We currently have three site-specific close reasons:

  • Requests for analyzing or decyphering a block of data are off-topic here, as the results are rarely useful to anyone else.
  • Requests for reference recommendations are off-topic here. For details, see: Do we want “literature recommendations” and similar “list/subjective questions”?
  • Questions on mathematics are off-topic unless they relate directly to cryptography. These questions can usually be asked on Mathematics Stack Exchange.

There is unfortunately no way to search custom close reasons or retrieve them from the API, which makes it impractical to make any statistics as to the use of the predefined site-specific close reasons or analyze the free-form close reasons that people have been using.

I see a lot of questions which involved a cryptography primitive, but that are off-topic on this site, and would instead:

  • be on-topic on Stack Overflow, because the question is fundamentally a programming problem (for a computation which happens to involve a cryptographic primitive);
  • be on-topic on Security Stack Exchange, because the question is fundamentally about achieving a security policy (which happens to rely on a cryptographic primitive for implementation).

My feeling as a frequent close reviewer is that each of these is more common than math questions, with Security about as common as reference recommendations, and Stack Overflow more than that and more and more so.

Therefore, please add two custom close reasons, one for each of these two cases. (When this site graduates, I expect that these close reasons would become migration targets; beta sites don't get migration targets, though moderators can migrate to any site.)

Unfortunately, the number of close reasons is limited to 3, but an increase has been requested on many meta sites and sometimes met with success.

  • 3
    $\begingroup$ Yes, please! If we are forced to pick then I think Security.SE should take priority: that one pops up a lot. Adding both is preferable, of course. $\endgroup$
    – Reid
    Commented Nov 25, 2013 at 17:12
  • $\begingroup$ I'm assuming these would end up in the belongs on another site section, rather than being top level close reasons? $\endgroup$
    – archie
    Commented Nov 26, 2013 at 0:37
  • $\begingroup$ @archie No, “belongs on another site” is only for migration targets, which we don't have (apart from meta) as long as the site is in beta. The site-specific close reasons have to be directly under “off-topic”. $\endgroup$ Commented Nov 26, 2013 at 0:41
  • $\begingroup$ I would take Reid's point one step further: if we can't have any more, can we have Security.SE instead of maths (see my post below for justification) $\endgroup$ Commented Nov 26, 2013 at 23:07
  • $\begingroup$ Is there any movement on this? It seems like the close reasons are still very limited. $\endgroup$
    – Maarten Bodewes Mod
    Commented Jan 24, 2015 at 14:16

3 Answers 3


For reverse, I got [very] bored and counted them (yeh, not the most productive half an hour!). Below are the results of counting the closed/on-hold questions since the start of September - I ignored any marked as [duplicate], and note that the only ones that had been successfully [migrated] were to Security.

(A) Security.SE:        1111111111
(8) Question too Broad: 11111111
(8) Question unclear:   11111111
(6) Opinion based:      111111
(4) Request to Decrypt: 1111
(4) StackOverflow:      1111
(3) Literature request: 111
(8) Misc Off-topic:     11111111

Just to state the obvious conclusion, this evidence suggests that Security.SE would be a better use for one of our 3 slots.

edit: Updated table for with items from last week. I didn't go back and check them all, so any old items that are now closed won't have been noticed, just posts formed and closed in the last week.

  • 2
    $\begingroup$ I don't see much point in having a close reason for security.SE. Just flag them for migration. $\endgroup$ Commented Dec 3, 2013 at 12:23
  • 1
    $\begingroup$ This is true in principal, but migration only offers us Meta currently. Yes, the best solution would be to add some more migration targets, but I think the understanding is that wouldn't happen whilst we were in beta? $\endgroup$ Commented Dec 3, 2013 at 12:25
  • $\begingroup$ We can't vote to migrate. But we can use custom flag, asking a diamond mod to migrate. I don't see much point in closing those questions while they wait for migration. $\endgroup$ Commented Dec 3, 2013 at 12:28
  • $\begingroup$ @CodesInChaos We don't migrate on-topic questions. So we need a signal to say that the question is off-topic. Making that signal public (at least to users with the vote-to-close privilege) allows it to be contested, otherwise it's just between one flagged and one moderator. It's really more of a UI design flaw that moderators can't migrate a closed question. $\endgroup$ Commented Dec 3, 2013 at 13:25

I was just about to ask the same because I noticed yet another question related to programming, which would make a perfect fit at the regular StackOverflow site.

From my personal experience, it's indeed Security.SE (and secondly StackOverflow) which would make great additions to the list. That also seems to fit both Gilles' as well as user9811's observations.

(Too bad we can't have "migration targets" as a beta though, since I frequently catch myself clicking all the way through Close > Off Topic because… > This question belongs on another site in the Stack Exchange network > Migration just to discover I again selected the wrong things.)


Here are our migration statistics for the last 90 days as of 2014-05-21:

  • 9 to Security.SE
  • 5 to Stack Overflow
  • 2 to Super User
  • 1 to Software Recommendations (rejected)
  • 1 to Bitcoin
  • 1 to Mathematics

And our all-time statistics:

120 security.stackexchange.com
 32 stackoverflow.com
 12 superuser.com
  7 math.stackexchange.com
  5 cs.stackexchange.com
  4 unix.stackexchange.com
  3 bitcoin.stackexchange.com
  2 serverfault.com
  2 meta.crypto.stackexchange.com
  2 askubuntu.com
  1 tor.stackexchange.com
  1 tex.stackexchange.com
  1 softwarerecs.stackexchange.com
  1 reverseengineering.stackexchange.com
  1 programmers.stackexchange.com
  1 history.stackexchange.com
  1 cstheory.stackexchange.com
  1 android.stackexchange.com

Security clearly stands out at #1, SO at #2, with SU behind and Math even behind.

Looking at questions that we don't migrate, the pattern seems to change a little. Going through comments on closed questions that were not migrated, it appears that Stack Overflow comes up more often than Security (beware that my selection method is very crude and may have erred significantly in either direction) — I count 14 recommendations of SO for only 8 of Security.SE (again, excluding questions that were actually migrated).

So I think “belongs on Security.SE” and “belongs on Stack Overflow” deserve equal billing as close reasons, while “belongs on Math.SE” can be removed from the presets. “Belongs on Super User” can remain off the presets or can be combined with “belongs on SO”.

I therefore propose to retire the existing custom off-topic close reason and add the following two, bringing up the total up to 4 (which will require Stack Exchange staff intervention).

  • Questions about programming or end-user tools are off-topic even if they involve cryptographic libraries and tools unless they related directly to cryptography concepts (e.g. side channel attack resistance). Programming questions can be asked on Stack Overflow. End-user questions can be asked on Super User.
  • Questions about security policies that may be based on cryptography (as opposed to the design of cryptographic algorithms and protocols) are off-topic here, but may be asked on Security.

Wording improvement suggestions welcome.

  • $\begingroup$ When I get a chance, I'll submit a request to have a 4th added. In the mean time, is there a wording that combines the two we should use? $\endgroup$
    – mikeazo
    Commented Oct 16, 2014 at 16:39
  • $\begingroup$ @mikeazo I suppose we could do that, but I fear that explaining the difference between Sec and SO/SU would take too much text. I'd favor getting rid of reference recommendations as a canned close reason — I think too broad or a write-in would work as well for the cases where it is warranted. But that's a separate debate. $\endgroup$ Commented Oct 16, 2014 at 16:47
  • $\begingroup$ @hendrikbrummermann, what do you think about the Security wording as you are a Mod there? $\endgroup$
    – mikeazo
    Commented Oct 16, 2014 at 17:24
  • $\begingroup$ I added the two reasons as worded by you, but have not activated them. If I don't hear back from hendrik in a few days, I'll just activate them (and deactivate the Math.SE and the reference request one). $\endgroup$
    – mikeazo
    Commented Oct 16, 2014 at 17:25
  • $\begingroup$ @mikeazo We shouldn't remove the reference request without a meta debate. This thread here only shows that we can should the math reason and add a security reason (more pressing than the SO/SU reason, though SO+SU does come close nowadays — in fact, now, I see that SO+SU > Sec, and I do get the feeling we are receiving more debug-my-openssl-call questions as time goes by). $\endgroup$ Commented Oct 16, 2014 at 17:28
  • $\begingroup$ You won't be able to activate a new close reason alone, it takes a second mod. $\endgroup$ Commented Oct 16, 2014 at 17:29
  • $\begingroup$ Didn't know it takes two mods. Do you want to add a meta question on the SO+SU reason? $\endgroup$
    – mikeazo
    Commented Oct 16, 2014 at 17:38
  • $\begingroup$ @mikeazo I thought this was the meta question on the SO+SU reason (initially SO, but I think it makes sense to combine them). If you feel we need another meta discussion, go ahead. $\endgroup$ Commented Oct 16, 2014 at 17:50
  • $\begingroup$ duh, that is what I get for trying to do too many things at once :) $\endgroup$
    – mikeazo
    Commented Oct 16, 2014 at 17:55
  • $\begingroup$ @mikeazo Bump... $\endgroup$ Commented Feb 9, 2015 at 15:44
  • $\begingroup$ @paulo I created the Security.SE reason a while back, but another mod has to approve it. Can you do that? $\endgroup$
    – mikeazo
    Commented Feb 9, 2015 at 16:15
  • $\begingroup$ @mikeazo Neither paulo nor Hendrik participated in this comment thread, so they won't be notified of your comments here. (Ignore this if you pinged them elsewhere.) $\endgroup$ Commented Feb 9, 2015 at 16:29
  • $\begingroup$ @mikeazo thanks for the ping ... I really didn't follow the thread. I just removed the Math reason and added the Security one. $\endgroup$ Commented Feb 10, 2015 at 19:10
  • $\begingroup$ @Gilles see meta.crypto.stackexchange.com/q/505/706, hopefully SE will act. $\endgroup$
    – mikeazo
    Commented Feb 10, 2015 at 19:35

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