&gt; But maybe they are too expensive.<p>Why would that be? You can fork your PRNG as many times as you have threads in initialization, so there&#x27;s no need for IO. And secure ones do spend many times more CPU than the cheapest PRNG available, both would be a rounding error on the performance on nearly all real world work-loads.<p>I&#x27;d support removing non-secure random functions from every standard library out there.