SHA-512, and 52 out of 64 rounds for SHA-256. Pseudo-collision attack against up to 46 rounds of SHA-256.
via Wikipedia infobox
Article
12 sectionsContents
- Hash standard
- Applications
- Cryptanalysis and validation
- Official validation
- Test vectors
- Pseudocode
- Comparison of SHA functions
- Implementations
- See also
- References
- Further reading
- External links
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher.
SHA-2 includes significant changes from its predecessor, SHA-1. The SHA-2 family consists of six hash functions with digests (hash values) that are 224, 256, 384 or 512 bits: SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256. SHA-256 and SHA-512 are hash functions whose digests are eight 32-bit and 64-bit words, respectively. They use different shift amounts and additive constants, but their structures are otherwise virtually identical, differing only in the number of rounds. SHA-224 and SHA-384 are truncated versions of SHA-256 and SHA-512 respectively, computed with different initial values. SHA-512/224 and SHA-512/256 are also truncated versions of SHA-512, but the initial values are generated using the method described in Federal Information Processing Standards (FIPS) PUB 180-4.