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Comment by jcranmer | Hacker News Reader

When it comes to optimization, there's a useful adage: make it work, then make it fast. Secure should really be seen as a necessary component of correct (and that it often isn't is a testament to the failure of our profession).

In that vein, the default random should be cryptographically-secure, with all the logic necessary to actually effect that security (e.g., not reusing seeds after a call to fork). You can also go ahead and provide an insecure random as well, but choosing the insecure random should always be something that the programmer has to go out of their way to do.

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Secure should really be seen as a necessary component of correct security. I don’t see random() as part of security, and the problem is that people use it as such (that’s the failure of our profession as I see it). You wouldn’t want the default string equality operator to be constant time to prevent a possible timing attack, and in the same way I don’t think random() should be cryptographically secure by default. If you need secure random values, you are (should be) a domain-expert and should be selecting an appropriate cryptographically secure random generator from a security library, in the same way you would with a constant-time equality function.

I guess it's a matter of perspective over who random() is for. I see random() as for the programmers who don't know what kind of randomness they need, and don't need to know that because they just need something 'random' not something secure. I expect the domain-experts to know that it's not what they need. In my mind it's not that random() is not secure, it's that using it for something it's not intended for is insecure.

>When it comes to optimization, there's a useful adage: make it work, then make it fast.

When you need something to be fast, you better design it from the start to be fast. This is terrible advice for everything but some UI/web cases.

Speed is a feature. Not every feature can be just 'added' to existing code without changing most of it.

All of that is especially true for running simulations and the like. Whether these are fast is often determined by the architecture you decided on in the beginning.

Nowadays the world is full of libraries, frameworks, etc. that will never be as fast the competition, because they can't become fast without changing their APIs completely.

It's true that there's no one-liner you can use to sum up the whole field of software engineering, but that doesn't mean none of them are useful.

I completely agree that things which need to be fast should be designed structurally to be fast.

But which RNG function you use in a given function is about as far you can get from an architectural decision. You shouldn't need to refactor large swathes of your codebase to accommodate a substitution of one random number generator for a faster one.

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