A cryptographic hash function is a hash algorithm that has special properties desirable for a cryptographic application: the probability of a particular n {\displaystyle n} -bit output result for a random input string is 2 − n {\displaystyle 2^{-n}}, so the hash value can be used as a representative of the message; finding an input string that matches a given hash value is unfeasible, assuming all input strings are equally likely. Wikipedia