During the proposal phase, there was considerable discussion of the overlap between Cryptography and the crypto-related areas of IT Security, Theoretical Computer Science , and Mathematics. See Scope of Cryptography proposal overlaps with other existing sites - Area 51

What scope would we like to see? In our faq, how should we guide folks that want to ask crypto-related questions?

Do we have input on what the other sites might want to put in their faqs?

See also: how to decide between Cryptography.SE and Security.SE?


2 Answers 2


Generally speaking, I do not recommend migrating questions to Mathematics (unless there is no cryptographic interest in the question, and it is a pure math question of interest only to mathematicians) or to Theoretical Computer Science (unless it is a pure CS theory question not of interest to cryptographers). My experience with the Theoretical Computer Science site is that most folks there don't have much interest in crypto for its own sake, they have limited expertise in crypto, and several cryptographic-related questions there have gotten bad answers. Therefore, I would be reluctant to migrate questions there unless they are clearly off-topic for the Crypto stack exchange.

Figuring out when to migrate to the Security stack exchange is a tougher question, and I don't have any great insights. I would have one recommendation: If you are going to migrate a question, do it right away, before it gets responses. I would be more reluctant to migrate questions after they've already received some questions and responses, as that is a sign where the community where the question was originally asked seems to be willing to engage with the question. I personally have some lowered tolerance for engaging with questions that are migrated from one site to another after they've already garnered many answers on a different site; I feel it can be an unwelcome chore to clean up mistaken answers entered on another site after the question is migrated.


The Mathematics FAQ implies that we shouldn't send many questions over that way:

And some kinds of questions are considered off-topic:

  • Physics, engineering and financial questions — it is fine to ask the mathematical model and techniques, but concepts of the field would be off-topic.
  • Typesetting equations — you can read our guideline for writing equations on this site, or visit TeX, LaTeX and Friends for questions about TeX
  • Numerology
  • Questions about the site itself — please ask on meta instead

The way I see it, we should only migrate purely mathematical questions that aren't exclusively related to cryptography to Math.SE, and they should be migrating purely (theoretical) cryptography questions to us.

As I am neither a cryptography expert nor a particularly talented mathematician, I can't give explicit examples of questions that would/wouldn't be migrated to Math.SE, but I expect they will be few and far between.

Also related is their list of questions that aren't off-topic but will receive better replies elsewhere:

There are certain subjects that, while still being on-topic here, you can get better response on our sister sites:

  • Research-level mathematics — Math Overflow
  • Research level Algorithm design, complexity theory, etc — Theoretical Computer Science - Stack Exchange
  • Algorithm implementation/design, computer simulation and modelling, etc — Stack Overflow
  • Statistical analysis — Statistical Analysis - Stack Exchange

Same thing here really, we shouldn't migrate research or hash/crypto design questions to Math.SE.

I also asked meta.math.SE what they have to say on this, but I expect it'll take some time before consensus is reached.

  • 3
    $\begingroup$ I think asking other sites (via meta or chat) is a good approach. We definitely don't want to dump questions on another SE site just to have them closed as off-topic ... we may find that some types of questions simply can't be asked (yet) on SE. $\endgroup$ Commented Jul 13, 2011 at 13:05

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