Cryptographically secure pseudorandom number generator: Difference between revisions

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==Requirements==

A cryptographically secure pseudorandom number generator (CSPRNG) or cryptographic pseudorandom number generator (CPRNG)<ref>{{cite book |last1=Huang |first1=Andrew |url=https://archive.org/details/Hacking_the_Xbox_An_Introduction_to_Reverse_Engineering_2003_No_Starch_Press |title=Hacking the Xbox: An Introduction to Reverse Engineering |publisher=[[No Starch Press]] |year=2003 |isbn=9781593270292 |series=No Starch Press Series |publication-date=2003 |page=[https://archive.org/details/Hacking_the_Xbox_An_Introduction_to_Reverse_Engineering_2003_No_Starch_Press/page/n123 111] |quote=[...] the keystream generator [...] can be thought of as a cryptographic pseudo-random number generator (CPRNG). |author1-link=Andrew Huang (hacker) |access-date=2013-10-24}}</ref> is a [[pseudorandom number generator]] (PRNG) with properties that make it suitable for use in [[cryptography]]. It is also loosely known as a cryptographic random number generator (CRNG),<ref>{{Cite web |last=Dufour |first=Cédric |title=How to ensure entropy and proper random numbers generation in virtual machines |url=https://www.exoscale.com/syslog/random-numbers-generation-in-virtual-machines/ |website=Exoscale}}</ref><ref>{{Cite web |title=/dev/random Is More Like /dev/urandom With Linux 5.6 - Phoronix |url=https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.6-Random-Rework |website=www.phoronix.com}}</ref> which can be compared to [[Random number generation#"True" vs. pseudo-random numbers|"true" vs. pseudo-random numbers]].

The requirements of an ordinary PRNG are also satisfied by a cryptographically secure PRNG, but the reverse is not true. CSPRNG requirements fall into two groups: first, that they pass statistical [[randomness tests]]; and secondly, that they hold up well under serious attack, even when part of their initial or running state becomes available to an attacker.{{sfn | Kelsey | Schneier | Wagner | Hall | 1998 | pp=}}