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A universal hashing scheme is a randomized algorithm that selects a hash function h among a family of such functions, in such a way that the probability of a collision of any two distinct keys is 1/m, where m is the number of distinct hash values desired—independently of the two keys. Universal hashing ensures (in a probabilistic sense) that ...
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
Finally, hashing directly maps keys to records based on a hash function. [6] Algorithms are often evaluated by their computational complexity, or maximum theoretical run time. Binary search functions, for example, have a maximum complexity of O(log n), or logarithmic time. In simple terms, the maximum number of operations needed to find the ...
A keyed hash function based on Keccak. Can also be used without a key as a regular hash function. KMAC256(K, X, L, S) KMACXOF128(K, X, L, S) KMACXOF256(K, X, L, S) TupleHash128(X, L, S) A function for hashing tuples of strings. The output of this function depends on both the contents and the sequence of input strings. TupleHash256(X, L, S)
[6] Estébanez et al. list the "most important" NCHFs: [7] The Fowler–Noll–Vo hash function (FNV) was created by Glenn Fowler and Phong Vo in 1991 with contributions from Landon Curt Noll. FNV with its two variants, FNV-1 and FNV-1a, is very widely used in Linux, FreeBSD OSes, DNS servers, NFS, Twitter, PlayStation 2, and Xbox, among others.
Then the received hash list is checked against the trusted top hash, and if the hash list is damaged or fake, another hash list from another source will be tried until the program finds one that matches the top hash. In some systems (for example, BitTorrent), instead of a top hash the whole hash list is available on a web site in a small file.
Then, to accumulate using Nyberg's scheme, use the quasi-commutative hash function (,):= (()), where is the bitwise and operation and : {,} {,} is the function that interprets its input as a sequence of -bit bitstrings of length , replaces every all-zero bitstring with a single 0 and every other bitstring with a 1, and outputs the result.
A common use of one-way compression functions is in the Merkle–Damgård construction inside cryptographic hash functions. Most widely used hash functions, including MD5, SHA-1 (which is deprecated [2]) and SHA-2 use this construction. A hash function must be able to process an arbitrary-length message into a fixed-length output.