I'm not sure if there is a real difference between a Pseudo-Random-Generator (PRG) and a Pseudo-Random-Number-Generator (PRNG), whiches tag is synomized with random-number-generator.

I think we should make , , synonyms of the tag .

Theoretically I could do this, but I wanted to ask here, to make sure there wasn't a reason behind the different tags.

  • $\begingroup$ The list of randomness related tags is longer than that: random-number-generator randomness pseudo-random-generator csprng $\endgroup$ Commented Jun 20, 2015 at 21:01
  • $\begingroup$ @CodesInChaos, nice finding! I only found prg because it had a poor tag wiki entry, but it looks like I actually missed those. I proposed most of them for synonymization with rng (spelled out). However I think randomness has its applications for questions about the nature of randomness. $\endgroup$
    – SEJPM
    Commented Jun 20, 2015 at 21:05
  • $\begingroup$ Related question (self deleted) Do the tags “random-number-generator” and “pseudo-random-generator” describe the same thing? $\endgroup$ Commented Jun 20, 2015 at 21:59
  • $\begingroup$ @CodesInChaos, well thank you for the related question, but unfortunaly I don't have the 2k rep yet to view such questions... $\endgroup$
    – SEJPM
    Commented Jun 21, 2015 at 12:36
  • $\begingroup$ @SOJPM: There's not a lot there, basically it just links to this answer and asks whether there is a difference between the tags and, if so, what it is. No comments or answers. $\endgroup$ Commented Jun 22, 2015 at 15:46

1 Answer 1


There is a distinction between pseudorandom generators, as defined in theoretical computer science, and pseudorandom number generators in general. Whether it's a useful distinction to make for tags on this site is a matter I will, at least for now, leave for others to argue.

(Unless somebody chimes in with "yes!", I'm somewhat inclined to assume "no" by default. But I'm also perfectly fine with leaving them separate, if someone finds the separation useful.)

As for the other tags mentioned above, I do agree that should certainly be a synonym for , just like and already are for . I also agree that on this site should be a synonym of ; this is Crypto.SE, so any on-topic discussion of (pseudo)random number generators pretty much has to concern those that have, or are claimed to have, at least some level of cryptographic security.

(There might be an argument to be made for having a separate tag for "true" hardware RNGs, as opposed to PRNGs, but so far nobody seems to have created one. I'd say wait and see; if there really is a need, someone will create it.)

I also agree that should remain separate, since it's mainly being used for cryptographic schemes that consume random numbers instead of generating them. Of course, there will naturally be some overlap in questions between this tag and , but that's perfectly fine and to be expected.

  • $\begingroup$ I see a seemingly random assortment of the mentioned tags being used by current and past questions. Shouldn't these all be normalized to random-number-generator? Or were the mentioned synonyms never implemented? $\endgroup$
    – rmalayter
    Commented Aug 29, 2016 at 13:31
  • $\begingroup$ @rmalayter: Looks like they weren't. I just went and added a suggested synonym from csprng to random-number-generator, but it still takes four users (or, more likely, a single moderator) to approve it. I can't suggest a synonym from prg to pseudo-random-generator, because there's apparently already a reverse synonym from pseudo-randomgenerator (with a missing hyphen) to prg, and the system considers those too similar. (By default, non-existent tags that only differ from an existing one by a hyphen are autocorrected.) That probably needs a mod to sort it out. $\endgroup$ Commented Aug 29, 2016 at 13:43
  • $\begingroup$ @SEJPM & Ilmari: I’ve approved, swapped and merged things a bit. Simply ping me if I forgot something. $\endgroup$
    – e-sushi
    Commented Sep 1, 2016 at 7:21

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