What is Hash function?
<!--[[File:Hash function.svg|thumb|right|How a hash function works]]-->[[File:Hash table 4 1 1 0 0 1 0 LL.svg|thumb|A hash function mapping names to the [[Integer|integers]], 0..15. John Smith and Sandra Dee get the same value, which is called hash collision. ]] A '''Hash function''' is a set of things to do to make an output that is always the same length from some other input [[Information|data]]. Hash functions can be used to tell a computer that two things are the same without sending the things twice. Hash functions use all the data they can to change the output. The input can be only a little bit different, and have a totally different output. When a hash function is made, care is taken to make sure two different inputs do not get the same hash value (this is called a ''hash collision''). A [[cryptographic hash function]] is a kind of hash function that is used in [[cryptography]]. It is made to make it hard to make two files with the same hash even if you try. It may also be called a 'message digest', 'digital fingerprint', 'digest' or 'checksum'. ==Related pages== *[[Hash table]] [[Category:Computer science]] {{tech-stub}}