|
Extendable-output Function
Extendable-output function (XOF) is an extension of the cryptographic hash that allows its output to be arbitrarily long. In particular, the sponge construction makes any sponge hash a natural XOF: the squeeze operation can be repeated, and the regular hash functions with a fixed-size result are obtained from a sponge mechanism by stopping the squeezing phase after obtaining the fixed number of bits). The genesis of a XOF makes it Collision resistance, collision, Preimage resistance, preimage and second preimage resistant. Technically, any XOF can be turned into a cryptographic hash by truncating the result to a fixed length (in practice, hashes and XOFs are defined differently for Domain separation (cryptography), domain separation). The examples of XOF include the algorithms from the Keccak family: SHAKE128, SHAKE256, and a variant with higher efficiency, KangarooTwelve. XOFs are used as key derivation functions (KDFs), stream ciphers, mask generation functions. Related-output ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptographic Hash
A cryptographic hash function (CHF) is a hash algorithm (a map of an arbitrary binary string to a binary string with a fixed size of n bits) that has special properties desirable for a cryptographic application: * the probability of a particular n-bit output result (hash value) for a random input string ("message") is 2^ (as for any good hash), so the hash value can be used as a representative of the message; * finding an input string that matches a given hash value (a ''pre-image'') is infeasible, ''assuming all input strings are equally likely.'' The ''resistance'' to such search is quantified as security strength: a cryptographic hash with n bits of hash value is expected to have a ''preimage resistance'' strength of n bits, unless the space of possible input values is significantly smaller than 2^ (a practical example can be found in ); * a ''second preimage'' resistance strength, with the same expectations, refers to a similar problem of finding a second message that m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |