I'm writing some code that needs to run with as small a footprint as possible, because it's on an embedded device. I want to encrypt its communications. I'm trying to find a good, resource-unintensive cryptosystem to use, but I'm struggling.

My first thought is that it fits here, because it's not about using a cryptosystem. The on-topic page seems to support this:

The rule of thumb, here, being that you should post to crypto.SE if you want to understand the internals, and to security.SE if you want to know what you should do now.

I want to pick a cryptosystem based on internal properties, like how much memory it uses. In my eyes, it fits.

On the other hand, asking for libraries is off-topic, and it seems like a small leap to go from "what crypto library should I use" to "what cryptosystem should I use". Basically the only difference is having to specify a language for the former.

So would such a question be on-topic here?

  • $\begingroup$ Regarding the question you wanted to ask: Check out Bearssl $\endgroup$
    – Ella Rose
    Jul 5, 2019 at 18:14
  • $\begingroup$ @EllaRose That'd be nice if I wasn't working with 2k of RAM. I did my research; I couldn't find anything. $\endgroup$
    – Nic
    Jul 6, 2019 at 12:55
  • $\begingroup$ Some of the excellent folks on this website will drop a morsel from their table once in a while (to feed the masses) and recommend a library, etc., and this can be very good--especially when they are clearly an expert. $\endgroup$
    – Patriot
    Jul 17, 2019 at 12:07
  • $\begingroup$ @Nic Hartley If you keep digging around in this website, you might just find what you are looking for without having to ask a question. $\endgroup$
    – Patriot
    Jul 17, 2019 at 12:11

2 Answers 2


No, it would not be on topic for two reasons:

  • StackExchange acts as a question / answer site and knowledgebase. However, requests for consultancy are not on topic. These kind of "questions" commonly lead to long discussions about the requirements and such. And to be honest, you are better off by getting a good consultant that knows how to ask you the right questions.
  • The answers will almost always be opinion based. One person recommends one library and others would prefer another. This would be the prime reason to close the question.

Another problem is that once your requirements have been established that it is unlikely that there will be others with the exact same requirements. Although that is not a reason to close a question by itself, we generally hope that questions benefit more people than just the asker.


I would like to point out that while asking certain types of questions on the main site may be off-topic, you can always* ask whatever questions you want in The Side Channel.

As long as it's about cryptography, it's on-topic for chat.

* You do require a minimum amount of reputation points to use chat


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