What is the difference between this stackexchange website and https://crypto.stackexchange.com/ ?

Are there some rules or guidelines to what to post here and not there, and vice versa?

To me, questions in both SE are almost identical thematically, but I might be looking wrong.


They are very different. There is only a very slight overlap, certainly, but that overlap on this site is only about the practical implementation of cryptography. From our faq:

IT Security Stack Exchange is for Information Security professionals to discuss protecting assets from threats and vulnerabilities. Topics include, but are not limited to:

  • web app hardening
  • network security
  • social engineering, including phishing
  • risk management
  • policies
  • penetration testing
  • security tools
  • using cryptography
  • incident response
  • physically securing the office, datacentre, information assets etc.

Questions on setting up your home PC antivirus may be more appropriate over at superuser.com; and questions on the deeper aspects of cryptography belong on crypto.SE.

and from the Crypto faq:

Crypto Stack Exchange is for software developers, mathematicians and others interested in cryptography.

Cryptography Stack Exchange is for asking questions about the mathematics and properties of cryptographic systems, their analysis ("cryptanalysis") and subsidiary topics that generally make up cryptology, such as random number generation. As such, we welcome questions on topics such as:

  • Asymmetric and symmetric cryptographic algorithms.
  • Cryptographic protocols.
  • Cryptanalysis techniques.
  • Hash functions, hashing.
  • Entropy and information theory.
  • Random number generation.

Here we don't worry about the algorithms, or the mathematics, or theoretical attacks on a set - we are focused on what those attacks might do to the enterprise we are trying to protect.

So if your question is about cryptography, in almost all cases you should ask on Cryptography.SE - the exceptions are when it comes to practical implementation, and then your question may be on topic here.

  • 1
    And in general, all the Stack Exchange sites have a help page with an FAQ, guidelines and help. These are shown to you when you register on the site.
    – Rory Alsop Mod
    Feb 18 '14 at 0:50
  • Although I could find several questions in this SE that, according to your answer, should belong to the other one and vice versa, this is a great answer and makes it pretty clear. Thanks! Feb 18 '14 at 0:51
  • If you think they really should be on the other site, please flag them so we can check and migrate if necessary. We may well have missed some, or they may be here for a specific reason.
    – Rory Alsop Mod
    Feb 18 '14 at 0:59
  • It's true they are all in "grey" territory, where they could be both in crypto and this one. Random examples (keyword "AES"): crypto.stackexchange.com/questions/14354/… security.stackexchange.com/questions/48504/… security.stackexchange.com/questions/48000/… crypto.stackexchange.com/questions/14380/… Feb 18 '14 at 1:07
  • ...I just think question like "Why would you need a salt for AES-CBS when IV is already randomly generated and stored with the encrypted data?" could belong to both this SE and crypto SE. Feb 18 '14 at 1:10
  • Questions like that are definitely crypto, not sec. That said, the few that are suited for both tend to just stay on the site they were asked.
    – Rory Alsop Mod
    Feb 18 '14 at 7:21
  • 2
    @KarelBílek think about it this way: We cover how to use crypto components, Crypto.se covers how to build them (e.g. "how to effectively use asymmetric encryption in my system" vs. "how to design an asymmetric algorithm")
    – AviD Mod
    Feb 18 '14 at 8:35
  • 1
    @KarelBílek It's also possible that there are some Crypto questions on here from before the time that the actual Crypto site existed. Those are not likely to be migrated, unless they've actually gone unanswered and people are looking for them to be answered.
    – Iszi
    Feb 19 '14 at 22:24

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