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In many applications, the range of hash values may be different for each run of the program or may change along the same run (for instance, when a hash table needs to be expanded). In those situations, one needs a hash function which takes two parameters—the input data z , and the number n of allowed hash values.
A hash variable is marked by a % sigil, to distinguish it from scalar, array, and other data types. A hash literal is a key-value list, with the preferred form using Perl's => token, which is semantically mostly identical to the comma and makes the key-value association clearer:
S (signing) outputs a tag t on the key k and the input string x. V (verifying) outputs accepted or rejected on inputs: the key k, the string x and the tag t. S and V must satisfy the following: Pr [ k ← G(1 n), V( k, x, S(k, x) ) = accepted] = 1. [5] A MAC is unforgeable if for every efficient adversary A
hash HAS-160: 160 bits hash HAVAL: 128 to 256 bits hash JH: 224 to 512 bits hash LSH [19] 256 to 512 bits wide-pipe Merkle–Damgård construction: MD2: 128 bits hash MD4: 128 bits hash MD5: 128 bits Merkle–Damgård construction: MD6: up to 512 bits Merkle tree NLFSR (it is also a keyed hash function) RadioGatún: arbitrary ideal mangling ...
BLAKE is a cryptographic hash function based on Daniel J. Bernstein's ChaCha stream cipher, but a permuted copy of the input block, XORed with round constants, is added before each ChaCha round. Like SHA-2 , there are two variants differing in the word size.
Lookup, find, or get find the value (if any) that is bound to a given key. The argument to this operation is the key, and the value is returned from the operation. If no value is found, some lookup functions raise an exception, while others return a default value (such as zero, null, or a specific value passed to the constructor).
For speed, the hash must be computed in constant time. The trick is the variable hs already contains the previous hash value of s[i..i+m-1]. If that value can be used to compute the next hash value in constant time, then computing successive hash values will be fast. The trick can be exploited using a rolling hash. A rolling hash is a hash ...
A rolling hash (also known as recursive hashing or rolling checksum) is a hash function where the input is hashed in a window that moves through the input.. A few hash functions allow a rolling hash to be computed very quickly—the new hash value is rapidly calculated given only the old hash value, the old value removed from the window, and the new value added to the window—similar to the ...