This is a site on Cryptography, but in the site, I couldn't find a definition of Cryptography. How will we define that?

Literally translated, cryptography is Greek for "hidden writing".

Wikipedia defines old cryptography as "synonymous with encryption", while modern cryptography as "heavily based on mathematical theory and computer science practice".

Which (or both?) of these is this site on? That might also be nice to have in the Tour, and/or the help center.

If you have a different definition, or I missed something in my research, answer with that as well. The point is to get this cleared up, and to keep improving this site.

Good Luck!


Check out the Help Center for a pretty detailed description:

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
  • Cryptographically Secure (Pseudo-)Random Number Generation

It doesn't define 'cryptography' directly, but it gives a good idea of what goes on here. Perhaps a stricter definition could be included here if others find it necessary. (I for one think it's pretty clear, but I am not a cryptographer, so that's not for me to judge!)


The site definitely has more of a slant towards modern cryptography, but we have had some historical cryptography questions (see , and ).

Sometimes I find it easier to define what we are not. We are not a site for people to post puzzles and ask others to solve them. The site is also not aimed at debugging software that uses cryptography, or even about how to use cryptographic libraries.

I think the most important keywords relating to the scope of this site are: mathematics, theory, primitives, analysis, foundations, protocols.

Standards related questions are usually sent to Security.SE. Programming questions are typically sent to StackOverflow. Mathematics questions that are not specific to cryptography are sent to Math.SE.


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