Random function: Difference between revisions

Revision as of 00:44, 17 August 2009

Revision as of 00:20, 3 March 2011

Line 1:

A '''random function''' is a function chosen at random from a finite family of functions. Typically, the family consists of the set of all maps from the [[Domain of a function|___domain]] to the image set[[codomain]]. Thus, a random function can be considered to map each input independently at random to any one of the possible outputs. Viewed this way it is an idealization of a [[cryptographic hash function]]. A special case of a random function is a '''[[random permutation]]'''.

A random function is a useful building block in enabling [[cryptographic protocol]]s. However, there are scenarios where it is not possible for mutually distrustful parties to agree on a random function (i.e, [[coin flipping]] is impossible). Therefore, cryptographers study models which explicitly allow for the use of a random function or a related object. See [[random oracle model]], [[common reference string model]].