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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.
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. [3] [4] 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.
Paul Hsieh's SuperFastHash [1] 32 bits Buzhash: variable XOR/table Fowler–Noll–Vo hash function (FNV Hash) 32, 64, 128, 256, 512, or 1024 bits xor/product or product/XOR Jenkins hash function: 32 or 64 bits XOR/addition Bernstein's hash djb2 [2] 32 or 64 bits shift/add or mult/add or shift/add/xor or mult/xor PJW hash / Elf Hash: 32 or 64 bits
SHA-256 hash function. Smart contracts use 256- or 257-bit integers; 256-bit words for the Ethereum Virtual Machine. "We realize that a 257 bits byte is quite unusual, but for smart contracts it is ok to have at least 256 bits numbers. The leading VM for smart contracts, Ethereum VM, introduced this practice and other blockchain VMs followed." [8]
Internal state size [note 1] Block size Length size Word size Rounds; BLAKE2b: 512 512 1024 128 [note 2] 64 12 BLAKE2s: 256 256 512 64 [note 3] 32 10 BLAKE3: Unlimited [note 4] 256 [note 5] 512 64 32 7 GOST: 256 256 256 256 32 32 HAVAL: 256/224/192/160/128 256 1024 64 32 3/4/5 MD2: 128 384 128 – 32 18 MD4: 128 128 512 64 32 3 MD5: 128 128 512 ...
SHA-3 uses the pattern 10...01 in its padding function: a 1 bit, followed by zero or more 0 bits (maximum r − 1) and a final 1 bit. The maximum of r − 1 zero bits occurs when the last message block is r − 1 bits long. Then another block is added after the initial 1 bit, containing r − 1 zero bits before the final 1 bit.
In cryptography, key size or key length refers to the number of bits in a key used by a cryptographic algorithm (such as a cipher).. Key length defines the upper-bound on an algorithm's security (i.e. a logarithmic measure of the fastest known attack against an algorithm), because the security of all algorithms can be violated by brute-force attacks.
As of 2017, collisions but not preimages can be found in MD5 and SHA-1. The future is therefore likely to bring increasing use of newer hash functions such as SHA-256. However, fingerprints based on SHA-256 and other hash functions with long output lengths are more likely to be truncated than (relatively short) MD5 or SHA-1 fingerprints.