> The sleep needs to be long enough, and random enough that it makes the other variance statistically insignificant. Given the restrictions, this is actually i

> The sleep needs to be long enough, and random enough that it makes the other variance statistically insignificant. Given the restrictions, this is actually impossible. (the operation has to be quick enough that it doesn't significantly erode user satisfaction, and the smallest possible "sleep" is a single machine instruction). Your adversary can easily collect millions of samples, or even a lot more. You cannot hide the latency difference well enough.