!!! Overview
[{$pagename}] ([PRF]), in [cryptography],  is a collection of efficiently-computable [functions] which emulate a random oracle in the following so no efficient [algorithm] can distinguish (with significant advantage) between a [function] chosen randomly from the [{$pagename}] family and a random oracle (a function whose outputs are fixed completely at [random]). 

[{$pagename}]s are vital tools in the construction of [cryptographic Primitive], especially secure [Encryption Schemes].

[{$pagename}]s are not to be confused with [pseudorandom generators] (PRGs). The guarantee of a [pseudorandom generator] is that a single output __appears random__ if the input was chosen at random. On the other hand, the [{$pagename}] __guarantees the outputs appear random__, regardless of how the corresponding inputs were chosen, as long as the [function] was drawn at random from the [{$pagename}] family.

!! What is Important
For [Cryptography] the randomness ([Entropy]) of a [{$pagename}] it is only __important to be unpredictable__. That no one can predict the next random number.

The [philosophical debate|http://www.2uo.de/myths-about-urandom/#stupid|target='_blank'] on __true randomness__ is a debate for outside of [Cryptography].

!! More Information
There might be more information for this subject on one of the following:
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